Re: [time-nuts] Chinese GPSDO 10 MHz error
So how does a frequency lock work? How is it implemented? Can someone sketch a schematic? And what equipment or technique is used to measure a 2hz error at 100GHz? Bob -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Tim Shoppa Sent: Wednesday, August 26, 2015 5:18 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Chinese GPSDO 10 MHz error Full KE5FX evaluation of BG7TBL GPSDO here: http://www.ke5fx.com/gpscomp.htm I'm wondering out loud if it might, like many hobbyist GPSDO's, be frequency-locked rather than phase-locked and thus susceptible to last-digit- counter bobble in some long-averaging counter. Tim N3QE On Wed, Aug 26, 2015 at 3:18 PM, Perry Sandeen via time-nuts time- n...@febo.com wrote: Hi, On the EEVBLOG (http://www.eevblog.com/forum/index.php) They mention that the 2014-11-06version GPSDO that was “most extensively tested, so far (by ke5x and others). (Has a) known bug, outputfrequency is not exactly 10mhz (9,999,999.999,800 Hz). This translates to ~2hzerror at 100ghz.” A question is if this bug isjust for this particular model or all other versions suspect? I realize that in and of itsself it is very small error, but errors tend to multiply or cause incorrectconclusions to testing. Another question is will the LHdisplay unit they offer work with other Trimble units such as are offered byRDR? That said, these models seem tobe a very nice turn-key systems. Regards, Perrier ___ 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] Chinese GPSDO 10 MHz error
Many hobbyist GPSDO's work, by counting OCXO cycles between some number of GPS PPS assertions. Software adjusts EFC based on frequency count. Often times the frequency count used as input to the software has not just random +/- 1 bobble in last digit, but also an extra count or two in last digit depending on the hobbyists' gating choices. The systematic extra count or two will result in a frequency offset between hobbyist GPSDO and PPS. Other times bugs in the software that drives EFC might result in a systematic frequency offset. We just had a poster last week who came here with such a scheme. Tim N3QE On Wed, Aug 26, 2015 at 11:54 PM, Bob Benward rbenw...@verizon.net wrote: So how does a frequency lock work? How is it implemented? Can someone sketch a schematic? And what equipment or technique is used to measure a 2hz error at 100GHz? Bob -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Tim Shoppa Sent: Wednesday, August 26, 2015 5:18 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Chinese GPSDO 10 MHz error Full KE5FX evaluation of BG7TBL GPSDO here: http://www.ke5fx.com/gpscomp.htm I'm wondering out loud if it might, like many hobbyist GPSDO's, be frequency-locked rather than phase-locked and thus susceptible to last-digit- counter bobble in some long-averaging counter. Tim N3QE On Wed, Aug 26, 2015 at 3:18 PM, Perry Sandeen via time-nuts time- n...@febo.com wrote: Hi, On the EEVBLOG (http://www.eevblog.com/forum/index.php) They mention that the 2014-11-06version GPSDO that was “most extensively tested, so far (by ke5x and others). (Has a) known bug, outputfrequency is not exactly 10mhz (9,999,999.999,800 Hz). This translates to ~2hzerror at 100ghz.” A question is if this bug isjust for this particular model or all other versions suspect? I realize that in and of itsself it is very small error, but errors tend to multiply or cause incorrectconclusions to testing. Another question is will the LHdisplay unit they offer work with other Trimble units such as are offered byRDR? That said, these models seem tobe a very nice turn-key systems. Regards, Perrier ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Chinese GPSDO 10 MHz error
Look in the manual for the 8640B as they use FLL there when the lock button is pushed on the front panel. Simply, in one case, in lock, the numbers driving the frequency readout is saved and then when the oscillator drifts one way or the other, an EFC is applied that attempts to make the new readout driver number equal to the saved number. 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 [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob Benward Sent: Wednesday, August 26, 2015 11:55 PM To: 'Discussion of precise time and frequency measurement' Subject: Re: [time-nuts] Chinese GPSDO 10 MHz error So how does a frequency lock work? How is it implemented? Can someone sketch a schematic? And what equipment or technique is used to measure a 2hz error at 100GHz? Bob -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Tim Shoppa Sent: Wednesday, August 26, 2015 5:18 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Chinese GPSDO 10 MHz error Full KE5FX evaluation of BG7TBL GPSDO here: http://www.ke5fx.com/gpscomp.htm I'm wondering out loud if it might, like many hobbyist GPSDO's, be frequency-locked rather than phase-locked and thus susceptible to last-digit- counter bobble in some long-averaging counter. Tim N3QE On Wed, Aug 26, 2015 at 3:18 PM, Perry Sandeen via time-nuts time- n...