Re: [time-nuts] Paper about DCF77 performance
Hi Attila Thanks for the feedback. * you have a lot of simulation and measurments on BER vs SNR. For time-nutty needs that's not so relevant. An ADEV plot would be much more informative on the stability. * Also some data on the absolute timing variations vs time would be nice to have. Yes that would be nice, but my spare time is short for this and the dozens of other ideas I have. * Fig 23 shows a very complex board. Given that you only have a relatively simple analog stage and an FPGA i wonder what the rest is for. Just the usual power supply, DAC for debugging FPGA-internal signals, galvanically isolated USB for logging, debug headers. * You use an LTC1562 8th order bandpass: Do you compensate for it's frequency dependend delay and its variation? Or is negligible compared to the antenna? I do compensate for it. The remaining uncertainty is taken into account in the paper. * Do you do any temperature stabilization? No, but it would be a nice addition. * What kind of reference oscillator do you use? Abracon ASV-12.000MHZ-E-J-T, 20 ppm, 12 MHz * You talk about 20 to 50ppm variations for XO's, are you aware that these are maximum variation including production variabiltiy and that the stability of an good XO is usually in the range of a few ppm in office conditions (i've measured an XO in a PC that showed a long term (months) stability in the ppb range) I worked with worst-case ranges as if it were a mass production. * Why did you use an FPGA and not a simple DSP or one of the more powerfull uC's like an Cortex-M3/4? The algorigthms don't look computationally intensive. And that would simplify the development considerably. At that time, I wanted to have some fun with FPGAs. It would also work on a uC, which BTW already is my next project. Both ways have advantages, for example the clock correction algorithm is easier to implement on an FPGA, while the signal processing would be simpler on a uC. * Where did you do your measurements? In Schlieren? Yes. * What is the application you had in mind while developing this? Building the best DCF77 receiver in the world :-) Regards, Daniel ___ 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] Paper about DCF77 performance
Attila, An ADEV plot would be much more informative on the stability. I have found an old publication from former PTB researcher Dr. Peter Hetzel. This publication holds a diagram which (while not being exactly an ADEV plot) holds some interesting information on the topic: It shows the STANDARD DEVIATION of timing measurements made on DCF77's signal abt. 273 km away from the transmitter location as a function of the averaging time of the measurements. So no ADEV but coming close... The diagram starts at abt. 8E-8 std dev for 1 s avaraging time and is basically a straight line with a slope of abt. -0.8. that extends to 7E-14 for averaging times of 100 days. I list a few values: 8E-8@ 1 s 1E-9 @ 10 s 2E-10 @ 100 s 5E-11 @ 1000 s 2E-12 @ 1 d 3E-13 @ 10 d 7E-14 @ 100 d The diagram has no log sub scale so the readings are my estimate. The diagram hold a lot of individual points between 10 and 100 days averaging time indicating that a lot of measurements with that averaging times have really been done. Best regards Ulrich Bangert -Ursprungliche Nachricht- Von: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] Im Auftrag von Attila Kinali Gesendet: Donnerstag, 14. Juni 2012 07:56 An: Discussion of precise time and frequency measurement Betreff: Re: [time-nuts] Paper about DCF77 performance Hoi Dani! I see you've found the time-nuts as well :-) On Wed, 13 Jun 2012 21:46:56 +0200 Daniel Engeler enge...@alumni.ethz.ch wrote: This is my first post to this mailing list. I wrote a paper about the German longwave time transmitter DCF77 which you may find interesting. Here is the link, unfortunately I am not allowed to post the full PDF: There is an easy way to get around that: Prepare a second paper with more data in it (all that stuff that IEEE tends to get rid of during the publication process) and put that onto your website. http://ieeexplore.ieee.org/xpl/articleDetails.jsp?tp=arnumber=6202411 Performance Analysis and Receiver Architectures of DCF77 Radio-Controlled Clocks, by Daniel Engeler IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control (May 2012) Nice paper. I haven't had time to read it yet, but a few comments after i skimmed it: * you have a lot of simulation and measurments on BER vs SNR. For time-nutty needs that's not so relevant. An ADEV plot would be much more informative on the stability. * Also some data on the absolute timing variations vs time would be nice to have. * Fig 23 shows a very complex board. Given