The danger of Ethernet is that it has high capacity and a interconnect
friendly interface. Thus, you might feel inclined to toss data over it
carlessly causing packet delays and you can hook it into a switch and
get delays and packet losses there.
I usually cure that by using
Jim Lux wrote:
if you're talking asynchronous RS232 (the by far most common, these days)
off hand, I'd expect the jitter to be on the order of 1/8 bit time, uniformly
distributed. An awful lot of UART implementations generate a 8x clock to
sample the input and find the rising edge of
the
Would it be possible to fake an interface with a parallel port and bit
banging?
That is certainly possibly, since it is precisely what I use. It's an old
printer cable where I adjusted the wiring to the GPIB connector. For the rest
it's all done with parport bitbanging under linux using
You do realize that around that same time of some time ago the T3000 goodies
were already there, just waiting for you to buy them. ;) I just checked, and
the T3100 datasheet I have from last year even has the same md5sum as the one
currently on their website.
It would be interesting to know
For a handy list of cheap fpga boards:
http://tristesse.org/CheapFPGADevelopmentBoards
I notice he's recently added the SOIO to the list. I've had my eye on that
board as well for a while. If all you want is say 20 odd counters as you
mentioned, then that even fits in the cheapest spartan-6
That looks like a great solution for monitoring oscillators/GPSDOs.
Where to find an application that inputs RS232 and writes a file?
I don't think you need anything very complex for that. One could
simply cat the serial port device to a log file
cat /dev/tty01 | somename.log
I see
Yeah, I was wondering about that. There's a reason they use helium to search
for leaks on vacuum chambers. Those pesky small atoms go everywhere...
From: J. Forster j...@quikus.com
To: Discussion of precise time and frequency measurement
Same here. Does anyone know of an alternative source for that paper by Oliver
Collins? I was trying to make sense of Bruce's generalization of the hard
limiter, but found that to be a bit tricky without original paper...
regards,
Fred
From: ehydra
You mean potentially the exact same hijacked e-mail account sending spam as
with the Hello subject from 24 August. Why not change e-mail address and be
done with it?
From: David VanHorn d.vanh...@elec-solutions.com
To: Discussion of precise time and frequency
Hi,
Well, I do have an interest in fpga applications to mess about in the 10 ps rms
ballpark.
It's along these lines:
http://portal.ipfn.ist.utl.pt/rt2010/Conference%20Presentations/4-Thursday/11h00%20-%2012h40%20-%20UFATD/04-UFATD-4-Bayer.pdf
times
== multi-channel TDC for a nice price.
regards,
Fred
From: Javier Herrero jherr...@hvsistemas.es
To: time-nuts@febo.com
Sent: Thursday, August 18, 2011 11:26 PM
Subject: Re: [time-nuts] any HP 5370B Available or other TIC
El 18/08/2011 22:16, Tijd Dingen
Hi,
I just checked http://www.ohwr.org/projects/tdc-core/wiki ... under Status it
says:
Basic data path of the TDC (delay line + encoder + LUT) designed. Timing is
met at 125MHz with a 400-tap ~12ns delay line. Total latency is 5 cycles
(40ns).
Any particular reason for choosing such a
John Miles jmi...@pop.net wrote:
None of the articles appear to be text-searchable, unfortunately, so that'll
take a few kilowatt-hours of CPU time to fix.
On that subject, what do you use for that?
Personally I do something like this:
- pdftohtml
- index the html pages with mnogosearch
-
How'd you guess? Now I feel all cross, and will just have to use pavuk for my
mirroring.
Other than that ... nice! Thanks for the heads up. :)
From: John Miles jmi...@pop.net
To: 'Discussion of precise time and frequency measurement' time-nuts@febo.com
Sent:
2. At the higher user-friendly level, rubber duckies like the one I'm
about to build take this fancy non-Earth-rotation-based techie time
as input and produce old-fashioned Earth orientation time on output,
or more precisely produce a synthetic timescale that is rubberized to
As someone who is currently tinkering with a design in an fpga I had to smile
at that statement. :-)
If you want the edit + compile, then you may want to rethink that part. There
are plenty of microcontrollers
out there that are significantly easier to get going. And yes, you can do
things
A quick check shows digikey sells them in single quantities, and has current
stock.
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detailname=ADUM4160BRWZ-ND
regards,
Fred
From: John Seamons j...@jks.com
To: Discussion of precise time and frequency
Is that the ZAPD-3DB-1675-3 or ZAPD-3DB-1575-3?
