Re: [time-nuts] rs-422 rs-232 to fast ethernet converter
Ser2net is the way to go for me. A hardware solution I have been using for this purpose for quite a while are those tiny USB-powered SoC-based 3G / 4G portable routers from vendors like TP-Link (good little case designs - TL-MR3020 for instance which I currently use). The 3G models don't actually have cellular modems, they just have a single USB port - and a Fast Ethernet port, and 802.11. They (can) run Linux. The newer ones have 4M onboard flash and you can flash them instantly with OpenWRT. You can drop the web UI to trim down flash usage if you want, but out of the box they will fit USB-serial drivers and ser2net. Just add a USB to serial cable (or even go wild and buy a quad one with an USB hub built in) and you are still below the price of a Raspberry Pi, nevermind a dedicated serial to Ethernet box. You can also add a mini USB hub, stick a mini USB key in and use it as storage overlay. OpenWRT has all the tools you need available in the package repositories. I paired mine with a 12Ah portable USB power bank, clipped on using 3M Command(tm) hook-and-loop straps. It ran on it for 48 hours straight. This setup has proven an invaluable tool in data centre work for emergencies and upgrades. I can hang it in a rack or keep it in my pocket, connect to kit using serial or Ethernet, and work from my smartphone over wifi. File transfers, firmware upgrades, whatever you want. Not sure if ser2net supports X/Zmodem somehow (it's probably down to the telnet client here) but for the times you need it, there's minicom. Naturally, USB-RS converters are not always the way to go, but the RPi needs one as well, it can only do TTL natively. With some DYI you can put the router board, USB hub and battery in a neat little box as well and add an antenna, for improved usability. Regards Wojciech Wojciech Owczarek -Original Message- From: Paul Alfille paul.alfi...@gmail.com Sender: time-nuts time-nuts-boun...@febo.comDate: Mon, 24 Nov 2014 22:38:04 To: Discussion of precise time and frequency measurementtime-nuts@febo.com Reply-To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] rs-422 rs-232 to fast ethernet converter There is a protocol for ending serial commands over telnet (tcp): RFC2217 See http://tools.ietf.org/html/rfc2217 A number of command line tools, like ser2net and netcat use the protocol. Some of the small serial servers support it and it can make using serial remotely tunneled over tcp seamless. On Mon, Nov 24, 2014 at 6:23 PM, Graham planoph...@aei.ca wrote: I have done a bit of searching and found that what I want to do is nothing really new and their are several off the shelf applications which will work just fine - linux and Windows based hence the mention of the Raspberry PI and Beaglebone Black. Some of the higher end Arduinos (i.e. Yu) are capable of running linux and Windows as well but it would be entirely possible to roll you own using the lower end Arduinos as well. I found some answers rather quickly after I started searching for the right things, for example Serial to Network Proxy. On Windows you could use a virtual serial port to do the redirecting from com port to network and on linux there are several the one I found often mentioned is socat. The little serial to fast ethernet boxes which I was finding would work in the situations where you don't have a computer near the device you are trying to connect to, they act as the Serial to Network Proxy. In my case, I have a computer nearby which runs linux and is my GPS disciplined NTP server. I have purchased a RS422 to USB interface cable which will connect the KS-24631 to my linux box. Now I just have to sort through all of the information I have found and figure out just which app I need on the linux box (likely socat) and which one on any of the other computers on my network with which I may want to connect to the KS-24631. And of course, how to configure them. cheers, Graham ve3gtc On 2014-11-24 08:42, Jim Lux wrote: On 11/24/14, 2:20 AM, Graham wrote: Interesting. I have also been thinking that it might not be too difficult to implement using Beaglebone Black, Raspberry PI, or even one or another flavour of Arduino. Lots of possibilities from simple to not so simple. The challenge is always trying to figure out what sort of protocol to use for encapsulating serial data in the Ethernet Stream. Do you send each character in its own UDP or TCP datagram? Do you batch them together and send a message every TBD milliseconds. Ideally, you'd like the protocol to match some commonly available client on the other end. Sure, things like telnet exist, but does software that expects an actual serial port know how to use telnet instead? That said, there's plenty of example code out there for, example, the Arduino Ethernet. There's a telnet server that could easily be modified.
[time-nuts] Lucent KS-24361 Simple Doubler
Paul, W1GHZ has put together a simple doubler for the 5 MHz OCXO in the Lucent boxes. It's based on a Minicircuits part with MIMIC amp. Details here: http://users.burlingtontelecom.net/~n1...@burlingtontelecom.net/images/Simple_Frequency_Doubler.pdf Mike -- 73, Mike, N1JEZ A closed mouth gathers no feet ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Practical considerations making a lab standard with an LTE lite
Hal wrote: So driving 50 Ohms inputs is not optimal here, 1M inputs are much better for this purpose. That only works if you have a (very) short connection to the next stage. Things get interesting if you have, say, 10 feet of unterminated coax. Thinking that the output was a sine wave, I previously suggested testing to determine what its actual impedance is and to proceed accordingly. Said pointed out that it is not a sine output, but rather 3v CMOS. Still, I think it is worthwhile to test to see what the actual output capability is. For example, most HC and AC CMOS outputs will source and sink 20-25mA. The Fairchild advanced CMOS family characteristics document says: All SSI and MSI devices (AC, ACT, ACQ or ACTQ) are guaranteed to source and sink 24 mA. 74AC/ACTxxx devices are capable of driving 50 [ohm] transmission lines. Some of the newer CMOS logic is similar, including Fairchild TinyLogic UHS (NC7xZ series), LCX, and LVC devices. Now AFAIK, we do not know what CMOS device is used for the TCXO output -- and it may well not be any of these. Testing will provide a definitive answer, and it may show that there are better options than a 1M termination. Of course, the TCXO output is used internally to the LTE Lite (and may be used internally to the TCXO itself), so one cannot count on having all of the rated device output current available to drive an external load. Avoid anything that pulls the output logic levels very far down (logic high) or up (logic low), say by more than 200mV (such as a termination resistance that is too low), or materially distorts the output wave shape (such as a Tee or Pi filter, which one might consider to convert the output to a sine wave and match it to coax). To test, one would use a voltage divider from the logic supply voltage to ground, with the TCXO output feeding the center point of the divider. (See attached diagram.) I will be very surprised if it will not drive 10k + 10k with ease (already MUCH better than 1M), and 1k + 1k is a distinct possibility [NOTE: in some cases, this scheme works best if the resistor to the positive supply is about 50% higher than the one to ground, for example 1.5k + 1k]. You may even find that it will drive 100 + 100 (or 150 + 100) without problems, in which case it should directly drive 50 ohm coax. With any of these, best performance in the final installation will be achieved with the termination resistors at the far end of any wire, PC trace, or transmission line longer than a few inches. [Note that the divider scheme is the right way to terminate CMOS logic for analog uses at any impedance -- to terminate in 1M ohm, one would use 2M + 2M, although at that level it matters less.] Because the CMOS device is a saturated switch, the TCXO and LTE Light power dissipation will not increase by a significant amount with the increased load current. The logic supply will need to source some extra power, but only 45mW even for the 100 + 100 ohm output network. If the gods are truly with us, we may even find that the TCXO output will source and sink sufficient current to drive a Tee network if the circuit is designed properly -- say, a divider with 150 + 150 ohm resistors (or 220 + 150) feeding a series 10nF capacitor and 200 ohm resistor to a Tee network using 10uH/50.5pF/10uH -- which would drive a 0dBm sine wave into terminated 50 ohm coax with harmonics below -40dBc. (See attached diagram.) This requires peak currents from the CMOS output of +/- 5mA. But don't count on this until you test and verify, and don't be surprised if the TCXO output will not support it. [If one can live with a sine output of 0dBm, the divider resistors and the series resistor can all be increased in value until it does work.] Best regards, Charles All electronics is analog. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Lucent KS-24361 Simple Doubler
Looks simple but trying to order 1 piece seems a challenge. Minicircuits wants 10 or $59. Not bad but don't need 10 :-) Regards Paul WB8TSL On Tue, Nov 25, 2014 at 6:08 AM, Mike Seguin n1...@burlingtontelecom.net wrote: Paul, W1GHZ has put together a simple doubler for the 5 MHz OCXO in the Lucent boxes. It's based on a Minicircuits part with MIMIC amp. Details here: http://users.burlingtontelecom.net/~n1...@burlingtontelecom.net/images/ Simple_Frequency_Doubler.pdf Mike -- 73, Mike, N1JEZ A closed mouth gathers no feet ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/ mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Practical considerations making a lab standard with an LTE lite
The 20 MHz output should be OK, since it is series-terminated with 50 ohms at the source and the buffer can source enough current. The driver sees a 100 ohm load (50 ohm resistor in series with 50 ohm coax impedance) for that 32 ns round trip time, so it will increase power dissipation (as you note). But the load at the far end of the coax should see a clean edge, and the reflection should be absorbed when it returns to the source (due to the source terminator). Just don't look at the signal half way along the coax. The other outputs apparently don't have either the current drive or the source terminator, so a long piece of coax is likely to do unpleasant things to the edge. In either case, if you want to run any of the signals 10 feet it's likely better to run a very short connection from the LTE-Lite to a proper 50 ohm line driver. That gets the power dissipation off the board, and then you can use drivers that give you whatever output swing you want, and which can drive a 100 ohm load continuously so you can use parallel termination at the far end. - Dave On Tue, Nov 25, 2014 at 12:23 AM, Hal Murray hmur...@megapathdsl.net wrote: Said Jackson said: Correct, and thats why its all a bad trade off if you have to use 50 Ohms termination. Either more heat or more PN, and more circuitry. So driving 50 Ohms inputs is not optimal here, 1M inputs are much better for this purpose. That only works if you have a (very) short connection to the next stage. Things get interesting if you have, say, 10 feet of unterminated coax. 10 MHz is 100 ns, or 50 ns between transitions. Coax is ballpark of 5/8 c so that's 16 ns one way or 32 ns round drip. That's 60% of the heat as well as lots of nasty reflections. (Somebody please check my numbers.) -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Lucent KS-24361 Simple Doubler
