Re: [time-nuts] Acam TDC's

2014-04-07 Thread Marek Peca
I looked into one of the high end units for a project. From what I recall, the resolution was high. The problem for me was the continuous throughput was not there. I was looking at making around 30 to 40 million measurements per second. As I recall, it it could burst at that, but not sustain it.

Re: [time-nuts] Confused about Rubidium oscillators

2012-11-14 Thread Marek Peca
Hello, There are no ?wear-out? or ?use-up? mechanisms in a Datum Efratom Rubidium oscillator. (..) But also: Unlike a quartz crystal oscillator which has no clearly-defined wear out period and, if well-designed, can actually improve as time goes on, a Rubidium reference has a definite

Re: [time-nuts] Very challenging phase noise measurement, does anyone have an idea??

2012-12-05 Thread Marek Peca
running mode and lock the other one to the first one using an XOR gate and then use the output of the XOR gate as an output signal. However, we are wondering if any of you know a better idea. Maybe there is an off-the-shelf piece Nearly any idea is better than the XOR gate you proposed. A

Re: [time-nuts] Very challenging phase noise measurement, does anyone have an idea??

2012-12-05 Thread Marek Peca
This last idea is interesting... could be simulated by Matlab or similar. It is known to work in ordinary non-linear transistor-based mixers. It will produce more messy spectrum than double-balanced mixer, however, for this purpose and completely within digital domain, it makes absolutely no

Re: [time-nuts] Phase noise measurement with a scope

2013-06-12 Thread Marek Peca
Hello, given that digital scopes have a multichannel ADC for acquisition, which is similar to what a cross-correlating phase noise measurement instrument has, it occurred to me that phase noise measurement might also be possible with a standard digital scope and some post-processing software.

Re: [time-nuts] Phase noise measurement with a scope

2013-06-12 Thread Marek Peca
(..) I have tried it with a very cheap one, Rigol 2-channel, originally 50MHz, reflashed to 100MHz. 2 signals, refmeasured, into Ch1, Ch2. Waveforms (2x500Msps) acquired, sinc() interpolated. Results: short-term single-shot jitter around 100ps RMS. Long-term was of no interest for my purpose

Re: [time-nuts] Phase noise measurement with a scope

2013-06-12 Thread Marek Peca
My point was, that DSO is basically an ADC. Therefore, there is some amount of noise, nonlinearity and drift, limiting the jitter measurement. Do you think any method can dig more information from given data than sinc() interpolation and zero-crossing computation? The cross-spectrum averaging

[time-nuts] 1. Clock ensembling; 2. Delay controller-synthesizer -- preprints of this year's UFFC IFCS-EFTF contributions

2013-07-26 Thread Marek Peca
Dear time-nuts In case of interest, you may check our fresh conference preprints from IEEE--UFFC International Frequency Control Symposium -- European Frequency and Time Forum 2013, just finished: 1. Clock Composition by Wiener Filtering Illustrated on Two Atomic Clocks - about clock

Re: [time-nuts] SITime oscillators

2013-08-06 Thread Marek Peca
SITime just got some press for their temperature insensitive mems oscillators. I went to the web site and saw some interesting parts with pretty ambitious claims. Specifically better than Quartz. http://www.sitime.com/index.php

Re: [time-nuts] exponential+linear fit

2013-10-04 Thread Marek Peca
Hello, Jim, On Fri, 4 Oct 2013, Jim Lux wrote: I'm trying to find a good way to do a combination exponential/linear fit (for baseline removal). It's modeling phase for a moving source plus a thermal transient, so the underlying physics is the linear term (the phase varies linearly with

Re: [time-nuts] exponential+linear fit

2013-10-04 Thread Marek Peca
Dear Jim, I'm removing a slowly varying bias term from fairly noisy data. Maybe several 10s of thousands of data points, And I want to do it quickly on a slow processor. I think the LTI framework should work very well for that; easy fixpoint implementation etc. Since I am a space fan,

Re: [time-nuts] fast edge, rise time.

