[Gumstix-users] Noise radiating from Verdex board iii

[Mark Ca <mar...@ya...>]

Hi all, (Apologies again, last time I promise! I deleted my first post to
keep the board clean which subsequently deleted my re-posted version... :-o)

I'm having a problem with noise emissions from the Verdex XL6P motherboard
(paired with a breakout-GS board) and am trying to figure out what is
responsible so that I can disable or minimise it. I'm only using the I2C and
the battery power headers on the breakout board.

Bascially, whenever I power-on the board I get a slew of harmonics across a
wide band at approximately 17.3 MHz intervals which last for approximately
6-8 minutes before disappearing. The lowest frequency harmonic that I've
been able to detect has been 234 MHz but I have observed them at frequencies
up to and including 997 MHz (I believe these limits to be due to the
limitations of my measurement equipment rather than being representative of
band within which the harmonics occur).

Having been through the datasheet for the PXA270 and looked over the Verdex
documentation I have been unable to find anything that might be responsible
for these signals. Whatever it is, it is clearly something which is turned
off (perhaps to conserve power?) after several minutes and doesn't obviously
appear to affect the performance of the motherboard for my application (i.e.
after the harmonics have gone, everything still works fine).

If anyone has any thoughts on what this might be and how I can deal with it
(disabling the source is preferable to putting in physical screening) I'd be
very grateful to hear from you.

Many thanks,

M
-- 
View this message in context: http://www.nabble.com/Noise-radiating-from-Verdex-board-iii-tp16447308p16447308.html
Sent from the Gumstix mailing list archive at Nabble.com.