[time-nuts] possible issue with LEA 6T eval board
Just a heads up on an issue I had with a LEA-6T timing receiver advertised on ebay in case any of you have one, or are thinking of investing. The model I got is the one advertised in ebay item 261294820006. It functioned OK for three months and then on powering up one day it seemed to be dead. On examining the board I found that the 3.3v regulator had a charred looking spot on top so I figured that it may have fried for some reason. I am not sure why. Maybe a duff part. I should be well under max current draw as my antenna connection is DC blocked with a 220R to ground for antenna detection. Hoping that the receiver had not perished as well I decided to replace the regulator. I could not identify the part on the board but replaced it with a MICREL MIC5205-3.3YM5 . Now all is well, at least from monitoring over a usb cable. Regards ___ time-nuts mailing 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] L1/L2 GPS Receiver
Magnus, I believe that he is referencing the the new L2 C/A code, which is not protected. Reference http://www.gps.gov/systems/gps/modernization/civilsignals/ Michael / K7HIL On Thu, Jan 16, 2014 at 2:04 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: On 16/01/14 20:29, Hal Murray wrote: anders.e.e.wal...@gmail.com said: The real benefit of dual-frequency is you can do post-processing with PPP. Javad has some modules but they start at 3 kUSD - if anyone knows of hobby level priced L1/L2 receivers that can produce rinex-files for PPP processing that would be interesting! Has anybody considered doing it in software? If I wanted to play with that sort of stuff, is there any particular SDR hardware package/project that would good to start with? You want P(Y) capable receivers, which means 20,46 MHz bandwidth on both L1 and L2 bands. You want say 12 channels. Lots of raw sample data to crunch on in real time. I'd say that you would really like to mimic the traditional style of doing the mechanical stuff in HW/FPGA and then do the remainder in some suitable processor. Going from C/A to P(Y) is a bit challangeing on it's own, as you where not supposed to be able to do that, only to get the P code. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/ mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] L1/L2 GPS Receiver
On 1/17/14 8:43 AM, Michael Perrett wrote: Magnus, I believe that he is referencing the the new L2 C/A code, which is not protected. Reference http://www.gps.gov/systems/gps/modernization/civilsignals/ Is the L2c officially on yet? and how many S/V are radiating it? I know there was some testing last summer for L2c but I don't recall the details. ___ time-nuts mailing 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] L1/L2 GPS Receiver
According to *GPS World*; The U.S. Air Force is directing transmission of continuous CNAV message-populated L2C and L5 signals starting in April 2014. . This is almost always optimistic, I would guess availability within 2014 a very high probability. Michael / K7HIL Ref: http://gpsworld.com/tag/l2c/ On Fri, Jan 17, 2014 at 10:11 AM, Jim Lux jim...@earthlink.net wrote: On 1/17/14 8:43 AM, Michael Perrett wrote: Magnus, I believe that he is referencing the the new L2 C/A code, which is not protected. Reference http://www.gps.gov/systems/gps/modernization/civilsignals/ Is the L2c officially on yet? and how many S/V are radiating it? I know there was some testing last summer for L2c but I don't recall the details. ___ time-nuts mailing 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] L1/L2 GPS Receiver
On 17 Jan, 2014, at 11:43 , Michael Perrett mkperr...@gmail.com wrote: Magnus, I believe that he is referencing the the new L2 C/A code, which is not protected. Reference http://www.gps.gov/systems/gps/modernization/civilsignals/ It would be nice to have a receiver for that when they turn it on, but I don't think that's what he wants. The observables used for PPP processing are L1 and L2 carrier phase. You don't need a receiver capable of decoding the P(Y) code but you do need a receiver capable of receiving the full bandwidth of its carrier on both L1 and L2 and tracking the phase. The commercial receivers which do this seem to cost dearly. Dennis Ferguson ___ time-nuts mailing 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] L1/L2 GPS Receiver
On 2014-01-16 20:29, Hal Murray wrote: anders.e.e.wal...@gmail.com said: The real benefit of dual-frequency is you can do post-processing with PPP. Javad has some modules but they start at 3 kUSD - if anyone knows of hobby level priced L1/L2 receivers that can produce rinex-files for PPP processing that would be interesting! Has anybody considered doing it in software? If I wanted to play with that sort of stuff, is there any particular SDR hardware package/project that would good to start with? Well, considering that you will need to get the P(Y) signal at 10,23 Mchip/s on both L1 and L2, requiring say 40 Msamples/s for both frequencies, and that you will need to do it for say 12 channeles and a bit of interesting processing beyond doing the same amount of channels for the C/A code, it will be an interesting challenge to do that in CPU code, rather than doing the baseband-processing in some form of hardware/FPGA. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] L1/L2 GPS Receiver
