Attempting DBPSK again

GNU Radio
1

I’ve lost the previous thread amidst other threads, and figured enough
new
developments and different issues have arisen to warrant another.

I’ve written a simple pipeline, which generates a signal, sends it
through
the dbpsk modulation block, and transmits it over the USRP. A receiving
USRP
intercepts this and transmits anything it receives. Finally, the
original
computer is also waiting to receive from the USRP, and stores the
results in
a file sink.

The results leave much to be desired, though. Even assuming the most
basic
sort of transmission, where all USRP input is monitored and stored
rather
than detecting when data is incoming (generating a constant signal by
removing gr.head() from the transmission executable), it still doesn’t
function properly. It compiles, and runs, and outputs… but I get a
file of
significantly smaller size than what has been transmitted. And even more
curiously, the received file isn’t playable by audio_play.py. It runs,
but
there is no sound. Even if audio_play.py were given pseudo-random
numbers
(supplied by urandom), it would still output sound, even if white noise.

This would all be far simpler if I were aware of how to remove the
modulation aspect from benchmark_tx. The goal here is to have the
capability
to supply a modulated bitstream from another source, and have that
transmitted, rather than GNU Radio handling modulation. We would
probably
get better results in the end anyway, if we made modifications to a
previously tried method. But… knowing what’s wrong here is still quite
helpful.

Code is as follows:
http://www.nabble.com/file/p20964979/loopback_transmitter.py
loopback_transmitter.py
http://www.nabble.com/file/p20964979/loopback_reciever.py
loopback_reciever.py
http://www.nabble.com/file/p20964979/loopback.py loopback.py

–
View this message in context:
http://www.nabble.com/Attempting-DBPSK-again-tp20964979p20964979.html
Sent from the GnuRadio mailing list archive at Nabble.com.

2

Scratch that… I just realized that with clever placement of the read()
function I could read file contents as the payload string. Also found
mod_pkts() and can modify that to accommodate any new modulation schemes
or
remove it entirely.

Just one question remains though, to put it to good use. Where do the
actual
packet contents go when benchmark_rx is unmodified? I’m getting
acknowledgment that packets are received, but they aren’t stored in a
file.

I’m currently trying to work a file sink into receiver_path.py. Is that
the
proper course of action?

Francesco B. wrote:

The results leave much to be desired, though. Even assuming the most basic
This would all be far simpler if I were aware of how to remove the
http://www.nabble.com/file/p20964979/loopback_reciever.py
loopback_reciever.py
http://www.nabble.com/file/p20964979/loopback.py loopback.py

–
View this message in context:
http://www.nabble.com/Attempting-DBPSK-again-tp20964979p20969862.html
Sent from the GnuRadio mailing list archive at Nabble.com.