Hey all:

I'm getting some odd results here with a PtP 5.8GHz link using MikroTik that I setup to test with. Let me describe the setup...

The link is 7.9 miles with clear LoS and clear Frenel zone. Each end has a 27db grid with a 3ft LMR-400 jumper to the MikroTik radio. Using the link calculator at http://www.zytrax.com/tech/wireless/calc.htm I get a predicted rx of -60.8db at each end with CM9 radio cards (17db output). Using the SR5 cards, (400mW), I get a predicted rx of -51.8

On to the real world results.... (all reading taken from the MikroTik's winbox. I am using version 2.9.11 on RouterBoard 230's)

With the CM9 cards, I get a measured rx of -62db, well within the margin of error. An interesting note here is that I must set the CM9's output power in the MikroTik at 30db to get these results.. I know that the MikroTik must be doing something odd with this setting, as the CM9 can not put out 30db. Reducing the setting drops the rx strenth by a like amount. This link is stable and will pass 30Mb/sec in UDP and 22Mb/sec in TCP mode

With the SR5 cards, I get a measured rx of -66db, well outside the margin of error and 15db below the expected rx strength! An interesting note here is that I must set the SR5's output power in the MikroTik at 30db to get these results. I know that the MikroTik must be doing something odd with this setting, as the SR5 should not put out 30db. Reducing the setting drops the rx strength by a like amount. This link is stable and will pass 24Mb/sec in UDP and 16Mb/sec in TCP mode.

Nothing else is changed when I swap the SR5's for the CM9's or back again. I use the same antennas, cables, boards and pigtails. The antennas and cables are not moved between tests. (except for moving the pigtail from one card to the other).

Can anyone tell me what I am doing wrong here? Or do I just have some bad SR5 cards? Or is the tx power setting in the MikroTik flakey? Or is the tx power setting relative db not absolute db?

BTW, I will be changing one end to a sector and wish to use the SR5 cards then. Otherwise I'd be happy with the -62 on the CM9's

Thanks in advance.

--
Blair Davis

AOL IM Screen Name --  Theory240

West Michigan Wireless ISP
269-686-8648

A division of:
Camp Communication Services, INC

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