Re: [time-nuts] WWVB Measurements
Living in Miami probably as far away as possible in the continental US I have no problem receiving WWVB. When I moved here in 1993, 60 KHz was my main reference source. I used a Tracor 599 and a HP 117 along with a 4 foot commercial loop. The 599 showed clearly superior performance. Later Austron Loran C was added. The 117 was put on the shelf because without paper it was not conducive for long term tracking.When $5 Million homes where build directly next to me the loop had to go, plus the homes where in the direct pass with the transmitting site. Homes here are built because of code with concrete cinder blocks and vertical 1" rebar every one or two feet. I did replace the loop with a commercial 60 KHz ferrite rod unit that also does an excellent job. With the new location of the antenna I try to peak between the two houses but there is also a power transformer on a pole within a 10 degree window. During the time I relied on 60 KHz the 599 worked flawless and as soon as I have room in my lab again I will run it against a tbolt. I am presently cleaning house in preparation for a next year move and it is depressing to throw out stuff that at one time I paid good money for. No room to move in the lab right now. In the nineties Junghans came to Miami to do some field strength measurements in preparation with their product roll out. Knowing their senior management I had an opportunity to host them. I ended up with four Junghans MEGA clocks and two MEGA watches. The watches have the antenna in the leather watch bands (their patent). All work well in a house with steel rebar and two houses next to me in the signal pass. The same is true of the receiver in my La Crosse weather station I bought three years ago. The only way I can really tell when we change daylight time and I make it a point to check the following morning. With out exception they all change. Bert Kehren In a message dated 3/28/2011 12:11:15 A.M. Eastern Daylight Time, hmur...@megapathdsl.net writes: > Pretty much before all these switching power supplies and cpfls etc. Does anybody know what frequency CPFLs are using today? I remember that we had some (non-compact) ceiling fluorescents at work with "electronic" ballasts that were in the 50-60 KHz range. That was 5 years ago. I wonder if all that junk will eventually migrate to well above 60 KHz to take advantage of the smaller magnetics and open up WWVB again. -- These are my opinions, not necessarily my employer's. 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] Allan Variance versus Allan Deviation
Hello, I'm trying to compare the stability specifications of two oscillators. The first spec is 2 x 10E-11 Allan Variance. The second spec is 3 x 10E-11 Allan Deviation. As Allan deviation (ADEV), is the square root of Allan variance, I thought the first spec is the better of the two, but a collegue disagrees, saying 3x10E-11 Allan Deviation is a better spec than 2 x 10E-11 Allan Variance. I'm sure the million experts at there will give me the correct answer Regards Steve Jones ___ 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] Allan Variance versus Allan Deviation
If Allan Deviation is the square root of Allan variance, would the 3 x 10E-11 Allan Deviation equate to an Allan Variance of 9 x 10E-22? Joe -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Martyn Smith Sent: Monday, March 28, 2011 6:24 AM To: time-nuts@febo.com Subject: [time-nuts] Allan Variance versus Allan Deviation Hello, I'm trying to compare the stability specifications of two oscillators. The first spec is 2 x 10E-11 Allan Variance. The second spec is 3 x 10E-11 Allan Deviation. As Allan deviation (ADEV), is the square root of Allan variance, I thought the first spec is the better of the two, but a collegue disagrees, saying 3x10E-11 Allan Deviation is a better spec than 2 x 10E-11 Allan Variance. I'm sure the million experts at there will give me the correct answer Regards Steve Jones ___ 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] Allan Variance versus Allan Deviation
Martyn Smith wrote: Hello, I'm trying to compare the stability specifications of two oscillators. The first spec is 2 x 10E-11 Allan Variance. The second spec is 3 x 10E-11 Allan Deviation. As Allan deviation (ADEV), is the square root of Allan variance, I thought the first spec is the better of the two, but a collegue disagrees, saying 3x10E-11 Allan Deviation is a better spec than 2 x 10E-11 Allan Variance. I'm sure the million experts at there will give me the correct answer Regards Steve Jones ___ 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. Strictly you are correct, however some early datasheets (eg Crystek, ) say Allan variance whilst they actually tabulated its square root or Allan deviation. Bruce ___ 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] Upgrading TS2100 from TCXO to OCXO
