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Microwave radio question

Posted: Sat May 28, 2005 6:38 pm
by Ray D O
6 Ghz microwave radio rcving BER and ES on it. Getting mux alarms indicating FEC and BER. Been happening intermittently last week but really got bad yesterday. Firebird on inbound DS3 shows a few parity errors then BER hits start. Swapped some boards in unit but no change. Did not ck RSL during episode but RSL was good when RCV ok. Beginning to suspect possible interfering signal. A few months ago passive antenna microwave repeater put on tower with one side of their shot very close to our azimuth on affected radio. Any suggestions on symptoms to verify this? Unfortunately we don't have a spec analyzer that will go up there. Will try to observe RSL on next visit to site. Tx side does not appear to be trouble-should have mentioned that earlier....

Thanks for any input-73

Posted: Sat May 28, 2005 8:35 pm
by xmo
Check and see if the receiver sections of your microwave radios have an IF output. In some of these systems the receiver is more or less a down-converter that provides an IF of 70 MHz to the demodulator. What you see at the IF monitoring point should be a replica of the actual over the air signal - just shifted down.

Look at the IF with a spectrum analyzer and see if you see a change between what it looks like when all is well and what it looks like when the BER goes up.

Thanks xmo

Posted: Sun May 29, 2005 4:37 pm
by Ray D O
Kinda had that in mind after thinking on it more. I appreciate the input. Will give it a try.

Posted: Sun May 29, 2005 7:37 pm
by techie
don't forget to check the fcc database as well..

Posted: Mon May 30, 2005 4:03 pm
by Jim202
[quote="techie"]don't forget to check the fcc database as well..[/quote]


That won't do you any good for the unlicensed operations. You just need to make friends with everyone in the area that may be running this equipment. Keep asking questions at all the radio shops and the cellular carriers.

Jim

Twas the TXU...

Posted: Fri Jun 03, 2005 6:48 pm
by Ray D O
Thanks for all of the input. Turns out it was the TXU on the other end of shot. Replaced it and all is well for a few days now.

73