Re: [time-nuts] DeLorme Tripmate GPS receiver
One thing I want to clarify - it is not a Jupiter GPS module - it just uses the chipset, presumably hooked up as in the application info. The board is proprietary, and there seems to be no standard electrical or operational interface as would be expected in an OEM GPS module. So, the only way to figure it out is to go by the chip details to see how it's supposed to work. previous message: I peeled open the shield can without too much deformation, so it can be restored. I found that it's a single board, with the DSP on one side, and the RF section on the other. It is a Rockwell chipset, with 11577-11 DSP, and 6732-13 RF. On searching I found that this seems to be called their Jupiter GPS from circa late 1990s - I found quite a lot of info at the module level, but not for the actual ICs, like pinout data. The set includes all the usual GPS stuff including 1 PPS, and is capable of several levels of on-ness. So, if the uP that makes it a DeLorme merely sets some control lines to activate it, then I should be able to override them to force it always on - if I can figure them out. If instead the uP programs something internal to the DSP to control power states, then fuggetabout it - it will be junk. So, does anyone know of the Jupiter chipset, and where to find chip-level info for these parts? Ed ___ 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] Simple AC mains zero-cross detector
On Sun, 21 Dec 2014 17:37:07 -0500 Charles Steinmetz csteinm...@yandex.com wrote: Ed wrote: It seems to me that a low voltage secondary should be OK by using a fast comparator IC rather than a transistor to decide - the gain of the IC allows for much smaller detection levels, so the equivalent zero-crossing velocity could be the same. An IC tripping in a 10 mV band should provide the same effective ZC velocity at 12 V input as a transistor working around 100 mV with 120 V input. Or am I missing something? When the switching band gets that small, device noise, input offset voltage drift, and other errors have a proportionally greater effect. I actually built a similar circuit with a 12v transformer and an LT1720 comparator, and it had worse jitter than the two-transistor circuit with a 120v feed. In this case, there is no substitute for starting with a higher-slew-rate signal. (Yes, the LT1720 did marginally better than the two-transistor circuit when both were fed from 120v -- but the fussiness of working with a fast comparator and the small gain over the two-transistor circuit made the latter the better choice, particularly in a design being put out there for others to build.) Best regards, Charles Looking at the data sheet of the LT1720, 1mv would have about 8ns delay. Call it 10ns. A Vp of 29 volts should be sufficient to put the delay around 90ns, making 100ns error or target percent of the 1uS target. ___ 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] LNA and Alias
Are you sure that the setup is aligned to minimise AM response? Are you using cross-correlation? Bruce On Monday, 22 December 2014 5:08 PM, Loïc Moreau loic.mor...@eai..fr wrote: Hi all, My phase noise measurements system give erroneous results in close in phase noise measurements, I got humps in the 1Hz-1000Hz area as high à 20 dB more than expected. The setup is using a mixer to compare reference and DUT witch drive an LNA http://www.ko4bb.com/~bruce/LowNoiseMixerPreamp.html , the output is driving an AD7760 ADC and an op amp circuity is connected to the VFC reference to achieve quadrature. The results are analyzed with an homebrew FFT charting software After struggling with different configurations, switched different LNA, ADC , sound card. A scope connected to the LNA output indicate steady 20MHz residuals just before the ADC ( around 10 mv peak-peak). In fact , it seems that the mixer 20Mhz residuals ( DUT + REF ) are entering the ADC and so theses alias give erroneous results in the 1Hz-100Hz area, displaying unexpected artifacts. In order to fix the problem I will probably include an analog filter just before the ADC input (same as LNA input 1nF 80µH), but I want to know if some more sophisticated measures should be undertaken as an 5th Order Lowpass Filter. I have not found many clue about alias problems in phase noise measurements literature so I may have missed something ? Any advice Loïc ___ 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] LNA and Alias