Give them a call... they are more than willing to sell single pieces of almost any of their products, at the listed lowest quantity price, especially if you are a Ham. I recently bought several items, some of them in single quantities. Many of their MMICs are priced so low that you can easily buy ten at a time. Even with shipping, they are cheaper than buying from the Chinese Ebay sellers. Dave M paul swed wrote: Looks simple but trying to order 1 piece seems a challenge. Minicircuits wants 10 or $59. Not bad but don't need 10 :-) Regards Paul WB8TSL On Tue, Nov 25, 2014 at 6:08 AM, Mike Seguin n1...@burlingtontelecom.net wrote: Paul, W1GHZ has put together a simple doubler for the 5 MHz OCXO in the Lucent boxes. It's based on a Minicircuits part with MIMIC amp. Details here: http://users.burlingtontelecom.net/~n1...@burlingtontelecom.net/images/ Simple_Frequency_Doubler.pdf Mike -- 73, Mike, N1JEZ A closed mouth gathers no feet ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/ mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. When the people fear the government, there is tyranny. When the government fears the people, there is liberty -- Thomas Jefferson Dave M ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Practical considerations making a lab standard with an LTE lite
Charles, The increased current for the driver will cause heating near the crystal in both the CMOS driver and the 3.0V LDO as the LDO has to convert the excess voltage into heat. This may or may not affect the crystal. One could certainly try, this is why I initially said its certainly possible, but up to the individual to decide. Adding an external buffer is so simple that I just did not think it would be worth it.. Bye, Said Sent From iPhone On Nov 25, 2014, at 4:12, Charles Steinmetz csteinm...@yandex.com wrote: Hal wrote: So driving 50 Ohms inputs is not optimal here, 1M inputs are much better for this purpose. That only works if you have a (very) short connection to the next stage. Things get interesting if you have, say, 10 feet of unterminated coax. Thinking that the output was a sine wave, I previously suggested testing to determine what its actual impedance is and to proceed accordingly. Said pointed out that it is not a sine output, but rather 3v CMOS. Still, I think it is worthwhile to test to see what the actual output capability is. For example, most HC and AC CMOS outputs will source and sink 20-25mA. The Fairchild advanced CMOS family characteristics document says: All SSI and MSI devices (AC, ACT, ACQ or ACTQ) are guaranteed to source and sink 24 mA. 74AC/ACTxxx devices are capable of driving 50 [ohm] transmission lines. Some of the newer CMOS logic is similar, including Fairchild TinyLogic UHS (NC7xZ series), LCX, and LVC devices. Now AFAIK, we do not know what CMOS device is used for the TCXO output -- and it may well not be any of these. Testing will provide a definitive answer, and it may show that there are better options than a 1M termination. Of course, the TCXO output is used internally to the LTE Lite (and may be used internally to the TCXO itself), so one cannot count on having all of the rated device output current available to drive an external load. Avoid anything that pulls the output logic levels very far down (logic high) or up (logic low), say by more than 200mV (such as a termination resistance that is too low), or materially distorts the output wave shape (such as a Tee or Pi filter, which one might consider to convert the output to a sine wave and match it to coax). To test, one would use a voltage divider from the logic supply voltage to ground, with the TCXO output feeding the center point of the divider. (See attached diagram.) I will be very surprised if it will not drive 10k + 10k with ease (already MUCH better than 1M), and 1k + 1k is a distinct possibility [NOTE: in some cases, this scheme works best if the resistor to the positive supply is about 50% higher than the one to ground, for example 1.5k + 1k]. You may even find that it will drive 100 + 100 (or 150 + 100) without problems, in which case it should directly drive 50 ohm coax. With any of these, best performance in the final installation will be achieved with the termination resistors at the far end of any wire, PC trace, or transmission line longer than a few inches. [Note that the divider scheme is the right way to terminate CMOS logic for analog uses at any impedance -- to terminate in 1M ohm, one would use 2M + 2M, although at that level it matters less.] Because the CMOS device is a saturated switch, the TCXO and LTE Light power dissipation will not increase by a significant amount with the increased load current. The logic supply will need to source some extra power, but only 45mW even for the 100 + 100 ohm output network. If the gods are truly with us, we may even find that the TCXO output will source and sink sufficient current to drive a Tee network if the circuit is designed properly -- say, a divider with 150 + 150 ohm resistors (or 220 + 150) feeding a series 10nF capacitor and 200 ohm resistor to a Tee network using 10uH/50.5pF/10uH -- which would drive a 0dBm sine wave into terminated 50 ohm coax with harmonics below -40dBc. (See attached diagram.) This requires peak currents from the CMOS output of +/- 5mA. But don't count on this until you test and verify, and don't be surprised if the TCXO output will not support it. [If one can live with a sine output of 0dBm, the divider resistors and the series resistor can all be increased in value until it does work.] Best regards, Charles All electronics is analog. CMOS_output_circuits.png ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Practical considerations making a lab standard with an LTE lite
Dave, Exactly. Sent From iPhone On Nov 25, 2014, at 7:34, Dave Martindale dave.martind...@gmail.com wrote: The 20 MHz output should be OK, since it is series-terminated with 50 ohms at the source and the buffer can source enough current. The driver sees a 100 ohm load (50 ohm resistor in series with 50 ohm coax impedance) for that 32 ns round trip time, so it will increase power dissipation (as you note). But the load at the far end of the coax should see a clean edge, and the reflection should be absorbed when it returns to the source (due to the source terminator). Just don't look at the signal half way along the coax. The other outputs apparently don't have either the current drive or the source terminator, so a long piece of coax is likely to do unpleasant things to the edge. In either case, if you want to run any of the signals 10 feet it's likely better to run a very short connection from the LTE-Lite to a proper 50 ohm line driver. That gets the power dissipation off the board, and then you can use drivers that give you whatever output swing you want, and which can drive a 100 ohm load continuously so you can use parallel termination at the far end. - Dave On Tue, Nov 25, 2014 at 12:23 AM, Hal Murray hmur...@megapathdsl.net wrote: Said Jackson said: Correct, and thats why its all a bad trade off if you have to use 50 Ohms termination. Either more heat or more PN, and more circuitry. So driving 50 Ohms inputs is not optimal here, 1M inputs are much better for this purpose. That only works if you have a (very) short connection to the next stage. Things get interesting if you have, say, 10 feet of unterminated coax. 10 MHz is 100 ns, or 50 ns between transitions. Coax is ballpark of 5/8 c so that's 16 ns one way or 32 ns round drip. That's 60% of the heat as well as lots of nasty reflections. (Somebody please check my numbers.) -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] anyone tried the cheap Lea-6T modules seen on eBay?
You may have seen them as in http://www.ebay.fr/itm/Ublox-LEA-6T-GPS-Module-w-Compass-for-APM2-5-APM2-6-Flight-Controller-Multirotor-/271641375221?pt=UK_ToysGames_RadioControlled_JNhash=item3f3f1671f5 There are other sellers with the same. My idea was to see if one was suitable as a 1PPS locking source for my PRS10. The interest for me being that it powers directly from a USB connection and can be configured with the Ublox’s u-center software, so implementation is a no brainer. All I needed to do was to replace the patch antenna with an SMA-F connector and add a wire for the 1PPS. Despite having less than ideal antenna position, once the survey was complete I was getting +/-20ns jitter on the 1PPS which is within spec and stable over the day. However I was most disappointed to see that the 1PPS output voltage is only 2.16 +/-0.4V. According to spec it should be Vcc+/-0.4V and I have Vcc measuring 3.3V. I can’t see the board trace but the measured voltage is the same on the PPS pad next to the JST-SH connector and on the GPS modules pin 28 so it is not a board issue. Unfortunately this is too low to tickle the PRS10 1PPS input. I guess I could add a buffer or AND gate to fix it, but that sort of defeats the object and introduces extra jitter and offset. It is however enough for a Raspberry-Pi GPIO input, so I have relegated it to NTP PPS. Has anyone out there got one of these and seen the same symptoms? Or maybe you have one and it is OK? I’d like to know. You will be able to see from the eBay photos that this a 6T-0-000 version which is an early version and it could be that they are cheap as some/all have this defect. So beware. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Lucent KS-24361 Simple Doubler
Dave call?? I don't see a #. I have skype so easy enough. Happy to. Regards Paul WB8TSL On Tue, Nov 25, 2014 at 10:46 AM, Dave M dgmin...@mediacombb.net wrote: Give them a call... they are more than willing to sell single pieces of almost any of their products, at the listed lowest quantity price, especially if you are a Ham. I recently bought several items, some of them in single quantities. Many of their MMICs are priced so low that you can easily buy ten at a time. Even with shipping, they are cheaper than buying from the Chinese Ebay sellers. Dave M paul swed wrote: Looks simple but trying to order 1 piece seems a challenge. Minicircuits wants 10 or $59. Not bad but don't need 10 :-) Regards Paul WB8TSL On Tue, Nov 25, 2014 at 6:08 AM, Mike Seguin n1...@burlingtontelecom.net wrote: Paul, W1GHZ has put together a simple doubler for the 5 MHz OCXO in the Lucent boxes. It's based on a Minicircuits part with MIMIC amp. Details here: http://users.burlingtontelecom.net/~n1...@burlingtontelecom.net/images/ Simple_Frequency_Doubler.pdf Mike -- 73, Mike, N1JEZ A closed mouth gathers no feet ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/ mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. When the people fear the government, there is tyranny. When the government fears the people, there is liberty -- Thomas Jefferson Dave M ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/ mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] anyone tried the cheap Lea-6T modules seen on eBay?
A Lea-6T is only worth any extra money if you are using the sawtooth correction data coming out of it. With out correction a $ 14 unit is just as good. Bert Kehren In a message dated 11/25/2014 11:25:34 A.M. Eastern Standard Time, michael.c...@sfr.fr writes: You may have seen them as in http://www.ebay.fr/itm/Ublox-LEA-6T-GPS-Module-w-Compass-for-APM2-5-APM2-6- Flight-Controller-Multirotor-/271641375221?pt=UK_ToysGames_RadioControlled_J Nhash=item3f3f1671f5 There are other sellers with the same. My idea was to see if one was suitable as a 1PPS locking source for my PRS10. The interest for me being that it powers directly from a USB connection and can be configured with the Ublox’s u-center software, so implementation is a no brainer. All I needed to do was to replace the patch antenna with an SMA-F connector and add a wire for the 1PPS. Despite having less than ideal antenna position, once the survey was complete I was getting +/-20ns jitter on the 1PPS which is within spec and stable over the day. However I was most disappointed to see that the 1PPS output voltage is only 2.16 +/-0.4V. According to spec it should be Vcc+/-0.4V and I have Vcc measuring 3.3V. I can’t see the board trace but the measured voltage is the same on the PPS pad next to the JST-SH connector and on the GPS modules pin 28 so it is not a board issue. Unfortunately this is too low to tickle the PRS10 1PPS input. I guess I could add a buffer or AND gate to fix it, but that sort of defeats the object and introduces extra jitter and offset. It is however enough for a Raspberry-Pi GPIO input, so I have relegated it to NTP PPS. Has anyone out there got one of these and seen the same symptoms? Or maybe you have one and it is OK? I’d like to know. You will be able to see from the eBay photos that this a 6T-0-000 version which is an early version and it could be that they are cheap as some/all have this defect. So beware. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] anyone tried the cheap Lea-6T modules seen on eBay?
