Re: [time-nuts] Zero-Crossing Detector Design?
For the specific application of driving an FPGA clock pin (that has an enormous input bandwidth) many things can go wrong. All fine about the advantages and disadvantages of the gate with resistor feedback, all I can say is that over here I it was not the best solution we found over many FPGA board versions with external clock. The latest design and the one we keep using standard now, uses a differential pair of PNP transistors (BFT91), this will have a moderate gain of x10 or so and the resistors set for making a limited wave of 0 to 3.0V (simple change of resistors can make it 0-2.0V or else required). we use a 100MHz narrow band limited bandwidth sin signal so no filter added, but we could add if we need one. The output signal into the FPGA looks very clean and has a few ns rise and fall times (not super steep, but the fpga input does the rest. It does depend also on the resistor values and current used in the transistor pair). This was the way we could get the very minimum clock jitter in the FPGA and a simple circuit quite tolerant to input levels and make a very clean and well defined signal into the FPGA. Way better than 74F or 74LV gates etc. The only inconvenience is that it needs +5V for the circuit to work (the VCCIO of +3.3V is not enough). My 2 euro cents ;-) Luis Cupido ct1dmk. On 7/22/2012 9:32 PM, Bill Fuqua wrote: Wow, I have not checked this list for some time. But there is a lot said about zero crossing detectors. Lots and lots of replies, so many that I have not looked at all of them. 1. Do not use CMOS inverters. Even though so much has been published on using these in linear mode by adding a feedback resistor, they can be a nightmare. The fast ones (74HC, 74AC, etc) have so much high frequency gain they are likely to take off into oscillation on their own. 2. The first thing you can do to get a good clean zero crossing is to reduce the noise. This means to pass it thru a narrow band pass filter such as a crystal filter. The narrower this filter is the closer to a pure sinewave it becomes and the less noise you have. 3. In research when we want a precise trigger we use what is called a constant fraction discriminator. This may not be needed if you have a very clean signal and its amplitude does not vary and you are wanting to trigger exactly at zero. But a constant fraction discriminator triggers on a point that is a constant fraction of the amplitude of the signal. They require a delay so that a fraction of the peak of the cycle can be compared with the rising edge of that cycle. This is mostly used with triggering on pulses of varying heights and when subnanosecond timing is required. My suggestion is to clean up your signal as much as possible and reduce noise bandwidth using a bandpass filter and then use a low noise amplifier for the front end of your zero-crossing detector. 73 Bill wa4lav ___ 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] Zero-Crossing Detector Design?
Hi Did you try running it at 3.3V and going into an LVDS input on the FPGA? Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of ct1dmk Sent: Monday, July 23, 2012 7:26 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Zero-Crossing Detector Design? For the specific application of driving an FPGA clock pin (that has an enormous input bandwidth) many things can go wrong. All fine about the advantages and disadvantages of the gate with resistor feedback, all I can say is that over here I it was not the best solution we found over many FPGA board versions with external clock. The latest design and the one we keep using standard now, uses a differential pair of PNP transistors (BFT91), this will have a moderate gain of x10 or so and the resistors set for making a limited wave of 0 to 3.0V (simple change of resistors can make it 0-2.0V or else required). we use a 100MHz narrow band limited bandwidth sin signal so no filter added, but we could add if we need one. The output signal into the FPGA looks very clean and has a few ns rise and fall times (not super steep, but the fpga input does the rest. It does depend also on the resistor values and current used in the transistor pair). This was the way we could get the very minimum clock jitter in the FPGA and a simple circuit quite tolerant to input levels and make a very clean and well defined signal into the FPGA. Way better than 74F or 74LV gates etc. The only inconvenience is that it needs +5V for the circuit to work (the VCCIO of +3.3V is not enough). My 2 euro cents ;-) Luis Cupido ct1dmk. On 7/22/2012 9:32 PM, Bill Fuqua wrote: > Wow, I have not checked this list for some time. But there is a lot said > about zero crossing detectors. > Lots and lots of replies, so many that I have not looked at all of them. > 1. Do not use CMOS inverters. Even though so much has been published on > using these in linear mode by > adding a feedback resistor, they can be a nightmare. The fast ones > (74HC, 74AC, etc) have so much high frequency gain they are > likely to take off into oscillation on their own. > 2. The first thing you can do to get a good clean zero crossing is to > reduce the noise. This means to pass it > thru a narrow band pass filter such as a crystal filter. The narrower > this filter is the closer to a pure sinewave it becomes > and the less noise you have. > 3. In research when we want a precise trigger we use what is called a > constant fraction discriminator. > This may not be needed if you have a very clean signal and its amplitude > does not vary and you are wanting to > trigger exactly at zero. But a constant fraction discriminator triggers > on a point that is a constant fraction of the > amplitude of the signal. They require a delay so that a fraction of the > peak of the cycle can be compared with the rising edge > of that cycle. This is mostly used with triggering on pulses of varying > heights and when subnanosecond > timing is required. > > My suggestion is to clean up your signal as much as possible and reduce > noise bandwidth using a bandpass filter and > then use a low noise amplifier for the front end of your zero-crossing > detector. > > 73 > Bill wa4lav > > > > ___ > 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] Zero-Crossing Detector Design?
