Whats wrong with using XR5's and lowering the TX power on them? They are more rugged and have better RX sensitivity than many other cards. -- Kurt Fankhauser WAVELINC P.O. Box 126 Bucyrus, OH 44820 419-562-6405 www.wavelinc.com
--------- Original Message -------- From: WISPA General List <wireless@wispa.org> To: WISPA General List <wireless@wispa.org> Subject: Re: [WISPA] RB333/433 eliminating self-interference test Date: 04/29/09 16:31 > > The first question is "why are the 4 mpci cards in teh RB600 seeing each > other so loudly"? > There lies the problem needing fixed, because of course we want to use one > RB433, instead of 3 RB433s, to accommodate 3 mpci cards. > (even if different channels and freqs). > > First question to you... "am I assuming correct that you still kept the > dummy loads on each of the mPCI cards, when testing all in teh same RB600"? > > What is a bot disturbing is that you said you used a XR5. That means the > card had a single antenna connector and a MMCX style, which is supposed to > give better isolation. > > (note: some have advocated that Ufl is as good as mmcx, regarding rssi loss, > stating that the UFl connector itself has less loss than the gain MMCX adds > by enabling thicker pigtail cable. I always still prefer MMCX because it is > more rugged abd less likely to break pigtails connectors in things like > Rootenas that are not easy to access with short pigtails. But surely I > thought mmcx would also add better shielding/isolation from outside > sources.) > > So using XR5s, it would infer that the cards saw each other because either > loss from pigtail cable, loss from mmcx connector, or simply the cards > electronics. > The next relevent info might be to determine if it is the amp circuitry > driving this interference. Just like a pair of PC speakers can sometimes > pickup music radio. > > For years Lonnie (StarOS) gave teswtimonials for lower power CM9s performing > better than Amplified cards (SR5) for short range applications, because they > were quieter. > > So there is about 8db difference between a SR5 and a CM9. I wonder if you > repeated your tests, but used CM9's instead (no ext embedded amps), whether > you'd just hear the other adjacenet radios at 8db lower, proportional to the > spec of the radios, or if you hear the otehr radio much much less, because > it doesn;t have the amp to pcikup the interference? > > > Tom DeReggi > RapidDSL & Wireless, Inc > IntAirNet- Fixed Wireless Broadband > > > ----- Original Message ----- > From: "Kurt Fankhauser" <k...@wavelinc.com> > To: "'WISPA General List'" <wireless@wispa.org> > Sent: Wednesday, April 29, 2009 10:33 AM > Subject: [WISPA] RB333/433 eliminating self-interference test > > > > About a week ago there was some discussion about 5ghz radio's being > > installed in the same board and causing self-interference on adjacent > > channels and possible even on the entire band thus decreasing throughput > > on > > backhauls. Because even if you were operating on frequency's 5745 and 5825 > > the two radio's would have side lobe harmonics that if installed in the > > same > > enclosure they would still "hear" each other at that short of separation. > > I > > decided to combat this problem and find a solution and share my experience > > with the list. > > > > > > > > I installed a single XR5 card into 3 different RB433's with indoor > > enclosures. I also installed foil tape which I obtained from the local > > True > > Value store for $2.49 on all the vent holes and unused bulkhead connector > > holes. This was done in order to prevent RF side lobe leaks from the three > > radio's that would escape from the indoor enclosures themselves. Having > > only > > 1 card inside each enclosures I should not have a heat problem as the > > outdoor box will not be in direct sunlight. > > > > > > > > I then stacked all 3 enclosures on top of each other with dummy loads on > > each of the N-bulkhead connectors and did some testing. This is what I > > found: > > > > > > > > I set the bottom board as AP and the middle board as Client on frequency > > 5825. Even with this close of separation the two XR5's could only see each > > other at -83 on the same channel. With the top board connecting to the > > bottom board they could only see each other at -90. Keep in mind this is > > on > > the same frequency so adjacent channels should be much less than that > > possibly even in the -100 ranges. Wish I had a spectrum analyzer. With two > > boards separating the AP and Client there was no link at all. The two > > boards > > could not even see each other in an AP scan. > > > > > > > > Just as a comparison with the same radio's installed all on a RB600 not on > > top of each other but in the adjacent mpci slots the radio's were all > > seeing > > each other at -30's. So I gained roughly -55 db of separation by doing it > > this way. So all I would have to do now is make sure that the antennas on > > the tower have at least 10 foot of vertical separation and the > > self-interference problem should be gone and I should be enjoying much > > more > > throughput! > > > > > > > > Thoughts anyone? > > > > > > > > > > > > Kurt Fankhauser > > WAVELINC > > P.O. Box 126 > > Bucyrus, OH 44820 > > 419-562-6405 > > www.wavelinc.com > > > > > > > > > > > > > > > > > > > -------------------------------------------------------------------------------- > > > > > > > > -------------------------------------------------------------------------------- > > WISPA Wants You! Join today! > > http://signup.wispa.org/ > > -------------------------------------------------------------------------------- > > > > WISPA Wireless List: wireless@wispa.org > > > > Subscribe/Unsubscribe: > > http://lists.wispa.org/mailman/listinfo/wireless > > > > Archives: http://lists.wispa.org/pipermail/wireless/ > > > > -------------------------------------------------------------------------------- > WISPA Wants You! Join today! > http://signup.wispa.org/ > -------------------------------------------------------------------------------- > > WISPA Wireless List: wireless@wispa.org > > Subscribe/Unsubscribe: > http://lists.wispa.org/mailman/listinfo/wireless > > Archives: http://lists.wispa.org/pipermail/wireless/ > > > > -------------------------------------------------------------------------------- WISPA Wants You! 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