Michael, On 17/01/14 17:43, Michael Perrett wrote: Magnus, I believe that he is referencing the the new L2 C/A code, which is not protected. Reference http://www.gps.gov/systems/gps/modernization/civilsignals/ Regardless of how much I love the new civilian signals, they are at best scars at this time, and won't give sufficient improvement just yet. Until then, doing it in processors is possible but interesting. PS. Sorry for the double-post, seems the first email got out but I didn't see it. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] L1/L2 GPS Receiver
On 17/01/14 19:17, Dennis Ferguson wrote: On 17 Jan, 2014, at 11:43 , Michael Perrett mkperr...@gmail.com wrote: Magnus, I believe that he is referencing the the new L2 C/A code, which is not protected. Reference http://www.gps.gov/systems/gps/modernization/civilsignals/ It would be nice to have a receiver for that when they turn it on, but I don't think that's what he wants. The observables used for PPP processing are L1 and L2 carrier phase. You don't need a receiver capable of decoding the P(Y) code but you do need a receiver capable of receiving the full bandwidth of its carrier on both L1 and L2 and tracking the phase. The commercial receivers which do this seem to cost dearly. The receivers out there use the fact that the known P-code is encrypted with a W-code into the Y-code using XOR. Over the years have various degrees of advanced methods provided means to measure L1 C/A-code phase, L1 P(Y) code phase, L1 carrier phase, L2 P(Y) code phase and L2 carrier phase. Some of the earlier receivers only provided a sub-set. Commercial receivers maintain a high price because they see a less price-sensitive market. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] possible issue with LEA 6T eval board
Hoping that the receiver had not perished as well I decided to replace the regulator. I could not identify the part on the board but replaced it with a MICREL MIC5205-3.3YM5 . Now all is well, at least from monitoring over a usb cable. Regards Just a FYI, those bipolar LDOs can get a bit unstable near dropout. One thing you usually don't see on a Micrel datasheet is the efficiency as you approach dropout. That is because the BJT is near saturation, the beta has dropped, and thus the chip itself needs more current just to regulate. Generally for that type of design, you add a bit of hidden circuitry to sat catch, i.e. keep the BJT out out saturation for stability reasons, though it is itself a second feedback loop. It is usually never shown on a functional diagram. However the pass device beta is very low near saturation, which can stress the part. The part does have a thermal shutdown, but with bipolar, the part can fail pretty quickly. Unless you need very low noise, a LDO with a Pfet pass device is more reliable. This patent explains one approach at sat catching: http://www.google.ca/patents/US5410241 So those bipolar LODs are a lot easier to fry than you would think. ___ time-nuts mailing 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] ADEV ScaleFactor correction
On 16/01/14 07:54, WarrenS wrote: ADEV is a great tool for measuring random noise but not so good for systematic errors like ageing drift. I have seen on the better oscillator's that the typical ADEV rise with time is often the effect of changing temperature and/or ageing drift. I did an experiment to determine what scale factor correction is needed for determining an oscillator's linear freq ageing drift rate over time using ADEV / MDEV data. I used a good HP10811 osc whose drift rate when left on continuously is well below 1e-10 / day with an ADEV / MDEV of around 1e-12 between 0.1 to 100 sec. This osc has not been powered up for a few months, so it's initial turn on drift rate was very high at ~1.3 e-8 / day. By plotting both its actual drift rate change and it's varying ADEV as the unit is restabilizing, I found that the oscillator's actual drift rate was equal to 1.4 times the ADEV value. That is with an ADEV value of 1e-10 at 1000 seconds, the oscillator's actual frequency ageing drift rate at that time was 1.4 e-10 per 1000 seconds. The 1.4 scale factor correction worked in this case from below 100 seconds to greater than 10K seconds. Of course this scale factor only applies when the oscillator's drift rate is constant and is the major error source for the given ADEV time period and data run. The same scale factor also works using MDEV data, because in this case, the MDEV values are the same as the