There are some hidden configuration parameters in the TS2100 that vary by oscillator type (between TCXO,OCXO, and Rb), and include some control loop parameters. It matters a lot that the firmware uses the correct algorithm and parameters. The Rubidiums are quite far from the crystals, but I assume that there is a smaller difference between crystal types. Joe From: Robert Watzlavick To: time-nuts@febo.com Date: 03/25/2011 12:39 AM Subject: [time-nuts] Upgrading TS2100 from TCXO to OCXO Sent by: time-nuts-boun...@febo.com I've been able to successfully upgrade my Datum TS2100 to an OCXO from the stock TCXO. I didn't see it in the archives so I thought I'd post my findings. I noticed that the same firmware was used regardless of oscillator configuration so there must either be jumpers or a hidden set of commands. The newer versions of the ET6000 have jumpers to select the oscillator but I couldn't find anything similar on the TS2100. However, in the back of the manual, 8500-0033 Rev K, Appendix I describes how to reconfigure the unit to output GPS instead of UTC for NTP. I'm not interested in that but there are some hints about a hidden menu structure (root eng ee) which allows you to change EEPROM settings. Here's the hidden menu items: root eng: start net interface timing tools / serial tools / eeprom tools / spi tools / flash tools / display tools / memory tools / intrinsic help Going further into one of them, root eng eeprom: ethernet address board serial number gain default filter constant low filter constant precision set eeprom get eeprom read serial eeprom write serial eeprom tx 16 bits to eeprom location for image info value eeprom_select intrinsic help So that's where the default gain and filter constants are set. You have to jumper across J4 on the PC board to allow EEPROM writes or you get an error. Not sure what the "precision" setting is for (it's currently -19). I don't have the proper OCXO (yet) but I do have an MV89A OCXO that I was able to wire into the circuit temporarily. There is 12V on the board and the 0.5-4.5V EFC range works well with the MV89A. I used a gain of +20 and a filter setting of 0.9994965 based on Jason Rabel's post from 9/26/2010 (note the sign change on the gain). The EFC algorithm had a pretty good overshoot during the first adjustment cycle and took over an hour to completely settle in but eventually the front panel Locked LED turned on. I couldn't find a way to change the starting value for EFC (d/a) value. I *think* an Abracon AOCJY1A-10.000MHz-E-SW part will be pin compatible on the board. Unfortunately nobody has that one in stock and it's a 10 week lead time so I may end up installing one off-board. The MV89A is too tall to fit with the lid on so it's not a long term option. I traced out the two SMA pads on the board and they are for the EFC out and RF in so I could always run them to the back of the unit and put the OCXO outside the unit. -Bob K5RLW ___ 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] JJY 40, Fukushima
I've not seen it mentioned but VLF time stations are on topic here. I saw that the Mount Ootakadoya VLF (40kHz) transmitter in Fukushima prefecture is off air : "Time Signal. 50kW. Transmission is stopped since 10h46 UT on March 12, 2011 because of the evacuation of the area around the Fukushima Nuclear Power Station damaged by the March 11, 2011 earthquake and tsunami JJY-40." (http://sidstation.loudet.org/stations-list-en.xhtml) Although inland, the station is close to the Fukushima Daiichi power plant so it's going to be down for a while, best wishes to the folk who operate the transmitter. http://www.tele.soumu.go.jp/e/sys/fees/purpose/other/index.htm ___ 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] JJY 40, Fukushima
I have picked this station up numbers of years ago. Extremely weak. I actually had no idea it was stil on the air On Mon, Mar 28, 2011 at 9:50 AM, David wrote: > I've not seen it mentioned but VLF time stations are on topic here. I saw > that the Mount Ootakadoya VLF (40kHz) transmitter in Fukushima prefecture > is off air : > > "Time Signal. 50kW. Transmission is stopped since 10h46 UT on March 12, > 2011 because of the evacuation of the area around the Fukushima Nuclear > Power Station damaged by the March 11, 2011 earthquake and tsunami JJY-40." > > (http://sidstation.loudet.org/stations-list-en.xhtml) > > Although inland, the station is close to the Fukushima Daiichi power plant > so it's going to be down for a while, best wishes to the folk who operate > the transmitter. > > http://www.tele.soumu.go.jp/e/sys/fees/purpose/other/index.htm > > ___ > 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] WWVB Measurements
