2013/11/12 Nick Kossifidis :
> On Tue 12 Nov 2013 11:55:43 AM GMT, Sergey Ryazanov wrote:
>> Hi list,
>>
>> we test pretty old hardware based on AR5414 chip with pretty old
>> madwifi driver, which even use binary hal. Our spectral analyzer shows
>> that in 2.4GHz band this chip transmits OFDM-preamble with any of the
>> OFDM rates (6-54 mbps), instead of .11b-compatable DSSS-preamble. Does
>> anybody could provide some clue: is this chip supports DSSS-OFDM mode
>> according to section 19.7 of IEEE 802.11-2012?
>>
>> When I digging the ath5k code I faced the AR_PHY_MODE (0xa200)
>> register, which seems to controls the behavior of chip. This register
>> contains two interesting bit:
>> AR_PHY_MODE_MOD_CCK bit 0 (0x0001)
>> AR_PHY_MODE_MOD_DYN bit 3 (0x0004)
>>
>> If I am correctly understand, _MOD_DYN just enables the CCK (DSSS)
>> block. But what the purpose of the AR_PHY_MODE_MOD_CCK bit?
>>
>
> From what I know:
> MOD_DYN = CCK + OFDM (for g)
> MOD_CCK = CCK only (for b)
>
Thank you Nick, for your quick answer,
may be you know, why we need such explicit option (I mean MOD_CCK
bit)? If we would like to act as pure dot11b node, then we could
simply limit rate set to DSSS/CCK rates only.
Did you know something about DSSS-OFDM mode support in the AR5xxx
chips, is it possible at all?
--
BR,
Sergey
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