On Friday 06 July 2012 19:32:41 Mohammed Shafi wrote: > Hi Simon, > > On Fri, Jul 6, 2012 at 6:20 PM, Simon Wunderlich > > <simon.wunderlich@xxxxxxxxxxxxxxxxxxxx> wrote: > > Hey, > > > > we have trouble with an AR9330 (Hornet) based AP. This device has 2 > > antennas, and is supposed to support diversity (2 RX, 1 TX). However, > > diversity is not really enabled because the "alternative" antenna is not > > considered as "good", because not enough frames are received. It seems > > that at 99% of the time, alt_rssi (read from rs->rs_rssi_ctl1) is invalid > > (set to ATH9K_RSSI_BAD, -128), while main_rssi (read from > > rs->rs_rssi_ctl0) usually has sane values. > its been some good amount of time i had taken/tested take a look at > this. actually Gabor Juhos added the support for AR9330. > seems AR9003 family chipsets can exhibit this behaviour. i quickly > checked with AR9285(AR9002) which seems to have a positive RSSI > regulary in ctl0/ctl1. > i also have a AR9485(AR9003 family) which might be similar to AR9330. > just checked with removing the antenna in chain0 seems to bring > positive values in rssi_ctl1. > I just also observer the chain0 is "preferred" unless the RSSI is so > poor in it so chain1 is taken. > Please check if this work out for your case too. Removing the antenna on chain0 doesn't change the alt_rssi value for us. We only noticed that frames with alt_rssi != -128 have the value rx_ant_conf == 1 (LNA2) when only chain1 is attached and rx_ant_conf == 2 (LNA1) when both/chain0-only are attached. Still most of the packets had alt_rssi == -128 and we saw changes in curr_main_set and curr_alt_set (after lot of data was sent). > also please see the throughput difference with/without antenna > diversity with one antenna broken. We (Simon and me) tried to play with the antennas and came to following results: * Both attached: 45 Mibit/s * chain0 attached: 45 Mibit/s * chain1 attached: 15 seconds nearly nothing, after that 25 Mibit/s > I will check out the proper technical reason for such a > preference/compare with AR9285 (or) if its a bug in the code itself. > thanks for looking into this feature! Thanks Kind regards, Sven
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