Re: [Discuss-gnuradio] BBN 802.11 bbn_80211b_rx.py

[yyzhuang]

Thanks.

When I use "./bbn_80211b_rx.py -f 2.44G -v -b ", no packets get printed out.
But the output of "./bbn_80211b_rx.py -f 2.462G -d 8 -b -v " is normal, we
got a bunch of packets:

Bits Per Encoded Sample = 8
adc frequency =  64000000
decimation frequency =  8
input_rate =  8000000
gain =  45.0
desired freq =  2462000000.0
baseband frequency 2460000000.0
dxc frequency -2000000.0
Samples per data bit =  8
>>> gr_fir_ccf: using SSE
PKT: len=77, rssi=-22, src=00:13:46:16:28:AA, time=557560, rate=1 Mbps
PKT: len=77, rssi=-29, src=00:13:46:16:28:AA, time=1786312, rate=1 Mbps
PKT: len=77, rssi=-26, src=00:13:46:16:28:AA, time=1991192, rate=1 Mbps
...........

I checked the code:

parser.add_option("-d", "--decim", type="int", default=16,
                          help="set fgpa decimation rate to DECIM
[default=%default]") 
parser.add_option("-b", "--barker", action="store_true",
                          default=False,
                          help="Use Barker Spreading [default=%default]") 

-d 8 is setting the fpga decimation rate to 8, and -b means Use Barker
Spreading. How should we know what decimation rate and spreading to use?
Thanks.

BTW, if one ursp for tx and one for rx, we dont have to specify these
options:
on the sending side: ./bbn_80211b_rx.py -f 2.44G -v -b
Using TX d'board A: Flex 2400 Tx MIMO B
>>> gr_fir_ccf: using SSE
spb:       8
interp:   32 
(spb = samples/baud, default 8; interp = fpga interpolation rate, default 32
)

on the receiving side: ./bbn_80211b_tx.py -f 2.44G
Bits Per Encoded Sample = 8
adc frequency =  64000000
decimation frequency =  16
input_rate =  4000000
gain =  45.0
desired freq =  2440000000.0
baseband frequency 2436000000.0
dxc frequency -4000000.0
Samples per data bit =  8
>>> gr_fir_ccf: using SSE
PKT: len=1477, rssi=-10, src=20:61:6e:64:20:73, time=16024824, rate=1 Mbps
PKT: len=1477, rssi=-12, src=20:61:6e:64:20:73, time=16036920, rate=1 Mbps
PKT: len=1477, rssi=-11, src=20:61:6e:64:20:73, time=16049016, rate=1 Mbps
PKT: len=1477, rssi=-13, src=20:61:6e:64:20:73, time=16061112, rate=1 Mbps 

Thanks!


Brian Padalino wrote:
> 
> On Mon, Jul 28, 2008 at 12:28 PM, yyzhuang <address@hidden> wrote:
>>
>> What does "combination of the LO in the front end and the digital
>> downconverter" mean please?
> 
> For general radio architecture, please see:
> 
>     http://en.wikipedia.org/wiki/Superheterodyne
> 
> Generally, the LO/synthesizer has some discrete step size (12.5kHz,
> 250kHz, etc).  To get down to baseband, the resultant signal is then
> shifted in frequency down using the digital downconverter:
> 
>     http://en.wikipedia.org/wiki/Digital_Down_Converter
> 
> Brian
> 
> 
> _______________________________________________
> Discuss-gnuradio mailing list
> address@hidden
> http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
> 
> 

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