On 06/18/2015 04:13 PM, Nick Kossifidis wrote: > [...] > I have NDA documents as well stating that the indices are from -64 to > 63 (-64 to -1, 1 to 63 and 0 is DC), you can check out for yourself > that we get 128bins on dynamic HT20/40, see the header files too: > > #define SPECTRAL_HT20_40_NUM_BINS 128 > Right, there are 128 in total, combined from 2 individual 64-bin sets. That's why you need to swap upper and lower when operating in HT40MINUS, since chip always puts primary channel to lower bin set.
> and/or the received packet length. Maybe you are talking about > "static" HT40 (I don't see anything about that on the documents I > have) or something else. > Yes, maybe different documents. Mine says that interpretation of upper/lower bin values (max_magnitude, bitmap_weight, max_index) is the same in static and dynamic modes - only the bin values differ. >> I used the proposed method with the chirp detector for FFTs provided for long >> radar pulses on an AR9590 (patch posted the same day). Max bin index is used >> there >> the same way as with spectral, but now I realize my mistake: for chirp >> detection, >> the relative max_index is sufficient, while for spectral the absolute value >> is needed. >> >> Toggling the MSB in HT20 shifts the signed values by 32 and leaves the index >> with >> an offset of 4, therefore the correct operation should be: >> ht20_max_index_absolute = (ht20_max_index ^ 0x20) - 4 >> > > Have in mind that on earlier chips (I did the testing on an AR9820) we > get corrupted frames sometimes so we also need the sanity check I put > there or else we can end up reading data out of bounds which is pretty > dangerous so please leave the current implementation there as is. > > The sanity checks / fixes are done before you look at the bin attributes and, which therefore is not relevant for interpreting them. But never mind - as said before, I proposed this to use the 3 functions for DFS chirp detection. I'm fine not touching the running system and instead keep a local copy of those. Thanks, Zefir -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