From: ewkeh...@aol.com ewkeh...@aol.com
To: time-nuts@febo.com
Sent: Thursday, May 26, 2011 4:45 PM
Subject: [time-nuts] ZAPD-3DB-1675-3
I am considering using the ZAPD-3DB for GPS distribution. Any information
Maybe he should just dial the firewall back or something. ;-
From: David VanHorn d.vanh...@elec-solutions.com
To: Richard W. Solomon w1...@earthlink.net; Discussion of precise time and
frequency measurement time-nuts@febo.com
Sent: Tuesday, May 24, 2011 5:35 PM
http://designtools.analog.com/dtDDSWeb/dtDDSMain.aspx
That seems to work (don't drop the x on the end ;)
regards,
Fred
From: WB6BNQ wb6...@cox.net
To: Discussion of precise time and frequency measurement time-nuts@febo.com
Sent: Monday, May 23, 2011 11:34
and frequency measurement time-nuts@febo.com
Cc: Tijd Dingen tijddin...@yahoo.com
Sent: Monday, May 16, 2011 5:56 PM
Subject: Re: [time-nuts] Results parts selection + commercial assembly poll?
I'll add that for some reason the discussion never morphed over to an
alternate list created just to discuss
Apologies to the rest of the list ...
@Bob Camp,
Thank you for your e-mail! I tried to send you a reply twice, but both attempts
bounced on what looks like spamcop handling mail for your domain. First attempt
was a direct reply-to with a legit reply header. The second attempt was a new
Hi Magnus,
Magnus Danielson wrote:
Notice that the pre-scaler is only used for higher frequencies.
Understood. I was just using the prescaler as an example for the what if
if take every Nth edge.
Consider then the typical measurement setup:
A counter is set up to make a time interval
Hi Magnus,
Magnus Danielson wrote:
There are many things you can get away with, just how much trouble you
want to verify it versus doing the proper thing is another issue.
Define proper thing. ;-) From what I understand taking the exact Nth edge,
and then do linear regression is equivalent
for
this particular applicaction?
regards,
Fred
- Original Message -
From: Magnus Danielson mag...@rubidium.dyndns.org
To: time-nuts@febo.com
Cc:
Sent: Saturday, May 14, 2011 9:28 AM
Subject: Re: [time-nuts] Continuous timestamping reciprocal counter question
On 05/13/2011 04:56 PM, Tijd Dingen wrote
Magnus Danielson wrote:
http://en.wikipedia.org/wiki/Allan_variance#Non-overlapped_variable_.CF.84_estimators
Nice to see people actually read and use what I wrote.
:-)
If you use a prescaler of say 1/64 then it takes 64 cycles of the original
signal to cause a cycle to the counter
Magnus Danielson wrote:
There are many things you can get away with, just how much trouble you
want to verify it versus doing the proper thing is another issue.
Define proper thing. ;-) From what I understand taking the exact Nth edge,
and then do linear regression is equivalent to taking
Incidentally, did something ever come of these two polls? I was trying find the
conclusion / results, but could not find it on the list. Entirely possible that
I am blind for which I apologize in advance. Anyone know what came of it?
regards,
Fred
___
The counters of the continuous timestamping variety I've read about all mention
taking the Nth edge of the input signal. For example:
http://www.spectracomcorp.com/Support/HowCanWeHelpYou/Library/tabid/59/Default.aspx?EntryId=450Command=Core_Download
In Picture 5 on page 5 you see a bunch of
In trying to put together a way to calculate Allan variance based on a series
of timestamps of every Nth cycle, I ran into the following...
Suppose you have an input signal, but it's a bit on the high side. So you use a
prescaler to divide it down to a manageable frequency range. And now you
much
better depends on the type of noise.
As long as you get the math right for your sample spacing, the result will
be ok.
In an FPGA keep in mind that your PLL may be a significant source of noise.
Enjoy!
Bob
-Original Message-
From: Tijd Dingen [mailto:tijddin...@yahoo.com]
Sent
Hi Bob,
Precisely the kind of sanity check I was looking for. Thank you!
regards,
Fred
- Original Message -
From: Bob Camp li...@rtty.us
To: 'Tijd Dingen' tijddin...@yahoo.com; 'Discussion of precise time and
frequency measurement' time-nuts@febo.com
Cc:
Sent: Friday, May 13, 2011 6
a timestamp
for exactly every Nth cycle.
Thanks!