I bought one of those recently. I haven't done more than power it on to see if it works. I will probably look at it more over Thanksgiving. Joe Gray W5JG On Nov 25, 2014 9:15 AM, Mike Cook michael.c...@sfr.fr wrote: You may have seen them as in http://www.ebay.fr/itm/Ublox-LEA-6T-GPS-Module-w-Compass-for-APM2-5-APM2-6-Flight-Controller-Multirotor-/271641375221?pt=UK_ToysGames_RadioControlled_JNhash=item3f3f1671f5 There are other sellers with the same. My idea was to see if one was suitable as a 1PPS locking source for my PRS10. The interest for me being that it powers directly from a USB connection and can be configured with the Ublox's u-center software, so implementation is a no brainer. All I needed to do was to replace the patch antenna with an SMA-F connector and add a wire for the 1PPS. Despite having less than ideal antenna position, once the survey was complete I was getting +/-20ns jitter on the 1PPS which is within spec and stable over the day. However I was most disappointed to see that the 1PPS output voltage is only 2.16 +/-0.4V. According to spec it should be Vcc+/-0.4V and I have Vcc measuring 3.3V. I can't see the board trace but the measured voltage is the same on the PPS pad next to the JST-SH connector and on the GPS modules pin 28 so it is not a board issue. Unfortunately this is too low to tickle the PRS10 1PPS input. I guess I could add a buffer or AND gate to fix it, but that sort of defeats the object and introduces extra jitter and offset. It is however enough for a Raspberry-Pi GPIO input, so I have relegated it to NTP PPS. Has anyone out there got one of these and seen the same symptoms? Or maybe you have one and it is OK? I'd like to know. You will be able to see from the eBay photos that this a 6T-0-000 version which is an early version and it could be that they are cheap as some/all have this defect. So beware. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Practical considerations making a lab standard with an LTE lite
Said wrote: The increased current for the driver will cause heating near the crystal in both the CMOS driver and the 3.0V LDO as the LDO has to convert the excess voltage into heat. This may or may not affect the crystal. There would be next to no additional heating in the CMOS driver, because there is very little voltage across it in either logic state. And the additional power supply current is so small that the increase in LDO dissipation will also be very low. At the extreme worst, any such effects would be somewhere between imperceptible and negligible. But on the other hand, if there is a possibility that a passive filter can create a clean, 50 ohm sine wave output for free, the potential up side is huge. Adding an external buffer is so simple that I just did not think it would be worth it.. An external buffer is a fine way to go, but it would need to be very close to the driver chip -- which is why I suggested on Sunday building it onto a breakout card that plugs directly onto the LTE Lite's MMCX output connector. You really don't want to run a naked CMOS output at 10MHz much farther than that, both for the corruption it may suffer and also for the mischief that radiation and capacitive coupling can cause to other nearby circuitry (the LTE Lite) as the loop gets larger than that. I'm not sure I see why a small additional source of heat is such a dramatic concern with the 10MHz TCXO, but apparently not for the 20MHz TCXO, which by accounts has an actual buffer amp that must create comparatively massive heating. A temperature difference isn't a problem in and of itself -- only a changing temperature creates a problem. Whatever the dissipation situation is, it should settle into stasis if one takes the slightest care with the thermal design. Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Lucent KS-24361 Simple Doubler
Hi Mike, It's indeed a very simple circuit, but... not if you want to double 5MHz. It's working from 10MHz onwards and it seems there is no other version available that goes lower. Or is it good enough to use it also for 5Mc? Regards, Rob. Date: Tue, 25 Nov 2014 06:08:10 -0500 From: n1...@burlingtontelecom.net To: time-nuts@febo.com Subject: [time-nuts] Lucent KS-24361 Simple Doubler Paul, W1GHZ has put together a simple doubler for the 5 MHz OCXO in the Lucent boxes. It's based on a Minicircuits part with MIMIC amp. Details here: http://users.burlingtontelecom.net/~n1...@burlingtontelecom.net/images/Simple_Frequency_Doubler.pdf Mike -- 73, Mike, N1JEZ A closed mouth gathers no feet ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Lucent KS-24361 Simple Doubler
Hi Rob, It works fine at 5 MHz to double to 10 MHz. The numbers Paul listed are for 5 to 10 MHz. Mike --- 73, Mike, N1JEZ A closed mouth gathers no feet On 2014-11-25 12:24, Rob040 . wrote: Hi Mike, It's indeed a very simple circuit, but... not if you want to double 5MHz. It's working from 10MHz onwards and it seems there is no other version available that goes lower. Or is it good enough to use it also for 5Mc? Regards, Rob. Date: Tue, 25 Nov 2014 06:08:10 -0500 From: n1...@burlingtontelecom.net To: time-nuts@febo.com Subject: [time-nuts] Lucent KS-24361 Simple Doubler Paul, W1GHZ has put together a simple doubler for the 5 MHz OCXO in the Lucent boxes. It's based on a Minicircuits part with MIMIC amp. Details here: http://users.burlingtontelecom.net/~n1...@burlingtontelecom.net/images/Simple_Frequency_Doubler.pdf Mike -- 73, Mike, N1JEZ A closed mouth gathers no feet ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Lucent KS-24361 Simple Doubler
Hi Mike, Thanks for your confirmation and indeed now I saw it. Sorry, I was confused after looking at the datasheet of the AMK-2-13+ *shame*. Bye, Rob. Date: Tue, 25 Nov 2014 12:59:07 -0500 From: n1...@burlingtontelecom.net To: time-nuts@febo.com Subject: Re: [time-nuts] Lucent KS-24361 Simple Doubler Hi Rob, It works fine at 5 MHz to double to 10 MHz. The numbers Paul listed are for 5 to 10 MHz. Mike --- 73, Mike, N1JEZ A closed mouth gathers no feet On 2014-11-25 12:24, Rob040 . wrote: Hi Mike, It's indeed a very simple circuit, but... not if you want to double 5MHz. It's working from 10MHz onwards and it seems there is no other version available that goes lower. Or is it good enough to use it also for 5Mc? Regards, Rob. Date: Tue, 25 Nov 2014 06:08:10 -0500 From: n1...@burlingtontelecom.net To: time-nuts@febo.com Subject: [time-nuts] Lucent KS-24361 Simple Doubler Paul, W1GHZ has put together a simple doubler for the 5 MHz OCXO in the Lucent boxes. It's based on a Minicircuits part with MIMIC amp. Details here: http://users.burlingtontelecom.net/~n1...@burlingtontelecom.net/images/Simple_Frequency_Doubler.pdf Mike -- 73, Mike, N1JEZ A closed mouth gathers no feet ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] anyone tried the cheap Lea-6T modules seen on eBay?
Bert, the LEA-6T actually has software bugs that show up in moving applications and that need to be handled by the users' software, and they are selling it for drone applications. Without any monitoring for these bugs the units may really only be useful for stationary applications. Why they would choose the 6T unit instead of a non-T unit at half the price would only be because they got those as surplus really cheap I would think. bye, Said In a message dated 11/25/2014 09:50:12 Pacific Standard Time, time-nuts@febo.com writes: A Lea-6T is only worth any extra money if you are using the sawtooth correction data coming out of it. With out correction a $ 14 unit is just as good. Bert Kehren In a message dated 11/25/2014 11:25:34 A.M. Eastern Standard Time, michael.c...@sfr.fr writes: You may have seen them as in http://www.ebay.fr/itm/Ublox-LEA-6T-GPS-Module-w-Compass-for-APM2-5-APM2-6- Flight-Controller-Multirotor-/271641375221?pt=UK_ToysGames_RadioControlled_J Nhash=item3f3f1671f5 There are other sellers with the same. My idea was to see if one was suitable as a 1PPS locking source for my PRS10. The interest for me being that it powers directly from a USB connection and can be configured with the Ublox’s u-center software, so implementation is a no brainer. All I needed to do was to replace the patch antenna with an SMA-F connector and add a wire for the 1PPS. Despite having less than ideal antenna position, once the survey was complete I was getting +/-20ns jitter on the 1PPS which is within spec and stable over the day. However I was most disappointed to see that the 1PPS output voltage is only 2.16 +/-0.4V. According to spec it should be Vcc+/-0.4V and I have Vcc measuring 3.3V. I can’t see the board trace but the measured voltage is the same on the PPS pad next to the JST-SH connector and on the GPS modules pin 28 so it is not a board issue. Unfortunately this is too low to tickle the PRS10 1PPS input. I guess I could add a buffer or AND gate to fix it, but that sort of defeats the object and introduces extra jitter and offset. It is however enough for a Raspberry-Pi GPIO input, so I have relegated it to NTP PPS. Has anyone out there got one of these and seen the same symptoms? Or maybe you have one and it is OK? I’d like to know. You will be able to see from the eBay photos that this a 6T-0-000 version which is an early version and it could be that they are cheap as some/all have this defect. So beware. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] LTE-Lite Plans
I have one of the LTE-Lite 20Mhz units and plan to use it as a frequency reference for my ham radio gear. My planned setup is as follows: I'm putting it in the recommended Hammond enclosure powered by a USB cable from my PC. I had originally planned to use the wall wart provided but I want to get status from the unit without hacking a window in the top to see the LEDs so I plan to use TBD software to provide a status check. I briefly thought about doing something with an Arduino and display shields but that seemed like too much work for now. I'm using a inverting D FF from TI (SN74aup1g80) as a divide by 2 to provide 10Mhz. The chip and associated passives will be on a little circuit board mounted in the open area normally reserved for the external oscillator. The output of the chip will be connected via a series resistor of about 400 ohms to a SMA connector. This resistor will limit the load on the FF and the LTE-Lite power source. Power will be taken from C6. This output will only go a few inches to a DEMI 10Mhz 4 way splitter The input of the splitter will be equipped with an additional ERA-2+ amplifier (50 ohm input) which will restore the signal levels lost due to the series resistor in the LTE-Lite addon. The DEMI splitter will also be equipped with a manual power switch which will allow me to kill the output of the box if the GPSDO fails for some reason. The little hockey puck antenna will be mounted directly outside the shack wall near a south facing wall which will limit the visibility to only half the horizon. I'm assuming this will be enough for my modest needs. The four outputs will be used as follows: One will go to the K3 ExtREF to provide an external reference. Two will go to separate TX/RX converters for low frequency (600Khz) use and be used with the transverter I/O on the K3. The last will be used as a general calibration reference. When the power switch on the DEMI splitter is turned off the K3 will revert to using its internal TXCO. I leave the PC running 24/7 and the power to the LTE-Lite would only be interrupted when the PC is rebooted. I don't need a frequency reference during the reboot time since I always operate my rig with the PC on and running. The TBD status software will tell me when the LTE-Lite is synched up again. The PC is served by a UPS and the shack circuit is one which is served by our whole house generator. I have the DEMI splitter built up and working. Now just waiting on enclosure from Digikey. I should have everything running by mid December. I still need to figure out what to use for the status software. Ideally I'd like an applet to display appropriate status indications on my monitor for now I'll examine the uBlox and Putty and if not satisfactory perhaps I'll write something in VB. Feedback and suggestions welcome. 73 Jim ab3cv ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Practical considerations making a lab standard with an LTE lite
That's why I said its up to the user to decide what they want their trade-off to be. For permanent installations I personally would not run the unbuffered 10MHz output through more than about a foot of coax cable to the buffer. The rise/fall time of the TCXO output is slow enough (typical spec is 4ns) to make that a lumped system rather than a reflected system. You won't see any reflections on a foot or less of cable. For short-term phase noise measurements I have run that signal through 6 feet of coax no problem, but there are quite significant reflections at that point so I would strongly advise against that. If I break the TCXO here on my bench due to my own stupidity its a different situation than if the customer has that happen in their setting.. bye, Said In a message dated 11/25/2014 09:34:11 Pacific Standard Time, csteinm...@yandex.com writes: Said wrote: The increased current for the driver will cause heating near the crystal in both the CMOS driver and the 3.0V LDO as the LDO has to convert the excess voltage into heat. This may or may not affect the crystal. There would be next to no additional heating in the CMOS driver, because there is very little voltage across it in either logic state. And the additional power supply current is so small that the increase in LDO dissipation will also be very low. At the extreme worst, any such effects would be somewhere between imperceptible and negligible. But on the other hand, if there is a possibility that a passive filter can create a clean, 50 ohm sine wave output for free, the potential up side is huge. Adding an external buffer is so simple that I just did not think it would be worth it.. An external buffer is a fine way to go, but it would need to be very close to the driver chip -- which is why I suggested on Sunday building it onto a breakout card that plugs directly onto the LTE Lite's MMCX output connector. You really don't want to run a naked CMOS output at 10MHz much farther than that, both for the corruption it may suffer and also for the mischief that radiation and capacitive coupling can cause to other nearby circuitry (the LTE Lite) as the loop gets larger than that. I'm not sure I see why a small additional source of heat is such a dramatic concern with the 10MHz TCXO, but apparently not for the 20MHz TCXO, which by accounts has an actual buffer amp that must create comparatively massive heating. A temperature difference isn't a problem in and of itself -- only a changing temperature creates a problem. Whatever the dissipation situation is, it should settle into stasis if one takes the slightest care with the thermal design. Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] LTE-Lite Plans
