RE: [linrad] Delta44 board

[leif.asbrink@xxxxxxxxxxxxxxxx>]

Hi Rein and Kohjin,
 
>   Thanks and OK about "word" I imagine that if the sampling is 
> not accurate this will
>   introduce distortion in music. Whether this is really a problem 
> I do not know.

For Linrad there is no reason to use synchronization 
of the sampling clock.

In music it is extremely important to synchronize boards to each
other if several boards are used for input simultaneously. 
Otherwise the phase relation between different channels will vary
slowly with time.

Linrad uses a single board for input and all channels on a Delta44
board are already properly synchronized. There may be other boards
which do not keep good synchronizm and such boards are useless
for direct conversion (I/Q) mode. 

Synchronizing the Delta44 sampling clock at 64*96kHz = 6.144 MHz
to an external frequency reference could be done by injecting
a stable signal at 24.576 MHz into X1, the 24.576 MHz X-tal.
This will be useful only if all other oscillators are GPS stabilized
and if you want a sub Hz absolute accuracy. Already a really bad 
X-tal with 100 ppm accuracy will not cause more than 1Hz frequency
error if the audio tone is 10kHz.

73

Leif  /  SM5BSZ



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