@febo.com wrote: Hi, On the EEVBLOG (http://www.eevblog.com/forum/index.php) They mention that the 2014-11-06version GPSDO that was “most extensively tested, so far (by ke5x and others). (Has a) known bug, outputfrequency is not exactly 10mhz (9,999,999.999,800 Hz). This translates to ~2hzerror at 100ghz.” A question is if this bug isjust for this particular model or all other versions suspect? I realize that in and of itsself it is very small error, but errors tend to multiply or cause incorrectconclusions to testing. Another question is will the LHdisplay unit they offer work with other Trimble units such as are offered byRDR? That said, these models seem tobe a very nice turn-key systems. Regards, Perrier ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Chinese GPSDO 10 MHz error
The simplest form of a frequency locked loop is the XOR gate, when the driving signals are 50% square waves. To achieve lock, the phase difference will be proportional to the voltage needed to the VCO to generate the desired frequency. Start with a 5V digital gate, suppose your VCO needs 2.5V to be in frequency: the XOR output will be at 50% duty cycle to generate, out of an RC, 2.5V and the phase difference (between the reference and the VCO) will be 90 (or 270) degrees. The difference will be more or less than 90 if the required voltage is more or less than 2.5V (positive EFC) or will be more or less than 270 if the VCO has a negative EFC. On Thu, Aug 27, 2015 at 5:54 AM, Bob Benward rbenw...@verizon.net wrote: So how does a frequency lock work? How is it implemented? Can someone sketch a schematic? And what equipment or technique is used to measure a 2hz error at 100GHz? Bob -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Tim Shoppa Sent: Wednesday, August 26, 2015 5:18 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Chinese GPSDO 10 MHz error Full KE5FX evaluation of BG7TBL GPSDO here: http://www.ke5fx.com/gpscomp.htm I'm wondering out loud if it might, like many hobbyist GPSDO's, be frequency-locked rather than phase-locked and thus susceptible to last-digit- counter bobble in some long-averaging counter. Tim N3QE On Wed, Aug 26, 2015 at 3:18 PM, Perry Sandeen via time-nuts time- n...@febo.com wrote: Hi, On the EEVBLOG (http://www.eevblog.com/forum/index.php) They mention that the 2014-11-06version GPSDO that was “most extensively tested, so far (by ke5x and others). (Has a) known bug, outputfrequency is not exactly 10mhz (9,999,999.999,800 Hz). This translates to ~2hzerror at 100ghz.” A question is if this bug isjust for this particular model or all other versions suspect? I realize that in and of itsself it is very small error, but errors tend to multiply or cause incorrectconclusions to testing. Another question is will the LHdisplay unit they offer work with other Trimble units such as are offered byRDR? That said, these models seem tobe a very nice turn-key systems. Regards, Perrier ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Chinese GPSDO 10 MHz error
On Thu, 27 Aug 2015 17:19:34 +0200 Azelio Boriani azelio.bori...@gmail.com wrote: The simplest form of a frequency locked loop is the XOR gate, when the driving signals are 50% square waves. To achieve lock, the phase difference will be proportional to the voltage needed to the VCO to generate the desired frequency. Start with a 5V digital gate, suppose your VCO needs 2.5V to be in frequency: the XOR output will be at 50% duty cycle to generate, out of an RC, 2.5V and the phase difference (between the reference and the VCO) will be 90 (or 270) degrees. The difference will be more or less than 90 if the required voltage is more or less than 2.5V (positive EFC) or will be more or less than 270 if the VCO has a negative EFC. This is the description of a XOR gate based PLL, not an FLL. The basic difference between PLL and FLL is very very simple: A PLL measures phase, a FLL measures frequency. The control loop then steers the measured value to be as close as possible to a predetermined constant. As this steering loop is not perfect, there will be a small error. Depending on what is measured, it's either a phase or a frequency error. Attila Kinali -- I must not become metastable. Metastability is the mind-killer. Metastability is the little-death that brings total obliteration. I will face my metastability. I will permit it to pass over me and through me. And when it has gone past I will turn the inner eye to see its path. Where the metastability has gone there will be nothing. Only I will remain. ___ 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] Chinese GPSDO 10 MHz error