Jim, please remember you need proper lightning protection if you put the antenna outside.. bye, Said In a message dated 11/25/2014 11:43:09 Pacific Standard Time, jim@jtmil ler.com writes: I have one of the LTE-Lite 20Mhz units and plan to use it as a frequency reference for my ham radio gear. My planned setup is as follows: I'm putting it in the recommended Hammond enclosure powered by a USB cable from my PC. I had originally planned to use the wall wart provided but I want to get status from the unit without hacking a window in the top to see the LEDs so I plan to use TBD software to provide a status check. I briefly thought about doing something with an Arduino and display shields but that seemed like too much work for now. I'm using a inverting D FF from TI (SN74aup1g80) as a divide by 2 to provide 10Mhz. The chip and associated passives will be on a little circuit board mounted in the open area normally reserved for the external oscillator. The output of the chip will be connected via a series resistor of about 400 ohms to a SMA connector. This resistor will limit the load on the FF and the LTE-Lite power source. Power will be taken from C6. This output will only go a few inches to a DEMI 10Mhz 4 way splitter The input of the splitter will be equipped with an additional ERA-2+ amplifier (50 ohm input) which will restore the signal levels lost due to the series resistor in the LTE-Lite addon. The DEMI splitter will also be equipped with a manual power switch which will allow me to kill the output of the box if the GPSDO fails for some reason. The little hockey puck antenna will be mounted directly outside the shack wall near a south facing wall which will limit the visibility to only half the horizon. I'm assuming this will be enough for my modest needs. The four outputs will be used as follows: One will go to the K3 ExtREF to provide an external reference. Two will go to separate TX/RX converters for low frequency (600Khz) use and be used with the transverter I/O on the K3. The last will be used as a general calibration reference. When the power switch on the DEMI splitter is turned off the K3 will revert to using its internal TXCO. I leave the PC running 24/7 and the power to the LTE-Lite would only be interrupted when the PC is rebooted. I don't need a frequency reference during the reboot time since I always operate my rig with the PC on and running. The TBD status software will tell me when the LTE-Lite is synched up again. The PC is served by a UPS and the shack circuit is one which is served by our whole house generator. I have the DEMI splitter built up and working. Now just waiting on enclosure from Digikey. I should have everything running by mid December. I still need to figure out what to use for the status software. Ideally I'd like an applet to display appropriate status indications on my monitor for now I'll examine the uBlox and Putty and if not satisfactory perhaps I'll write something in VB. Feedback and suggestions welcome. 73 Jim ab3cv ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] LTE-Lite Plans
Jim Because of the short runs you should be quite fine with your approach. I used the 74HC version to do my dividing using the second section to get 5 MHz. Lots of gear still uses that. Frankly ublox and such don't show you much and I am using PUTTY. There is another pgm from India but shows much the same as ublox. They do show more if NEMA. But what we want typically is the status. So the suggestion of VB is very reasonable to create a more useful interface. That is mostly watching the frequency offset and such in the status message. I sure all that can be dressed up easily and nicely. Regards Paul WB8TSL On Tue, Nov 25, 2014 at 2:42 PM, Jim Miller j...@jtmiller.com wrote: I have one of the LTE-Lite 20Mhz units and plan to use it as a frequency reference for my ham radio gear. My planned setup is as follows: I'm putting it in the recommended Hammond enclosure powered by a USB cable from my PC. I had originally planned to use the wall wart provided but I want to get status from the unit without hacking a window in the top to see the LEDs so I plan to use TBD software to provide a status check. I briefly thought about doing something with an Arduino and display shields but that seemed like too much work for now. I'm using a inverting D FF from TI (SN74aup1g80) as a divide by 2 to provide 10Mhz. The chip and associated passives will be on a little circuit board mounted in the open area normally reserved for the external oscillator. The output of the chip will be connected via a series resistor of about 400 ohms to a SMA connector. This resistor will limit the load on the FF and the LTE-Lite power source. Power will be taken from C6. This output will only go a few inches to a DEMI 10Mhz 4 way splitter The input of the splitter will be equipped with an additional ERA-2+ amplifier (50 ohm input) which will restore the signal levels lost due to the series resistor in the LTE-Lite addon. The DEMI splitter will also be equipped with a manual power switch which will allow me to kill the output of the box if the GPSDO fails for some reason. The little hockey puck antenna will be mounted directly outside the shack wall near a south facing wall which will limit the visibility to only half the horizon. I'm assuming this will be enough for my modest needs. The four outputs will be used as follows: One will go to the K3 ExtREF to provide an external reference. Two will go to separate TX/RX converters for low frequency (600Khz) use and be used with the transverter I/O on the K3. The last will be used as a general calibration reference. When the power switch on the DEMI splitter is turned off the K3 will revert to using its internal TXCO. I leave the PC running 24/7 and the power to the LTE-Lite would only be interrupted when the PC is rebooted. I don't need a frequency reference during the reboot time since I always operate my rig with the PC on and running. The TBD status software will tell me when the LTE-Lite is synched up again. The PC is served by a UPS and the shack circuit is one which is served by our whole house generator. I have the DEMI splitter built up and working. Now just waiting on enclosure from Digikey. I should have everything running by mid December. I still need to figure out what to use for the status software. Ideally I'd like an applet to display appropriate status indications on my monitor for now I'll examine the uBlox and Putty and if not satisfactory perhaps I'll write something in VB. Feedback and suggestions welcome. 73 Jim ab3cv ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] NIST isolation amplifiers
Hi Charles, Thanks a bunch for the comments and the article reprints. This is just what I was looking for to get started on my distribution amplifier. Regards...Bill -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Charles Steinmetz Sent: Tuesday, November 25, 2014 11:35 AM To: TimeNuts Subject: [time-nuts] NIST isolation amplifiers A couple of people were asking about NIST isolation amplifiers recently. I'm attaching circuit diagrams of the 5-10 MHz amp from 1997 and the 1-200 MHz amp from 1990. I think Bruce has the papers linked at his ko4bb.com pages. I built some of the 5-10 MHz amps with minor variations and they work very well (I used a separate capacitance multiplier for the base divider string, and changed the first 4.3k resistor to 6.65k to achieve symmetrical clipping and a small increase in headroom). I used 2N3904s for the two lower transistors and a 2N2219A for the top transistor, which dissipates over 300mW. I tried some fancy transistors with very low base spreading resistance, which reduced the noise -- but the increased junction capacitance made the AM to PM conversion worse, so the overall residual PM was worse. On the other hand, GHz transistors had higher noise due to lower gain. So the 3904/2219A combination appears to be just about optimum. (Note that the 200 ohm resistor at the input contributes about half of the circuit's noise, and you can't use the Norton trick because it would ruin the isolation.) The transistor stack draws 32mA and the base divider stack draws ~1.5mA. The amplifiers have an input impedance of 250 ohms, so paralleling the inputs of 5 sections creates an overall 50 ohm input impedance. When a circuit has reverse isolation of well over 150dB, as this one does, you need to pay very careful attention to shielding. Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] LTE-Lite Plans
On 25 November 2014 at 19:42, Jim Miller j...@jtmiller.com wrote: I'm putting it in the recommended Hammond enclosure powered by a USB cable from my PC. I had originally planned to use the wall wart provided but I want to get status from the unit without hacking a window in the top to see the LEDs so I plan to use TBD software to provide a status check. You could consider using a light pipe, fibre optic or whatever you want to call it. Perspex or similar material will guide light from an LED by total internal reflection. You could probably use a panel-mounted LED, remove the electronics and just use the lens, and holder so it looks better than it would be able do with just a hole. Dave ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] LTR-Lite GPS
Looking closely at the board, I see it uses a Venus GPS chipset. And yet folks here are using the ublox ucenter software with it. What am I missing? Joe Gray W5JG ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] For Sale New JLT LTE-Lite 20MHz UK Only
Having dived in with great enthusiasm as soon as the LTE-Lite was made available I've had it on test for a couple of days now and have not been disappointed, I'm very impressed. However, given the number of existing GPS and other off air systems and projects already running here I have to admit I might have been a bit over enthusiastic and I don't really have any immediate need for another one. Rather than park it on the shelf in its box for the time being, or leaving it just running in the background, I'd be happy to pass it on for what I paid for it to someone else in the UK who can make more immediate use of it. I'm not looking to make any profit on the transaction but I'm not looking to make a loss either, if that was the only option then I'd just keep it until I did find more use for it. With carriage and UK import taxes it cost me just over 165 GBP and I'd be willing to sell it for 175 GBP with the extra to cover tracked and insured next day delivery, or for 165 GBP to anyone able to collect from the west coast of Scotland. Although not actually saving anything significant on the cost the purchaser would be guaranteed fast delivery of a unit that's just come off test and is available now, and please note I would only want to ship this to the UK. The kit is totally as new and as in the original packaging as supplied, with the module itself, the antenna, two straight MMCX to BNC adapter cables, USB power adapter and USB lead, plus the instruction leaflet with optional 14pin DIL socket and 3 pin header still attached inside a small plastic bag. If any is interested please reply directly and not via the list, I'm back to just receiving daily digests due to ongoing problems with live list traffic sent to AOL so won't see replies to the list for some time, and I will be working on a first come first served basis. Regards Nigel GM8PZR ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 1/f^2 noise
Jim, I assume from your previous comments that you went the FFT way. As I was flying I had some time to kill, so I read some papers. You should be reading FFT-Based Methods for Simulating Flicker FM by Charles A. Greenhall of JPL. If you read it carefully enough you will find several methods of operating it. If you are nice, Chuck might hand you some code. Cheers, Magnus On 11/24/2014 04:06 PM, Jim Lux wrote: Started plotting some sampled data from my experimental system, and interestingly, it seems to have a 1/f^2 slope, rather than a 1/f slope. I had expected the amplifier noise to dominate, but perhaps one of the myriad other noise sources is contributing as well (e.g. sample clock jitter, ADC quantization). ADC quantization should be white, though. only 6000 samples at 200 Hz here (30 seconds) so the data below 1 Hz is getting pretty sketchy.. The input to the system wasn't necessarily AWGN or DC (it might be an oscillator beating against itself in a mixer with a very short difference in time (nanoseconds). I'll run another test with the input shorted. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] LTR-Lite GPS
I assume the Venus chipset NMEA output sentence set is a subset of the uBlox NMEA output set, and the NMEA messages are sufficiently standardized that the uCenter software can read them and display the results in a meaningful way. Any other program that reads and displays NMEA data (and can be set to 38400 bps, instead of NMEA default 4800 bps) would likely work. Of course, none of the commands in uCenter that configure the receiver are going to work, both because the receiver isn't a uBlox and because the serial port is unidirectional. You only get status. - Dave On 25/11/2014 16:07, Joseph Gray wrote: Looking closely at the board, I see it uses a Venus GPS chipset. And yet folks here are using the ublox ucenter software with it. What am I missing? Joe Gray W5JG ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] LTR-Lite GPS
NMEA is a company-independent format.. and the uBlox application is nice. In a message dated 11/25/2014 13:08:07 Pacific Standard Time, jg...@zianet.com writes: Looking closely at the board, I see it uses a Venus GPS chipset. And yet folks here are using the ublox ucenter software with it. What am I missing? Joe Gray W5JG ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] LTE Lite SkyTraq chip info