that you only have a relatively simple analog stage and an FPGA i wonder what the rest is for. * You use an LTC1562 8th order bandpass: Do you compensate for it's frequency dependend delay and its variation? Or is negligible compared to the antenna? * Do you do any temperature stabilization? * What kind of reference oscillator do you use? * You talk about 20 to 50ppm variations for XO's, are you aware that these are maximum variation including production variabiltiy and that the stability of an good XO is usually in the range of a few ppm in office conditions (i've measured an XO in a PC that showed a long term (months) stability in the ppb range) * Why did you use an FPGA and not a simple DSP or one of the more powerfull uC's like an Cortex-M3/4? The algorigthms don't look computationally intensive. And that would simplify the development considerably. * Where did you do your measurements? In Schlieren? * What is the application you had in mind while developing this? Attila Kinali -- Why does it take years to find the answers to the questions one should have asked long ago? ___ 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] Paper about DCF77 performance
enge...@alumni.ethz.ch said: Building the best DCF77 receiver in the world :-) You have found the right place. :) -- 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] Another ThunderBolt cabling question
Acrually the PPS output has very low impedance, so you can probably load it with 5 instruments, each with 50 termination. Not so for the 10MHz though Didier KO4BB Sent from my BlackBerry Wireless thingy while I do other things... -Original Message- From: David C. Partridge david.partri...@perdrix.co.uk Sender: time-nuts-boun...@febo.com Date: Thu, 14 Jun 2012 01:59:42 To: 'Chris Wilson'ch...@chriswilson.tv; 'Discussion of precise time and frequency measurement'time-nuts@febo.com Reply-To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Another ThunderBolt cabling question No you can't load the 10MHz (or the PPS) with five instruments in parallel. You need a distribution amplifier. Dave -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Chris Wilson Sent: 13 June 2012 22:33 To: Discussion of precise time and frequency measurement Subject: [time-nuts] Another ThunderBolt cabling question 13/06/2012 22:27 About to do the permanent installation, if I bring two leads from the 10 MHz and 1 PPS BNC sockets on the TB to a panel in my shck can i have say 5 BNC sockets on the panel wired in parallel, with the lead from the 10 MHz socket on the TB feeding them all? And a single socket for the 1 PPS? Any need to screen the back of the socket panel, or enclose it in a metal box? Cheers. Oh, I have been running lady Heather for a while tonight, here's a screen capture, does it look OK, ther's suddenly just two traces appeared? Thanks. http://www.chriswilson.tv/heather.png -- Best Regards, Chris Wilson. mailto: ch...@chriswilson.tv ___ 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] Miller Divider
Hi, Has anybody had any experience with the Miller frequency divider: input --- mixer --o-- output F | | F/2 ^ | |--- LPF --| There are more details in Wiki: http://en.wikipedia.org/wiki/Frequency_divider There were similar dividers used in the GR Synthesizers in the mid-1960s. My current interest is only in the divide-by-two. Thanks, -J = ___ 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] Miller Divider
Hi A parametric (varicap based) divider might be an alternative. There's a lot of design information on them out there. They are pretty easy to build and reasonably robust. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of J. Forster Sent: Thursday, June 14, 2012 8:37 AM To: time-nuts@febo.com; gen...@yahoogroups.com Subject: [time-nuts] Miller Divider Hi, Has anybody had any experience with the Miller frequency divider: input --- mixer --o-- output F | | F/2 ^ | |--- LPF --| There are more details in Wiki: http://en.wikipedia.org/wiki/Frequency_divider There were similar dividers used in the GR Synthesizers in the mid-1960s. My current interest is only in the divide-by-two. Thanks, -J = ___ 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] Strange E3610A PSU - Old revision
