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.
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
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
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,
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
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
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.
(..)
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
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
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
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
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
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
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
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
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
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
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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
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
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
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
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
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
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
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.
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
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
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
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
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
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
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
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
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