FM kills Ethernet.  Inductors - Period.  Set to 10 Mbps until then.


Brad H





On 3/30/07, Edward J. Hatfield III <[EMAIL PROTECTED]> wrote:

Nearly 40 dB of variations in the link S/N ratio? Holy cat crap, Batman!



How accurate is the test equipment yielding that measurement? SNR
variations
of 40 dB means four orders of magnitude in signal levels relative to the
noise floor, a 10,000:1 change in the power ratio. No wonder the bloody
link
isn't stable!



Frankly I'm not inclined to trust the accuracy of those measurements
over-much; it's been my experience that few people own or even have access
to the kind of test equipment (like Network Vector Analyzers and Power
Meters) required to properly trouble shoot microwave systems. But there
obviously IS a problem.



OK, now for the (hopefully) helpful part: My hunch is that the FM
broadcast
signal, being in relatively close proximity to your antenna mount, is
generating harmonics or other spurious energy of sufficient power to
overload the front end of your radio. (Sharp Q, ultra-deep microwave
filters
are expensive and I'd be very surprised if your radio was so equipped).



So, the question before you is: How important is this site to your overall
network? Is it worth the expense of having a properly trained and equipped
microwave field engineer find and characterize the problem, and suggest
some
options for corrective measures?



Sorry if this sounds a bit harsh but sometimes there aren't any easy
answers
to difficult problems .



Hope this helps, Ted



Edward J. Hatfield III, President

E.J. Hatfield & Company

5142 Edgemoor Drive

Norcross, GA  30071-4342  USA

1-770-209-9236 - Office

1-770-209-9238 - Fax

1-770-560-0736 - Sprint

1-678-457-8411 - Cingular

154*273*18       - NexTel



-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Sent: Friday, March 30, 2007 4:01 PM
To: wireless@wispa.org
Subject: [WISPA] fm towers



mikrotik 5.8 ptp links off an FM tower. We have a ptp link with a signal
to
noise of 66 to 103. Our access points will only link for a few seconds and
quit. we have the exact same links on other towers that work great and the
one to this fm tower will not work. any suggestions?

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