Hi Bob, No, never tried but it looks a good idea. Our boards all have 5v so there was never any pressure... ... for a 0.5v in the tail resistor to vcc and 0.7v of vbe I could easily allow collectors to swing some 300mv around 1.2V... a couple of resistors more than my single ended solution... but it should work fine from 3v3. Must try that. tks, lc ct1dmk, On 7/23/2012 12:35 PM, Bob Camp wrote: Hi Did you try running it at 3.3V and going into an LVDS input on the FPGA? Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of ct1dmk Sent: Monday, July 23, 2012 7:26 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Zero-Crossing Detector Design? For the specific application of driving an FPGA clock pin (that has an enormous input bandwidth) many things can go wrong. All fine about the advantages and disadvantages of the gate with resistor feedback, all I can say is that over here I it was not the best solution we found over many FPGA board versions with external clock. The latest design and the one we keep using standard now, uses a differential pair of PNP transistors (BFT91), this will have a moderate gain of x10 or so and the resistors set for making a limited wave of 0 to 3.0V (simple change of resistors can make it 0-2.0V or else required). we use a 100MHz narrow band limited bandwidth sin signal so no filter added, but we could add if we need one. The output signal into the FPGA looks very clean and has a few ns rise and fall times (not super steep, but the fpga input does the rest. It does depend also on the resistor values and current used in the transistor pair). This was the way we could get the very minimum clock jitter in the FPGA and a simple circuit quite tolerant to input levels and make a very clean and well defined signal into the FPGA. Way better than 74F or 74LV gates etc. The only inconvenience is that it needs +5V for the circuit to work (the VCCIO of +3.3V is not enough). My 2 euro cents ;-) Luis Cupido ct1dmk. On 7/22/2012 9:32 PM, Bill Fuqua wrote: Wow, I have not checked this list for some time. But there is a lot said about zero crossing detectors. Lots and lots of replies, so many that I have not looked at all of them. 1. Do not use CMOS inverters. Even though so much has been published on using these in linear mode by adding a feedback resistor, they can be a nightmare. The fast ones (74HC, 74AC, etc) have so much high frequency gain they are likely to take off into oscillation on their own. 2. The first thing you can do to get a good clean zero crossing is to reduce the noise. This means to pass it thru a narrow band pass filter such as a crystal filter. The narrower this filter is the closer to a pure sinewave it becomes and the less noise you have. 3. In research when we want a precise trigger we use what is called a constant fraction discriminator. This may not be needed if you have a very clean signal and its amplitude does not vary and you are wanting to trigger exactly at zero. But a constant fraction discriminator triggers on a point that is a constant fraction of the amplitude of the signal. They require a delay so that a fraction of the peak of the cycle can be compared with the rising edge of that cycle. This is mostly used with triggering on pulses of varying heights and when subnanosecond timing is required. My suggestion is to clean up your signal as much as possible and reduce noise bandwidth using a bandpass filter and then use a low noise amplifier for the front end of your zero-crossing detector. 73 Bill wa4lav ___ 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.
[time-nuts] Trimble T Lassen 2 - suitable antenna....advice.....questions
Hi Guys, I have a couple of Trimble T Lassen 2 boards I bought at a Hamfest - the guy told me they were left over from a contract he had and were brand new. He had a load and i bought a couple for use as a precision 1 PPS output for radio stuff. They were packed in static protection. When I apply power to both units I can hear the oscillator (12.504 MHz) on my comms RX. So I am assuming that they work. I bought what claims to be a Trimble compatible active antenna on EBay. I hooked it up to one of the boards and applied power, and put the scope on the one pps pin. However after 20 mins (which I assume is much longer than the unit requires to get a lock) I see no 1pps trace on the screen. :-( So my working assumption is that the antenna is not working. The antenna position is fine as my elderly Garmin GPS2 which must be 12 years old sees 6 satellites there. Can anyone recommend a suitable antenna? I have a number of DIY designs I can try (Patch, Turnstile) but the Trimble docs say it needs an active antenna so I guess I'll have to spend money :-( While i am on, can anyone suggest a reasonably priced unit that has a 1pps output, NMEA and a built in antenna. Because I want to use this with an 8 bit embedded system I am probably not going to be able to hack one of the many cheap USB dongle GPS's. Lastly, has anyone found a GPS that will work with an Ipad. What the man in the Apple shop failed to tell me was the non 3g model lacked the built in GPS :-( Thanks in advice Steve -- Wisdom demands a new orientation of science and technology towards the organic, the gentle, the non-violent, the elegant and beautiful. E. F. Schumacher ___ 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] Trimble T Lassen 2 - suitableantenna....advice.....questions