Hi At the most basic level: FLL is frequency locked. Consider a lock system driven by an FM discriminator. (That’s how the idea originally was done.) The output of the detector is a voltage proportional to the frequency error. With a simple loop (gain only / no integrator) you have a static frequency error. More gain gets you less frequency error. PLL is a phase locked loop. A system with a DBM running as a detector is an old school way to do this. The output of the detector is proportional to the phase difference. With a simple loop (gain only, no integrator) you have a static phase error. More gain gets you less phase error and possibly stability issues. If you add an integrator to either control loop, things get more complicated. If you go further than that they get you into a lot of debates :) The distinction between the two is much easier to see when each is paired with a simple loop. Bob On Aug 27, 2015, at 7:36 PM, Azelio Boriani azelio.bori...@gmail.com wrote: Since I have not found a strong definition for the FLL, I assumed: if PLL= zero phase error (and so zero frequency error) the FLL= same frequency, random phase. The XOR with RC is a perfect fit for this: same frequency all the time but phase determined by the EFC needed to have that frequency. The phase = constant, in the XOR/RC is true as long as the VCO is stable and the EFC has not to be altered to steer the VCO, that constant is not a design parameter but walks with the VCO frequency movement. On Thu, Aug 27, 2015 at 10:50 PM, Attila Kinali att...@kinali.ch wrote: On Thu, 27 Aug 2015 17:19:34 +0200 Azelio Boriani azelio.bori...@gmail.com wrote: The simplest form of a frequency locked loop is the XOR gate, when the driving signals are 50% square waves. To achieve lock, the phase difference will be proportional to the voltage needed to the VCO to generate the desired frequency. Start with a 5V digital gate, suppose your VCO needs 2.5V to be in frequency: the XOR output will be at 50% duty cycle to generate, out of an RC, 2.5V and the phase difference (between the reference and the VCO) will be 90 (or 270) degrees. The difference will be more or less than 90 if the required voltage is more or less than 2.5V (positive EFC) or will be more or less than 270 if the VCO has a negative EFC. This is the description of a XOR gate based PLL, not an FLL. The basic difference between PLL and FLL is very very simple: A PLL measures phase, a FLL measures frequency. The control loop then steers the measured value to be as close as possible to a predetermined constant. As this steering loop is not perfect, there will be a small error. Depending on what is measured, it's either a phase or a frequency error. Attila Kinali -- I must not become metastable. Metastability is the mind-killer. Metastability is the little-death that brings total obliteration. I will face my metastability. I will permit it to pass over me and through me. And when it has gone past I will turn the inner eye to see its path. Where the metastability has gone there will be nothing. Only I will remain. ___ 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] Chinese GPSDO 10 MHz error
Attila, I concur with you, what Azelio described is a standard off the shelf PLL. An XOR for a Type I phase discriminator, characterized by a 90 degree phase lock, and with more complicated logic, a Type II PLL which locks at zero degrees. In a well designed loop, in both cases over the long term the frequency is exact, what it does have to a large extent, is phase jitter. So how does someone measure an error to 2 parts in a hundred billion? Or is that a 2 cycle slip in 100 gig cycles? Thanks to all that replied. Bob -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Attila Kinali Sent: Thursday, August 27, 2015 4:51 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Chinese GPSDO 10 MHz error On Thu, 27 Aug 2015 17:19:34 +0200 Azelio Boriani azelio.bori...@gmail.com wrote: The simplest form of a frequency locked loop is the XOR gate, when the driving signals are 50% square waves. To achieve lock, the phase difference will be proportional to the voltage needed to the VCO to generate the desired frequency. Start with a 5V digital gate, suppose your VCO needs 2.5V to be in frequency: the XOR output will be at 50% duty cycle to generate, out of an RC, 2.5V and the phase difference (between the reference and the VCO) will be 90 (or 270) degrees. The difference will be more or less than 90 if the required voltage is more or less than 2.5V (positive EFC) or will be more or less than 270 if the VCO has a negative EFC. This is the description of a XOR gate based PLL, not an FLL. The basic difference between PLL and FLL is very very simple: A PLL measures phase, a FLL measures frequency. The control loop then steers the measured value to be as close as possible to a predetermined constant. As this steering loop is not perfect, there will be a small error. Depending on what is measured, it's either a phase or a frequency error. Attila Kinali -- I must not become metastable. Metastability is the mind-killer. Metastability is the little-death that brings total obliteration. I will face my metastability. I will permit it to pass over me and through me. And when it has gone past I will turn the inner eye to see its path. Where the metastability has gone there will be nothing. Only I will remain. ___ 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] Chinese GPSDO 10 MHz error
