[Discuss-gnuradio] problem with 2Mbps of BBN code(802.11b)

[Mohammad Hamed Firooz]

  Hi
I hope at least one of the members of BBN group read this email.
I used BBN implementation of IEEE802.11b to receive packets from  
commercial products. So I always use Barker code as the spreading key.
As it had been reported before, Their code works with 1Mbps and  
doesn't work with 2Mbps. I cannot understand why. Since bandwidth of  
DBPSK and DQPSK are the same, the problem is not because of low  
sampling rate. I went precisely through thier code step by step and  
everything seems to be correct. In fact, there is a little difference  
between 1Mbps and 2Mbps modes.
To explain the problem clearly I copy and paste results of receiving  
preamble and header of the short PLCP. You may know that for short  
PLCP, preamble is sent by 1Mbps while Header is transmitted using  
DQPSK (2Mbps) and both of them uses Barker code.

Recieved (short) header!
  signal: 0xBA
  service: 0xE7
  length: 0x640D
  crc: 0x388A
Calculated crc: 0x5112
Recieved (short) header!
  signal: 0xFF
  service: 0xCB
  length: 0x1A50
  crc: 0x2C29
Calculated crc: 0x761C
Recieved (short) header!
  signal: 0xF9
  service: 0x11
  length: 0x8340
  crc: 0x8B78
Calculated crc: 0x5D2A
Recieved (short) header!
  signal: 0x31
  service: 0x1F
  length: 0xC729
  crc: 0xA902
Calculated crc: 0x255D
Recieved (short) header!
  signal: 0x04
  service: 0x09
  length: 0x9170
  crc: 0xBD57
Calculated crc: 0x67E8

Almost never header is received correctly. I am looking for the reason  
of the bug. As I mentioned before it is not because of low sampling  
rate (the sampling rate is 8MSPs)

regards,
hamed