There appears to be some massive contamination on the board, apparently not only from a leaked electrolytic cap. It looks much like some unknown liquid flooded a large area of the board and dried. I do not see any reworked solder joints on the board, so the 'unusual' components have to be original to the unit. Do not attempt to change the circuit (replace components with values from a schematic that does not match the given circuit exactly), otherwise you'll end up in a mess. You may perform the service note changes though, given you check carefully if they work for your unit. Especially the voltage overshoot issue should be easy to check in advance. The 12/91 date code on the transformer (unfortunately, the serial number is still undisclosed) indicates a very early example of the E3610A that was actually introduced in the 1992 catalog. As by the 1992 catalog, there is a 10-turn voltage pot and a 1-turn current pot. More recent versions have 10-turn current pots as does mine from 1998. Also, it has U2 = LM340T (!), U4 = LF442CN, U5 = LM393N, U1 = LF411CN, U3 = LM336. Hope that helps. Adrian cfo schrieb: I just bought a E3610A PSU on ebay , as defective. Main problem right now is ... This seems to be an older revision And has other comp values , than the Schematic on the net CompItem - Org Value - Inserted value - --- - - R19 CC frontpanel Pot - 10 turn 10k - 1 turn 10K U2 12v Regulator - MC7812CT - LM340T12 U4 Current OpAmp - LF442CN - LM1458N U5 CC/CV Indicator - LM393CN - LM393N U1 Voltage OpAmp - LF411CN - LM741EN U3 Volt Ref - LM336-5.0 5.0v- LM329 6.9v PCB PCB number- ?? C7 Pos. REF CAP - 330uF 50v - 330uF 50v C13 Neg. REF CAP - 470uF 50v - 330uF 50v I posted some pics here. http://tinyurl.com/cn9p4s9 Does anyone have a schematic of a E3610A , that might have ie. LM1458 in it or a 6.9v Ref , instead of a 5v Ref ? Tia CFO Denmark ___ 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] Strange E3610A PSU - Old revision
On Thu, 14 Jun 2012 16:58:41 +0200, Adrian wrote: There appears to be some massive contamination on the board, apparently not only from a leaked electrolytic cap. It looks much like some unknown liquid flooded a large area of the board and dried. I do not see any reworked solder joints on the board, so the 'unusual' components have to be original to the unit. Do not attempt to change the circuit (replace components with values from a schematic that does not match the given circuit exactly), otherwise you'll end up in a mess. You may perform the service note changes though, given you check carefully if they work for your unit. Especially the voltage overshoot issue should be easy to check in advance. The 12/91 date code on the transformer (unfortunately, the serial number is still undisclosed) indicates a very early example of the E3610A that was actually introduced in the 1992 catalog. As by the 1992 catalog, there is a 10-turn voltage pot and a 1-turn current pot. More recent versions have 10-turn current pots as does mine from 1998. Also, it has U2 = LM340T (!), U4 = LF442CN, U5 = LM393N, U1 = LF411CN, U3 = LM336. Hope that helps. Adrian Hi Adrian Thanx for the ansver. I have come to the same result That the parts are original mounted , and it's an early model. I have already been recommended a 2'nd cleanup of the PCB , and after a 2'nd washdown with IPA , and a top-side resolder of all the resistors in the PSU-Meter voltage divider section. The PSU volt meter is actually stable , and is following the PSU-Output , quite nicely. I verified by having my 34401A on the PSU-Output. Now i'll wait for the new CAPS to arrive , and then calibrate it according to the manual. First Current , and then voltage. I don't have the Current cal. resistors specified in the manual , but i just got an Agilent 6632B. Witch should be able to work as a variable 0..5 Amp load. Providing i can get it to do that (manual reading). I actually think i have gotten the PSU to behave now. Thanx for all the hints. Ps: Current Calibration hints are welcome ... CFO ___ 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] Another ThunderBolt cabling question
On Thu, Jun 14, 2012 at 3:59 AM, shali...@gmail.com wrote: Acrually the PPS output has very low impedance, so you can probably load it with 5 instruments, each with 50 termination. My problem with PPS distribution was the fast raise time got smeared by the long cable. Lots of guesses about why. Could be reflections off the end, capacitance in the cable. The problem is that I want WAY under 1 microsecond level performance out of a PPS signal. The trouble is that the PPS is a single ended signal and the leading edge is defined by some voltage threshold. So it is sensitive to noise. Two solutions I found (1) differential transmitters and receivers at each end, like RS-422 type work, or (2) simply move the thunderbolt physicaly close and use an 18 inch cable. Take my word for it, the T-Bolt is not able to drive a 100 foot long twisted pair cable Not so for the 10MHz though Didier KO4BB Sent from my BlackBerry Wireless thingy while I do other things... -Original Message- From: David C. Partridge david.partri...@perdrix.co.uk Sender: time-nuts-boun...@febo.com Date: Thu, 14 Jun 2012 01:59:42 To: 'Chris Wilson'ch...