Thank Marcus.

"packet decoding" recovers message from received packet

and i got false from crc.py

def check_crc32(s):
    if len(s) < 4:
        return (False, '')
    msg = s[:-4]
    #print "msg = '%s'" % (msg,)
    actual = digital.crc32(msg)
    (expected,) = struct.unpack(">I", s[-4:])
    #print "actual =", hex(actual), "expected =", hex(expected)
   * print actual == expected*
    return (actual == expected, msg)

2016-02-21 20:52 GMT+09:00 Marcus Müller <marcus.muel...@ettus.com>:

> Dear Sang Hyuk Kim,
>
> what "packet decoding" are you specifically talking about, and could you
> show us the code you've modified?
>
> Best regards,
> Marcus
>
>
> On 21.02.2016 12:32, SangHyuk Kim wrote:
>
> Hi, I transmit simple text file using two USRP N210
>
> Tx)
> file source -> packet encoding -> mod(GMSK) -> usrp sink
>
> Rx)
> usrp source -> demod(GMSK) -> packet decoding -> file sink
>
>
> To make corrupt packet, I tried to modify part of crc check
>
> I guess if the crc of received packet doesn't match with original one,
> receiver would discard the packet.
>
> However, I found receiver accepts every packet even if crc check returns
> 'false'.
> (I expected receiver accepts packet only pass crc check by 'true')
>
>  Why it always return false and how can I corrupt packet with other ways ?
>
>
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