I'm very interested in your reported data. Its nice to see the results actually using a spectrum analyzer.
Actually, we thought it was possibly advantageous to have the slots stacked because of the ease to fasten a isolation barrier between cards. And we feared that cards side by side would equally get interference comming from reflections from the metal case walls, trapped inside the case. What we did was take card stock cut to size and wrap it with aluminum foil, and then put that inside a static bag. We always mount the SBC with the card Slots at the top side of the case. We then slide the static bag inbetween the two cards, and follow up with a peice of electrical tape. Even if the electrical tape unsticks over time, the isolation barrier is resting in a position where it would likely stay in place over time. We also are more selective on which cards we use in these stacked slots. We never use a dual antenna port card, unless both have a pigtail on it. As well, prefer mmcx ports because they have better isolation than UFL. Some report that UFL actually has lower loss of its own signal than mmcx so UFL preferred in systems with single cards. But when stacking cards, isolation of mmcx may be more advantageous. Its also relevent to point out a large part of RF escape can be the pigtail itself, if not a high quality pigtail, so one should avoid having the multiple pigtail paths interwine, when possible. It should also be noted that the locations in which RF is injected into an adjacent circuit is not always as it seems. For example... If can be absorbed simply circuit board to circuit board, not only through antenna ports. Or it can even be injected in through the mPCI slot's pins or DC power pins. It might be interesting to try to discover for sure where exactly the majority of the bleed is getting transferred from one card to the other, to know how to best isolate. Since you now have the Analyzer, and the know how to test, would you mind repeating your tests, after inserting foil isolation (like I described above), to see how it compares, to without foil isolation or to slots positioned side by side alledged not to experience similar bleed levels? Tom DeReggi RapidDSL & Wireless, Inc IntAirNet- Fixed Wireless Broadband ----- Original Message ----- From: "Robert West" <robert.w...@just-micro.com> To: "'WISPA General List'" <wireless@wispa.org> Sent: Friday, April 23, 2010 5:31 PM Subject: Re: [WISPA] Ever wonder how bad RB333/444 stacked cards interfere? > Kurt, > > I always put laminated foil between the cards. You able to try putting a > shield of aluminum foil between to see if that does anything useful? > > Bob- > > > -----Original Message----- > From: wireless-boun...@wispa.org [mailto:wireless-boun...@wispa.org] On > Behalf Of Kurt Fankhauser > Sent: Saturday, April 24, 2010 4:44 PM > To: 'WISPA General List' > Subject: Re: [WISPA] Ever wonder how bad RB333/444 stacked cards > interfere? > > If you physically move them to anywhere but on top of each other, like the > sides or above or below then the bleed over goes away. So if you mounted > them side by side in a RB600 or RB800 then your ok. Heres some pics of > that. > > > Kurt Fankhauser > WAVELINC > P.O. Box 126 > Bucyrus, OH 44820 > 419-562-6405 > www.wavelinc.com > > > -----Original Message----- > From: wireless-boun...@wispa.org [mailto:wireless-boun...@wispa.org] On > Behalf Of Ryan Spott > Sent: Friday, April 23, 2010 2:21 PM > To: WISPA General List > Subject: Re: [WISPA] Ever wonder how bad RB333/444 stacked cards > interfere? > > Wow, > > So my question would be, what sort of separation is required to keep the > noise down? > > ryan > > > On Sat, Apr 24, 2010 at 8:27 AM, Kurt Fankhauser <k...@wavelinc.com> > wrote: > >> If anyone is like me and ever wondered how bad that stacking cards of >> the same band in RB333 or RB433 interfere with each other, well, I >> finally answered my own question. I've been wondering this for the >> past 3 years > and >> no one could really give an answer, or show proof. Well I bought a > spectrum >> analyzer and decided to do some testing. I plugged the spectrum >> analyzer directly into the antenna port on a disabled card that was >> stacked on top of a card that was transmitting. Bleed-over on the >> adjacent channels started at >> -76 !!!! >> >> >> >> Won't be doing that anymore! Just thought I would share this valuable >> information with the list. For more tests at different channel widths >> and such check out this thread. >> >> http://forum.mikrotik.com/viewtopic.php?f=7 >> <http://forum.mikrotik.com/viewtopic.php?f=7&t=30657&p=204642#p204642> >> &t=30657&p=204642#p204642 >> >> >> >> >> >> 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! 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/