There is a method to recover a very weak signal out of the mud that is fairly easy to build. It uses a multiplying DAC run by a local reference look up table that is phase locked into the noise. BW can be effectively 1 Hz. Output of the DAC would be integrated to a DC value to control the LO. Once lock is achieved then the LO can be used to look at the modulated signal in a wider BW. Maybe some useful modulation maybe not. An 8 bit MDAC with 256 or 512 samples per wave would work ok, no problem to go to 12 14 16 bits to polish the idea if desired. Reference LO would be 30M72 for 512 or 15M36 for 256. Other ratios could be made using some extra logic to make whole ratios better suited for 10M0 final detected values. Greg On 3/28/2011 4:51 AM, ewkeh...@aol.com wrote: Living in Miami probably as far away as possible in the continental US I have no problem receiving WWVB. When I moved here in 1993, 60 KHz was my main reference source. I used a Tracor 599 and a HP 117 along with a 4 foot commercial loop. The 599 showed clearly superior performance. Later Austron Loran C was added. The 117 was put on the shelf because without paper it was not conducive for long term tracking.When $5 Million homes where build directly next to me the loop had to go, plus the homes where in the direct pass with the transmitting site. Homes here are built because of code with concrete cinder blocks and vertical 1" rebar every one or two feet. I did replace the loop with a commercial 60 KHz ferrite rod unit that also does an excellent job. With the new location of the antenna I try to peak between the two houses but there is also a power transformer on a pole within a 10 degree window. During the time I relied on 60 KHz the 599 worked flawless and as soon as I have room in my lab again I will run it against a tbolt. I am presently cleaning house in preparation for a next year move and it is depressing to throw out stuff that at one time I paid good money for. No room to move in the lab right now. In the nineties Junghans came to Miami to do some field strength measurements in preparation with their product roll out. Knowing their senior management I had an opportunity to host them. I ended up with four Junghans MEGA clocks and two MEGA watches. The watches have the antenna in the leather watch bands (their patent). All work well in a house with steel rebar and two houses next to me in the signal pass. The same is true of the receiver in my La Crosse weather station I bought three years ago. The only way I can really tell when we change daylight time and I make it a point to check the following morning. With out exception they all change. Bert Kehren In a message dated 3/28/2011 12:11:15 A.M. Eastern Daylight Time, hmur...@megapathdsl.net writes: Pretty much before all these switching power supplies and cpfls etc. Does anybody know what frequency CPFLs are using today? I remember that we had some (non-compact) ceiling fluorescents at work with "electronic" ballasts that were in the 50-60 KHz range. That was 5 years ago. I wonder if all that junk will eventually migrate to well above 60 KHz to take advantage of the smaller magnetics and open up WWVB again. ___ 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] WWVB Measurements
In message <4d90b859.2080...@comcast.net>, Greg Broburg writes: >There is a method to recover a very weak signal >out of the mud that is fairly easy to build. I did this slightly differently: Take a 1MSPS ADC and average it into 1000 buckets in round robin form, one after the other. This can be done very quickly in an interrupt routine or even in hardware. The Aduc72xx family of ARM can do this running a sweat, any DSP would have absolutely no trouble doing it. In Europe use 2000 buckets so you can capture DCF77 also. By multiplying the buckets with a suitable IQ signal, you can pull out any signal of integral kHz frequency you care for, and measure its relative phase and change of phase over time. Here are some experiements I did many years ago with one million buckets, so I could demodulate the second pulses: http://phk.freebsd.dk/loran-c/CW/ I would love to find somebody who can design some proper hardware for this, so that we can have an "VLF-All-band Time/Phase Receiver", basically a receiver you can ask, at any time, "What is the phase of the signal at N kHz, for any value of N you care for. Poul-Henning -- 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] WWVB PPS clock pulse ?
