[time-nuts] Spread Spectrum Spam!

Alan Melia alan.melia at btinternet.com
Fri Nov 27 22:41:41 UTC 2009


Some synth sig-gens use the reference divided down to drive the PSU (Marconi
2955 for instance) for the same reason I think
Alan G3NYK

----- Original Message -----
From: "Lux, Jim (337C)" <james.p.lux at jpl.nasa.gov>
To: "Discussion of precise time and frequency measurement"
<time-nuts at febo.com>
Sent: Friday, November 27, 2009 10:03 PM
Subject: Re: [time-nuts] Spread Spectrum Spam!


Some spacecraft have a requirement that all the PWM supplies by
synchronizable to an external source.  The idea is that at least the spur is
in a constant location, rather than wandering around (PWM natural switching
rates not being the most stable in the world)


On 11/27/09 12:40 PM, "Robert Atkinson" <robert8rpi at yahoo.co.uk> wrote:

> Interestingly some amateur radio 13.8V switch mode supplies have a QRM
> (interference) reduction control. This shifts the PWM frequency slightly
so
> you an shift the noise off of the signal you are listening too! Complete
> fudge. In Europe the CE EMC tests use Quasi-peak detectors and slow scan
rates
> that respond less to spred clocks. The spreading can be turned off in the
BIOS
> on most machines if needed.
>


_______________________________________________
time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.




More information about the time-nuts mailing list