Bruce Griffiths bruce.griffiths@... writes: Are you sure that the setup is aligned to minimise AM response? Are you using cross-correlation? Bruce On Monday, 22 December 2014 5:08 PM, Loïc Moreau loic.moreau at eai..fr wrote: Hi all, My phase noise measurements system give erroneous results in close in phase noise measurements, I got humps in the 1Hz-1000Hz area as high à 20 dB more than expected. The setup is using a mixer to compare reference and DUT witch drive an LNA http://www.ko4bb.com/~bruce/LowNoiseMixerPreamp.html , the output is driving an AD7760 ADC and an op amp circuity is connected to the VFC reference to achieve quadrature. The results are analyzed with an homebrew FFT charting software After struggling with different configurations, switched different LNA, ADC , sound card. A scope connected to the LNA output indicate steady 20MHz residuals just before the ADC ( around 10 mv peak-peak). In fact , it seems that the mixer 20Mhz residuals ( DUT + REF ) are entering the ADC and so theses alias give erroneous results in the 1Hz-100Hz area, displaying unexpected artifacts. In order to fix the problem I will probably include an analog filter just before the ADC input (same as LNA input 1nF 80µH), but I want to know if some more sophisticated measures should be undertaken as an 5th Order Lowpass Filter. I have not found many clue about alias problems in phase noise measurements literature so I may have missed something ? Any advice Loïc ___ time-nuts mailing list -- time-nuts@... To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time- nuts and follow the instructions there. Hi, I have a simple setup to measure the noise floor, the mixer is a SYM-2 and a divider is feeding RF and LO inputs ports for that purpose. a pi network give the 90° phase difference. The test is running with an HP 10811 giving around 7dBm, but i have the same results with any sources, especially a 33521A witch can be adjusted in level and frequency. I intend to use cross-correlation later when i will be confident with my the setup, for now i run a simple FFT. I have no clue about AM noise problem, i suppose that a sufficient input level on LO will put that problem aside. by the way, I was a bit surprised that nobody pay any attention to RF leakage from multiplier as the low frequency level is order or magnitude lower than 20Mhz product present at the input. regards Loïc ___ 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] Simple AC mains zero-cross detector
On Sat, 20 Dec 2014 18:31:29 -0500 Mike Garvey r3m...@verizon.net wrote: From a Time-Nut perspective, isn't phase/frequency of the (nominal) 60 Hz all we'd be interested in? Phase is best measured at a zero crossing as this is the (only) phase measurement point which is independent of amplitude. Mike One overkill AFSK demod is to sample the signal and compute the arcsin, essentially producing a straight line of phase versus time. We had made a AFSK demod using linear regression on this line to determine frequency. This isn't overkill when you have a DSP chip there anyway. Now I don't see a reason why similar analysis couldn't be done with power line monitoring. Over some moving window of time, you could even produce the difference signal between the sine wave due to the regression fitting from the raw signal and thus display the noise on the line. ___ 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] Simple AC mains zero-cross detector
Actually, the core saturation depends on how much voltage is applied at a given frequency. Most power transformers are run partly into saturation at rated line, to get the most from the copper and iron available, in exchange for heat and less efficiency. The magnetizing current and losses will occur even with no load. The resistive loss will go up more with load. But, I don't think this matters in this application anyway. Ed ___ 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] LNA and Alias
Hi At the moment Comcast and ko4bb.com don’t seem to like each other. I can’t refer directly to the schematic or the page. What you *should* have (assuming 10 MHz inputs for clarity): 1) The RF inputs go into the mixer from what ever sources you happen to want to test. At least one source needs to be high level. 2) The mixer output goes to an L/C lowpass filter. That filter serves several purposes: a) It resistively terminates the mixer at RF (both at 10 and 20 MHz) in the proper IF impedance b) It passes the phase noise information on to the LNA c) It rejects all RF going to the LNA 3) The LNA can be just about anything provided: a) It handles the signal levels without overload b) It does have low enough noise (that depends a lot on the mixer and sources) c) It has enough gain d) Terminates the mixer in a reasonable resistive impedance at audio. 4) The LNA feeds two things: a) Your FFT box b) Your DC bias box It sounds like the FFT part is working so the DC bias may be an issue. The bias box is used to force the two oscillators into quadrature. It forms a PLL around the oscillator pair. With the two signals 90 degrees apart your mixer has a ~ 0V output. That is the point it is most sensitive to phase noise and the least sensitive to AM noise. There are lots of ways to do this. Since I can’t see the schematic. Here’s one based on an RPD-1 (500 ohm out) mixer: One side of the mixer is grounded, the other feeds the filter. 