Greetings, Is there an accepted form for the PPS clock pulses that are produced by the various time equipment in use today ? A 1 hz square wave ? -- Does the duty cycle have to be exact or only its "rising" edge ? Or can I do a rising edge PPs pulse that's active for 10ms then lowers ? Is there an equipment manual(s) that you guys can recommend, that I can refer to ? Thanks, yet again, -lenny -- Sent from my mobile device ___ 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] Allan Variance versus Allan Deviation
On 03/28/2011 02:36 PM, Bruce Griffiths wrote: Martyn Smith wrote: Hello, I'm trying to compare the stability specifications of two oscillators. The first spec is 2 x 10E-11 Allan Variance. The second spec is 3 x 10E-11 Allan Deviation. As Allan deviation (ADEV), is the square root of Allan variance, I thought the first spec is the better of the two, but a collegue disagrees, saying 3x10E-11 Allan Deviation is a better spec than 2 x 10E-11 Allan Variance. I'm sure the million experts at there will give me the correct answer Regards Steve Jones ___ 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. Strictly you are correct, however some early datasheets (eg Crystek, ) say Allan variance whilst they actually tabulated its square root or Allan deviation. It's also common to have plots saying "Allan Variance" and plotting the Allan Deviation. Since Allan Deviation is the square root of Allan Variance, 2E-11 Allan Variance is about 4.5E-6 in Allan Deviation so an Allan Deviation of 3E-11 is better than an Allan Variance of 2E-11... by far. Use Allan Deviation through-out. Cheers, Magnus ___ 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] WWVB PPS clock pulse ?
Greetings, Is there an accepted form for the PPS clock pulses that are produced by the various time equipment in use today ? A 1 hz square wave ? -- Does the duty cycle have to be exact or only its "rising" edge ? Or can I do a rising edge PPs pulse that's active for 10ms then lowers ? Is there an equipment manual(s) that you guys can recommend, that I can refer to ? Thanks, yet again, -lenny Lenny, programs such as NTP expect a pulse in the region of 100-200ms long, it's not critical. That's what the GPS pucks produce. A few microseconds might be too short for the interrupt to be properly handled, 10ms would likely be OK, but with 100ms you can put an LED on the signal and verify visibly that it's present and perhaps correct. Cheers, David -- SatSignal software - quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ 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] WWVB PPS clock pulse ?
On Mon, Mar 28, 2011 at 9:46 AM, Lenny Story wrote: > Or can I do a rising edge PPs pulse that's active for 10ms then lowers ? Yes. It's the leading edge that matters but 10ms is more of a spike than a pulse. It should be longer, maybe at least 10X longer. It should be something easy enough to notice even on a DMM. There is a question about polarity and voltages. The RS232 standard has data inverted from what TTL uses with a 1 being negative but RS232 does not invert control signals So the PPS if gong into a serial port is not inverted. But the common ttl->rs232 level converter chip inverts the signals o you need to invert the control signals before level shifting. Not rocket science just a need to be careful. Now, if your pulse is long enough to be seen by eye you can verify by eye you are doing the conversion correctly. If you get it wrong then the computer sees what you thought was the trailing edge as the raising edge. A long 200ms pulse makes this error easier to see. -- = Chris Albertson Redondo Beach, California ___ 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] cheap 5V OCXO in 14DIP has about 1E-9 drift per day
Just FYI, I'm not sure how this compares to other similar parts, but I'm seeing about +/- 1 ppb (1E-9) frequency drift per 24 hour period from one sample of the Pletronics OHM40480526, which I've had running for about 10 days now. It runs on +5V and after a warmup current of 250 mA for a few seconds, it draws about 60 mA steady state at room temperature. I'm driving the tuning voltage on pin 1 from a separate +5V reference to avoid variations due to heater current shifts. I use a simple resistive trimpot divider to set the voltage, this is not a GPSDO (yet :-). I'm sure most on this list have more refined tastes in oscillators than this one (and probably want 10 MHz instead of 26 MHz), but I thought it noteworthy because it is so cheap. These parts are currently available online for $2 each. I'm not affiliated with the seller. a few more details: http://www.bealecorner.org/best/measure/time/Pletronics-26MHz-OCXO-tuning.pdf http://www.bealecorner.org/best/measure/time/26MHz-osc-notes.txt ___ 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] JJY40
I've also observed that JJY40 is now off the air. It has been excellent
reception down here in New Zealand for many years, generally better than
the JJY signal on 60kHz, where of course it competes with other signals.