@chriswilson.tv; 'Discussion of precise time and frequency measurement'time-nuts@febo.com Reply-To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Another ThunderBolt cabling question No you can't load the 10MHz (or the PPS) with five instruments in parallel. You need a distribution amplifier. Dave -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Chris Wilson Sent: 13 June 2012 22:33 To: Discussion of precise time and frequency measurement Subject: [time-nuts] Another ThunderBolt cabling question 13/06/2012 22:27 About to do the permanent installation, if I bring two leads from the 10 MHz and 1 PPS BNC sockets on the TB to a panel in my shck can i have say 5 BNC sockets on the panel wired in parallel, with the lead from the 10 MHz socket on the TB feeding them all? And a single socket for the 1 PPS? Any need to screen the back of the socket panel, or enclose it in a metal box? Cheers. Oh, I have been running lady Heather for a while tonight, here's a screen capture, does it look OK, ther's suddenly just two traces appeared? Thanks. http://www.chriswilson.tv/heather.png -- Best Regards, Chris Wilson. mailto: ch...@chriswilson.tv ___ 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] Another ThunderBolt cabling question
Yes, highly recommended the differential line approach. On Thu, Jun 14, 2012 at 6:38 PM, Chris Albertson albertson.ch...@gmail.comwrote: On Thu, Jun 14, 2012 at 3:59 AM, shali...@gmail.com wrote: Acrually the PPS output has very low impedance, so you can probably load it with 5 instruments, each with 50 termination. My problem with PPS distribution was the fast raise time got smeared by the long cable. Lots of guesses about why. Could be reflections off the end, capacitance in the cable. The problem is that I want WAY under 1 microsecond level performance out of a PPS signal. The trouble is that the PPS is a single ended signal and the leading edge is defined by some voltage threshold. So it is sensitive to noise. Two solutions I found (1) differential transmitters and receivers at each end, like RS-422 type work, or (2) simply move the thunderbolt physicaly close and use an 18 inch cable. Take my word for it, the T-Bolt is not able to drive a 100 foot long twisted pair cable Not so for the 10MHz though Didier KO4BB Sent from my BlackBerry Wireless thingy while I do other things... -Original Message- From: David C. Partridge david.partri...@perdrix.co.uk Sender: time-nuts-boun...@febo.com Date: Thu, 14 Jun 2012 01:59:42 To: 'Chris Wilson'ch...@chriswilson.tv; 'Discussion of precise time and frequency measurement'time-nuts@febo.com Reply-To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Another ThunderBolt cabling question No you can't load the 10MHz (or the PPS) with five instruments in parallel. You need a distribution amplifier. Dave -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Chris Wilson Sent: 13 June 2012 22:33 To: Discussion of precise time and frequency measurement Subject: [time-nuts] Another ThunderBolt cabling question 13/06/2012 22:27 About to do the permanent installation, if I bring two leads from the 10 MHz and 1 PPS BNC sockets on the TB to a panel in my shck can i have say 5 BNC sockets on the panel wired in parallel, with the lead from the 10 MHz socket on the TB feeding them all? And a single socket for the 1 PPS? Any need to screen the back of the socket panel, or enclose it in a metal box? Cheers. Oh, I have been running lady Heather for a while tonight, here's a screen capture, does it look OK, ther's suddenly just two traces appeared? Thanks. http://www.chriswilson.tv/heather.png -- Best Regards, Chris Wilson. mailto: ch...@chriswilson.tv ___ 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.
[time-nuts] LEA-6T kit
I thought this may be of some interest. http://shop.sysmocom.de/products/osmo-lea6t-gps Doc KX0O Sent from my iPad Sent from my iPad ___ 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] LEA-6T kit
I bought one several months ago, but summer activities prevented building yet. Well done and doesn't look too hard. The LEA-6 isn't real small if you have a magnifier of some sort. N0UU ___ 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] LEA-6T kit
Careful when soldering the lea pins they are very close to the metal shield and it's very hard to clear a short between the pin and the shield.. It can happen in an instant.. Sent From iPhone On Jun 14, 2012, at 20:22, lstosk...@cox.net wrote: I bought one several months ago, but summer activities prevented building yet. Well done and doesn't look too hard. The LEA-6 isn't real small if you have a magnifier of some sort. N0UU ___ 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.