ADEV values at time periods when ageing drift is the major error source. Attached are two TimeLab plots that I used to find the scale factor correction, showing the ageing drift rate and the changing ADEV values as this oscillator restabilizes. The linear frequency drift causes an ADEV linear ramp of D*tau/sqrt(2) as found here: http://en.wikipedia.org/wiki/Allan_variance#Linear_response For raw measures being uncompensated of oscillator systematic drift, the drift will indeed overshadow the upper end of the ADEV/MDEV plot. It turns out that below the linear frequency drift is higher terms, so just removing the linear drift does not completely remove the systematic components. ADEV was only means for the noise components, so systematic components should be separated and analysed separately. Their confidence bounds is way different. I try to let oscillators sit powered up as long as possible to reduce the drift from my measurements. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] HP 5328A fan - suspected issue
Hi all, This is my first post to this list. I recently acquired three HP 5328A counters and have been using one in my shack. They all seem to have fan issues, with the fans not running in two of them and in the third unit a resistor near the fan starts to smoke if I turn it on. All of the fans look identical, being 110V AC units. So, I have some questions: - should the fan run all of the time or is it on a thermostat - does the smoking resistor mean that the fan is seized - can I replace it with a 5V/12V computer fan. If so, can I safely tap DC off the power supply and will the fan introduce any electrical noise? I am 240V here so sourcing a fan 110V fan locally may be difficult The counter I have running seems ok without the fan running. It is the pick of the bunch with the OCXO, 525MHz and DVM option. Being the best oscillator I have currently, I have checked it against WWV and it seems ok. I also used it as an alignment reference for a funcube dongle receiver (with tcxo) and am receiving WSPR spots on frequency, so I think it is good. I am slowly getting the time-nuts bug and am building a GPSDO with a Morion MV89A ocxo ... Many Thanks es 73 Brett VK6EZ -- Mobile: +61 468 512095 ___ time-nuts mailing 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] New Symmetricom 1000C oscillator
I noticed today that Symmetricom has upgraded it's venerable 1000B. The 5MHz C model has a premium version with a rated -130dB @ 1Hz offset. I think that is the best rated spec I have seen. Noise floor is a lackluster 160dB @ 100KHz. Sounds like a BVA. The data sheet is at: http://www.symmetricom.com/resources/download-library/documents/datasheets/1000c/ Thomas Knox ___ time-nuts mailing 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] saving Lady Heather set-up?
Hi, I have now got my thunderbolt/Lady Heather set-up pretty much where I want it, and want to keep all the changes I have made. Is there a way to have Lady Heather save all the changes so when the inevitable reboot occurs, I don't have to go through all the changes manually again- always assuming I can remember them of course! Thanks, Ken. ___ time-nuts mailing 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] HP 5328A fan - suspected issue
Brett Welcome to the group. If you do not have a pdf of the 5328 manual go here to get a copy. http://www.ko4bb.com/manuals/index.php I had several 5328s a long time ago and they are quite nice counters. Looking at the schematic there is indeed a tstat that controls a SCR that runs the fan. Now its not clear to me what resistor might be smoking. There is a .47 ohm resistor for current sensing. If thats smoking you have a short or something. But thats speculation. Take a look at the schematic and let us know what R is smoking. That may help us a lot. To the fan 12 vdc or such it could work but they may draw a fair amount of current and do generate noise that may possibly effect low level readings. So certainly can work. Regards Paul WB8TSL/1 On Fri, Jan 17, 2014 at 6:03 PM, Brett Owen Rees bre...@gmail.com wrote: Hi all, This is my first post to this list. I recently acquired three HP 5328A counters and have been using one in my shack. They all seem to have fan issues, with the fans not running in two of them and in the third unit a resistor near the fan starts to smoke if I turn it on. All of the fans look identical, being 110V AC units. So, I have some questions: - should the fan run all of the time or is it on a thermostat - does the smoking resistor mean that the fan is seized - can I replace it with a 5V/12V computer fan. If so, can I safely tap DC off the power supply and will the fan introduce any electrical noise? I am 240V here so sourcing a fan 110V fan locally may be difficult The counter I have running seems ok without the fan running. It is the pick of the bunch with the OCXO, 525MHz and DVM option. Being the best oscillator I have currently, I have checked it against WWV and it seems ok. I also used it as an alignment reference for a funcube dongle receiver (with tcxo) and am receiving WSPR spots on frequency, so I think it is good. I am slowly getting the time-nuts bug and am building a GPSDO with a Morion MV89A ocxo ... Many Thanks es 73 Brett VK6EZ -- Mobile: +61 468 512095 ___ time-nuts mailing 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] L1/L2 GPS Receiver