JJY40 was typically strong enough to hear by ear during the day as well
as at night here, and fades considerably for an hour or two at sunrise
and sunset. There is some evidence that Japanese radio-controlled
('Atomic') clocks work in New Zealand using this signal, as there is no
closer source.
73,
Murray ZL1BPU
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Re: [time-nuts] Allan Variance versus Allan Deviation
Magnus is quite right. Variance is almost always just a value on its way to becoming another value. Squared units make little sense in most applications. Bill (the statistician) On Mon, Mar 28, 2011 at 1:10 PM, Magnus Danielson < mag...@rubidium.dyndns.org> wrote: > On 03/28/2011 02:36 PM, Bruce Griffiths wrote: > >> Martyn Smith wrote: >> >>> Hello, >>> >>> I'm trying to compare the stability specifications of two oscillators. >>> >>> The first spec is 2 x 10E-11 Allan Variance. >>> The second spec is 3 x 10E-11 Allan Deviation. >>> >>> As Allan deviation (ADEV), is the square root of Allan variance, I >>> thought the first spec is the better of the two, but a collegue >>> disagrees, saying 3x10E-11 Allan Deviation is a better spec than 2 x >>> 10E-11 Allan Variance. >>> >>> I'm sure the million experts at there will give me the correct answer >>> >>> Regards >>> >>> Steve Jones >>> >>> >>> ___ >>> 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. >>> >>> Strictly you are correct, however some early datasheets (eg Crystek, ) >> say Allan variance whilst they actually tabulated its square root or >> Allan deviation. >> > > It's also common to have plots saying "Allan Variance" and plotting the > Allan Deviation. > > Since Allan Deviation is the square root of Allan Variance, 2E-11 Allan > Variance is about 4.5E-6 in Allan Deviation so an Allan Deviation of 3E-11 > is better than an Allan Variance of 2E-11... by far. > > Use Allan Deviation through-out. > > Cheers, > Magnus > > > ___ > 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] Allan Variance versus Allan Deviation
On 03/28/2011 09:33 PM, William H. Fite wrote: Magnus is quite right. Variance is almost always just a value on its way to becoming another value. Squared units make little sense in most applications. Bill (the statistician) Variance has it's place, but for most of our uses, stick with the Deviation just to keep things simple. Cheers, Magnus ___ 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] improved WWVB signal being planned?
I thought this was interesting... I don't know if this had been already mentioned here- probably some list members are already part of the process! I wonder if this would be a spread-spectrum code like the GPS signal? "[...] Another idea being actively investigated is to add phase modulation to the existing WWVB signal while leaving the AM BCD code intact. This would allow all existing devices to continue to work, but allow a new generation of radio-controlled clocks to be developed. These new devices would have greater processing gain and therefore be capable of reading the time code with a lower signal-to-noise ratio." from "We Help Move Time Through the Air Managers of WWVB Explore Options to Improve the Service Further" by John Lowe, manager of NIST radio stations WWV/WWVH/WWVB. http://tf.boulder.nist.gov/general/pdf/2504.pdf ___ 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] HP 5065A low serial numbers
Hi Everyone, A while ago I posted for anyone with a 5065A that had a 2816A prefix serial number to try and determine the last HP 5065A sold. Now I'd like to know what the earliest SN anyone has seen. The current winner is SN 0940-00203. If anyone knows of an earlier or similar vintage please let me know! Thanks! Corby Dawson Get Free Email with Video Mail & Video Chat! http://www.juno.com/freeemail?refcd=JUTAGOUT1FREM0210 ___ 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] Allan Deviation
Hi, Thanks for the answers but I'm still confused. The Stanford PRS10 has an Allan Variance of 2E-11 but a Symmetricomm unit has a Allan Deviation of 3E-11. So according to the answers you gave, the Symmetricomm unit has a stability thousands of times better than the PRS10. This, dispite the Symmetricon unit having 25 to 40 dB worse phase phase noise than the PRS10 (at 1 and 10 Hz offsets). Surely that's not possible since the PRS10 is pretty good in the first place. Steve ___ 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] improved WWVB signal being planned?