Do not be too quick to toss out the antennas. Some receivers need the antenna power to be connected to a pin on the receiver connector that is then internally routed to the antenna. John WA4WDL -- From: "Stephen Farthing" Sent: Monday, July 23, 2012 12:11 PM To: Subject: [time-nuts] Trimble T Lassen 2 - suitableantennaadvice.questions Hi Guys, I have a couple of Trimble T Lassen 2 boards I bought at a Hamfest - the guy told me they were left over from a contract he had and were brand new. He had a load and i bought a couple for use as a precision 1 PPS output for radio stuff. They were packed in static protection. When I apply power to both units I can hear the oscillator (12.504 MHz) on my comms RX. So I am assuming that they work. I bought what claims to be a Trimble compatible active antenna on EBay. I hooked it up to one of the boards and applied power, and put the scope on the one pps pin. However after 20 mins (which I assume is much longer than the unit requires to get a lock) I see no 1pps trace on the screen. :-( So my working assumption is that the antenna is not working. The antenna position is fine as my elderly Garmin GPS2 which must be 12 years old sees 6 satellites there. Can anyone recommend a suitable antenna? I have a number of DIY designs I can try (Patch, Turnstile) but the Trimble docs say it needs an active antenna so I guess I'll have to spend money :-( While i am on, can anyone suggest a reasonably priced unit that has a 1pps output, NMEA and a built in antenna. Because I want to use this with an 8 bit embedded system I am probably not going to be able to hack one of the many cheap USB dongle GPS's. Lastly, has anyone found a GPS that will work with an Ipad. What the man in the Apple shop failed to tell me was the non 3g model lacked the built in GPS :-( Thanks in advice Steve -- Wisdom demands a new orientation of science and technology towards the organic, the gentle, the non-violent, the elegant and beautiful. E. F. Schumacher ___ 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] Trimble T Lassen 2 - suitableantenna....advice.....questions
...And don't forget that the PPS pulse is very narrow so you have to use a 'scope with memory, a digital 'scope or turn the brightness at max. On Mon, Jul 23, 2012 at 6:31 PM, jmfranke wrote: > Do not be too quick to toss out the antennas. Some receivers need the > antenna power to be connected to a pin on the receiver connector that is > then internally routed to the antenna. > > John WA4WDL > > -- > From: "Stephen Farthing" > Sent: Monday, July 23, 2012 12:11 PM > To: > Subject: [time-nuts] Trimble T Lassen 2 - > suitableantennaadvice.questions > > > Hi Guys, >> >> I have a couple of Trimble T Lassen 2 boards I bought at a Hamfest - >> the guy told me they were left over from a contract he had and were >> brand new. He had a load and i bought a couple for use as a precision >> 1 PPS output for radio stuff. They were packed in static protection. >> When I apply power to both units I can hear the oscillator (12.504 >> MHz) on my comms RX. So I am assuming that they work. >> >> I bought what claims to be a Trimble compatible active antenna on >> EBay. I hooked it up to one of the boards and applied power, and put >> the scope on the one pps pin. However after 20 mins (which I assume is >> much longer than the unit requires to get a lock) I see no 1pps trace >> on the screen. :-( >> >> So my working assumption is that the antenna is not working. The >> antenna position is fine as my elderly Garmin GPS2 which must be 12 >> years old sees 6 satellites there. >> >> Can anyone recommend a suitable antenna? I have a number of DIY >> designs I can try (Patch, Turnstile) but the Trimble docs say it needs >> an active antenna so I guess I'll have to spend money :-( >> >> While i am on, can anyone suggest a reasonably priced unit that has a >> 1pps output, NMEA and a built in antenna. Because I want to use this >> with an 8 bit embedded system I am probably not going to be able to >> hack one of the many cheap USB dongle GPS's. >> >> Lastly, has anyone found a GPS that will work with an Ipad. What the >> man in the Apple shop failed to tell me was the non 3g model lacked >> the built in GPS :-( >> >> Thanks in advice >> >> Steve >> >> >> >> -- >> Wisdom demands a new orientation of science and technology towards the >> organic, the gentle, the non-violent, the elegant and beautiful. E. F. >> Schumacher >> >> ___ >> 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] Trimble T Lassen 2 - suitableantenna....advice.....questions
I wass fooled by this too. My analog scope does not sync on athe1Hz pulse. You have to breadboard something that will detect it, maybe a flip flop and then look at the FF's output. On Mon, Jul 23, 2012 at 9:49 AM, Azelio Boriani wrote: > ...And don't forget that the PPS pulse is very narrow so you have to use a > 'scope with memory, a digital 'scope or turn the brightness at max. > > On Mon, Jul 23, 2012 at 6:31 PM, jmfranke wrote: > >> Do not be too quick to toss out the antennas. Some receivers need the >> antenna power to be connected to a pin on the receiver connector that is >> then internally routed to the antenna. >> >> John WA4WDL >> >> -- >> From: "Stephen Farthing" >> Sent: Monday, July 23, 2012 12:11 PM >> To: >> Subject: [time-nuts] Trimble T Lassen 2 - >> suitableantennaadvice.questions >> >> >> Hi Guys, >>> >>> I have a couple of Trimble T Lassen 2 boards I bought at a Hamfest - >>> the guy told me they were left over from a contract he had and were >>> brand new. He had a load and i bought a couple for use as a precision >>> 1 PPS output for radio stuff. They were packed in static protection. >>> When I apply power to both units I can hear the oscillator (12.504 >>> MHz) on my comms RX. So I am assuming that they work. >>> >>> I bought what claims to be a Trimble compatible active antenna on >>> EBay. I hooked it up to one of the boards and applied power, and put >>> the scope on the one pps pin. However after 20 mins (which I assume is >>> much longer than the unit requires to get a lock) I see no 1pps trace >>> on the screen. :-( >>> >>> So my working assumption is that the antenna is not working. The >>> antenna position is fine as my elderly Garmin GPS2 which must be 12 >>> years old sees 6 satellites there. >>> >>> Can anyone recommend a suitable antenna? I have a number of DIY >>> designs I can try (Patch, Turnstile) but the Trimble docs say it needs >>> an active antenna so I guess I'll have to spend money :-( >>> >>> While i am on, can anyone suggest a reasonably priced unit that has a >>> 1pps output, NMEA and a built in antenna. Because I want to use this >>> with an 8 bit embedded system I am probably not going to be able to >>> hack one of the many cheap USB dongle GPS's. >>> >>> Lastly, has anyone found a GPS that will work with an Ipad. What the >>> man in the Apple shop failed to tell me was the non 3g model lacked >>> the built in GPS :-( >>> >>> Thanks in advice >>> >>> Steve >>> >>> >>> >>> -- >>> Wisdom demands a new orientation of science and technology towards the >>> organic, the gentle, the non-violent, the elegant and beautiful. E. F. >>> Schumacher >>> >>> ___ >>> 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. -- 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.
