Re: [Discuss-gnuradio] How does benchmark_rx.py know the packet size?

[adeel anwar]

Song,

Every transmitted pkt has structure

          preamble:access_code:header:payload_with_crc:'\x55'

header consists of 2 16-bit shorts, having payload length and whitener offset.

On receiver side "framer sink" extracts the payload depending upon the value of header (2 shorts). 

see "packet_utils.py" and doxygen doc of "gr_framer_sink"

 -Adeel

On Thu, Dec 8, 2011 at 12:07 PM, Songsong Gee <address@hidden> wrote:

When I run benchmark_tx.py, the packet size has to be specified (default is 1500)

However, I could see nothing defining the packet size on benchmark_rx.py

In benchmark_rx.py, messages from benchmark_tx.py are queued after passing demodulator, correlator, and framer sink.

But, I'm wondering that how can the receiver queue a message which has the exact size defined by the transmitter without defining the packet size on the receiver.

Are there any steps or procedures inside the demodulator, correlator, or framer sink that recognize the start and the end of the packet?

--

Seokseong Jeon, PhD Candidate

Communication & Networks Lab

IT Convergence Engineering (ITCE), POSTECH, Korea

+82 10 8338 1229, gee.songsong at gmail . com

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