Nope never heard about this it makes sense many of the cw signals for the navy and such moved to either msk or psk a long time ago. It would effectively screw up the old receivers like the HP 117, Tracor 599 and several others as frequency references. But I would agree that PSK might indeed allow additional processing gain and hopefully a steady carrier for frequency reference could be regenerated. Regards Paul WB8TSL On Mon, Mar 28, 2011 at 5:02 PM, beale wrote: > I thought this was interesting... I don't know if this had been already > mentioned here- probably some list members are already part of the process! > I wonder if this would be a spread-spectrum code like the GPS signal? > > "[...] Another idea being actively investigated is to add phase modulation > to the existing WWVB signal while leaving the AM BCD code intact. This would > allow all existing devices to continue to work, but allow a new generation > of radio-controlled clocks to be developed. These new devices would have > greater processing gain and therefore be capable of reading the time code > with a lower signal-to-noise ratio." > > from "We Help Move Time Through the Air > Managers of WWVB Explore Options to Improve the Service Further" > by John Lowe, manager of NIST radio stations WWV/WWVH/WWVB. > http://tf.boulder.nist.gov/general/pdf/2504.pdf > > ___ > 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] Allan Deviation
Martyn Smith wrote: Hi, Thanks for the answers but I'm still confused. The Stanford PRS10 has an Allan Variance of 2E-11 but a Symmetricomm unit has a Allan Deviation of 3E-11. So according to the answers you gave, the Symmetricomm unit has a stability thousands of times better than the PRS10. This, dispite the Symmetricon unit having 25 to 40 dB worse phase phase noise than the PRS10 (at 1 and 10 Hz offsets). Surely that's not possible since the PRS10 is pretty good in the first place. Steve The PRS10 specs say Allan Variance but the actual figures given are for its Allan Deviation. No rubidium commercial standard is as noisy as their specs would otherwise imply. This error is still surprisingly common. Bruce ___ 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] improved WWVB signal being planned?
On 03/28/2011 11:52 PM, paul swed wrote: Nope never heard about this it makes sense many of the cw signals for the navy and such moved to either msk or psk a long time ago. It would effectively screw up the old receivers like the HP 117, Tracor 599 and several others as frequency references. But I would agree that PSK might indeed allow additional processing gain and hopefully a steady carrier for frequency reference could be regenerated. DCF77 has this, so it should not come as a big surprise. Wonder if they would use the same 511 chip PRBS pattern or not. Cheers, Magnus ___ 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] WWVB PPS clock pulse ?