it is a bit more complicated FLL need circuit which is sensitive to frequency difference, it looks always, PLL need a phase detector and has a capture range, which is depend mainly on the bandwidth of the loop filter there are combined phase /frequency detectors, which are sequential circuits/logic, usually with some uncertainty --and therefore more phase noise-- at zero phase difference 73 Alex On 8/27/2015 1:50 PM, Attila Kinali wrote: On Thu, 27 Aug 2015 17:19:34 +0200 Azelio Boriani azelio.bori...@gmail.com wrote: The simplest form of a frequency locked loop is the XOR gate, when the driving signals are 50% square waves. To achieve lock, the phase difference will be proportional to the voltage needed to the VCO to generate the desired frequency. Start with a 5V digital gate, suppose your VCO needs 2.5V to be in frequency: the XOR output will be at 50% duty cycle to generate, out of an RC, 2.5V and the phase difference (between the reference and the VCO) will be 90 (or 270) degrees. The difference will be more or less than 90 if the required voltage is more or less than 2.5V (positive EFC) or will be more or less than 270 if the VCO has a negative EFC. This is the description of a XOR gate based PLL, not an FLL. The basic difference between PLL and FLL is very very simple: A PLL measures phase, a FLL measures frequency. The control loop then steers the measured value to be as close as possible to a predetermined constant. As this steering loop is not perfect, there will be a small error. Depending on what is measured, it's either a phase or a frequency error. Attila Kinali ___ 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] Chinese GPSDO 10 MHz error
Since I have not found a strong definition for the FLL, I assumed: if PLL= zero phase error (and so zero frequency error) the FLL= same frequency, random phase. The XOR with RC is a perfect fit for this: same frequency all the time but phase determined by the EFC needed to have that frequency. The phase = constant, in the XOR/RC is true as long as the VCO is stable and the EFC has not to be altered to steer the VCO, that constant is not a design parameter but walks with the VCO frequency movement. On Thu, Aug 27, 2015 at 10:50 PM, Attila Kinali att...@kinali.ch wrote: On Thu, 27 Aug 2015 17:19:34 +0200 Azelio Boriani azelio.bori...@gmail.com wrote: The simplest form of a frequency locked loop is the XOR gate, when the driving signals are 50% square waves. To achieve lock, the phase difference will be proportional to the voltage needed to the VCO to generate the desired frequency. Start with a 5V digital gate, suppose your VCO needs 2.5V to be in frequency: the XOR output will be at 50% duty cycle to generate, out of an RC, 2.5V and the phase difference (between the reference and the VCO) will be 90 (or 270) degrees. The difference will be more or less than 90 if the required voltage is more or less than 2.5V (positive EFC) or will be more or less than 270 if the VCO has a negative EFC. This is the description of a XOR gate based PLL, not an FLL. The basic difference between PLL and FLL is very very simple: A PLL measures phase, a FLL measures frequency. The control loop then steers the measured value to be as close as possible to a predetermined constant. As this steering loop is not perfect, there will be a small error. Depending on what is measured, it's either a phase or a frequency error. Attila Kinali -- I must not become metastable. Metastability is the mind-killer. Metastability is the little-death that brings total obliteration. I will face my metastability. I will permit it to pass over me and through me. And when it has gone past I will turn the inner eye to see its path. Where the metastability has gone there will be nothing. Only I will remain. ___ 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] Chinese GPSDO 10 MHz error
Hi On Aug 26, 2015, at 11:54 PM, Bob Benward rbenw...@verizon.net wrote: So how does a frequency lock work? How is it implemented? Can someone sketch a schematic? And what equipment or technique is used to measure a 2hz error at 100GHz? As with all things, this is a “that depends sort of thing. You can measure it with a (accurate) wall clock if you wait for 10^11 seconds (that’s quite a while). If you have a counter than can measure 1x10^-9 s (1 ns) then you can get to 1x10^-11 by watching a pps for about a hundred seconds. That’s not to bad to do. If you want to do it quickly, there are commercial test boxes (the TimePod is one of many) that will measure much better than this at 1 second. If you want do it in the basement, a DMTD is a cheap way to do it. In all of these cases, you need something “better than” the device you are trying to measure to use as a comparison standard. Put another way - your counter needs to be calibrated to