Fred
- Original Message -
From: Bob Camp li...@rtty.us
To: 'Tijd Dingen' tijddin...@yahoo.com; time-nuts@febo.com
Cc:
Sent: Friday, May 13, 2011 6:26 PM
Subject: RE: [time-nuts] Continuous timestamping reciprocal counter question
Hi
Possibly of interest for those who are into software defined radio:
http://comblock.com/com3011.html
http://comblock.com/download/com3011.pdf
Looks like a nice board for $345.
On that subject, I am still looking for a good board to be used for a software
defined gps receiver.
And in particular
John Miles jmiles at pop.net wrote:
That's my vote as well. Can do it, have done it, will do it again, but
only for things that are interesting enough to spend the time on. In
other words, no, I would not build a kit that replicated functionality
available in cheap surplus gear and was not
On the subject of manufacture and design for volume, Dave Jones from EEVblog
did
I nice vid on that some time ago...
http://www.eevblog.com/2010/11/15/eevblog-127-pcb-design-for-manufacture-tutorial/
- Original Message
From: Bob Paddock bob.padd...@gmail.com
To: Discussion of
Ooops, forgot to answer the actual poll. sorry about that.
$250-$500 project size. An extra $100 for electrical test assembly of the
entire board: yes
An extra $100 for just the 3 tricky IC's and then have to do the other 70+
parts
anyway: no.
(Well, maybe, but make it $60 and it better be
Didn't know that outfit, thanks for the link. :) Would you say they are durable
enough to say 5 boards with it? (I would hope so, but you never know...)
With regard to the delivery of the fine pitch stuff ... as long as the one
putting together the kit is ordering those as cut-tape then that
Well put. One man's noise is another man's signal... Just apply filter where
applicable.
- Original Message
From: William H. Fite omni...@gmail.com
To: Discussion of precise time and frequency measurement time-nuts@febo.com
Sent: Sat, March 26, 2011 10:40:20 PM
Subject: Re:
How about Planetized Back Yard (*) Medium LBI? If you, the measurement
enthusiast, have decent gps hardware + see yourself as 1 point in the LBI +
have
good timestamps for your measurement + a decent protocol to combine them I
would
say Radio astronomy for fun profit!. Mostly fun in this
Same here. A GPSDO like the thunderbolt is really nice from a system
integration point of view. Buy an easy thingy kit on ebay, and you have
your 10 MHz reference. However, cannot a lot be gained from using a
more up-to-date design with newer gps engine?
On the one hand we have a thunderbolt
in
phase noise. Plenty of good PLL's available since you will not have to use
fraction.
Bert Kehren
-Ursprüngliche Mitteilung-
Von: Tijd Dingen tijddin...@yahoo.com
An: Discussion of precise time and frequency measurement time-nuts@febo.com
Verschickt: Do., 17. Mrz. 2011, 14:01
Oh yeah, forgot to mention this with regard to the tapped delay line...
Make sure you don't use the fpga dcm/pll for clock generation. It is
too jittery. Generate an external reference as high as feasible that
is still acceptable to the IOB's of the fpga you intend to use. It makes
sense to make
For that kind of sampling rate you may want to consider the ADS1258EVM.
At 46 euro it's a pretty good deal IMO. I've been using it for some time
now and I really like it. Got mine from Mouser...
Yes this is very much possible! I am doing a spartan-6 implementation of
a frequency counter that uses some of the ideas in that paper. Both the
coarse counter and interpolator are done in the fpga. For the coarse
counter I use a fast free running counter inside the clock domain of
the frequency
Hello Bert,
That rationale sounds suspiciously familiar. The quest for an ever simpler VCO,
that is. At the expense of some additional phase noise compared to VCXO+PLL, you
could use an ADF4360-9. It is readily available at for example digikey,
currently
for $6.26.
For my fpga based counter
Well, I know Geraldo Lino de Campos on this list is using an ICS670-03 for
this purpose. For me personally that part is too jittery by about a decade,
but for your purpose it might just be the right compromise. Certainly has a
friendlier package.
datasheet:
Hello Chris,
No I didn't know SchmartBoards, thanks for the tip.
Although maybe I am missing something... I just checked their site, and
watched the videos, but I couldn't find anything I'd spend $12 on.
When you say that it is expensive at $12 each, but you need only one,
do you mean that as
Heh, I could care less about typos. I just honestly didn't understand what
you meant. The best matches I could come up with was bubble counter and
doubler. And since a bubble counter made no sense in this context and a
doubler did, I thought I'd go with that guess and run with it.
So now with
albertson.ch...@gmail.comwrote:
On Fri, Feb 25, 2011 at 11:02 AM, Tijd Dingen tijddin...@yahoo.com
wrote:
Hello Chris,
No I didn't know SchmartBoards, thanks for the tip.