Re: [time-nuts] Trimble T Lassen 2 - suitableantenna....advice.....questions
The pulse from my T-Bolt is on the order of 1uS wide. I captured it on the digital scope for posterity and future reference. http://www.fastbobs.com/pictures/1pps.jpg Bob On Mon, Jul 23, 2012 at 12:58 PM, Chris Albertson wrote: > I wass fooled by this too. My analog scope does not sync on athe1Hz > pulse. You have to breadboard something that will detect it, maybe a > flip flop and then look at the FF's output. > > On Mon, Jul 23, 2012 at 9:49 AM, Azelio Boriani > wrote: > > ...And don't forget that the PPS pulse is very narrow so you have to use > a > > 'scope with memory, a digital 'scope or turn the brightness at max. > > > > On Mon, Jul 23, 2012 at 6:31 PM, jmfranke wrote: > > > >> Do not be too quick to toss out the antennas. Some receivers need the > >> antenna power to be connected to a pin on the receiver connector that is > >> then internally routed to the antenna. > >> > >> John WA4WDL > >> > >> -- > >> From: "Stephen Farthing" > >> Sent: Monday, July 23, 2012 12:11 PM > >> To: > >> Subject: [time-nuts] Trimble T Lassen 2 - > >> suitableantennaadvice.questions > >> > >> > >> Hi Guys, > >>> > >>> I have a couple of Trimble T Lassen 2 boards I bought at a Hamfest - > >>> the guy told me they were left over from a contract he had and were > >>> brand new. He had a load and i bought a couple for use as a precision > >>> 1 PPS output for radio stuff. They were packed in static protection. > >>> When I apply power to both units I can hear the oscillator (12.504 > >>> MHz) on my comms RX. So I am assuming that they work. > >>> > >>> I bought what claims to be a Trimble compatible active antenna on > >>> EBay. I hooked it up to one of the boards and applied power, and put > >>> the scope on the one pps pin. However after 20 mins (which I assume is > >>> much longer than the unit requires to get a lock) I see no 1pps trace > >>> on the screen. :-( > >>> > >>> So my working assumption is that the antenna is not working. The > >>> antenna position is fine as my elderly Garmin GPS2 which must be 12 > >>> years old sees 6 satellites there. > >>> > >>> Can anyone recommend a suitable antenna? I have a number of DIY > >>> designs I can try (Patch, Turnstile) but the Trimble docs say it needs > >>> an active antenna so I guess I'll have to spend money :-( > >>> > >>> While i am on, can anyone suggest a reasonably priced unit that has a > >>> 1pps output, NMEA and a built in antenna. Because I want to use this > >>> with an 8 bit embedded system I am probably not going to be able to > >>> hack one of the many cheap USB dongle GPS's. > >>> > >>> Lastly, has anyone found a GPS that will work with an Ipad. What the > >>> man in the Apple shop failed to tell me was the non 3g model lacked > >>> the built in GPS :-( > >>> > >>> Thanks in advice > >>> > >>> Steve > >>> > >>> > >>> > >>> -- > >>> Wisdom demands a new orientation of science and technology towards the > >>> organic, the gentle, the non-violent, the elegant and beautiful. E. F. > >>> Schumacher > >>> > >>> ___ > >>> 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. > > > > -- > > 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 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] Trimble T Lassen 2 - suitableantenna....advice.....questions
Wow, that is indeed narrow. Only 1us out of a 1 second rep rate. That is one millionth of the rep rate. No wonder analog scopes will not catch it. I'll have to try it some time. Regards - Mike Mike B. Feher, EOZ Inc. 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 office 908-902-3831 cell -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob Bownes Sent: Monday, July 23, 2012 1:06 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Trimble T Lassen 2 - suitableantennaadvice.questions The pulse from my T-Bolt is on the order of 1uS wide. I captured it on the digital scope for posterity and future reference. http://www.fastbobs.com/pictures/1pps.jpg 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.
