DPSK Block - Verifying Received Message

All,
I was playing around with the DPSK block provided with GNU Radio. I
was
able to get my two USRPs talking to each other. I placed a file sink on
the random source generator (set to transmit 10 random binary digits)
and
I’m able to see what was actually sent from that file (command: od -d
filename.bin). I was curious how I go about verifying that the message
in
my filename.bin is received as transmitted on the other end? I tried
placing a file sink on the DPSK demod block however because the receiver
is
constantly pulling in information my file becomes extremely large and
it’s
difficult to determine where the message would be amongst the other
‘noise’. Does anyone have any ideas on how to verify my transmitted
message is making it to my receiver?

Thank you
Domenic

Domenic,

Whenever you are transferring data from a transmitter to a receiver it
is reasonable to use some sort of framing. If you want a quick test,
use a packet encoder and decoder on your transmitter and receiver,
respectively. This will packetize the data and eliminate the continuous
flow of “garbage” data to your file since the decoder will only output
data from valid packets(w/ header + crc are removed). Bit errors will
manifest themselves as a “short file”, since bad packets will be
discarded. If you run the block in verbose mode there may also be
reporting for when packets are discarded.

Set the payload length number in the encoder so you have a known
relationship between the number of bytes missing from the file and the
number of packet errors.

There are numerous ways to improve this simple test, but this is a start
for you. Also, you may want to perform a more fundamental bit error
test. See error rate block.

-J

All excellent advice. I would also add that the gr-digital blocks
already do a lot of this–framing and the like. They’re a good place to
get some clues even if you want to roll your own.


Principal Investigator
Shirleys Bay Radio
Astronomy Consortium
http://www.sbrac.org

Thanks for adding to the discussion Paul. I should have made it clear
that testing w/ the packets should have been independent from the
“streaming” BER test.

-John

2011/12/9 John M. [email protected]

discarded.

Set the payload length number in the encoder so you have a known
relationship between the number of bytes missing from the file and the
number of packet errors.

There are numerous ways to improve this simple test, but this is a start
for you. Also, you may want to perform a more fundamental bit error test.
See error rate block.

Just a word of warning:
If you use the package en/decoder and the BER block , it might just go
haywire
The BER block cannot regain from a missing frame (which would be the
case
if the framer threw it away)

was able to get my two USRPs talking to each other. I placed a file sink
Thank you
[email protected]
https://lists.gnu.org/mailman/listinfo/discuss-gnuradio

Best
Paul

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