-ascii
Hi
The simple answer is that Google maps may or may not be correct. There are a
lot
of examples of them being off by 10M or more. That said, my *guess* would be
that the
Thunderbolt is closer to the truth.
Bob
On May 18, 2015, at 2:34 AM, Demian Martin demianm@gmail.com wrote:
I
wrong in the Thunderbolt? Would it affect the
operation as a frequency standard in any way?
Demian Martin
San Leandro, CA 94577
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I have used an FM tuner pretty successfully to look at modulation and phase
noise in oscillators. For a 10 MHz oscillator you will be looking at the 10th
harmonic so modulation and phase noise is multiplied and much easier to see.
You do need a square wave output to get a lot of harmonics.
Most routers use a similar model and can save important settings but still
recover from a crash with no problem. There are several router distros that
are good examples on how to do it. I would suggest looking at Voyage Linux
http://linux.voyage.hk/ for an example. They have a specific versing
-datasheet.pdf
They look too good to be true. However the phase noise plot stops at 1 KHz.
There is another that stops at 100 Hz elsewhere on the site. Does anyone
have real experience with the technology?
Demian Martin
PDS
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From: kevin-use...@horizon.com
To: albertson.ch...@gmail.com
Cc: time-nuts@febo.com, kevin-use...@horizon.com
Subject: Re: [time-nuts] have 10MHz need 19.5Mhz
Message-ID: 20130606162408.10277.qm...@science.horizon.com
Any 2-pin crystal connection to an IC is a simple Pierce oscillator.
I asked Wenzel about mixers for phase noise measurement and they directed me
to Marki Microwave as what they use:
http://www.markimicrowave.com/2770/Mixers.aspx I have not obtained or
tested any myself but it's a pretty solid recommendation I think.
I got this guy to add cross correlation to his
Bob:
Perhaps you can describe how to do this. I can't see a way that would not
make a huge mess (big torch) or not ever get there (big soldering iron). I
would really like to be able to get inside of some of these without making
them all into trash.
Demian
a count down from the 10 MHz to an audio frequency and
capture it. Do a really deep fft and look for stuff that should not be there
(anything but the countdown).
Demian Martin
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There are a number of sound cards (and have been for 10 years now) that can
capture up to 95 KHz with extraordinary fidelity. They sample at 192 KHz and
usually have 24 bit converters good tor 20+ bits. These can capture the
complete FM MPX output pretty easily.
Some of the newer ADC's have less
I have tested a number of soundcards and while the EMU 2020 has issues
(serious jitter and noise from the USB interface) I can recommend the ESI
Juli@ as having flat response and good SNR up to 90 KHz. It's a PCI card, no
USB. I have measured the performance of FM MPX adapters and tested FM
feel that way. How do we organize enough to exert some political
pressure? Notwithstanding the impact of obsolescing the GPS in my car (not
replacable) so they can make some money.
Demian Martin
Product Design Services
784 Cary Drive
San Leandro, CA 94577
demian...@yahoo.com
209 613
Paul
The quick and cheap migration to a desktop PC if you have the PCMCIA GPIB
card is to get a PCI to PCMCIA adapter. They are cheap and plentiful for as
little at $6.50. e.g.
http://www.ebay.com/itm/PCI-PCMCIA-CARD-ADAPTER-/130584195663?pt=LH_DefaultD
omain_0hash=item1e676cb24f#ht_500wt_1413
I would like to see more in one place about implementing these ideas. The
bits are scattered in different places and I'm not sure where to find them
all.
One resource for getting the signals sampled at SOTA performance for a
reasonable price is this demo board from TI: PCM4222EVM
custom SC
crystals that would work in an HP10811? I have been quoted prices in the
$500+ range for finished products and want to explore a more cost effective
option before I spend a lot of money.
Demian Martin
Product Design Services
San Leandro, CA 94577
209 613 6990
Another perspective on time: http://www.longnow.org/clock/
And some fascinating mechanical stuff.
-Demian
Message: 4
Date: Fri, 23 Jul 2010 02:11:04 +0200
From: Magnus Danielson mag...@rubidium.dyndns.org
Subject: Re: [time-nuts] A different timenuts interest
To:
At some point I'll re-run tempco and jitter measurements of the dividers
and 1PPS distribution amps I have here.
Last time I used a 5370B and a SR620. This time I'd like to try a
Wavecrest. If someone on the list has done this already can you let me
know?
Thanks,
/tvb
I have read through the
I got an almost perfect 5370A some years ago for less than $100. It had one
dead input. I discovered that those input devices were essentially
unobtanium so I went shopping for a substitute. I found a Maxim chip that
seems to work as well as the original comparator, possibly slightly better.
I
Being naïve I didn't know the HP custom chip would be difficult to
substitute. Since it was blown and not available I went searching and found
a Maxim chip (MAX9691 I think) that would work on paper. It is surface mount
and I managed to find a header that fit the HP socket and some careful
wiring
While I have little experience looking at phase noise I have a lot with
using commercial sound cards in acoustic analysis. I use a system from this
guy : http://libinst.com/ called Praxis. The designer had to resolve the
same issues re: calibration of the chain. He uses an external box that
in the basement I'd certainly use it
in the setup. Last time I checked the stuff was not cheap
Bob
Demian Martin
Product Design Services
*
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Oscillator.
Demian Martin
Product Design Services
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and follow the instructions there.
but not used
except by a few devices. A lot of the pro market uses Firewire for this
reason and others.
The spec for a good digital audio chip is here:
http://envy24.svobodno.com/datasheets/via/vt1724.pdf and a lot more here:
http://envy24.svobodno.com/datasheets/
Demian Martin
PDS
From: Hal Murray
to
get around. You can use ASIO drivers to go around the internal engine if you
write your app for that. The EMU 0202 isn't supported fully in Linux yet.
Demian Martin
PDS
Ok, I have looked at a few USB cards and reviews. For SD radios, and as far
as I can tell for time use, the Creative E-MU
the cheap solutions. If it helped the measurement you could drive the
crystal input with an external oscillator etc. For more extended low
frequency response you could bypass the input caps but the dc offsets would
need attention.
Demian Martin
Product Design Services
Date: Fri, 21 Aug 2009 22:51
Modern soundcards using stereo DACs have very little shift between the
channels. Usually much less than a sample period, probably less than m-clock
period (64 to 256 X the sample period). And a high res card at 24 bits
(probably 20 usable) will give you a lot of data to chew on.
Demian Martin
high sample rates etc, but they use special drivers to work. Emu has several
high performance boxes to consider. Linux support is problematic. . .
Demian Martin
PDS
From: Don Latham d...@montana.com
Subject: Re: [time-nuts] Using cheap sound cards for measurements
To: Discussion of precise time
be better if I bypass the input module and drive the output
modules with a sine wave? I'm using it as a reference for some
not-too-sophisticated counters and generators so the phase noise will be
much better than those could benefit from regardless.
Demian Martin
PDS
about it? I'm planning to mount a
Thunderbolt inside it. There is a decent datasheet on the family of products
here: http://www.freewebs.com/beststuff2u/MFS-207.pdf
Demian Martin
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for a business application since it supports
DHCP and NI supports it in the latest releases.
Demian Martin
Product Design Service
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Magnus Danielson wrote:
The digital link in question is S/PDIF; with the current popularity
of Home Theater systems cheap cards with digital I/O have become
quite prevalent. As an added bonus, S/PDIF can be run over both
coaxial and optical media, the latter being attractive in further
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