On 3/28/2011 9:46 AM, Lenny Story wrote: Greetings, Is there an accepted form for the PPS clock pulses that are produced by the various time equipment in use today ? Short answer -- No. Examples: HP GPSDOs like 3801A and 3816A have a positive-going square pulse that is 10's of microseconds long. From the 3801 manual, "1 PPS Output Characteristics Jitter of leading edge: < 200 nanoseconds between pulses. Accumulated time error: < 7 microseconds per day unlocked, for 24 hours, after one day of stabilization and 2 days of locked operation with a fixed antenna location. Waveform: Pulse width 10 to 50 microseconds. Time Accuracy: < 1 microsecond (Locked to GPS) Connector: DBÂ25 (J3)" I just looked at the PPS from my 3816A and it is about 3V into 50 ohms and a bit over 20 uS long. The T-bolt manual says 10 uS wide and can be configured either positive or negative pulse. Looking at the M12 receiver manual, looks like a 6-7 mS pulse. ___ 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] WWVB Measurements using DSP recovery
Yes, your idea is very nice. So, many basement engineers have not moved into the world of programmable DSP concepts, missing some basic breadboard circuit and some example demonstration software to try out. Perhaps your idea would be the perfect tool to inspire and learn from. The general nature of this is very good. Can you show a circuit of what you have done? Would you recommend the 7200 again or something else that is better suited? Many thanks; Greg On 3/28/2011 9:56 AM, Poul-Henning Kamp wrote: In message<4d90b859.2080...@comcast.net>, Greg Broburg writes: There is a method to recover a very weak signal out of the mud that is fairly easy to build. I did this slightly differently: Take a 1MSPS ADC and average it into 1000 buckets in round robin form, one after the other. This can be done very quickly in an interrupt routine or even in hardware. The Aduc72xx family of ARM can do this running a sweat, any DSP would have absolutely no trouble doing it. In Europe use 2000 buckets so you can capture DCF77 also. By multiplying the buckets with a suitable IQ signal, you can pull out any signal of integral kHz frequency you care for, and measure its relative phase and change of phase over time. Here are some experiements I did many years ago with one million buckets, so I could demodulate the second pulses: http://phk.freebsd.dk/loran-c/CW/ I would love to find somebody who can design some proper hardware for this, so that we can have an "VLF-All-band Time/Phase Receiver", basically a receiver you can ask, at any time, "What is the phase of the signal at N kHz, for any value of N you care for. Poul-Henning ___ 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] Upgrading TS2100 from TCXO to OCXO
I think a couple of those bits do correspond to the oscillator type installed but I think you can ignore them. If I remember right, those oscillator bits were only used to calculate the dispersion update for ntp packets when flywheeling through a loss of signal. As far as I recall, you just need to change gain and filter. And the setting for the current d/a value should have been accessible in root tim utils as d2a. As someone pointed out, the default ovenized for those boxes was the MTI 240 low profile. -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Robert Watzlavick Sent: Sunday, March 27, 2011 3:54 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Upgrading TS2100 from TCXO to OCXO If anybody has a TS2100 that came from the factory with an OCXO, can you telnet into the unit and run the following command? root eng ee info This appears to be some sort of factory-configured personality of the board. My TS2100-GPS unit with a TCXO has an info value of 0024. A TS2100-IRIG unit (no GPS) with a TCXO has a value of . I'm curious whether any of those bits correspond to the oscillator type or if all that needs to be changed is the gain. Thanks, -Bob ___ 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] Upgrading TS2100 from TCXO to OCXO
I have MTI 240s if you need one. Greg On 3/28/2011 6:28 PM, Greg Dowd wrote: I think a couple of those bits do correspond to the oscillator type installed but I think you can ignore them. If I remember right, those oscillator bits were only used to calculate the dispersion update for ntp packets when flywheeling through a loss of signal. As far as I recall, you just need to change gain and filter. And the setting for the current d/a value should have been accessible in root tim utils as d2a. As someone pointed out, the default ovenized for those boxes was the MTI 240 low profile. -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Robert Watzlavick Sent: Sunday, March 27, 2011 3:54 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Upgrading TS2100 from TCXO to OCXO If anybody has a TS2100 that came from the factory with an OCXO, can you telnet into the unit and run the following command? root eng ee info This appears to be some sort of factory-configured personality of the board. My TS2100-GPS unit with a TCXO has an info value of 0024. A TS2100-IRIG unit (no GPS) with a TCXO has a value of . I'm curious whether any of those bits correspond to the oscillator type or if all that needs to be changed is the gain. Thanks, -Bob ___ 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] improved WWVB signal being planned?