Re: [time-nuts] time-nuts Digest, Vol 96, Issue 89
Guys, Thanks for all the advice. I'll let you know how it goes... Steve On 23 July 2012 18:06, wrote: > Send time-nuts mailing list submissions to > time-nuts@febo.com > > To subscribe or unsubscribe via the World Wide Web, visit > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > or, via email, send a message with subject or body 'help' to > time-nuts-requ...@febo.com > > You can reach the person managing the list at > time-nuts-ow...@febo.com > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of time-nuts digest..." > > > Today's Topics: > >1. Re: Zero-Crossing Detector Design? (ct1dmk) >2. Trimble T Lassen 2 - suitable antennaadvice.questions > (Stephen Farthing) >3. Re: Trimble T Lassen 2 - > suitableantennaadvice.questions (jmfranke) >4. Re: Trimble T Lassen 2 - > suitableantennaadvice.questions (Azelio Boriani) >5. Re: Trimble T Lassen 2 - > suitableantennaadvice.questions (Chris Albertson) >6. Re: Trimble T Lassen 2 - > suitableantennaadvice.questions (Bob Bownes) > > > -- > > Message: 1 > Date: Mon, 23 Jul 2012 13:37:25 +0100 > From: ct1dmk > To: Discussion of precise time and frequency measurement > > Subject: Re: [time-nuts] Zero-Crossing Detector Design? > Message-ID: <500d4585.8080...@gmail.com> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > Hi Bob, > > No, never tried but it looks a good idea. > Our boards all have 5v so there was never any pressure... > > ... for a 0.5v in the tail resistor to vcc and 0.7v of vbe > I could easily allow collectors to swing some 300mv around 1.2V... > > a couple of resistors more than my single ended solution... > but it should work fine from 3v3. Must try that. tks, > > lc > ct1dmk, > > > > > On 7/23/2012 12:35 PM, Bob Camp wrote: >> Hi >> >> Did you try running it at 3.3V and going into an LVDS input on the FPGA? >> >> Bob >> >> -Original Message- >> From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On >> Behalf Of ct1dmk >> Sent: Monday, July 23, 2012 7:26 AM >> To: Discussion of precise time and frequency measurement >> Subject: Re: [time-nuts] Zero-Crossing Detector Design? >> >> For the specific application of driving an FPGA clock pin (that has an >> enormous input bandwidth) many things can go wrong. >> All fine about the advantages and disadvantages of >> the gate with resistor feedback, all I can say is that over here I it >> was not the best solution >> we found over many FPGA board versions with external clock. >> The latest design and the one we keep using standard now, uses a >> differential pair of PNP >> transistors (BFT91), this will have a moderate gain of x10 or so and the >> resistors set >> for making a limited wave of 0 to 3.0V (simple change of resistors can >> make it 0-2.0V >> or else required). we use a 100MHz narrow band limited bandwidth sin >> signal so no filter >> added, but we could add if we need one. >> The output signal into the FPGA looks very clean and has a few ns rise >> and fall times >> (not super steep, but the fpga input does the rest. It does depend also >> on the resistor values and current used in the transistor pair). >> This was the way we could get the very minimum clock jitter in the FPGA >> and a >> simple circuit quite tolerant to input levels and make a very clean and >> well defined signal >> into the FPGA. Way better than 74F or 74LV gates etc. >> The only inconvenience is that it needs +5V for the circuit to work (the >> VCCIO of +3.3V is not enough). >> >> My 2 euro cents ;-) >> >> Luis Cupido >> ct1dmk. >> >> >> On 7/22/2012 9:32 PM, Bill Fuqua wrote: >>> Wow, I have not checked this list for some time. But there is a lot said >>> about zero crossing detectors. >>> Lots and lots of replies, so many that I have not looked at all of them. >>> 1. Do not use CMOS inverters. Even though so much has been published on >>> using these in linear mode by >>> adding a feedback resistor, they can be a nightmare. The fast ones >>> (74HC, 74AC, etc) have so much high frequency gain they are >>> likely to take off into oscillation on their own. >>> 2. The first thing you can do to get a good clean zero crossing is to >>> reduce the noise. This means to pass it >>> thru a narrow band pass filter such as a crystal filter. The narrower >>> this filter is the closer to a pure sinewave it becomes >>> and the less noise you have. >>> 3. In research when we want a precise trigger we use what is called a >>> constant fraction discriminator. >>> This may not be needed if you have a very clean signal and its amplitude >>> does not vary and you are wanting to >>> trigger exactly at zero. But a constant fraction discriminator triggers >>> on a point that is a constant fraction of the >>> amplitude of the signal. They require a
Re: [time-nuts] Trimble T Lassen 2 - suitable antenna....advice.....questions
squir...@gmail.com said: > While i am on, can anyone suggest a reasonably priced unit that has a 1pps > output, NMEA and a built in antenna. Because I want to use this with an 8 > bit embedded system I am probably not going to be able to hack one of the > many cheap USB dongle GPS's. Garmin GPS 18x-LVC GlobalSat MR-350 http://support.ntp.org/bin/view/Support/InexpensiveOemGps azelio.bori...@screen.it said: > ...And don't forget that the PPS pulse is very narrow so you have to use a > 'scope with memory, a digital 'scope or turn the brightness at max. Most scopes that I've used have some sort of indication if they are/aren't getting triggered, so even if you can't see the pulse you can tell if there is a pulse there. Sometimes, it helps to run in Triggered mode rather than Auto. If you are using Auto, at least with the Rigol DS1102E, it may take a while to lock up. I assume it searches for a while, doesn't find anything, so it stops to display the current buffer. While it is stopped, the pulse happens. I don't know how big the blind spot is, but it takes several seconds to show a PPS signal. Works fine in Triggered mode as long as you are happy without seeing anything when the trigger doesn't happen. bow...@gmail.com said: > The pulse from my T-Bolt is on the order of 1uS wide. Interesting. Mine is 10 uS wide. Rev E, 5/31/05 -- 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.
Re: [time-nuts] Trimble T Lassen 2
And here it goes again for about the umpteenth time, how to detect the presents of a short low rep rate pulse. This can be done with ANY analog scope by using the "normal trigger mode" and setting the trigger correctly. An analog scope can detect the presents of any short pulse no matter how low it's rep rate is, so long as the pulse is wide enough that it is in the scope's (trigger) bandwidth. Under 5ns for a 100 MHz scope. So detecting if there is a very short pulse even once every 10 or 100 seconds sec is NO problem. Now measuring how wide the pulse really is, that is a problem for an analog scope. ** Wow, that is indeed narrow. Only 1us out of a 1 second rep rate. That is one millionth of the rep rate. No wonder analog scopes will not catch it. I'll have to try it some time. Regards The pulse from my T-Bolt is on the order of 1uS wide. I captured it on the digital scope for posterity and future reference. *** I was fooled by this too. My analog scope does not sync on the 1Hz pulse. You have to breadboard something that will detect it, maybe a flip flop and then look at the FF's output. * ...And don't forget that the PPS pulse is very narrow so you have to use a 'scope with memory, a digital 'scope or turn the brightness at max. ___ 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] Zero-Crossing Detector Design?