Here is a link to a company that at least shares details of the SkyTraq venus 8 chip on the LTE-Lite. The actual skytraq sites is pretty useless. https://www.tindie.com/products/smokingresistor/venus838flpx-gps-breakout-board/ There is a program that will read the nema codes and such also. Have used it and its not better or worse then ublox. A bit of humor it only ever shows Asia for the ground track. The venus 8 seems to have a lot of capability. Not sure how to get to it, but the fact is for the LTE Lite its not needed. It has a single job to perform. It would be curious to obtain the board tindie sells because it supports all of the satellites. But have to say thats a project for another day wa down the list. But at least you can have some further technical details for the system. Regards Paul WB8TSL ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] LTE Lite SkyTraq chip info
Now that the cat is out of the bag - notice that on these boards we used the special -T timing version which is more than twice as expensive than the normal navigation version used by others.. I personally use the uBlox software because the Skytrack software had a habit of crashing itself and my computer from time to time.. In a message dated 11/25/2014 14:02:41 Pacific Standard Time, paulsw...@gmail.com writes: Here is a link to a company that at least shares details of the SkyTraq venus 8 chip on the LTE-Lite. The actual skytraq sites is pretty useless. https://www.tindie.com/products/smokingresistor/venus838flpx-gps-breakout-bo ard/ There is a program that will read the nema codes and such also. Have used it and its not better or worse then ublox. A bit of humor it only ever shows Asia for the ground track. The venus 8 seems to have a lot of capability. Not sure how to get to it, but the fact is for the LTE Lite its not needed. It has a single job to perform. It would be curious to obtain the board tindie sells because it supports all of the satellites. But have to say thats a project for another day wa down the list. But at least you can have some further technical details for the system. Regards Paul WB8TSL ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] LTE Lite SkyTraq chip info
Said Really did not run it very long a few hours. In that time it ran fine and on Vista no less. Now thats scary. The fact that it had my location and insists on Asia along with fixed screen scaling hints that its half beaked. But there was little additional value compared to ublox accept for one thing I noticed. On ublox the update to the C/N updates every other second same with other screens. Then blanks the screen and repeats. A bit annoying. PUTTY isn't pretty but has what I care about. The offset. Regards Paul WB8TSL On Tue, Nov 25, 2014 at 5:12 PM, S. Jackson via time-nuts time-nuts@febo.com wrote: Now that the cat is out of the bag - notice that on these boards we used the special -T timing version which is more than twice as expensive than the normal navigation version used by others.. I personally use the uBlox software because the Skytrack software had a habit of crashing itself and my computer from time to time.. In a message dated 11/25/2014 14:02:41 Pacific Standard Time, paulsw...@gmail.com writes: Here is a link to a company that at least shares details of the SkyTraq venus 8 chip on the LTE-Lite. The actual skytraq sites is pretty useless. https://www.tindie.com/products/smokingresistor/venus838flpx-gps-breakout-bo ard/ There is a program that will read the nema codes and such also. Have used it and its not better or worse then ublox. A bit of humor it only ever shows Asia for the ground track. The venus 8 seems to have a lot of capability. Not sure how to get to it, but the fact is for the LTE Lite its not needed. It has a single job to perform. It would be curious to obtain the board tindie sells because it supports all of the satellites. But have to say thats a project for another day wa down the list. But at least you can have some further technical details for the system. Regards Paul WB8TSL ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] LTE Lite SkyTraq chip info
In message 7da89.51b7dfcf.41a65...@aol.com, S. Jackson via time-nuts writes : Now that the cat is out of the bag - notice that on these boards we used the special -T timing version which is more than twice as expensive than the normal navigation version used by others.. That reminds me: I have yet to see anthing that uses Galileo or GNONASS in a position-hold mode, are those constellations still not competitive with GPS in that niche ? -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Lucent KS-24361 Simple Doubler
Hi Based on using the same amp for other projects, I would strongly suggest checking the phase noise / ADEV of that doubler before depending on it’s output. Bob On Nov 25, 2014, at 6:08 AM, Mike Seguin n1...@burlingtontelecom.net wrote: Paul, W1GHZ has put together a simple doubler for the 5 MHz OCXO in the Lucent boxes. It's based on a Minicircuits part with MIMIC amp. Details here: http://users.burlingtontelecom.net/~n1...@burlingtontelecom.net/images/Simple_Frequency_Doubler.pdf Mike -- 73, Mike, N1JEZ A closed mouth gathers no feet ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] LTR-Lite GPS
Yes, I know that NMEA is standard. I assumed that your board was also putting out proprietary messages.sounds like not. Joe Gray W5JG On Nov 25, 2014 2:50 PM, S. Jackson via time-nuts time-nuts@febo.com wrote: NMEA is a company-independent format.. and the uBlox application is nice. In a message dated 11/25/2014 13:08:07 Pacific Standard Time, jg...@zianet.com writes: Looking closely at the board, I see it uses a Venus GPS chipset. And yet folks here are using the ublox ucenter software with it. What am I missing? Joe Gray W5JG ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] LTE Lite SkyTraq chip info
Thanks for the link. The Navspark also uses a Venus GPS, but I don't know if it the same one. I can't look it up at the moment. Joe Gray W5JG On Nov 25, 2014 3:02 PM, paul swed paulsw...@gmail.com wrote: Here is a link to a company that at least shares details of the SkyTraq venus 8 chip on the LTE-Lite. The actual skytraq sites is pretty useless. https://www.tindie.com/products/smokingresistor/venus838flpx-gps-breakout-board/ There is a program that will read the nema codes and such also. Have used it and its not better or worse then ublox. A bit of humor it only ever shows Asia for the ground track. The venus 8 seems to have a lot of capability. Not sure how to get to it, but the fact is for the LTE Lite its not needed. It has a single job to perform. It would be curious to obtain the board tindie sells because it supports all of the satellites. But have to say thats a project for another day wa down the list. But at least you can have some further technical details for the system. Regards Paul WB8TSL ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] NIST isolation amplifiers
Hi For a modern build, the PZT3904’s and PZT’s are a pretty good way to go with this amp. For normal distribution to instruments, there’s really no need to do anything this complex. Bob On Nov 25, 2014, at 2:34 PM, Charles Steinmetz csteinm...@yandex.com wrote: A couple of people were asking about NIST isolation amplifiers recently. I'm attaching circuit diagrams of the 5-10 MHz amp from 1997 and the 1-200 MHz amp from 1990. I think Bruce has the papers linked at his ko4bb.com pages. I built some of the 5-10 MHz amps with minor variations and they work very well (I used a separate capacitance multiplier for the base divider string, and changed the first 4.3k resistor to 6.65k to achieve symmetrical clipping and a small increase in headroom). I used 2N3904s for the two lower transistors and a 2N2219A for the top transistor, which dissipates over 300mW. I tried some fancy transistors with very low base spreading resistance, which reduced the noise -- but the increased junction capacitance made the AM to PM conversion worse, so the overall residual PM was worse. On the other hand, GHz transistors had higher noise due to lower gain. So the 3904/2219A combination appears to be just about optimum. (Note that the 200 ohm resistor at the input contributes about half of the circuit's noise, and you can't use the Norton trick because it would ruin the isolation.) The transistor stack draws 32mA and the base divider stack draws ~1.5mA. The amplifiers have an input impedance of 250 ohms, so paralleling the inputs of 5 sections creates an overall 50 ohm input impedance. When a circuit has reverse isolation of well over 150dB, as this one does, you need to pay very careful attention to shielding. Best regards, Charles NIST_200_iso.pngNIST_5_10_iso_amp.png___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] LTE Lite SkyTraq chip info
Hi I think it’s more a supply and demand thing right now. There are a lot of systems (CDMA for example) that run on GPS time. There do not seem to be quite as many people putting out spec’s for the other systems (yet). Bob On Nov 25, 2014, at 5:29 PM, Poul-Henning Kamp p...@phk.freebsd.dk wrote: In message 7da89.51b7dfcf.41a65...@aol.com, S. Jackson via time-nuts writes : Now that the cat is out of the bag - notice that on these boards we used the special -T timing version which is more than twice as expensive than the normal navigation version used by others.. That reminds me: I have yet to see anthing that uses Galileo or GNONASS in a position-hold mode, are those constellations still not competitive with GPS in that niche ? -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] anyone tried the cheap Lea-6T modules seen on eBay?
Hi I looked at the boards on the eBay listing. Last time I looked at the layout guidelines for the LEA-6T’s they pretty much said “don’t do it that way” …. Who knows what they did that board for or why they did it that way. That’s not to say the boards don’t work. They probably do work. Often guidelines are a bit over restrictive….. Bob On Nov 25, 2014, at 2:41 PM, S. Jackson via time-nuts time-nuts@febo.com wrote: Bert, the LEA-6T actually has software bugs that show up in moving applications and that need to be handled by the users' software, and they are selling it for drone applications. Without any monitoring for these bugs the units may really only be useful for stationary applications. Why they would choose the 6T unit instead of a non-T unit at half the price would only be because they got those as surplus really cheap I would think. bye, Said In a message dated 11/25/2014 09:50:12 Pacific Standard Time, time-nuts@febo.com writes: A Lea-6T is only worth any extra money if you are using the sawtooth correction data coming out of it. With out correction a $ 14 unit is just as good. Bert Kehren In a message dated 11/25/2014 11:25:34 A.M. Eastern Standard Time, michael.c...@sfr.fr writes: You may have seen them as in http://www.ebay.fr/itm/Ublox-LEA-6T-GPS-Module-w-Compass-for-APM2-5-APM2-6- Flight-Controller-Multirotor-/271641375221?pt=UK_ToysGames_RadioControlled_J Nhash=item3f3f1671f5 There are other sellers with the same. My idea was to see if one was suitable as a 1PPS locking source for my PRS10. The interest for me being that it powers directly from a USB connection and can be configured with the Ublox’s u-center software, so implementation is a no brainer. All I needed to do was to replace the patch antenna with an SMA-F connector and add a wire for the 1PPS. Despite having less than ideal antenna position, once the survey was complete I was getting +/-20ns jitter on the 1PPS which is within spec and stable over the day. However I was most disappointed to see that the 1PPS output voltage is only 2.16 +/-0.4V. According to spec it should be Vcc+/-0.4V and I have Vcc measuring 3.3V. I can’t see the board trace but the measured voltage is the same on the PPS pad next to the JST-SH connector and on the GPS modules pin 28 so it is not a board issue. Unfortunately this is too low to tickle the PRS10 1PPS input. I guess I could add a buffer or AND gate to fix it, but that sort of defeats the object and introduces extra jitter and offset. It is however enough for a Raspberry-Pi GPIO input, so I have relegated it to NTP PPS. Has anyone out there got one of these and seen the same symptoms? Or maybe you have one and it is OK? I’d like to know. You will be able to see from the eBay photos that this a 6T-0-000 version which is an early version and it could be that they are cheap as some/all have this defect. So beware. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] LTR-Lite GPS
On Tue, Nov 25, 2014 at 6:03 PM, Joseph Gray jg...@zianet.com wrote: Yes, I know that NMEA is standard. I assumed that your board was also putting out proprietary messages Yes there are two such messages. PSTI and PJLTS. STI is emitted with the other NMEA messages and JLTS is emitted when the message switch is in the status position, See the manual pages 6 and 25. JLTS is sufficiently interesting that I wish it was always available. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] NIST isolation amplifiers
On 25 Nov 2014 23:10, Bob Camp kb...@n1k.org wrote: Hi For a modern build, the PZT3904’s and PZT’s are a pretty good way to go with this amp. For normal distribution to instruments, there’s really no need to do anything this complex. Bob I am also thinking about the construction of a distribution amplifier with 15 or so outputs. One thing that came to my mind, is that there may be some point in having one or two outputs where more money is spent. Then if one thinks an item might be particularly sensitive to some aspect of the reference, one can use that. One could for example have one or two outputs which have harmonics suppressed 100 dB, without going to unnecessary expensive on all outputs. Dave ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] LTR-Lite GPS
Hey Paul thats what I look at in PUTTY. Works for me. On Tue, Nov 25, 2014 at 6:37 PM, Paul tic-...@bodosom.net wrote: On Tue, Nov 25, 2014 at 6:03 PM, Joseph Gray jg...@zianet.com wrote: Yes, I know that NMEA is standard. I assumed that your board was also putting out proprietary messages Yes there are two such messages. PSTI and PJLTS. STI is emitted with the other NMEA messages and JLTS is emitted when the message switch is in the status position, See the manual pages 6 and 25. JLTS is sufficiently interesting that I wish it was always available. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] NIST isolation amplifiers