I'm concerned that, in their quest to address the needs of the general public's radio clocks, NIST might overlook the frequency standards needs of our metrology community. (Unless the metrology community provides adequate feedback to NIST *before* it might be too late?) According to their interpretations of ISO/IEC 17025, many customers require metrology labs to include inter-comparison procedures for assurance. For example, they might require a GPS disciplined house frequency standard to be cross-checked against another non-GPS frequency standard (for assurance purposes). In the past Loran-C served this need well as the alternate source of traceable frequency. But with the demise of Loran-C, WWVB has become more important for this purpose. Yes, we know that GPS out-performs WWVB for frequency; but within a stated uncertainty (that's adequate for many purposes), WWVB still supplies the alternate source of traceable frequency comparison. Do any of the resident gurus of this list have opinions as to whether or not NIST's proposals might exclude WWVB as a source of traceable frequency comparisons? At least, I think it prudent that some of us let NIST know that we're still relying on WWVB for traceable frequency comparison systems. Greg - Original Message - From: "beale" To: Sent: Monday, March 28, 2011 3:02 PM Subject: [time-nuts] improved WWVB signal being planned? I thought this was interesting... I don't know if this had been already mentioned here- probably some list members are already part of the process! I wonder if this would be a spread-spectrum code like the GPS signal? "[...] Another idea being actively investigated is to add phase modulation to the existing WWVB signal while leaving the AM BCD code intact. This would allow all existing devices to continue to work, but allow a new generation of radio-controlled clocks to be developed. These new devices would have greater processing gain and therefore be capable of reading the time code with a lower signal-to-noise ratio." from "We Help Move Time Through the Air Managers of WWVB Explore Options to Improve the Service Further" by John Lowe, manager of NIST radio stations WWV/WWVH/WWVB. http://tf.boulder.nist.gov/general/pdf/2504.pdf ___ 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] Upgrading TS2100 from TCXO to OCXO
That's good to know. I've been running the TS2100 for a few days with a Morian MV89A (too big to fit into the case though) and it seems to work well, definitely more stable than the TCXO. A test that I haven't run yet is to pull the GPS antenna and see how long the NTP server reports Stratum 1 performance and what the dispersion values are. You're correct about the d/a setting - it seems all you have to is set it and it stores it in NVRAM. -Bob On 03/28/2011 07:28 PM, Greg Dowd wrote: I think a couple of those bits do correspond to the oscillator type installed but I think you can ignore them. If I remember right, those oscillator bits were only used to calculate the dispersion update for ntp packets when flywheeling through a loss of signal. As far as I recall, you just need to change gain and filter. And the setting for the current d/a value should have been accessible in root tim utils as d2a. As someone pointed out, the default ovenized for those boxes was the MTI 240 low profile. -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Robert Watzlavick Sent: Sunday, March 27, 2011 3:54 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Upgrading TS2100 from TCXO to OCXO If anybody has a TS2100 that came from the factory with an OCXO, can you telnet into the unit and run the following command? root eng ee info This appears to be some sort of factory-configured personality of the board. My TS2100-GPS unit with a TCXO has an info value of 0024. A TS2100-IRIG unit (no GPS) with a TCXO has a value of . I'm curious whether any of those bits correspond to the oscillator type or if all that needs to be changed is the gain. Thanks, -Bob ___ 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] Allan Variance versus Allan Deviation
On Mar 28, 2011, at 12:33 PM, "William H. Fite" wrote: > Magnus is quite right. Variance is almost always just a value on its way to > becoming another value. Squared units make little sense in most > applications. > The exception that springs to mind is noise power, which is the variance, as opposed to the ms noise voltage ___ 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] WWVB Measurements using DSP recovery
In message <4d9129d8.4060...@comcast.net>, Greg Broburg writes: >Can you show a circuit of what you have done? Basically I have a 20MSPS PCI card in a PC and do it all in software. I did use similar principles to implement a LORAN-C receiver in a aduc7216 (http://phk.freebsd.dk/AducLoran/) but that is passe for US people now. >Would you recommend the 7200 again or something >else that is better suited? The most user friendly way to do it, would be to have a small FPGA which takes data from the ADC and averages it into a small piece of multiplext or dual port RAM, and a microcontroller (ARM ?) on the other port, doing all the high level stuff. That way there is no real-time component to deal with in the programming, and anybody should be able to play with the code. The alternative is to use a DSP to read the ADC, do the averaging and perform the high level functions. That would be a lot harder to program for most people. The ADC could be 16 bits, and run directly from a house standard of 5 or 10 MHz (looks like that would cost $4 from analog.com, isn't this future amazing ?) Add a high resolution DAC for steering OCXO's and a serial port or USB interface and we're done... -- 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.
