How to Access Received Data for Use In Changing RX Parameters

Hey List,

I have two scripts I am running, the ofdm_v1_tx_freq_test.py and the RX
version of it (see flow graph images and attached transmitter Python
script). I am transmitting a sinusoid using OFDM modulation over the
USRP,
it works perfectly.

I have made an alteration to the transmitter script by adding a
frequency
change function that goes off every 2.5 seconds. The frequency will
inclemently go up 1 MHz 20 times before going back to the default. That
code works; what I want to do now is to cease the sinusoid broadcast at
every 2.5 seconds so I can transmit the new frequency to the receiver
right
before I change it. I think I can figure that part out, I may just use
another vector source with the new frequency and have transmit five
times.
Probably use another flow graph to implement it. If there is a better
way
to do, I am open for ideas.

Now for my question: after receiving this new frequency on the RX side,
how
do I get my script to read this data and use it to change frequencies? I
have a feeling that this may be simple to do but I am at a loss in
figuring
it out.

Please note, this is more of a proof of concept work, so there is a
reason
why I do not have identical frequency change functions in both TX and
RX,
the goal down the road is to get some DSA capabilities.

Thanks,

Jon

Jonathan F. wrote

code works; what I want to do now is to cease the sinusoid broadcast at
have a feeling that this may be simple to do but I am at a loss in


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ofdm_v1_tx_freq_test.py (7K)

<http://gnuradio.4.n7.nabble.com/attachment/47642/0/ofdm_v1_tx_freq_test.py&gt;

ofdm_v1_rx.png (97K)
<http://gnuradio.4.n7.nabble.com/attachment/47642/1/ofdm_v1_rx.png&gt;
ofdm_v1_tx.png (77K)
<http://gnuradio.4.n7.nabble.com/attachment/47642/2/ofdm_v1_tx.png&gt;

You can use a message queue to get data in and out of the flow from your
Python script. I’m sure there are better ways, but this is what I have
been
experimenting with recently. It’s just a matter of polling the queue
and
clearing it when there is new data. This is a good write up:


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