Hi Dave, That's exactly the approach I'm going to use. Outputs that go to instruments that might see the low noise and then outputs that go to devices that aren't phase noise sensitive like counters, scopes, pulse generators and others. Regards...Bill -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Dr. David Kirkby (Kirkby Microwave Ltd) Sent: Tuesday, November 25, 2014 3:46 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] NIST isolation amplifiers On 25 Nov 2014 23:10, Bob Camp kb...@n1k.org wrote: Hi For a modern build, the PZT3904’s and PZT’s are a pretty good way to go with this amp. For normal distribution to instruments, there’s really no need to do anything this complex. Bob I am also thinking about the construction of a distribution amplifier with 15 or so outputs. One thing that came to my mind, is that there may be some point in having one or two outputs where more money is spent. Then if one thinks an item might be particularly sensitive to some aspect of the reference, one can use that. One could for example have one or two outputs which have harmonics suppressed 100 dB, without going to unnecessary expensive on all outputs. Dave ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Lucent KS-24361 Simple Doubler
Using an attenuator between the doubler output and the amplifier input degrades the phase noise significantly. Bruce On Tuesday, November 25, 2014 06:00:30 PM Bob Camp wrote: Hi Based on using the same amp for other projects, I would strongly suggest checking the phase noise / ADEV of that doubler before depending on it’s output. Bob On Nov 25, 2014, at 6:08 AM, Mike Seguin n1...@burlingtontelecom.net wrote: Paul, W1GHZ has put together a simple doubler for the 5 MHz OCXO in the Lucent boxes. It's based on a Minicircuits part with MIMIC amp. Details here: http://users.burlingtontelecom.net/~n1...@burlingtontelecom.net/images/ Sim ple_Frequency_Doubler.pdf Mike ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] LTE Lite SkyTraq chip info
We evaluated a Glonass unit for 1PPS and it was really quite bad. Unless you are near the poles or get jammed a lot I would not see much advantage.. Sent From iPhone On Nov 25, 2014, at 15:10, Bob Camp kb...@n1k.org wrote: Hi I think it’s more a supply and demand thing right now. There are a lot of systems (CDMA for example) that run on GPS time. There do not seem to be quite as many people putting out spec’s for the other systems (yet). Bob On Nov 25, 2014, at 5:29 PM, Poul-Henning Kamp p...@phk.freebsd.dk wrote: In message 7da89.51b7dfcf.41a65...@aol.com, S. Jackson via time-nuts writes : Now that the cat is out of the bag - notice that on these boards we used the special -T timing version which is more than twice as expensive than the normal navigation version used by others.. That reminds me: I have yet to see anthing that uses Galileo or GNONASS in a position-hold mode, are those constellations still not competitive with GPS in that niche ? -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] NIST isolation amplifiers
An alternative is to use a Norton style amp (or other low noise high linearity amp without stellar reverse isolation) to boost the signal level and drive a set of high isolation output stages. A relatively simple discrete current feedback amp may suffice. For higher reverse isolation a cascode arrangement may suffice. Alternatively the input amp could drive a passive splitter each output of which drives a high reverse isolation stage. Even a series shunt feedback stage with a low noise bias circuit can have low PN. Just avoid the design error in the HP3048 option K22 where the bias circuit is more susceptible to power supply noise than it needs to be. Bruce On Tuesday, November 25, 2014 11:45:47 PM Dr. David Kirkby wrote: On 25 Nov 2014 23:10, Bob Camp kb...@n1k.org wrote: Hi For a modern build, the PZT3904’s and PZT’s are a pretty good way to go with this amp. For normal distribution to instruments, there’s really no need to do anything this complex. Bob I am also thinking about the construction of a distribution amplifier with 15 or so outputs. One thing that came to my mind, is that there may be some point in having one or two outputs where more money is spent. Then if one thinks an item might be particularly sensitive to some aspect of the reference, one can use that. One could for example have one or two outputs which have harmonics suppressed 100 dB, without going to unnecessary expensive on all outputs. Dave ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] LTR-Lite GPS
It does output two proprietary messages, one from Skytrack, but not sure I would use the Skytrack application due to the low information content of that message and the instability of the Skytrack app. The uBlox app lets you view the two proprietary messages too and is stable. Everyone can use the app they like best. Sent From iPhone On Nov 25, 2014, at 15:03, Joseph Gray jg...@zianet.com wrote: Yes, I know that NMEA is standard. I assumed that your board was also putting out proprietary messages.sounds like not. Joe Gray W5JG On Nov 25, 2014 2:50 PM, S. Jackson via time-nuts time-nuts@febo.com wrote: NMEA is a company-independent format.. and the uBlox application is nice. In a message dated 11/25/2014 13:08:07 Pacific Standard Time, jg...@zianet.com writes: Looking closely at the board, I see it uses a Venus GPS chipset. And yet folks here are using the ublox ucenter software with it. What am I missing? Joe Gray W5JG ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] LTR-Lite GPS
Paul, You can listen to PJLTS on the USB and grab the Skytrack NMEA in TTL format from pin 13 of header JP1 at the same time.. Sent From iPhone On Nov 25, 2014, at 15:37, Paul tic-...@bodosom.net wrote: On Tue, Nov 25, 2014 at 6:03 PM, Joseph Gray jg...@zianet.com wrote: Yes, I know that NMEA is standard. I assumed that your board was also putting out proprietary messages Yes there are two such messages. PSTI and PJLTS. STI is emitted with the other NMEA messages and JLTS is emitted when the message switch is in the status position, See the manual pages 6 and 25. JLTS is sufficiently interesting that I wish it was always available. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] NIST isolation amplifiers
Am 25.11.2014 um 20:34 schrieb Charles Steinmetz: A couple of people were asking about NIST isolation amplifiers recently. I'm attaching circuit diagrams of the 5-10 MHz amp from 1997 and the 1-200 MHz amp from 1990. I think Bruce has the papers linked at his ko4bb.com pages. I have built _this_ version of the NIST preamp 6 or seven years ago. It is quite ok and feeds the signal generators, counters, SAs and VNA in my lab without issues. There is 1 successor that corrects the awful S11 and has no output transformer but it still awaits characterisation. Maybe over the holiday season to come. Noise on the base voltage string is attenuated by transistor beta in the cascode, so there is not too much to gain here. The next 2 versions use even more current to support 13 dBm without transformer, they run pretty hot ( 2 BFG31 chains/channel). http://www.hoffmann-hochfrequenz.de/downloads/downloads.html regards, Gerhard ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Lucent KS-24361
received my Lucent KS-24361 today. just as being described, appears new in original box. I bought one of the pairs REF-0 and REF-1 plus one additional REF-0. There is a date of manufacture on each box, the pair was 2000 week 20 and 21 whereas the additional REF-0 was 2000 week 5. I mention this only in passing as the packaging inside the box for additional REF-0 was a bit different than for the pair. The pair was packed with the pink colored foam and the units were wrapped in clear plastic bag whereas the individual REF-0 had a blue colored foam and the unit was wrapped in a mylar ESD bag. Perhaps an indication of different sources or different manufacturing or assembly plants? It will be a while til everything is hooked up and working but in the mean time I continue to the discussion on the list. cheers, Graham ve3gtc ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] LTE-Lite Plans
Jim, I have somewhere a piece of VB 6.0 code that decodes NMEA sentences and puts it pretty on the screen (at least that's how I remember it :). I am not at home at the moment but I'll be glad to send it to you if you are interested. May not do what you want, but it will get you started. Didier KO4BB www.ko4bb.com On November 25, 2014 1:42:42 PM CST, Jim Miller j...@jtmiller.com wrote: I have one of the LTE-Lite 20Mhz units and plan to use it as a frequency reference for my ham radio gear. My planned setup is as follows: I'm putting it in the recommended Hammond enclosure powered by a USB cable from my PC. I had originally planned to use the wall wart provided but I want to get status from the unit without hacking a window in the top to see the LEDs so I plan to use TBD software to provide a status check. I briefly thought about doing something with an Arduino and display shields but that seemed like too much work for now. I'm using a inverting D FF from TI (SN74aup1g80) as a divide by 2 to provide 10Mhz. The chip and associated passives will be on a little circuit board mounted in the open area normally reserved for the external oscillator. The output of the chip will be connected via a series resistor of about 400 ohms to a SMA connector. This resistor will limit the load on the FF and the LTE-Lite power source. Power will be taken from C6. This output will only go a few inches to a DEMI 10Mhz 4 way splitter The input of the splitter will be equipped with an additional ERA-2+ amplifier (50 ohm input) which will restore the signal levels lost due to the series resistor in the LTE-Lite addon. The DEMI splitter will also be equipped with a manual power switch which will allow me to kill the output of the box if the GPSDO fails for some reason. The little hockey puck antenna will be mounted directly outside the shack wall near a south facing wall which will limit the visibility to only half the horizon. I'm assuming this will be enough for my modest needs. The four outputs will be used as follows: One will go to the K3 ExtREF to provide an external reference. Two will go to separate TX/RX converters for low frequency (600Khz) use and be used with the transverter I/O on the K3. The last will be used as a general calibration reference. When the power switch on the DEMI splitter is turned off the K3 will revert to using its internal TXCO. I leave the PC running 24/7 and the power to the LTE-Lite would only be interrupted when the PC is rebooted. I don't need a frequency reference during the reboot time since I always operate my rig with the PC on and running. The TBD status software will tell me when the LTE-Lite is synched up again. The PC is served by a UPS and the shack circuit is one which is served by our whole house generator. I have the DEMI splitter built up and working. Now just waiting on enclosure from Digikey. I should have everything running by mid December. I still need to figure out what to use for the status software. Ideally I'd like an applet to display appropriate status indications on my monitor for now I'll examine the uBlox and Putty and if not satisfactory perhaps I'll write something in VB. Feedback and suggestions welcome. 73 Jim ab3cv ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Sent from my Motorola Droid Razr HD 4G LTE wireless tracker while I do other things. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] NIST isolation amplifiers
Hi Harmonics are (in general) the least of your issues on a distribution amp. There is very little difference in ADEV or instrument performance at -20 dbc versus -120 dbc. Since filtering is relatively easy, adding another inductor or two is about all it takes. ——— If you are going with the NIST approach rather than gates, remember that there are a few issues: 1) These circuits tend to “sing like a bird” at UHF if built from leaded parts. Often it’s tough to spot due to the output filter. 2) Past a handful of outputs, the input impedance of the circuit will become an issue. You will need a more complex approach. 3) The isolation you achieve is far more dependent on the layout than on the circuit. You need a *very* good layout to achieve the numbers commonly tossed around for the circuit. That’s much easier to do with SMT parts. 4) Any (hopefully) low noise circuit needs a quiet supply. This one is no different. That’s not just the regulator, the rest of the feed (ground loops etc) matters as well. 5) There is a tradeoff between filter bandwidth and temperature induced ADEV issues. Going crazy on filtering will likely degrade your ADEV. 6) The amp(s) as shown are not matched either at the input or the output. That may or may not be an issue to you. If it is, you will need to do some mods to the circuit. I’d suggest at least a 3 to 6 db pad on the input and output. Bob On Nov 25, 2014, at 6:45 PM, Dr. David Kirkby (Kirkby Microwave Ltd) drkir...@kirkbymicrowave.co.uk wrote: On 25 Nov 2014 23:10, Bob Camp kb...@n1k.org wrote: Hi For a modern build, the PZT3904’s and PZT’s are a pretty good way to go with this amp. For normal distribution to instruments, there’s really no need to do anything this complex. Bob I am also thinking about the construction of a distribution amplifier with 15 or so outputs. One thing that came to my mind, is that there may be some point in having one or two outputs where more money is spent. Then if one thinks an item might be particularly sensitive to some aspect of the reference, one can use that. One could for example have one or two outputs which have harmonics suppressed 100 dB, without going to unnecessary expensive on all outputs. Dave ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] NIST isolation amplifiers
Hi I’ve built that one as well. It’s a bit easier with +/- supplies. It has the same “you need a good layout” issues as any of the other versions. It’s got a bit higher input impedance than the others so it’s better choice for 4 outputs. Bob On Nov 25, 2014, at 6:53 PM, Gerhard Hoffmann dk...@arcor.de wrote: Am 25.11.2014 um 20:34 schrieb Charles Steinmetz: A couple of people were asking about NIST isolation amplifiers recently. I'm attaching circuit diagrams of the 5-10 MHz amp from 1997 and the 1-200 MHz amp from 1990. I think Bruce has the papers linked at his ko4bb.com pages. I have built _this_ version of the NIST preamp 6 or seven years ago. It is quite ok and feeds the signal generators, counters, SAs and VNA in my lab without issues. There is 1 successor that corrects the awful S11 and has no output transformer but it still awaits characterisation. Maybe over the holiday season to come. Noise on the base voltage string is attenuated by transistor beta in the cascode, so there is not too much to gain here. The next 2 versions use even more current to support 13 dBm without transformer, they run pretty hot ( 2 BFG31 chains/channel). http://www.hoffmann-hochfrequenz.de/downloads/downloads.html regards, Gerhard ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Lucent KS-24361