2013-12-26 Thread Marek Peca
The target is 4ns, while ideas seemed to be clear at some point, now I'm having doubts if better to use a MOSFET or a bipolar transistor as the switch element. Experiments with MOSFETs presented me some difficulties charging the gate capacitance having some trouble to achieve something in the

Re: [time-nuts] WWVB BPSK Receiver Project?

2012-03-14 Thread Marek Peca
Dear Time-Nuts, (new at this list, but reading for long time excellent timekeeping oscillator articles) I sure would like a WWVB BPSK receiver for the new modulation. (..) I'm sure in time there will be plenty of low cost ICs designed to receive the new signal, but my guess is that many

Re: [time-nuts] WWVB BPSK Receiver Project?

2012-03-14 Thread Marek Peca
I will share my few bits of worked experience. But it may seem obvious. I'd say to go 100% SDR. In other words a simple front and that pushes as much of the functionality into software as possible. The carrier is only 60K. That is low enough that one can directly digitize the RF using an

Re: [time-nuts] WWVB BPSK Receiver Project?

2012-03-15 Thread Marek Peca
I know I am not one of the good-ole-boys here but I'd say go 100% SDR with your PC without an external A/D converter. Ok, how would you do this? You use under sampling. Many A/D converter systems use a sample and hold before the A/D converter. If you do the same before your sound card (your

Re: [time-nuts] WWVB BPSK Receiver Project?

2012-03-15 Thread Marek Peca
Dear american colleagues, as I read last few posts about WWVB, I am very tempted to return to LF time signal fun. As I wrote you, there vere very good results using cheap 2 IC circuitry and a PC with our local DCF77 signal. Under influence of this maillist, I am thinking about recreating of

Re: [time-nuts] WWVB BPSK Receiver Project? (fwd)

2012-03-15 Thread Marek Peca
Forgot to Cc: the maillist, sorry. So, FYI: -- Forwarded message -- Date: Thu, 15 Mar 2012 16:31:14 +0100 (CET) From: Marek Peca ma...@duch.cz To: David J Taylor david-tay...@blueyonder.co.uk Subject: Re: [time-nuts] WWVB BPSK Receiver Project? Hello, I would perhaps

Re: [time-nuts] WWVB BPSK Receiver Project? (fwd)

2012-03-16 Thread Marek Peca
Hello, thank you for your oppinion. On Thu, 15 Mar 2012, Poul-Henning Kamp wrote: In message Pine.LNX.4.64.1203152001370.3542@tesla, Marek Peca writes: Yes, it should work on any USB audio capable OS, ie. Linux, Windows, MacOS etc. I would like to recommend against this approach

Re: [time-nuts] WWVB BPSK Receiver Project? (fwd)

2012-03-17 Thread Marek Peca
Hello, gary, I lost track of who wrote this, but why is it assume a ferrite rod has non-linear phase. [Group delay error I presume). Now I assume this presumes the rod is used in a LC circuit, but if the Q is not high, the phase linearity won't necessarily be bad. Basically I'd like to hear

Re: [time-nuts] WWVB BPSK Receiver Project? (fwd)

2012-03-17 Thread Marek Peca
Dear Poul-Henning, My only argument against your versatile and well-performing solution is that it is a little bit overkill. As if running a handfull precision oscillators just for fun isn't overkill also ? :-) I don't know -- are there any limits for the fun in a time-nut sense? :-) I hope

Re: [time-nuts] WWVB BPSK Receiver Project? (fwd)

2012-03-17 Thread Marek Peca
I've designed filters for datacom chips. I know filtering. My point is the original author is making some assumptions in the design which are not stated. Yes, my fault, I didn't write it properly, so by a ferrite rod in context of DCF/WWVB reception, I meand a ferrite antenna in an LC tuned

Re: [time-nuts] WWVB BPSK Receiver Project? (fwd)

2012-03-17 Thread Marek Peca
Any filter's group delay can be equalized by all pass filters. Delay builds up at the filter corner. Since everything in the real world is causal, you add delay outside that corner frequency but in the passband to equalize it. This is to say, you can't remove delay, but just add it to flatten

