joshg409
join:2005-05-03
Ottumwa, IA
| reply to davesims
Re: Migrating from FHSS to OFDM
Here is what we do. We connectorize a canopy 2.4 and attach an omni. We do an SA from the canopy, pick a quiet frequency then go into the three Alvarions and exclude the Canopy frequencies from the hopping sets. I know, not the best but it solves the problem of not having to run around to everyone on the sector and change CPE. If you are going from Alvarion to OFDM, you will have to pull new cable. The nice part is the Alvarions only handle about 20-30 clients and you can get three times that on a canopy. So one Canopy versus three AU's to start out. |
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EMC_guy
join:2007-10-13
Sharbot Lake, ON
 ·Rogers Hi-Speed
edit:
May 8th, @04:54PM
| said by joshg409  :We do an SA from the canopy, pick a quiet frequency then go into the three Alvarions and exclude the Canopy frequencies from the hopping sets. Yes, this is the correct approach.
Sorry, my previous comment is valid for only BFSK radios - Canopy and some SCADA. It should read:
"You can find out the exact BFSK center frequencies for 0 and 1 bits using the emission test reports under FCC ID. Now set your OFDM radio for a narrow channel width (5Mhz or 10Mhz) with center frequency that is 5Mhz away from those BFSK frequencies. "
Older FHSS radios have longer hopping periods - many milliseconds per hop - so it is possible to co-locate after some "trial-and-error" timing coordination.
First make the 802.11 beacon fall in the middle of 2 FHSS hops (by trying different inter-beacon timing (use spectrum analyzer if necessary) - that will make sure beacons do not get clobbered. Now set RTS to a low value both AP and CPE to create shorter 802.11 packets that fit within the FHSS hops. |
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davesims
join:2004-10-09
Roseburg, OR | Thanks guys you all have provided me with some good insight and some validation of my thinking.
Dave |
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