Hi All of the pairs that I have received have been in the pink foam. They span the date code range from 1999 (US factory) through 2000 (Korea manufacture) to 2001 (also from Korea). The blue ones may be factory re-builds. Bob On Nov 25, 2014, at 7:26 PM, Graham planoph...@aei.ca wrote: received my Lucent KS-24361 today. just as being described, appears new in original box. I bought one of the pairs REF-0 and REF-1 plus one additional REF-0. There is a date of manufacture on each box, the pair was 2000 week 20 and 21 whereas the additional REF-0 was 2000 week 5. I mention this only in passing as the packaging inside the box for additional REF-0 was a bit different than for the pair. The pair was packed with the pink colored foam and the units were wrapped in clear plastic bag whereas the individual REF-0 had a blue colored foam and the unit was wrapped in a mylar ESD bag. Perhaps an indication of different sources or different manufacturing or assembly plants? It will be a while til everything is hooked up and working but in the mean time I continue to the discussion on the list. cheers, Graham ve3gtc ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] LTE-Lite Plans
Guys, I never expected such an intense discussion about using and buffering the outputs from the LTE-Lite board since the actual circuit to use can be quite simple. To address these questions, I drew up a simple schematic that uses a DIP-14 74AC04 gate, six resistors, and two caps. Everyone who can solder should be able to build this simple circuit as a dead-bug type build on a copper-clad board. This circuit will buffer all three outputs (1PPS, TCXO RF, and Synthesixed RF) of the LTE-Lite eval board with CMOS 3.0V levels that can drive 50 Ohms terminations. For simplicity I grab the 3.0V power from the DIP-14 TCXO on pin 14 of that part on the eval board, even though I would strongly suggest to use a separate low noise 3.3V or 5V power supply to power the 74AC04 chip. You can add 100nF caps in series to the two RF signals before they feed into the coax output connectors for less power consumption and removing DC for instruments that don't like DC inputs. Using a single IC for the three signals will result in crosstalk between the signals, but it should be clear from the schematics how one could break up the signals by using three independent ICs to minimize crosstalk. We use this circuit in a small box here using SMT components, and it works really well. Excuse my horrible writing, using keyboards has made my fingers numb.. Hope that helps, Said ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Lucent KS-24361 Simple Doubler
Paul, there's a list of sales office contacts (depending on your location) at http://www.minicircuits.com/contact/na_sales_reps.html (assuming that you're in North America; if not, go to the International offices link). Dave M paul swed wrote: Dave call?? I don't see a #. I have skype so easy enough. Happy to. Regards Paul WB8TSL On Tue, Nov 25, 2014 at 10:46 AM, Dave M dgmin...@mediacombb.net wrote: Give them a call... they are more than willing to sell single pieces of almost any of their products, at the listed lowest quantity price, especially if you are a Ham. I recently bought several items, some of them in single quantities. Many of their MMICs are priced so low that you can easily buy ten at a time. Even with shipping, they are cheaper than buying from the Chinese Ebay sellers. Dave M paul swed wrote: Looks simple but trying to order 1 piece seems a challenge. Minicircuits wants 10 or $59. Not bad but don't need 10 :-) Regards Paul WB8TSL On Tue, Nov 25, 2014 at 6:08 AM, Mike Seguin n1...@burlingtontelecom.net wrote: Paul, W1GHZ has put together a simple doubler for the 5 MHz OCXO in the Lucent boxes. It's based on a Minicircuits part with MIMIC amp. Details here: http://users.burlingtontelecom.net/~n1...@burlingtontelecom.net/images/ Simple_Frequency_Doubler.pdf Mike -- 73, Mike, N1JEZ A closed mouth gathers no feet Dave M ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] LTE-Lite Plans
Hi If you decide to run the circuit from +5V, get the 74ACT04 instead of the 74AC04. It will trigger better on the 3.3V output from the LTE. The 74AC(T)04 will not in any way impact the phase noise or ADEV coming out of the LTE, if a reasonable supply is used… With a decent PCB layout and SMT parts, the isolation can be *very* good if multiple gate packages are used. Bob On Nov 25, 2014, at 8:28 PM, S. Jackson via time-nuts time-nuts@febo.com wrote: Guys, I never expected such an intense discussion about using and buffering the outputs from the LTE-Lite board since the actual circuit to use can be quite simple. To address these questions, I drew up a simple schematic that uses a DIP-14 74AC04 gate, six resistors, and two caps. Everyone who can solder should be able to build this simple circuit as a dead-bug type build on a copper-clad board. This circuit will buffer all three outputs (1PPS, TCXO RF, and Synthesixed RF) of the LTE-Lite eval board with CMOS 3.0V levels that can drive 50 Ohms terminations. For simplicity I grab the 3.0V power from the DIP-14 TCXO on pin 14 of that part on the eval board, even though I would strongly suggest to use a separate low noise 3.3V or 5V power supply to power the 74AC04 chip. You can add 100nF caps in series to the two RF signals before they feed into the coax output connectors for less power consumption and removing DC for instruments that don't like DC inputs. Using a single IC for the three signals will result in crosstalk between the signals, but it should be clear from the schematics how one could break up the signals by using three independent ICs to minimize crosstalk. We use this circuit in a small box here using SMT components, and it works really well. Excuse my horrible writing, using keyboards has made my fingers numb.. Hope that helps, Said CMOS_buffer_for_LTE-Lite-Eval.JPG___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] NIST isolation amplifiers
Another issue is that if even one output needs high reverse isolation and low crosstalk, then even those outputs that arent so critical will also need high reverse isolation and low crosstalk to avoid degrading the crosstalk to the critical output. Bruce On Tuesday, November 25, 2014 07:54:02 PM Bob Camp wrote: Hi Harmonics are (in general) the least of your issues on a distribution amp. There is very little difference in ADEV or instrument performance at -20 dbc versus -120 dbc. Since filtering is relatively easy, adding another inductor or two is about all it takes. ——— If you are going with the NIST approach rather than gates, remember that there are a few issues: 1) These circuits tend to “sing like a bird” at UHF if built from leaded parts. Often it’s tough to spot due to the output filter. The small resistors in series with each CB stage emitter are useful in suppressing such parasitics as is a low inductance ground connection for each base. 2) Past a handful of outputs, the input impedance of the circuit will become an issue. You will need a more complex approach. A low noise input amp driving a splitter can be useful in resolving that issue. 3) The isolation you achieve is far more dependent on the layout than on the circuit. You need a *very* good layout to achieve the numbers commonly tossed around for the circuit. That’s much easier to do with SMT parts. Shielding each individual amp from the others (SMT or not) may be necessary. 4) Any (hopefully) low noise circuit needs a quiet supply. This one is no different. That’s not just the regulator, the rest of the feed (ground loops etc) matters as well. 5) There is a tradeoff between filter bandwidth and temperature induced ADEV issues. Going crazy on filtering will likely degrade your ADEV. 6) The amp(s) as shown are not matched either at the input or the output. That may or may not be an issue to you. If it is, you will need to do some mods to the circuit. I’d suggest at least a 3 to 6 db pad on the input and output. ' Input pads will increase the PN floor. With slight modifications up to 6 such isolation amp inputs can be driven by a single 50 ohm source. Bob On Nov 25, 2014, at 6:45 PM, Dr. David Kirkby (Kirkby Microwave Ltd) drkir...@kirkbymicrowave.co.uk wrote: On 25 Nov 2014 23:10, Bob Camp kb...@n1k.org wrote: Hi For a modern build, the PZT3904’s and PZT’s are a pretty good way to go with this amp. For normal distribution to instruments, there’s really no need to do anything this complex. Bob I am also thinking about the construction of a distribution amplifier with 15 or so outputs. One thing that came to my mind, is that there may be some point in having one or two outputs where more money is spent. Then if one thinks an item might be particularly sensitive to some aspect of the reference, one can use that. One could for example have one or two outputs which have harmonics suppressed 100 dB, without going to unnecessary expensive on all outputs. Dave ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] LTE-Lite Plans
Hi Mark, Bob, two comments: * I forgot to mention that feeding the 1PPS signal through the IC inverts the signal of course, so the falling edge becomes the active edge. Use the two inverters in series rather than parallel to avoid that problem, at the cost of lower drive capability and higher Tpd. * On the interaction between the three signals: the worst is when the 1PPS signal hits and drives 3V into the 100 Ohms equivalent termination (30mA). At that point the power supply will sag, causing AM modulation to appear on the RF signals. The result is humps in the ADEV plot at 1Hz, 2Hz, 3Hz, etc etc all the way up to a couple of KHz. This is why separate power supplies and driver IC's are recommended (a separate LDO for the RF signals and one just for the 1PPS would solve this 1PPS crosstalk). This is one reason why I don't like DC 50 Ohms terminations and love open-ended coax cables. In fact Tom V.B. some years ago reported here that he could measure the 1PPS LED current (!!!) from one of his GPSDOs as it fed THROUGH THE AC POWER LINE into another unit.. Albeit at levels of xE-014 or lower if I remember correctly.. bye, Said In a message dated 11/25/2014 17:51:37 Pacific Standard Time, m...@alignedsolutions.com writes: Thanks Said. Strangely enough I was just about to ask the group for comments re the practicality of using inverters in parallel with resistors as a simple means of buffering 1 pps signals. I'll give this a try. Thanks Mark Spencer On 2014-11-25, at 5:28 PM, S. Jackson via time-nuts time-nuts@febo.com wrote: Guys, I never expected such an intense discussion about using and buffering the outputs from the LTE-Lite board since the actual circuit to use can be quite simple. To address these questions, I drew up a simple schematic that uses a DIP-14 74AC04 gate, six resistors, and two caps. Everyone who can solder should be able to build this simple circuit as a dead-bug type build on a copper-clad board. This circuit will buffer all three outputs (1PPS, TCXO RF, and Synthesixed RF) of the LTE-Lite eval board with CMOS 3.0V levels that can drive 50 Ohms terminations. For simplicity I grab the 3.0V power from the DIP-14 TCXO on pin 14 of that part on the eval board, even though I would strongly suggest to use a separate low noise 3.3V or 5V power supply to power the 74AC04 chip. You can add 100nF caps in series to the two RF signals before they feed into the coax output connectors for less power consumption and removing DC for instruments that don't like DC inputs. Using a single IC for the three signals will result in crosstalk between the signals, but it should be clear from the schematics how one could break up the signals by using three independent ICs to minimize crosstalk. We use this circuit in a small box here using SMT components, and it works really well. Excuse my horrible writing, using keyboards has made my fingers numb.. Hope that helps, Said CMOS_buffer_for_LTE-Lite-Eval.JPG ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] NIST isolation amplifiers
