On 4/14/17 5:09 PM, Faisal Imtiaz wrote: > I would love to be more 'educated' in this matter... > > How exactly is this achieved in real world ? > I have been told that if another operator is using that channel & polarity, I > cannot use it in the other direction... > > So, technically it is feasible, but practically how is this accomplished ?
By designing the path so that they can't hear each other. You can easily use the same or overlapping frequency pair back to back or any orientation where it won't pick up the other far side because of high/low separation. I've got a couple channels that overlap with another operator, but the azimuth/elevation are different enough (not back to back) and we're both using 3' Radiowaves antennas with deep shrouds. Among other things, the shrouds reduce sidelobes. Good antennas make a difference. Two or more "high" side or "low" side radios together won't interfere since they can't tune the RX side in the same part of the band. That's how FDD reuse works. A "high" side radio is deaf to anything else in the "high" side, it only hears a matching "low" side radio. Obviously the paths have to be different enough that each tower radio won't hear the other's far side. If you mix high/low at the same location that's when you run into trouble by creating a situation known as "bucking". GPS sync in TDD where you're having to use the same frequency for TX and RX syncs all the TX together so you don't have one radio in TX while another nearby is in RX, thus causing interference. But since FDD has frequency separation this is not a problem. Think of FDD radios together at a tower as always only in TX mode. The Mimosa B11 has created this weird myth among WISPs that only it allows for reuse because WISPs are used to using the same frequency for TX and RX, but that's not really the case with FDD equipment. ~Seth _______________________________________________ Ubnt_users mailing list [email protected] http://lists.wispa.org/mailman/listinfo/ubnt_users