better than 1 ppm to measure 1 ppm. In the case of the GPSDO measurement, checking against a Cs standard or a Hydrogen Maser would work. You might also use a “known good” GPSDO. The comparison may be between 1 pps outputs or between 10 MHz outputs. In both cases the data should be the same. Your choice of 1 pps or 10 MHz needs to match up between your measuring gear, your DUT, and your reference standard. Lots of choices, lots of ways to do it. Many pieces of gear you could use to get the job done. Bob Bob -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Tim Shoppa Sent: Wednesday, August 26, 2015 5:18 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Chinese GPSDO 10 MHz error Full KE5FX evaluation of BG7TBL GPSDO here: http://www.ke5fx.com/gpscomp.htm I'm wondering out loud if it might, like many hobbyist GPSDO's, be frequency-locked rather than phase-locked and thus susceptible to last-digit- counter bobble in some long-averaging counter. Tim N3QE On Wed, Aug 26, 2015 at 3:18 PM, Perry Sandeen via time-nuts time- n...@febo.com wrote: Hi, On the EEVBLOG (http://www.eevblog.com/forum/index.php) They mention that the 2014-11-06version GPSDO that was “most extensively tested, so far (by ke5x and others). (Has a) known bug, outputfrequency is not exactly 10mhz (9,999,999.999,800 Hz). This translates to ~2hzerror at 100ghz.” A question is if this bug isjust for this particular model or all other versions suspect? I realize that in and of itsself it is very small error, but errors tend to multiply or cause incorrectconclusions to testing. Another question is will the LHdisplay unit they offer work with other Trimble units such as are offered byRDR? That said, these models seem tobe a very nice turn-key systems. Regards, Perrier ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Chinese GPSDO 10 MHz error
Hi Further investigation by list members in China came back with the information that this particular design is indeed a FLL. The error is considered “acceptable” by the designer. This is not the case on the various CDMA oriented GPSDO’s we typically play with in the US and Europe. All of those designs (as far as I have seen) use PLL’s as their final lock stage. Bob On Aug 26, 2015, at 3:18 PM, Perry Sandeen via time-nuts time-nuts@febo.com wrote: Hi, On the EEVBLOG (http://www.eevblog.com/forum/index.php) They mention that the 2014-11-06version GPSDO that was “most extensively tested, so far (by ke5x and others). (Has a) known bug, outputfrequency is not exactly 10mhz (9,999,999.999,800 Hz). This translates to ~2hzerror at 100ghz.” A question is if this bug isjust for this particular model or all other versions suspect? I realize that in and of itsself it is very small error, but errors tend to multiply or cause incorrectconclusions to testing. Another question is will the LHdisplay unit they offer work with other Trimble units such as are offered byRDR? That said, these models seem tobe a very nice turn-key systems. Regards, Perrier ___ 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] Chinese GPSDO 10 MHz error
Full KE5FX evaluation of BG7TBL GPSDO here: http://www.ke5fx.com/gpscomp.htm I'm wondering out loud if it might, like many hobbyist GPSDO's, be frequency-locked rather than phase-locked and thus susceptible to last-digit-counter bobble in some long-averaging counter. Tim N3QE On Wed, Aug 26, 2015 at 3:18 PM, Perry Sandeen via time-nuts time-nuts@febo.com wrote: Hi, On the EEVBLOG (http://www.eevblog.com/forum/index.php) They mention that the 2014-11-06version GPSDO that was “most extensively tested, so far (by ke5x and others). (Has a) known bug, outputfrequency is not exactly 10mhz (9,999,999.999,800 Hz). This translates to ~2hzerror at 100ghz.” A question is if this bug isjust for this particular model or all other versions suspect? I realize that in and of itsself it is very small error, but errors tend to multiply or cause incorrectconclusions to testing. Another question is will the LHdisplay unit they offer work with other Trimble units such as are offered byRDR? That said, these models seem tobe a very nice turn-key systems. Regards, Perrier ___ 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] Chinese GPSDO 10 MHz error
Hi, On the EEVBLOG (http://www.eevblog.com/forum/index.php) They mention that the 2014-11-06version GPSDO that was “most extensively tested, so far (by ke5x and others). (Has a) known bug, outputfrequency is not exactly 10mhz (9,999,999.999,800 Hz). This translates to ~2hzerror at 100ghz.” A question is if this bug isjust for this particular model or all other versions suspect? I realize that in and of itsself it is very small error, but errors tend to multiply or cause incorrectconclusions to testing. Another question is will the LHdisplay unit they offer work with other Trimble units such as are offered byRDR? That said, these models seem tobe a very nice turn-key systems. Regards, Perrier ___ 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.