Although maybe I am missing something... I just checked their site, and
watched the videos, but I couldn't find anything I'd
That's a bit of an open question since it depends on many things. So
I realize this may be a bit too generic, but hey you said any hints ;).
Simple example that I know to work in linux, and the same principle should
work in windows.
1 - make i2c interface with parallel port + couple of
Which I suppose goes to show that:
1) know your instrument
2) never trust any single source of information
- Original Message
From: Hal Murray hmur...@megapathdsl.net
To: Discussion of precise time and frequency measurement time-nuts@febo.com
Sent: Wed, February 16, 2011 6:53:23 PM
- Original Message
From: Magnus Danielson mag...@rubidium.dyndns.org
To: time-nuts@febo.com
Sent: Wed, February 9, 2011 10:08:40 PM
Subject: Re: [time-nuts] Calculate spectral content from a series of zero
crossing time stamps?
Wavecrest just fell of the Internet for some time and
- Original Message
From: jimlux jim...@earthlink.net
To: time-nuts@febo.com
Sent: Tue, February 8, 2011 4:00:43 PM
Subject: Re: [time-nuts] Calculate spectral content from a series of zero
crossing time stamps?
The Chirp-z transform (Bluestein) is also useful when you want a small
- Original Message
From: Henk h...@deriesp.demon.nl
To: Discussion of precise time and frequency measurement time-nuts@febo.com
Sent: Tue, February 8, 2011 10:19:38 PM
Subject: Re: [time-nuts] Calculate spectral content from a series of zero
crossing time stamps?
Wavecrest uses
Henk wrote:
Wavecrest uses algorithms for this and their software gives a spectrum.
They also give some info on their site.
Henk, the paper you mentioned put me on the right track. Thanks. :)
Magnus wrote:
In Jitter, Noise and Signal Integrity at High-Speed by Mike Peng Li,
Prentice Hall,
From what I could find so far, one method to go about this is use a
Lomb/Scargle Periodogram. And specifically the method by Press Rybicki
that extirpolates the unevenly timed samples to an regular timed mesh,
after which a regular DFT is done.
Just knowing the time of the
Consider the following scenario. We have a signal source of about 10 kHz,
with unknown phase noise. Let's for simplicity's sake assume for now that
the phase noise is large enough that it will be detectable by the following
approach.
We measure every zero crossing with lets say 1 ns accuracy.
Forgot to mention that in this example we are only counting the zero crossings
on the positive edge.
(before some clever soul points out that it should be 20,000 zero crossings. :P
)
- Original Message
From: Tijd Dingen tijddin...@yahoo.com
To: time-nuts@febo.com
Sent: Tue, February 8
-boun...@febo.com] On
Behalf Of Tijd Dingen
Sent: Monday, February 07, 2011 9:02 PM
To: time-nuts@febo.com
Subject: [time-nuts] Calculate spectral content from a series of
zerocrossing time stamps?
Consider the following scenario. We have a signal source of about 10 kHz,
with unknown phase noise
?
Thanks,
Joe
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Tijd Dingen
Sent: Monday, February 07, 2011 9:02 PM
To: time-nuts@febo.com
Subject: [time-nuts] Calculate spectral content from a series of
zerocrossing time
Possibly you mean the CVS575 datasheet does not have any aging specs The
datasheet for the CVHD-950 specifies aging as 3ppm 1st/yr, 1ppm
thereafter which is good enough for me. So it's now on the shopping list.
No, what I meant was that the data sheets didn't have any total
Additionally, the definition as used in this appnote from Vectron:
http://www.vectron.com/products/literature_library/absolute_pull_range.pdf
- Original Message
From: Tijd Dingen tijddin...@yahoo.com
To: Discussion of precise time and frequency measurement time-nuts@febo.com
Sent
possibly it's 20 years of aging at 40 degrees within the spec.
regards,
Fred
- Original Message
From: Tijd Dingen tijddin...@yahoo.com
To: Discussion of precise time and frequency measurement time-nuts@febo.com
Sent: Sun, February 6, 2011 4:47:20 PM
Subject: Re: [time-nuts] Fwd: 10MHz
Perhaps a bit late, but have you considered the ICS670?
http://www.idt.com/products/getDoc.cfm?docID=18461996
I just checked the datasheet. Wouldn't you say that it would result in more
noise when compared to a CVHD-950/ADF4002 combo?
regards,
Fred
Hopefully you mean this along the lines of: should you decide to feed two
different clocks into the Virtex-2, and use the dedicated global clocks,
then
you guess the isolation between those 2 global clock lines to be on the
order
of about 20-30 dB. So basically...