Hi The nice thing about going into the LVDS inputs is that you are differential right at the FPGA. Often that's where a *lot* of junk is running around. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of ct1dmk Sent: Monday, July 23, 2012 8:37 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Zero-Crossing Detector Design? Hi Bob, No, never tried but it looks a good idea. Our boards all have 5v so there was never any pressure... ... for a 0.5v in the tail resistor to vcc and 0.7v of vbe I could easily allow collectors to swing some 300mv around 1.2V... a couple of resistors more than my single ended solution... but it should work fine from 3v3. Must try that. tks, lc ct1dmk, On 7/23/2012 12:35 PM, Bob Camp wrote: > Hi > > Did you try running it at 3.3V and going into an LVDS input on the FPGA? > > Bob > > -Original Message- > From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On > Behalf Of ct1dmk > Sent: Monday, July 23, 2012 7:26 AM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] Zero-Crossing Detector Design? > > For the specific application of driving an FPGA clock pin (that has an > enormous input bandwidth) many things can go wrong. > All fine about the advantages and disadvantages of > the gate with resistor feedback, all I can say is that over here I it > was not the best solution > we found over many FPGA board versions with external clock. > The latest design and the one we keep using standard now, uses a > differential pair of PNP > transistors (BFT91), this will have a moderate gain of x10 or so and the > resistors set > for making a limited wave of 0 to 3.0V (simple change of resistors can > make it 0-2.0V > or else required). we use a 100MHz narrow band limited bandwidth sin > signal so no filter > added, but we could add if we need one. > The output signal into the FPGA looks very clean and has a few ns rise > and fall times > (not super steep, but the fpga input does the rest. It does depend also > on the resistor values and current used in the transistor pair). > This was the way we could get the very minimum clock jitter in the FPGA > and a > simple circuit quite tolerant to input levels and make a very clean and > well defined signal > into the FPGA. Way better than 74F or 74LV gates etc. > The only inconvenience is that it needs +5V for the circuit to work (the > VCCIO of +3.3V is not enough). > > My 2 euro cents ;-) > > Luis Cupido > ct1dmk. > > > On 7/22/2012 9:32 PM, Bill Fuqua wrote: >> Wow, I have not checked this list for some time. But there is a lot said >> about zero crossing detectors. >> Lots and lots of replies, so many that I have not looked at all of them. >> 1. Do not use CMOS inverters. Even though so much has been published on >> using these in linear mode by >> adding a feedback resistor, they can be a nightmare. The fast ones >> (74HC, 74AC, etc) have so much high frequency gain they are >> likely to take off into oscillation on their own. >> 2. The first thing you can do to get a good clean zero crossing is to >> reduce the noise. This means to pass it >> thru a narrow band pass filter such as a crystal filter. The narrower >> this filter is the closer to a pure sinewave it becomes >> and the less noise you have. >> 3. In research when we want a precise trigger we use what is called a >> constant fraction discriminator. >> This may not be needed if you have a very clean signal and its amplitude >> does not vary and you are wanting to >> trigger exactly at zero. But a constant fraction discriminator triggers >> on a point that is a constant fraction of the >> amplitude of the signal. They require a delay so that a fraction of the >> peak of the cycle can be compared with the rising edge >> of that cycle. This is mostly used with triggering on pulses of varying >> heights and when subnanosecond >> timing is required. >> >> My suggestion is to clean up your signal as much as possible and reduce >> noise bandwidth using a bandpass filter and >> then use a low noise amplifier for the front end of your zero-crossing >> detector. >> >> 73 >> Bill wa4lav >> >> >> >> ___ >> 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
Re: [time-nuts] Trimble T Lassen 2 - suitableantenna....advice.....questions
My old '465 will trigger on the 1pps, but it's far easier to see the trigger LED flash than finesse the brightness/sweep to make it visible - something possible only on a 'scope with a decently bright tube. Another cheap/easy trick to detect the 1pps pulse is simply to "listen" to it with an audio amplifier. While it can be heard on my Tbolt and '3801 with just a headphone connected, a cheap audio amplifier works better, stretching the pulse out and making an obvious "tick" at the 1 PPS rate. I suppose that a diode/cap (1N914/1000pf) could be used to further stretch it... Clint ___ 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] Trimble T Lassen 2 -suitableantenna....advice.....questions
Set the scope sweep speed to 10 milliseconds per division and then even a dull scope is easy to see. You are looking for trigger events from the 1PPS, not the 1PPS itself. John WA4WDL -- From: "C. Turner" Sent: Monday, July 23, 2012 2:26 PM To: Subject: Re: [time-nuts] Trimble T Lassen 2 -suitableantennaadvice.questions My old '465 will trigger on the 1pps, but it's far easier to see the trigger LED flash than finesse the brightness/sweep to make it visible - something possible only on a 'scope with a decently bright tube. Another cheap/easy trick to detect the 1pps pulse is simply to "listen" to it with an audio amplifier. While it can be heard on my Tbolt and '3801 with just a headphone connected, a cheap audio amplifier works better, stretching the pulse out and making an obvious "tick" at the 1 PPS rate. I suppose that a diode/cap (1N914/1000pf) could be used to further stretch it... Clint ___ 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] Trimble T Lassen 2