Hi The reverse isolation of a “typical” pc layout for this sort of thing is maybe 60 db. Getting to 120 is far from simple. Achieving the 160 (or whatever) numbers you see in some papers is “isolation nuts” territory. The circuit its self can do great numbers. Coming up with a box that has 17 100’ long coax cables into it that isolates well …. good luck if you haven’t done is before. Good luck even if you have and you can’t afford to tool a fancy enclosure. So back to the “what do you need” rant. If: 1) You are running signals into the reference inputs on the back of test gear. 2) You are using BNC connectors and using something like RG-58 or RG-59 3) Your gear is all on one bench or a bench plus a rack 4) The longest run of cable is 20’ 5) Nothing much ever gets unplugged from the distribution line (or if it does you don’t care about a 100 ps burp). Then reverse isolation is not all that big a deal. I’ve seen people run this kind of setup with passive power splitters. If they had 30 db of isolation I’d be amazed. The power splitter might not even be the weak link isolation wise. I’ve seen some really rotten cables and connectors being used. Now, if you have “many hundreds of feet” type runs, you stop talking to Mars when a 100 ps bump hits, or you routinely measure phase noise on 20 day runs with this setup - yes that’s different. Hopefully you have a lot of money in your wallet. Bob On Nov 25, 2014, at 8:57 PM, Bruce Griffiths bruce.griffi...@xtra.co.nz wrote: Another issue is that if even one output needs high reverse isolation and low crosstalk, then even those outputs that arent so critical will also need high reverse isolation and low crosstalk to avoid degrading the crosstalk to the critical output. Bruce On Tuesday, November 25, 2014 07:54:02 PM Bob Camp wrote: Hi Harmonics are (in general) the least of your issues on a distribution amp. There is very little difference in ADEV or instrument performance at -20 dbc versus -120 dbc. Since filtering is relatively easy, adding another inductor or two is about all it takes. ——— If you are going with the NIST approach rather than gates, remember that there are a few issues: 1) These circuits tend to “sing like a bird” at UHF if built from leaded parts. Often it’s tough to spot due to the output filter. The small resistors in series with each CB stage emitter are useful in suppressing such parasitics as is a low inductance ground connection for each base. 2) Past a handful of outputs, the input impedance of the circuit will become an issue. You will need a more complex approach. A low noise input amp driving a splitter can be useful in resolving that issue. 3) The isolation you achieve is far more dependent on the layout than on the circuit. You need a *very* good layout to achieve the numbers commonly tossed around for the circuit. That’s much easier to do with SMT parts. Shielding each individual amp from the others (SMT or not) may be necessary. 4) Any (hopefully) low noise circuit needs a quiet supply. This one is no different. That’s not just the regulator, the rest of the feed (ground loops etc) matters as well. 5) There is a tradeoff between filter bandwidth and temperature induced ADEV issues. Going crazy on filtering will likely degrade your ADEV. 6) The amp(s) as shown are not matched either at the input or the output. That may or may not be an issue to you. If it is, you will need to do some mods to the circuit. I’d suggest at least a 3 to 6 db pad on the input and output. ' Input pads will increase the PN floor. With slight modifications up to 6 such isolation amp inputs can be driven by a single 50 ohm source. Bob On Nov 25, 2014, at 6:45 PM, Dr. David Kirkby (Kirkby Microwave Ltd) drkir...@kirkbymicrowave.co.uk wrote: On 25 Nov 2014 23:10, Bob Camp kb...@n1k.org wrote: Hi For a modern build, the PZT3904’s and PZT’s are a pretty good way to go with this amp. For normal distribution to instruments, there’s really no need to do anything this complex. Bob I am also thinking about the construction of a distribution amplifier with 15 or so outputs. One thing that came to my mind, is that there may be some point in having one or two outputs where more money is spent. Then if one thinks an item might be particularly sensitive to some aspect of the reference, one can use that. One could for example have one or two outputs which have harmonics suppressed 100 dB, without going to unnecessary expensive on all outputs. Dave ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to
Re: [time-nuts] Lucent KS-24361
On Tue, Nov 25, 2014 at 8:10 PM, Bob Camp kb...@n1k.org wrote: All of the pairs that I have received have been in the pink foam. I have a 2005 pair that came in blue foam and mylar. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] LTE-Lite Plans
Hi One simple point: Do you *need* ultra low phase noise on your 1 pps output or is real good ADEV all you are after? If you need good phase noise .. exactly what are you doing ??? So… tack a 78L05 onto your bulk power and run the pps output “empire” off of that supply. Maybe wire the 1 pps stuff on it’s own little chunk of PCB material. Save the fancy low noise regulator(s) for the 10 MHz “empire”. ( If you get a good one, 78L05 might do just fine there as well). What’s the massive cost impact of this radical approach? Well the inverter chips are $0.20 each from several outfits. The 78L05 is also $0.20. The resistors and caps should be on your bench already. If not plan on another $0.30 for the bunch. So you have added (at most) $0.70 to the cost of the circuit by doing this. Skip the order of fries with lunch and it’s paid for. The above does not include the cost of connectors, enclosure, power or switches. All of that will be part of any design you do. Enclosures and power are going to be lower with this circuit than just about anything else you could do. No hogging pockets out of a 1 foot cube of aluminum required ….. Bob On Nov 25, 2014, at 9:14 PM, S. Jackson via time-nuts time-nuts@febo.com wrote: Hi Mark, Bob, two comments: * I forgot to mention that feeding the 1PPS signal through the IC inverts the signal of course, so the falling edge becomes the active edge. Use the two inverters in series rather than parallel to avoid that problem, at the cost of lower drive capability and higher Tpd. * On the interaction between the three signals: the worst is when the 1PPS signal hits and drives 3V into the 100 Ohms equivalent termination (30mA). At that point the power supply will sag, causing AM modulation to appear on the RF signals. The result is humps in the ADEV plot at 1Hz, 2Hz, 3Hz, etc etc all the way up to a couple of KHz. This is why separate power supplies and driver IC's are recommended (a separate LDO for the RF signals and one just for the 1PPS would solve this 1PPS crosstalk). This is one reason why I don't like DC 50 Ohms terminations and love open-ended coax cables. In fact Tom V.B. some years ago reported here that he could measure the 1PPS LED current (!!!) from one of his GPSDOs as it fed THROUGH THE AC POWER LINE into another unit.. Albeit at levels of xE-014 or lower if I remember correctly.. bye, Said In a message dated 11/25/2014 17:51:37 Pacific Standard Time, m...@alignedsolutions.com writes: Thanks Said. Strangely enough I was just about to ask the group for comments re the practicality of using inverters in parallel with resistors as a simple means of buffering 1 pps signals. I'll give this a try. Thanks Mark Spencer On 2014-11-25, at 5:28 PM, S. Jackson via time-nuts time-nuts@febo.com wrote: Guys, I never expected such an intense discussion about using and buffering the outputs from the LTE-Lite board since the actual circuit to use can be quite simple. To address these questions, I drew up a simple schematic that uses a DIP-14 74AC04 gate, six resistors, and two caps. Everyone who can solder should be able to build this simple circuit as a dead-bug type build on a copper-clad board. This circuit will buffer all three outputs (1PPS, TCXO RF, and Synthesixed RF) of the LTE-Lite eval board with CMOS 3.0V levels that can drive 50 Ohms terminations. For simplicity I grab the 3.0V power from the DIP-14 TCXO on pin 14 of that part on the eval board, even though I would strongly suggest to use a separate low noise 3.3V or 5V power supply to power the 74AC04 chip. You can add 100nF caps in series to the two RF signals before they feed into the coax output connectors for less power consumption and removing DC for instruments that don't like DC inputs. Using a single IC for the three signals will result in crosstalk between the signals, but it should be clear from the schematics how one could break up the signals by using three independent ICs to minimize crosstalk. We use this circuit in a small box here using SMT components, and it works really well. Excuse my horrible writing, using keyboards has made my fingers numb.. Hope that helps, Said CMOS_buffer_for_LTE-Lite-Eval.JPG ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to
Re: [time-nuts] Lucent KS-24361
Hi Which would suggest that the earlier date code parts in blue foam may be some sort of re-build. It is interesting that the seem to be stocked in pairs. The date codes on both boxes in each pair I’ve received have been very close to each other. Bob On Nov 25, 2014, at 9:35 PM, Paul tic-...@bodosom.net wrote: On Tue, Nov 25, 2014 at 8:10 PM, Bob Camp kb...@n1k.org wrote: All of the pairs that I have received have been in the pink foam. I have a 2005 pair that came in blue foam and mylar. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] LTE-Lite Plans
Bob, Its not the 1PPS that would be suffering, its the 10MHz that will have all the 1Hz and its harmonics making the PN graph look ugly.. Agree with you that the regulators cost zip these days and using individual buffer ICs and regs is the best way to go. Bye, Said Sent From iPhone On Nov 25, 2014, at 18:45, Bob Camp kb...@n1k.org wrote: Hi One simple point: Do you *need* ultra low phase noise on your 1 pps output or is real good ADEV all you are after? If you need good phase noise .. exactly what are you doing ??? So… tack a 78L05 onto your bulk power and run the pps output “empire” off of that supply. Maybe wire the 1 pps stuff on it’s own little chunk of PCB material. Save the fancy low noise regulator(s) for the 10 MHz “empire”. ( If you get a good one, 78L05 might do just fine there as well). What’s the massive cost impact of this radical approach? Well the inverter chips are $0.20 each from several outfits. The 78L05 is also $0.20. The resistors and caps should be on your bench already. If not plan on another $0.30 for the bunch. So you have added (at most) $0.70 to the cost of the circuit by doing this. Skip the order of fries with lunch and it’s paid for. The above does not include the cost of connectors, enclosure, power or switches. All of that will be part of any design you do. Enclosures and power are going to be lower with this circuit than just about anything else you could do. No hogging pockets out of a 1 foot cube of aluminum required ….. Bob On Nov 25, 2014, at 9:14 PM, S. Jackson via time-nuts time-nuts@febo.com wrote: Hi Mark, Bob, two comments: * I forgot to mention that feeding the 1PPS signal through the IC inverts the signal of course, so the falling edge becomes the active edge. Use the two inverters in series rather than parallel to avoid that problem, at the cost of lower drive capability and higher Tpd. * On the interaction between the three signals: the worst is when the 1PPS signal hits and drives 3V into the 100 Ohms equivalent termination (30mA). At that point the power supply will sag, causing AM modulation to appear on the RF signals. The result is humps in the ADEV plot at 1Hz, 2Hz, 3Hz, etc etc all the way up to a couple of KHz. This is why separate power supplies and driver IC's are recommended (a separate LDO for the RF signals and one just for the 1PPS would solve this 1PPS crosstalk). This is one reason why I don't like DC 50 Ohms terminations and love open-ended coax cables. In fact Tom V.B. some years ago reported here that he could measure the 1PPS LED current (!!!) from one of his GPSDOs as it fed THROUGH THE AC POWER LINE into another unit.. Albeit at levels of xE-014 or lower if I remember correctly.. bye, Said In a message dated 11/25/2014 17:51:37 Pacific Standard Time, m...@alignedsolutions.com writes: Thanks Said. Strangely enough I was just about to ask the group for comments re the practicality of using inverters in parallel with resistors as a simple means of buffering 1 pps signals. I'll give this a try. Thanks Mark Spencer On 2014-11-25, at 5:28 PM, S. Jackson via time-nuts time-nuts@febo.com wrote: Guys, I never expected such an intense discussion about using and buffering the outputs from the LTE-Lite board since the actual circuit to use can be quite simple. To address these questions, I drew up a simple schematic that uses a DIP-14 74AC04 gate, six resistors, and two caps. Everyone who can solder should be able to build this simple circuit as a dead-bug type build on a copper-clad board. This circuit will buffer all three outputs (1PPS, TCXO RF, and Synthesixed RF) of the LTE-Lite eval board with CMOS 3.0V levels that can drive 50 Ohms terminations. For simplicity I grab the 3.0V power from the DIP-14 TCXO on pin 14 of that part on the eval board, even though I would strongly suggest to use a separate low noise 3.3V or 5V power supply to power the 74AC04 chip. You can add 100nF caps in series to the two RF signals before they feed into the coax output connectors for less power consumption and removing DC for instruments that don't like DC inputs. Using a single IC for the three signals will result in crosstalk between the signals, but it should be clear from the schematics how one could break up the signals by using three independent ICs to minimize crosstalk. We use this circuit in a small box here using SMT components, and it works really well. Excuse my horrible writing, using keyboards has made my fingers numb.. Hope that helps, Said CMOS_buffer_for_LTE-Lite-Eval.JPG ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the
Re: [time-nuts] LTE Lite SkyTraq chip info
I spent a bit of time poking around the SkyTraq web site on the weekend. I couldn't find a datasheet for the chip on the LTE-Lite - perhaps it's so new that SkyTraq has not put together the datasheet yet. Under timing, they only list the Venus638LPx-T, which is a older (2011 copyright on the datasheet) 65-channel receiver. The LTE-Lite documentation mentions 65 channels somewhere too, suggesting that the LTE-Lite started out using this chip. Under navigation receivers, Skytraq lists the newer (2013) Venus838FLPx with 167 channels. So I would assume that the Venus838LPx-T-L used in the LTE-Lite is the same 167-channel hardware with timing firmware, and that the LTE-Lite switched from the 638LPx-T to the 838LPx-T-L sometime during development. - Dave On Tue, Nov 25, 2014 at 5:12 PM, S. Jackson via time-nuts time-nuts@febo.com wrote: Now that the cat is out of the bag - notice that on these boards we used the special -T timing version which is more than twice as expensive than the normal navigation version used by others.. I personally use the uBlox software because the Skytrack software had a habit of crashing itself and my computer from time to time.. In a message dated 11/25/2014 14:02:41 Pacific Standard Time, paulsw...@gmail.com writes: Here is a link to a company that at least shares details of the SkyTraq venus 8 chip on the LTE-Lite. The actual skytraq sites is pretty useless. https://www.tindie.com/products/smokingresistor/venus838flpx-gps-breakout-bo ard/ There is a program that will read the nema codes and such also. Have used it and its not better or worse then ublox. A bit of humor it only ever shows Asia for the ground track. The venus 8 seems to have a lot of capability. Not sure how to get to it, but the fact is for the LTE Lite its not needed. It has a single job to perform. It would be curious to obtain the board tindie sells because it supports all of the satellites. But have to say thats a project for another day wa down the list. But at least you can have some further technical details for the system. Regards Paul WB8TSL ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
