[Collins] Any Frequency

[Dr. Gerald N. Johnson]

On Tue, 2009-10-06 at 23:46 +0000, Kees & Sandy wrote:
> I ask you to please check the results of testing done by Jack Smith of
> Clifton Labs and check the specs SiLabs has on the part. The lack of
> spurs on the Si570 output relative to very frequency agile DDS chips
> is very impressive. It's as good/better than the HP 8640 signal
> generators.
> 
> 73 Kees K5BCQ 
> 
By his instrumentation its good, but I'm not yet convinced his spectrum
analyzer is good enough to see the typical DDS problems when it shows
the same phase noise and spurs for all his test signals. Especially
spurs on his wide range scan showing harmonics of the square wave
output, his spectrum analyzer selectivity is about a MHz and that makes
is spectrum analyzer background noise only 60 or 70 dB down from the
signal, and a receiver needs an oscillator spur free 120 dB down or
better.

-- 
73, Jerry, K0CQ, Technical Advisor to the CRA
All content copyright Dr. Gerald N. Johnson, electrical engineer