That works when there is a trigger LED, OR Just need to slow down the sweep rate to say 10ms / div or slower and then there will be a nice clear, easy to see, can't miss, white line, across ANY scope with each pulse when the scope is triggered by a short low rep input pulse. * My old '465 will trigger on the 1pps, but it's far easier to see the trigger LED flash than finesse the brightness/sweep to make it visible - something possible only on a 'scope with a decently bright tube. ... * Most scopes that I've used have some sort of indication if they are/aren't getting triggered, so even if you can't see the pulse you can tell if there is a pulse there. ... it helps to run in Triggered mode rather than Auto. Works fine in Triggered mode as long as you are happy without seeing anything when the trigger doesn't happen. * This can be done with ANY analog scope by using the "normal trigger mode" and setting the trigger correctly. An analog scope can detect the presents of any short pulse no matter how low it's rep rate is, so long as the pulse is wide enough that it is in the scope's (trigger) bandwidth. Under 5ns for a 100 MHz scope. So detecting if there is a very short pulse even once every 10 or 100 seconds sec is NO problem. Now measuring how wide the pulse really is, that is a problem for an analog scope. ** Wow, that is indeed narrow. Only 1us out of a 1 second rep rate. That is one millionth of the rep rate. No wonder analog scopes will not catch it. I'll have to try it some time. Regards The pulse from my T-Bolt is on the order of 1uS wide. I captured it on the digital scope for posterity and future reference. *** I was fooled by this too. My analog scope does not sync on the 1Hz pulse. You have to breadboard something that will detect it, maybe a flip flop and then look at the FF's output. * ...And don't forget that the PPS pulse is very narrow so you have to use a 'scope with memory, a digital 'scope or turn the brightness at max. ___ 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] Shorthand
Is there a commonly accepted shorthand for a frequency, say 10MHz, generated at the maximum accuracy of the lab generating it? ie instead of writing 10.5MHz? Pete G4GJL ___ 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] Shorthand
Yes, 5E-10, valid for every frequency. On Mon, Jul 23, 2012 at 10:50 PM, wrote: > Is there a commonly accepted shorthand for a frequency, say 10MHz, > generated at the maximum accuracy of the lab generating it? > > ie instead of writing 10.5MHz? > > Pete > G4GJL > ___ > 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] Heather Problem..
I'm having a problem getting Lady Heather up and running with Windows 7.I attempted to change the com port to 3 per KE5FX's web site using the command "C:\Program Files\Heather\heather.exe"/2 and I get an error message that tells me that the command is not valid. What gives? Bud WØLCP Time is only there to prevent everything from happening at once. Einstein ___ 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] Heather Problem..
Hi Bud, the /2 should be inside the quotes as you show it. Of course the quotes are not used in the windows environment. That should be /3 if you are wanting to go to port 3. So your command line, used in the ICON or link, should read: C:\Program Files\Heather\heather.exe /3 Hopefully that is helpful, BillWB6BNQ Bud Patten wrote: > I'm having a problem getting Lady Heather up and running with Windows 7.I > attempted to change the com port to 3 per KE5FX's web site using the command > "C:\Program Files\Heather\heather.exe"/2 and I get an error message that > tells me that the command is not valid. What gives? > > Bud > WØLCP > > Time is only there to prevent > everything from happening at once. > > Einstein > ___ > 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] Heather Problem..
I think you need a space before the /2. "C:\Program Files\Heather\heather.exe" /2 But I could be wrong. Tom - Original Message - From: "Bud Patten" To: Sent: Monday, July 23, 2012 6:00 PM Subject: [time-nuts] Heather Problem.. I'm having a problem getting Lady Heather up and running with Windows 7. I attempted to change the com port to 3 per KE5FX's web site using the command "C:\Program Files\Heather\heather.exe"/2 and I get an error message that tells me that the command is not valid. What gives? Bud WØLCP Time is only there to prevent everything from happening at once. Einstein ___ 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] Shorthand
Hi Pete, Yes, there are several ways to represent frequencies: 1) Absolute units of Hz. For example 60 Hz, or 32.768 kHz, or 3.579545 MHz, or 9.192631770 GHz. Note some modern texts use s⁻¹ (1/s or s-1) instead of Hz or Hertz. Or, you can always show your age and use cps (cycles per second). 2) Arithmetic error from some nominal value. For example 3 Hz above 1 MHz, or 17 Hz below 40 GHz. Your frequency is 10 MHz plus 0.005 Hz, or 5 mHz (milli-Hertz) too high. 3) Relative, or geometric error. For example, 60 Hz with 1% error, or 32.768 kHz with -10 ppm error, or 10 MHz with +0.5 ppb error. Note these errors values are unit-less. The general form is F = F0 x (1 + E) where F0 is the nominal frequency and E is the relative error. In your example 10.5 MHz is 10 MHz x (1 + 0.05). Note carefully the decimal point; 10.000 000 005 MHz is 10 MHz x (1.000 000 000 5) so E = 0.5 ppb. In most cases one need only specify the relative error since F0 is either implied or irrelevant. For example, if you multiplied your oscillator to 1 GHz or divided it down to 1 PPS the relative frequency error would remain 0.5 ppb. 3½) When using percents, ppb (parts per million), or ppb (parts per billion) is not convenient, you can always use scientific notation. So instead of 0.5 ppb (or 500 ppt) it's more common to see 5e-10. This is much more informative than saying "10.5MHz" and making the poor reader count each of the zeros. In summary, 10.5 MHz 5 mHz above 10 MHz +0.5 ppb error +5e-10 /tvb - Original Message - From: To: Sent: Monday, July 23, 2012 1:50 PM Subject: [time-nuts] Shorthand > Is there a commonly accepted shorthand for a frequency, say 10MHz, generated > at the maximum accuracy of the lab generating it? > > ie instead of writing 10.5MHz? > > Pete > G4GJL ___ 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] Heather Problem..