500 ohms in series with 820 pf to ground as the input to the filter. Some sort of coil in the vicinity of 100 uH as the first series lowpass element. Next a 470 pf to ground. Then another 100 uH in series. Another 470 pf to ground. Another 100 uH in series. Another 470 pf to ground. At this point you have a three coil and five capacitor lowpass filter. You should poke it into spice to make sure it’s not going to be a problem with your parts. The issue is cutoff at the highest frequency you want to look at phase noise. You may need to tweak values a bit. The final stage may be overkill depending on the quality of your coils. You will always have a tradeoff between highest phase noise frequency and lowest RF frequency with this setup. LNA can be a good audio op-amp. Run it in positive gain mode. Termination resistance for the filter is simply set with a resistor to ground. I prefer to use 5K for the RPD-1’s. It gives you a bit more output voltage. It also makes the cutoff of the lowpass a bit lower. The DC bias box is an op amp plus a pot, resistors and capacitors. You need to set the output to the EFC voltage on the OCXO’s. That will vary between different parts. One pot is for centering this up. You need to set the loop gain, so feedback resistors on the op amp need to be adjusted. Some sort of R/C may be used to roll off noise. The cutoff frequency of the loop will determine the lowest phase noise frequency you can check unless you measure loop dynamics and correct all your data. Now that that’s all working, you need to calibrate the setup. Two common approaches. Both use a beat note formed when the bias box is shut off: 1) Measure an power or voltage at the LNA output and do math based on some assumptions. 2) Capture the full beat note and look at the actual slope as it crosses zero. You pretty much have to do number 2 before you can use number 1. The LNA needs to have low enough gain in this case to not distort passing the full signal. The math for 2 is pretty simple. Each cycle is 2*PI radians. Phase modulation is normalized to one radian (yes it’s phase … ). You get a radians per volt number and move on. Wish I knew what Comcast was doing this morning …. Bob On Dec 22, 2014, at 4:26 AM, Loïc loic.mor...@eai.fr wrote: Bruce Griffiths bruce.griffiths@... writes: Are you sure that the setup is aligned to minimise AM response? Are you using cross-correlation? Bruce On Monday, 22 December 2014 5:08 PM, Loïc Moreau loic.moreau at eai..fr wrote: Hi all, My phase noise measurements system give erroneous results in close in phase noise measurements, I got humps in the 1Hz-1000Hz area as high à 20 dB more than expected. The setup is using a mixer to compare reference and DUT witch drive an LNA http://www.ko4bb.com/~bruce/LowNoiseMixerPreamp.html , the output is driving an AD7760 ADC and an op amp circuity is connected to the VFC reference to achieve quadrature. The results are analyzed with an homebrew FFT charting software After struggling with different configurations, switched different LNA, ADC , sound card. A scope connected to the LNA output indicate steady 20MHz residuals just before the ADC ( around 10 mv peak-peak). In fact , it seems that the mixer 20Mhz residuals ( DUT + REF ) are entering the ADC and so theses alias give erroneous results in the 1Hz-100Hz area, displaying unexpected
Re: [time-nuts] LNA and Alias
Loic, If you have a single-pole low-pass filter at say 20 kHz you will have a 60 dB damping as you hit 20 MHz. No reason to get really fancy. Either just do a two-pole low-pass filter (inductance, capacitance) or a two-stage RC-link, or consider doing a LC-series link between signal and ground to swallow that 20 MHz, providing a notch. Do it near the mixer, no need to polute the amplifier with the signal. You can do another LC-link at the ADC end to make sure you swallow that 20 MHz. Consider adding additional such links for say 10 MHz or other reasonable likely mixer products. Cheers, Magnus On 12/21/2014 09:39 PM, Loïc Moreau wrote: Hi all, My phase noise measurements system give erroneous results in close in phase noise measurements, I got humps in the 1Hz-1000Hz area as high à 20 dB more than expected. The setup is using a mixer to compare reference and DUT witch drive an LNA http://www.ko4bb.com/~bruce/LowNoiseMixerPreamp.html , the output is driving an AD7760 ADC and an op amp circuity is connected to the VFC reference to achieve quadrature. The results are analyzed with an homebrew FFT charting software After struggling with different configurations, switched different LNA, ADC , sound card. A scope connected to the LNA output indicate steady 20MHz residuals just before the ADC ( around 10 mv peak-peak). In fact , it seems that the mixer 20Mhz residuals ( DUT + REF ) are entering the ADC and so theses alias give erroneous results in the 1Hz-100Hz area, displaying unexpected artifacts. In order to fix the problem I will probably include an analog filter just before the ADC input (same as LNA input 1nF 80µH), but I want to know if some more sophisticated measures should be undertaken as an 5th Order Lowpass Filter. I have not found many clue about alias problems in phase noise measurements literature so I may have missed something ? Any advice Loïc ___ 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] LNA and Alias
