[time-nuts] Re: Low cost synchronization, kitchen appliances

[Brian Kirby]

I run a LynxOne sound card.  It has clock in and out (75 ohms- TTL).  
The clock can be 25 Khz to 27 Mhz.  In its control software, it can use 
a 13.5 Mhz video dot clock, a 27 Mhz video dot clock, a word clock or a 
X256 word clock.

I had considered using a synthesizer to locked up the sound card to the 
rubidium during the ARRL frequency test back a few years ago.  I worked 
out everything in advance.  I had a heart attack about 2 hours before 
the contest - so I never got to work the contest...

I did not buy the card for the clock capability.  It was bought because 
it could handle 24 bit resolution and had digital and analog ins/outs.  
You can also use multiple cards and the way they slave them, is via the 
clock. 

Brian N4FMN

John Ackermann N8UR wrote:

>Alberto di Bene wrote:
>
>  
>
>>Hmmm, the sound card used is the M-Audio Delta 44, a professional sound
>>card, used also by musicians and composers for studio works. I don't
>>know the accuracy of its time base, but certainly it is quite good.
>>    
>>
>
>I previously did some rough accuracy tests of my Delta 44 cards and
>found they were "pretty good" but I didn't record the results.
>
>Just for the fun of it, I am now measuring one and see about a 1.5Hz
>error at 25kHz -- that's 6x10e5.  The setup is an HP3325A synthesizer,
>locked to an Rb standard, feeding 0.5v p-p into the Delta 44 on an
>Athlon 2200 running the Linux-based Baudline spectrum analyzer program.
> I'm sampling at 96kHz and decimating by 4096; Baudline has a very cool
>measurement function that will give the absolute frequency reading with
>a resolution of better than a mHz.  I'm measuring ~24998.5Hz against the
>nominal 25000Hz.  The Delta 44 has been running in the computer for
>several weeks, so it should be thermally stable.  I've attached a
>screenshot of the Baudline display.
>
>One thing I want to explore is how difficult it would be to provide an
>external clock for the Delta 44.  Higher-end boards in the M-Audio
>series have a "wordclock" input, and I suspect that the Delta 44 PC
>board may be hackable to enable that.
>
>John
>  
>
>
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