[linrad] Lynx Two phase noise

[Leif Åsbrink <leif.asbrink@xxxxxxxxxxxxxxxx>]

Hi All,

The excellent results I reported previously for the Lynx 
Two card does was a special case.

As I understand it, Lynx Two uses a PLL to get a sampling
clock that is 64 times above the clock used for synchronizing
cards. As a consequence the sampling clock has strong
phase noise and therefore the good performance I reported
previously can only be obtained if the frequency of the strong
signal is low so it changes slowly enough for some time
jitter on the sampling clock to make no difference.

If a signal is placed at 90 kHz, the phase noise is at 
-135 dBc/Hz and that is not enough for a high performance
system.

There is some more info here:
http://antennspecialisten.se/~sm5bsz/linuxdsp/rxiq/rx2500lynx.htm

with the usual mirrors:
http://g7rau.demon.co.uk/sm5bsz/linuxdsp/rxiq/rx2500lynx.htm
and
http://nitehawk.com/sm5bsz/linuxdsp/rxiq/rx2500lynx.htm


73

Leif / SM5BSZ

 

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