On Monday, December 22, 2014 09:26:15 AM Loïc wrote: Bruce Griffiths bruce.griffiths@... writes: Are you sure that the setup is aligned to minimise AM response? Are you using cross-correlation? Bruce On Monday, 22 December 2014 5:08 PM, Loïc Moreau loic.moreau at eai..fr wrote: Hi all, My phase noise measurements system give erroneous results in close in phase noise measurements, I got humps in the 1Hz-1000Hz area as high à 20 dB more than expected. The setup is using a mixer to compare reference and DUT witch drive an LNA http://www.ko4bb.com/~bruce/LowNoiseMixerPreamp.html , the output is driving an AD7760 ADC and an op amp circuity is connected to the VFC reference to achieve quadrature. The results are analyzed with an homebrew FFT charting software After struggling with different configurations, switched different LNA, ADC , sound card. A scope connected to the LNA output indicate steady 20MHz residuals just before the ADC ( around 10 mv peak-peak). In fact , it seems that the mixer 20Mhz residuals ( DUT + REF ) are entering the ADC and so theses alias give erroneous results in the 1Hz-100Hz area, displaying unexpected artifacts. In order to fix the problem I will probably include an analog filter just before the ADC input (same as LNA input 1nF 80µH), but I want to know if some more sophisticated measures should be undertaken as an 5th Order Lowpass Filter. I have not found many clue about alias problems in phase noise measurements literature so I may have missed something ? Any advice Loïc ___ time-nuts mailing list -- time-nuts@... To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time- nuts and follow the instructions there. Hi, I have a simple setup to measure the noise floor, the mixer is a SYM-2 and a divider is feeding RF and LO inputs ports for that purpose. a pi network give the 90° phase difference. Have you measured the phase shift when connected to the mixer? I usually use a narrowband 90 degree hybrid. The test is running with an HP 10811 giving around 7dBm, but i have the same results with any sources, especially a 33521A witch can be adjusted in level and frequency. I intend to use cross-correlation later when i will be confident with my the setup, for now i run a simple FFT. I have no clue about AM noise problem, i suppose that a sufficient input level on LO will put that problem aside. The phase shift between the RF and LO ports needs to be adjusted to minimise the response to AM in the source. To do this an AM modulator with low incidental PM is required. The phase is adjusted to minimise the sideband amplitude in the mixer output. by the way, I was a bit surprised that nobody pay any attention to RF leakage from multiplier as the low frequency level is order or magnitude lower than 20Mhz product present at the input. Sufficient attenuation is usually achieved by using a well balanced mixer and by the mixer IF port termination and the low pass filter network between the mixer IF port and the low noise preamp. Using a JFET preamp can be useful in minimising any RF rectification effects due to input stage nonlinearity at RF. Bruce regards Loïc ___ 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] LNA and Alias
Bob, It may not have been Comcast. I had issues (cockpit error on my part) with the server this morning around the time you wrote your message. It should be OK now. However, the new setup is making it more difficult to attach links to documents because when you click on a document in the Manuals pages, you get a link that is associated with your IP address, so that link may not work for other people. The best way is to simply reference the page name and let people search for the page for themselves, so that they can get their own link and download the document. Overall it is a better method anyhow because I occasionally move things around to try and keep some organization, so any document is susceptible to change folder, which will break old links. I rarely change the documents names though (once they are moved out of the ManualUpload folder), so searching for the name should always work. Didier KO4BB On Mon, Dec 22, 2014 at 8:39 AM, Bob Camp kb...@n1k.org wrote: Hi At the moment Comcast and ko4bb.com don’t seem to like each other. I can’t refer directly to the schematic or the page. What you *should* have (assuming 10 MHz inputs for clarity): 1) The RF inputs go into the mixer from what ever sources you happen to want to test. At least one source needs to be high level. 2) The mixer output goes to an L/C lowpass filter. That filter serves several purposes: a) It resistively terminates the mixer at RF (both at 10 and 20 MHz) in the proper IF impedance b) It passes the phase noise information on to the LNA c) It rejects all RF going to the LNA 3) The LNA can be just about anything provided: a) It handles the signal levels without overload b) It does have low enough noise (that depends a lot on the mixer and sources) c) It has enough gain d) Terminates the mixer in a reasonable resistive impedance at audio. 