[time-nuts] Is this measurement for real?

Ed, k1ggi k1ggi at comcast.net
Sun Dec 8 21:51:27 EST 2013


Dave -
Let me call your attention to the FMT nuts list if you are not already on it
(I didn't find an entry from you in the November ARRL FMT).
I'm not sure how many of the gurus there are on this one, although the HP
3586B is a tool used by some. I myself depend on some HP gear, a 105B and
8640B.
There you can inquire and learn about AM BC stations locked or not to gps,
as well as intentional carrier offset applied to mitigate slow deep fading
in zones of overlapping coverage.
http://groups.yahoo.com/neo/groups/FMT-nuts/info
73,
Ed, k1ggi

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of quartz55
Sent: Sunday, December 08, 2013 21:06 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Is this measurement for real?

Well, thanks for the comments.  I really didn't know what to expect from the
SoundBlaster card. I thought AM stations were better than that. I started
everything cold today and the 1K from the SM started at around 999.998600
and drifted up to 999.999800 in about an hour and half, stayed there around
4 hours but then started back down to 999.999290 in another 4 hours. It's
going back up a bit tonight, it's around 999.999420 now.

I do see in SpecLab there is a way to lock the sound card to a 1pps GPSDO.
I may try that, but my Nortel only puts out even second pulses and I really
haven't seen them yet.

Anyhow, after warm up, it looks like I should be able to detect 1 mHz
differences given other things are stable, like the DSP in the TS2000, I'm
thinking about running the fan full time in it to try to stabalize that.

How about the UHF TV stations, are they locked to something, they all seem
to be on even .025 KHz on my service monitor which can only resolve to 1 Hz?

I'm looking for frequency standards I can receive better than the 2M/440
beacons (N4MW) I can hardly hear from central VA.  WWV is about useless, I
get 2 Hz spreads from them with SpecLab at 20 MHz, it may be WWVH
interefering.

I have to say, I've gone from hardly being able to measure 1 Hz differences
with the service moniter to nearly mHz differences, that's what 3 decimel
places?  It's funny how the closer you get the closer you want to get.  And
now to figure out how accurate it is. I've got a FT897D I'm not using, been
thinking about selling it and get  Jackson Labs unit, but I'm not sure what
that will get me past the Nortel unless the extra satellites/bands will make
it more accurate?

Dave
N3DT
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