Jack and Brian, I noticed this thread just a few minutes ago. I didn't see mention of what polarity the OMNI in question is.
Most, if not all, 900 paging is VERTically Polarized. That is why the integrated antenna Canopy products all use HORIZontal polarization out of the box. So one would naturally want your omni to be HORIZontally polarized. This little trick all by itself should get 25 db or so rejection of the unwanted 929-930 stuff. I also agree with Marlon that sectorizing could help (depending on the direction of the offending signal) Basically selecting an AP operating frequency as far away from 929-930 as possible (preferably 906 Mhz) and facing THAT sector toward the offending signal, should help since the AP's receiver selectivity will maximally attenuate the out of band signal. The Subscriber Modules in that sector would all "have their backs to" the offending noise, so the front-to-back ratio of the antenna is buying them 20+ db rejection. Of course if the Subscriber Modules in another sector (and another channel) are facing the noise, the problem may pop-up there. It's all about angles and SM antenna pattern at that point. Maybe this will help. Hope so. Dave Brenton General Manager Rural Tennessee Wireless Broadband Bringing FAST Internet to the rest of us (sm) Dover TN (931) 232-0914 office (931) 627-1142 cell [EMAIL PROTECTED] ----- Original Message ----- From: "Marlon K. Schafer" <[EMAIL PROTECTED]> To: "WISPA General List" <wireless@wispa.org> Sent: Tuesday, February 20, 2007 21:30 Subject: Re: [WISPA] failing Canopy 900 > 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 > >>>>>> -- > >>>>>> WISPA Wireless List: wireless@wispa.org > >>>>>> > >>>>>> Subscribe/Unsubscribe: > >>>>>> http://lists.wispa.org/mailman/listinfo/wireless > >>>>>> > >>>>>> Archives: http://lists.wispa.org/pipermail/wireless/ > >>>>>> > >>>>> > >>> > > > > -- > > Jack Unger ([EMAIL PROTECTED]) - President, Ask-Wi.Com, Inc. > > Serving the License-Free Wireless Industry Since 1993 > > Author of the WISP Handbook - "Deploying License-Free Wireless WANs" > > True Vendor-Neutral WISP Consulting-Training-Troubleshooting > > Newsletters Downloadable from http://ask-wi.com/newsletters.html > > Phone (VoIP Over Broadband Wireless) 818-227-4220 www.ask-wi.com > > > > > > > > -- > > WISPA Wireless List: wireless@wispa.org > > > > Subscribe/Unsubscribe: > > http://lists.wispa.org/mailman/listinfo/wireless > > > > Archives: http://lists.wispa.org/pipermail/wireless/ > > -- > WISPA Wireless List: wireless@wispa.org > > Subscribe/Unsubscribe: > http://lists.wispa.org/mailman/listinfo/wireless > > Archives: http://lists.wispa.org/pipermail/wireless/ > -- WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