No guessing.. I've
That CVHD-950-100 looks to be just the ticket. Nice price/performance. Thank
you for the recommendation! :)
I just looked at the data sheet. It says:
Frequency Pulling: ±20ppm APR Min.
I was going to ask what APR meant. In case anybody else is also curious...
The CVS575-500 data
You don't feed the ADC from the FPGA if you can avoid it.
especially if your ADC clock is a different frequency from the processor
clock that's being used for most of the other logic on the FPGA. I'd
give a ballpark estimate of 20-30 dB isolation between the two on a
Virtex 2.
I read
Hello Said,
Low Noise 100MHz VCXO's are readily available at mouser and digikey (so
are 80MHz units), and programming the ADF4002 is straight forward with the
help from the AD online tools. It can be bit-banged with any microcontroller.
Any particular ones that are in stock at
I'd like to second John's suggestion to go with the Nexys2. As far as I'm
concerned it has pretty good value for money.
Regarding the standalone use, it has a configuration prom that you can use.
That way it will automatically load your design on powerup, without needing
a programmer every time.
On that note, does anyone know if this counter project is still active? Some
time ago I asked about this, but never got a reply. Maybe the e-mail got
eaten by a spam filter, or maybe I just didn't ask nice enough, I don't
know. ;-
If there is still an active project, I'd be interested. If not,
know enough
however.
I think your email got eaten by the spam filter. I'll respond to that shortly.
Bob
On Sun, Jan 30, 2011 at 8:11 PM, Tijd Dingen tijddin...@yahoo.com wrote:
On that note, does anyone know if this counter project is still active? Some
time ago I asked about this, but never got
Suppose I want to make a GPSDO using the 1PPS output of generic GPS device
XYZ, what kind of accuracy should I be looking for?
I understand the concept of smaller error is better, but I lack the
practical experience and would like to get a handle on the actual numbers.
When a GPS devide XYZ
--- On Sat, 1/8/11, Magnus Danielson mag...@rubidium.dyndns.org wrote:
...
How will the input side work? How will you handle
input
signals of various kinds? In particular sine of
various
amplitudes and frequencies. Slew-rate can be a
limiting
factor as white noise will convert into
You saved me a lot of typing. :) Comments inline...
--- On Mon, 1/10/11, Bob Bownes bow...@gmail.com wrote:
From: Bob Bownes bow...@gmail.com
Subject: Re: [time-nuts] Archiving Timing Data
To: scmcgr...@gmail.com, Discussion of precise time and frequency
measurement time-nuts@febo.com
, 10:42 PM
On 1/10/2011 1:42 PM, Tijd Dingen
wrote:
...
I read up on it on Bruce's site. At least I think it
is Bruce's site, what with the /~bruce/ in the url. ;)
...
regards,
Fred
I assume you mean: http://www.ko4bb.com/~bruce
That is not Bruce's site, rather DIDIER's
Indeed. The ADCMP573 and ADCMP553 are already on my digikey order list. :)
Complete with nice pecl output that I can connect to the LVPECL input of the
spartan-6.
Thanks for the tip though, always good to know I'm not the only one who thinks
of using it. let's call it confirmation. Thanks! :)
For prescaling, I'd suggest using the dividers in one of the Analog Devices
PLL parts (ADF4xxx) instead of Hittite chips. Many of the AD parts can
still be purchased in packages with actual pins, and you can always get them
in small quantities. They will also take a lot less power.
Then I
PM
On 01/06/2011 08:02 PM, Tijd Dingen
wrote:
To whom it may concerns,
Currently I am building a DIY frequency counter. Since
this is my first serious counter project I am trying to keep
things simple, hence It Will Not Be State Of The Art. Maybe
a not-too-difficult hobby level counter
To whom it may concerns,
Currently I am building a DIY frequency counter. Since this is my first serious
counter project I am trying to keep things simple, hence It Will Not Be State
Of The Art. Maybe a not-too-difficult hobby level counter will be of interest
to some, so I'd thought I'd post
-
From: Tijd Dingen tijddin...@yahoo.com
Sender: time-nuts-boun...@febo.com
Date: Thu, 6 Jan 2011 11:02:12
To: time-nuts@febo.com
Reply-To: Discussion of precise time and frequency
measurement
time-nuts@febo.com
Subject: [time-nuts] No State Of The Art Counter
To whom it may
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