I have 3 sectors within 10 m on the same tower with a major cell of gsm network (6+ sector antennas for 900mhz) (1 r52 + 2 generic AR5212 radios + uplink - 5180 mhz.)
Should there be any interference for 2.4 and/or 5.8 clients from the gsm ?
I do have sometimes weird ping times, in range from 1 to 1500 ms.
I guess I have to answer myself⌠
Maybe there is, maybe there isnâtâŚ
Wish I could help. I didnât notice an increase near a cell tower, but I wasnât co-located, just testing.
I am concerned, however, as my cell phone has done some odd things since testing the SR9 with the antenna in my office.
We have trango 900 and alvarion 900 gear in close proximity to verizon cell stuff on a tower - they are in the high 800mhz range. No problems. Not sure what frequencies 900 gsm uses. At another site, there is some higher 900mhz stuff that doesnât mess with the trango.
Here is the spectrum:
926 MHz peak -86 dBm avg -94 dBm
928 MHz peak -59 dBm avg -59 dBm ****
930 MHz peak -58 dBm avg -59 dBm ****
932 MHz peak -59 dBm avg -60 dBm ****
934 MHz peak -79 dBm avg -79 dBm *
936 MHz peak -47 dBm avg -48 dBm ****
938 MHz peak -46 dBm avg -46 dBm ****
940 MHz peak -50 dBm avg -50 dBm ****
942 MHz peak -96 dBm avg -97 dBm
944 MHz peak -99 dBm avg -99 dBm
Well, iti seems gsm doesntât mess with our wifi. Thatâs good. 
We were out testing 900 access the the other day, w/2 GPS receivers on the dash of the car. Both GPS lost lock within a few seconds of each other, began displaying error messages. We were halfway convinced that The Shrub or maybe Vlad had lost his mind, started WWIII. That is, until we remembered the 12dBi panel w/SR9 lying in the back seat, powered up and as it happens associated w/an AP. Unplugged the radio, voila âWWIIIâ over almost as soon as it began⌠
I realize proximity has a bit to do with it, but it is a bit disconcerting that the SR9 is interfering with GPS and GSMâŚ
Iâd hate to finally get broadband here and then have a couple of cell companies breathing down my neck.
GPS receivers are insanely senstive as their antenna is very small and they pick up a very weak signal basically from solar powered transmitters thousands of miles away in space.
I think the sr9 is probably a bit messier in spectrum behavior than purpose built 900mhz products since it has to downconvert the frequency from 2.4. We already know it is senstive to 2.4 radio cards in close proximity. The conversion could introduce harmonics, as frequency conversion is basically âmixingâ frequencies together to create new frequencies.
The RB power supply or an unshielded ethernet cable could also be producing noise that blocks the GPS signal and it could be no fault of the SR9 at all.
True, didnât think about that.
As I mentioned above tho, my cell has done some odd stuff since I started testing the SR9 indoors. It may not occur with the radio, or at least the 13dBi yagi, outdoors.
We have a big round concrete water tower with 9 900/1800 cell sectors on it and due to the layout of the tower, the one sector had to face âpastâ a cell sector. It gave us endless headaches, pinging sometimes ok, sometimes very very bad. Signal strength allways seemed ok but youâd always have a periodic timeout on pings. Eventually put in another RB and mounted our 2 sectors on the edges of the tower, facing away (as opposed to in the middle back-to-back) and now it is much better. Iâm guessing the reflector in the cell-sector was causing to much of an echo.(?) But then again it seemed better (at night) or worse (during day). Maybe as the cell tower was busier, it caused more hasstlesâŚ
My point is, keep 'em sectors facing away as far as possible and do not even concider an omni⌠(We installed s-type bends on the sector poles to get them sticking out further than the edge of the tower.)