On 1/17/14 11:35 AM, Magnus Danielson wrote: On 2014-01-16 20:29, Hal Murray wrote: anders.e.e.wal...@gmail.com said: The real benefit of dual-frequency is you can do post-processing with PPP. Javad has some modules but they start at 3 kUSD - if anyone knows of hobby level priced L1/L2 receivers that can produce rinex-files for PPP processing that would be interesting! Has anybody considered doing it in software? If I wanted to play with that sort of stuff, is there any particular SDR hardware package/project that would good to start with? Well, considering that you will need to get the P(Y) signal at 10,23 Mchip/s on both L1 and L2, requiring say 40 Msamples/s for both frequencies, and that you will need to do it for say 12 channeles and a bit of interesting processing beyond doing the same amount of channels for the C/A code, it will be an interesting challenge to do that in CPU code, rather than doing the baseband-processing in some form of hardware/FPGA. ALmost certainly in an FPGA. But unless you want fast acquisition, implementing the tracking loop and despreading in FPGA isn't mindbendingly difficult. I'll bet there's open source out there. You could also record raw bits and decode off line in software in non-real time, as long as your clock that you timestamp with isn't too bad. ___ time-nuts mailing 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] saving Lady Heather set-up?
Yes, Lady Heather has two ways of loading/changing a configuration. You can put a heather.cfg file in your Lady Heather directory. This file should contain any command line parameters that you want to use... one per line with the '/' in the first column. Use heather /? (or ? from the keyboard) for a list of command line options. At the end of that help dialog screen it will tell you what your heather directory is. Also see the comments at the start of the heather.cpp source code file... that is where what passes for program documentation is... You can also make keyboard script files that when read in with the /r=???.scr command line option or the 'R' keyboard command will be read and the text in the file will act just like you typed it from the keyboard (with a few extensions that are documented in the comments at the start of the hearher.cpp source code file). There is not a way to have heather automatically write a .SCR file that will re-create any changes to the configuration that you may have made... your have to create the script file manually. Script files can be nested up to five levels deep. ___ time-nuts mailing 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] saving Lady Heather set-up?
Oh, and there is an another way to configure the program if you can do it with command line options... edit the startup command line in the program PREFERENCES (right click on the Heather icon). You can also do this to automatically load your desired keyboard script file or a different .CFG file (the /R command or 'R keyboard command can load .CFG files (and a whole lot more)) ___ time-nuts mailing 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] saving Lady Heather set-up?
Thanks Mark, one heather.cfg file coming up- now all I have to do is remember what I changed... Ken. On Sat, Jan 18, 2014 at 2:52 PM, Mark Sims hol...@hotmail.com wrote: Yes, Lady Heather has two ways of loading/changing a configuration. You can put a heather.cfg file in your Lady Heather directory. This file should contain any command line parameters that you want to use... one per line with the '/' in the first column. Use heather /? (or ? from the keyboard) for a list of command line options. At the end of that help dialog screen it will tell you what your heather directory is. Also see the comments at the start of the heather.cpp source code file... that is where what passes for program documentation is... You can also make keyboard script files that when read in with the /r=???.scr command line option or the 'R' keyboard command will be read and the text in the file will act just like you typed it from the keyboard (with a few extensions that are documented in the comments at the start of the hearher.cpp source code file). There is not a way to have heather automatically write a .SCR file that will re-create any changes to the configuration that you may have made... your have to create the script file manually. Script files can be nested up to five levels deep. ___ time-nuts mailing 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.