4) The LNA feeds two things: a) Your FFT box b) Your DC bias box It sounds like the FFT part is working so the DC bias may be an issue. The bias box is used to force the two oscillators into quadrature. It forms a PLL around the oscillator pair. With the two signals 90 degrees apart your mixer has a ~ 0V output. That is the point it is most sensitive to phase noise and the least sensitive to AM noise. There are lots of ways to do this. Since I can’t see the schematic. Here’s one based on an RPD-1 (500 ohm out) mixer: One side of the mixer is grounded, the other feeds the filter. 500 ohms in series with 820 pf to ground as the input to the filter. Some sort of coil in the vicinity of 100 uH as the first series lowpass element. Next a 470 pf to ground. Then another 100 uH in series. Another 470 pf to ground. Another 100 uH in series. Another 470 pf to ground. At this point you have a three coil and five capacitor lowpass filter. You should poke it into spice to make sure it’s not going to be a problem with your parts. The issue is cutoff at the highest frequency you want to look at phase noise. You may need to tweak values a bit. The final stage may be overkill depending on the quality of your coils. You will always have a tradeoff between highest phase noise frequency and lowest RF frequency with this setup. LNA can be a good audio op-amp. Run it in positive gain mode. Termination resistance for the filter is simply set with a resistor to ground. I prefer to use 5K for the RPD-1’s. It gives you a bit more output voltage. It also makes the cutoff of the lowpass a bit lower. The DC bias box is an op amp plus a pot, resistors and capacitors. You need to set the output to the EFC voltage on the OCXO’s. That will vary between different parts. One pot is for centering this up. You need to set the loop gain, so feedback resistors on the op amp need to be adjusted. Some sort of R/C may be used to roll off noise. The cutoff frequency of the loop will determine the lowest phase noise frequency you can check unless you measure loop dynamics and correct all your data. Now that that’s all working, you need to calibrate the setup. Two common approaches. Both use a beat note formed when the bias box is shut off: 1) Measure an power or voltage at the LNA output and do math based on some assumptions. 2) Capture the full beat note and look at the actual slope as it crosses zero. You pretty much have to do number 2 before you can use number 1. The LNA needs to have low enough gain in this case to not distort passing the full signal. The math for 2 is pretty simple. Each cycle is 2*PI radians. Phase modulation is normalized to one radian (yes it’s phase … ). You get a radians per volt number and move on. Wish I knew what Comcast was doing this morning …. Bob On Dec 22, 2014, at 4:26 AM, Loïc loic.mor...@eai.fr wrote: Bruce Griffiths bruce.griffiths@... writes: Are you sure that the setup is aligned to minimise AM response? Are you using
[time-nuts] GUI installer with ntp-4.2.8 for Windows now available
Folks, a new GUI installer with ntp-4.2.8 for Windows is now available at Meinberg's NTP download page: http://www.meinbergglobal.com/english/sw/ntp.htm#ntp_stable This also includes the current version v1.0.1j of the openSSL DLL, which also fixes some openSSL vulnerabilities. Martin ___ 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] DeLorme Tripmate GPS receiver
Ed, Not 100% sure this is the same model, but it would seem to indicate there's a PPS signal on the DCD pin (from the gpsd-users list circa 2007): http://marc.info/?l=gpsd-usersm=118340900010559w=2 Have a 'scope to check what that pin looks like? -Ryan Stasel On Dec 21, 2014, at 23:07 , ed breya e...@telight.com wrote: One thing I want to clarify - it is not a Jupiter GPS module - it just uses the chipset, presumably hooked up as in the application info. The board is proprietary, and there seems to be no standard electrical or operational interface as would be expected in an OEM GPS module. So, the only way to figure it out is to go by the chip details to see how it's supposed to work. previous message: I peeled open the shield can without too much deformation, so it can be restored. I found that it's a single board, with the DSP on one side, and the RF section on the other. It is a Rockwell chipset, with 11577-11 DSP, and 6732-13 RF. On searching I found that this seems to be called their Jupiter GPS from circa late 1990s - I found quite a lot of info at the module level, but not for the actual ICs, like pinout data. The set includes all the usual GPS stuff including 1 PPS, and is capable of several levels of on-ness. So, if the uP that makes it a DeLorme merely sets some control lines to activate it, then I should be able to override them to force it always on - if I can figure them out. If instead the uP programs something internal to the DSP to control power states, then fuggetabout it - it will be junk. So, does anyone know of the Jupiter chipset, and where to find chip-level info for these parts? Ed ___ 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.
