Hello Adrian,
thank you for posting this and the explanation!
On Sat, Dec 15, 2012 at 08:06:47PM -0800, Adrian Chadd wrote:
> The formats are as follows. Please note that if a pulse terminates
> during an FFT, the final entry may be truncated. So yes, you may not
> always get an integer multiple of the relevant frame length.
OK - my data is mostly in the range of 55-58 bytes (see below), sometimes
I got some longer packets, but I'm currently dropping them.
The variation still puzzles me though.
>
> Note that you shift each of the readings by max_exp to get a total
> reading. max_index and max_magnitude I think are just derived from the
> existing dataset; they're just a shortcut for software so it doesn't
> have to parse the whole frame looking for the peak.
Ah ok, that makes sense. Thanks for the clarification. :)
>
> Static 20 mode:
>
> 0 bin -28 magnitude[7:0] = (|i| + |q|) >> max_exp
> 1 bin -27 magnitude[7:0] = (|i| + |q|) >> max_exp
> 2 - 53 …
> 54 bin 26 magnitude[7:0] = (|i| + |q|) >> max_exp
> 55 bin 27 magnitude[7:0] = (|i| + |q|) >> max_exp
I've checked my data again: On my AR9280 in 2.4GHz, I get 55 or 57 bytes plus
7 "special bytes" (4 bytes meta info plus 3 bytes "radar trailer?"). In 5 GHz
and on my AR9380 in both bands, it is always either 56 or 58 bytes. The number
of bytes comes from rs_datalen from the rx_status struct as found in the patch
sent earlier.
So to summarise, what I currently get:
* 55-58 bytes of "data"
* 4 bytes of meta-information (as you provided)
* 3 bytes of "radar trailer" (bwinfo and such)
The variation in the data puzzles me, I've already checked bit 4 in bwinfo
as Felix suggested. Is there any other "header" to the DFS data? Or should I
just skip the first few bytes and always use the last 55 bytes? At least from the
distribution, all of these numbers look like normal data and not a bitfield.
Ideas welcome. :)
I've also noticed that the middle of the data (like data[28]) is usually higher
than the rest - this might be the carrier, or something alike?
> 56 [7:0]: all bins {max_magnitude[1:0], bitmap_weight[5:0]}
> 57 [7:0]: all bins max_magnitude[9:2]
> 58 [7:0]: all bins {max_index[5:0], max_magnitude[11:10]}
> 59 [3:0]: max_exp (shift amount to size max bin to 8-bit unsigned)
>
> Dynamic 20/40 mode:
>
> 0 bin -64 magnitude[7:0] = (|i| + |q|) >> max_exp or power (in dBm)
> 1 bin -63 magnitude[7:0] = (|i| + |q|) >> max_exp or power (in dBm)
> 2 - 125 …
> 126 bin 62 magnitude[7:0] = (|i| + |q|) >> max_exp or power (in dBm)
> 127 bin 63 magnitude[7:0] = (|i| + |q|) >> max_exp or power (in dBm)
> 128 [7:0]: lower bins {max_magnitude[1:0], bitmap_weight[5:0]}
> Baseband DFS 2 (Radar) Micro-Architecture
> 129 [7:0]: lower bins max_magnitude[9:2]
> 130 [7:0]: lower bins {max_index[5:0], max_magnitude[11:10]}
> 131 [7:0]: upper bins {max_magnitude[1:0], bitmap_weight[5:0]}
> 132 [7:0]: upper bins max_magnitude[9:2]
> 133 [7:0]: upper bins {max_index[5:0], max_magnitude[11:10]}
> 134 [3:0]: max_exp (shift amount to size max bin to 8-bit unsigned)
Thanks again, also for posting the radar packet format! I'll play a little bit more
with spectral for now ...
Cheers,
Simon
Attachment:
signature.asc
Description: Digital signature