Re: [time-nuts] WWVB BPSK Receiver Project? (fwd)

2012-03-17 Thread Marek Peca
Which basically matched my assumption. If the inductor is loaded, you have a narrowband filter. So again, this does not imply that a ferrite rod antenna per se has phase distortion. It is the LC filter than effects the group delay. Yes, exactly. Excuse my loose speech before not explicitly

Re: [time-nuts] WWVB BPSK Receiver Project? (fwd)

2012-03-17 Thread Marek Peca
Yes, in order to equalize group delay, you need to know what to equalize. But with an educated guess as to the system response, he could get close. All this said, in 2012, I would rather the amplifier be simple gain, the inductor not loaded with capacitance and the filtering done past the

Re: [time-nuts] WWVB BPSK Receiver Project? (fwd)

2012-03-17 Thread Marek Peca
I think the tempco of the ferrite is more significant than drift in the analog filter. Perhaps I was unclear in this as well. I do not use nor plan to use any other filter than the (ferrite-L)-C resonant circuit itself. So, yes, the tempco of the ferrite makes its coefficients variation.

Re: [time-nuts] WWVB BPSK Receiver Project? (fwd)

2012-03-17 Thread Marek Peca
That would be 36ns group delay variation if I did the math correctly. OK And in article P. Hetzel: Time dissemination via the LF transmitter DCF77 using a pseudo-random phase-shift keying of the carrier, 2nd EFTF Neuchatel, 1988., they conclude with timing results of about 2..10e-6 s RMS

Re: [time-nuts] WWVB BPSK Receiver Project? (fwd)

2012-03-17 Thread Marek Peca
Dear Henry, I don't know where you are in CZ. I'm on the boarder in DE near PL and CZ. my former measurement (the one at YouTube, fairly good reception, winter) has been done under Erzgebirge, Teplice, CZ. Now I moved near Sumava (Boehmischer Wald), so tests may follow, if I will return to

Re: [time-nuts] WWVB BPSK Receiver Project? (fwd)

2012-03-18 Thread Marek Peca
My choice would be a center tapped, shielded, air core loop, running into a low noise instrumentation amp. Center tap of loop to twinax shield, grounded at preamp. The instrumentation amp has fixed gain, and very high CMRR and PSRR. It also does the differential to single ended conversion

[time-nuts] EFTF 2012 -- anyone to meet there?

2012-04-18 Thread Marek Peca
Dear Time-Nuts, is there anybody coming to 2012 EUROPEAN FREQUENCY AND TIME FORUM, http://www.eftf2012.org/ (next week, Sweden)? It would be nice to meet there live. Greetings, Marek ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go

Re: [time-nuts] GLONASS receiver

2012-08-05 Thread Marek Peca
Hello, Miguel, [sorry for replying to 2nd e-mail, accidentally deleted the original msg] Everything is fine but I am a bit worried about the GPS reliability because GPS is ruled by the USA. Me too, this is why I welcome upcoming expensive Galileo. Would a GPS disciplined oscillator solve

Re: [time-nuts] Multiple Time Interval Counters to measure Transients?

2012-09-08 Thread Marek Peca
Hello, On Sat, 8 Sep 2012, Florian Teply wrote: (..) But then I'll have to throw a few hundred Time Interval Counters at the problem in order to get the information on the duration of the transients. So in general, amplitude information comes from the comparator trigger levels, time

Re: [time-nuts] Multiple Time Interval Counters to measure Transients?

2012-09-08 Thread Marek Peca
Hello, Well, for the CMOS stuff 100ps should do just fine. Of course, less is better, but there's only so much one can reasonably do for so many channels... Even a PICTIC should be able to do better than 500 ps for a single channel. From what I've read, a few hundred units of HP5370 should

Re: [time-nuts] Multiple Time Interval Counters to measure Transients?

2012-09-10 Thread Marek Peca
Hello, just few quick comments: Unfortunately, I don't have a more precise technical spec. I'm just trying to find a viable solution to characterize a chip manufacturing process with regard to Single-Event Transients. As this is supposed to only be a side task for my PhD, I would prefer to use