Remember that the tighter the filter the more loss you'll have going through
it too....
marlon
----- Original Message -----
From: "Jack Unger" <[EMAIL PROTECTED]>
To: "WISPA General List" <wireless@wispa.org>
Sent: Tuesday, February 20, 2007 10:50 AM
Subject: Re: [WISPA] failing Canopy 900
Brian,
Bandpass filters come in different band "widths". Some are full-band
filters that pass 902-928 MHz and some are single-channel filters that are
narrower and pass only one channel. The bandwidth of the two Ubiquity
filters are a little narrow to use across the entire band but if you are
using 912 or 917 as center frequencies, they should work well. If you're
using a lower center frequency, you'll need a filter that has a bit wider
bandwidth but which still attenuates the paging frequencies a lot. The
availability of good whole-band bandpass filters seems to have
deteriorated a bit in the last year. There are more filters available but
they seem to have poorer characteristics and sometimes higher prices. I
just looked at RFLinx and Hyperlinktech and I am not happy with their
current offerings. I did discover a notch filter that is tuned to
attenuate the paging frequencies while passing the 902-928 frequencies. I
don't know the pricing but if it's priced reasonably then it looks like
your best bet. Here's the link:
http://www.microwavefilter.com/2ghzRelocation.htm#ism
It's the filter at the bottom of the page. If you call them to get a spec
sheet and to check pricing, please share that info.
Thanks,
jack
Brian Rohrbacher wrote:
Thanks, Jack. Would installing this one http://www.ubnt.com/cf.php4 be
the correct move? Or is something else preferred.
Brian
Jack Unger wrote:
Brian,
A -36 dBm signal probably won't destroy your receiver or permanently
desensitize it however your best bet is to get confirmation from a
Motorola rep. The signals you see at 928-930 MHz are from one or more
paging transmitters. These paging signals could easily desensitize your
AP receivers temporarily and cause a temporary inability to hear
incoming SM signals.
Since you appear to be using antennas that are external to your APs, you
can insert a bandpass filter between each AP and its antenna. This will
attenuate the paging signals and allow the APs to receive SM's from
further away. If the paging transmitters ARE the cause of your apparent
AP receiver sensitivity deterioration, then the bandpass filters should
be helpful in reducing the frequency of occurance of the problem.
jack
Brian Rohrbacher wrote:
How would that help? One sector is still pointing at the
interference.......Wouldn't that sector still make the radio fail, if
the -36 signal is what is doing it?
My question from the original post. Will that strong signal
desensitize the radio into failure? If not, then I need to figure out
what kills my radios. Why do they work fine for a month and then die?
I replace just the radio and they are fine for a while.
Brian
Marlon K. Schafer (509) 982-2181 wrote:
If you are that close to a source of interference you need to ditch
the omnis and sectorize our tower.
laters,
Marlon
(509) 982-2181 Equipment sales
(408) 907-6910 (Vonage) Consulting services
42846865 (icq) And I run my own
wisp!
[EMAIL PROTECTED]
www.odessaoffice.com/wireless
www.odessaoffice.com/marlon/cam
----- Original Message ----- From: "Brian Rohrbacher"
<[EMAIL PROTECTED]>
To: "Conversations over a new WISP Trade Organization"
<wireless@wispa.org>
Sent: Tuesday, February 20, 2007 7:05 AM
Subject: [WISPA] failing Canopy 900
I keep losing canopy 900 APs. I used the spectrum analyzer yesterday
and saw -36 signal on channels 928, 929, and 930. Will that strong
signal desensitize the radio into failure? because for some reason
SMs that used to be -65 are -80 (on both sides of the like) and 17
out of 33 associations have dropped off the AP. I've been fighting
this for a year. I've installed my own grounding, a lighting
dissipater, 6 new APs, 2 new omnis, and 3 new cables. I think I have
ruled out anything that could be killing this AP except if something
RF is killing it. Any input will help.
Brian
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Jack Unger ([EMAIL PROTECTED]) - President, Ask-Wi.Com, Inc.
Serving the License-Free Wireless Industry Since 1993
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