> -Original Message- > From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On > Behalf Of WB6BNQ > Sent: Monday, July 23, 2012 3:07 PM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] Heather Problem.. > > Hi Bud, > > the /2 should be inside the quotes as you show it. Of course the quotes are not > used in the windows environment. That should be /3 if you are wanting to go to > port 3. So your command line, used in the ICON or link, should read: > > C:\Program Files\Heather\heather.exe /3 Actually that's not the case; the quotes are required anytime a pathname with spaces is used. Otherwise there would be no easy way for the OS to tell where the filename stops and any command-line parameters begin. If it weren't for the space in the "Program Files" subdirectory name, the quotes wouldn't be needed at all. So in the case of Heather, yes, you do need the quotes for Windows' benefit, and you also need a space after the closing quote for Heather's benefit. (Pro tip: If you know that your Program Files directory has the short name progra~1, you could change the shortcut to use c:\progra~1\heather\heather.exe and dispense with the quotes. This hack is less straightforward now that 64-bit versions of Windows use "Program Files (x86)" for legacy 32-bit software like LH. On my system, Heather ends up in c:\progra~2\heather\heather.exe.) -- john, KE5FX ___ 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] Heather Problem..
Hi John, I stand corrected. I fooled myself because I usually load my programs in a different directory where no spaces exists. thus I was lulled into not learning something before. Thanks for the refresher. BillWB6BNQ John Miles wrote: > > -Original Message- > > From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On > > Behalf Of WB6BNQ > > Sent: Monday, July 23, 2012 3:07 PM > > To: Discussion of precise time and frequency measurement > > Subject: Re: [time-nuts] Heather Problem.. > > > > Hi Bud, > > > > the /2 should be inside the quotes as you show it. Of course the quotes > are not > > used in the windows environment. That should be /3 if you are wanting to > go to > > port 3. So your command line, used in the ICON or link, should read: > > > > C:\Program Files\Heather\heather.exe /3 > > Actually that's not the case; the quotes are required anytime a pathname > with spaces is used. Otherwise there would be no easy way for the OS to > tell where the filename stops and any command-line parameters begin. If it > weren't for the space in the "Program Files" subdirectory name, the quotes > wouldn't be needed at all. > > So in the case of Heather, yes, you do need the quotes for Windows' benefit, > and you also need a space after the closing quote for Heather's benefit. > > (Pro tip: If you know that your Program Files directory has the short name > progra~1, you could change the shortcut to use > c:\progra~1\heather\heather.exe and dispense with the quotes. This hack is > less straightforward now that 64-bit versions of Windows use "Program Files > (x86)" for legacy 32-bit software like LH. On my system, Heather ends up in > c:\progra~2\heather\heather.exe.) > > -- john, KE5FX > > ___ > 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] Trimble T Lassen 2 - suitableantenna....advice.....questions
Www. KO4BB.com/Test_Equipment/Thunderbolt/PulseStretching/ It does not have to be complicated Didier KO4BB Mike Feher wrote: >Wow, that is indeed narrow. Only 1us out of a 1 second rep rate. That >is one >millionth of the rep rate. No wonder analog scopes will not catch it. >I'll >have to try it some time. Regards - Mike > >Mike B. Feher, EOZ Inc. >89 Arnold Blvd. >Howell, NJ, 07731 >732-886-5960 office >908-902-3831 cell > >-Original Message- >From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On >Behalf Of Bob Bownes >Sent: Monday, July 23, 2012 1:06 PM >To: Discussion of precise time and frequency measurement >Subject: Re: [time-nuts] Trimble T Lassen 2 - >suitableantennaadvice.questions > >The pulse from my T-Bolt is on the order of 1uS wide. I captured it on >the >digital scope for posterity and future reference. > >http://www.fastbobs.com/pictures/1pps.jpg > >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. -- Sent from my Motorola Droid Razr phone with K-9 Mail. Please excuse my brevity. ___ 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 3586 Questions
Now that I have my new [30 year old] HP 3586 making measurements over the GPIB bus I have a few questions. Setting AVErage makes measurements take about three seconds. Is there a way to control the number of samples averaged? How difficult is it to open up the 3586 to replace the input connector with a BNC connector? Is there a way to update and/or hack the firmware? Is source code available? -- Chuck Forsberg WA7KGX N2469R c...@omen.com www.omen.com Developer of Industrial ZMODEM(Tm) for Embedded Applications Omen Technology Inc "The High Reliability Software" 10255 NW Old Cornelius Pass Portland OR 97231 503-614-0430 ___ 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] Shorthand
On 7/23/12 3:23 PM, Tom Van Baak wrote: Hi Pete, Yes, there are several ways to represent frequencies: 1) Absolute units of Hz. For example 60 Hz, or 32.768 kHz, or 3.579545 MHz, or 9.192631770 GHz. Note some modern texts use s⁻¹ (1/s or s-1) instead of Hz or Hertz. Or, you can always show your age and use cps (cycles per second). or, as the directional couplers I've been working with the last few weeks say, 2-4 KMC We have boxes of these Narda 10,20 and 30 dB couplers with N connectors, all bought for Ranger and Mariner. I joke that they are older than most of the engineers using them. The cal tags on some probably qualify as historical documents. ___ 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] Heather Problem..
For any programs which may need user-level access to their directory (e.g. for the user to edit a .INI file) I now use a \Tools\ rather than the Program Files directory, so I would use: C:\Tools\Heather\ and so forth. It also avoids the requirement for quotation marks round paths with spaces. This makes things easier on Windows Vista and Windows-7, although you lose a little protection, so I would only use this for programs I trusted. 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.
