Forum: GNU Radio access code detection threshold in benchmark tx/rx scripts

I'm trying to understand the benchmark receive path. The access code 
detection threshold is set to -1 in receive_path.py. After looking at 
the digital_correlate_access_code_bb block, it appears the INT32 
threshold, -1, is being compared with the *UINT32* Hamming distance 
between the known code and the received code. If I'm not mistaken, C/C++ 
will do unsigned comparison and therefore *any* number of errors < 
UINT32_MAX (2^32 - 1) will be accepted. Am I reading this incorrectly?

--sean

Inside receive path you have packet_demod block, which is hier block
written i npython. Inside you can find that they assign positive value.

Nemanja


On Fri, Feb 15, 2013 at 3:02 AM, Nowlan, Sean

>Inside receive path you have packet_demod block, which is hier block written i 
npython. Inside you can
>find that they assign positive value.

Ah, just found it.

gnuradio/gr-digital/python/pkt.py lines 140-141 in class demod_pkts:

if threshold == -1:
    threshold = 12

Thanks for pointing this out.

>Nemanja


--sean