Re: [Discuss-gnuradio] change frequency in gr-ieee802-15-4 example transceiver_OQPSK.py

[Marcus Müller]

Hi Jaeho,

there's three blocks that use the "freq" variable from that WX GUI slider:

* the USRP source
* the USRP sink
* the FFT sink

The first two have an input message port; you can connect a message-emitting block to these, and send PMTs containing commands to these [1]. The WX FFT sink doesn't have such an input port, but frankly, that doesn't matter, because it only needs the center frequency to display it [2]

To test your case, try a "Message strobe" block, with the message set to something like

pmt.pmt_to_python.python_to_pmt({"freq":2.4e9})

Obviously, that will just periodically set the same frequency (2.4GHz) over and over again. However, as soon as you have verified that works, you can just write your own (python or C++) block that has no stream in- or outputs, but spawns a new thread that periodically sends a message out; see [1] for the syntax you'd need to use to add exact timing to the command dictionaries.

Best regards,
Marcus

[1] https://gnuradio.org/doc/doxygen/page_uhd.html#uhd_command_syntax
[2] if that bothers you, replace all the WX things in your flow graph by Qt elements; you can enable message ports on these

On 21.09.2015 08:11, Jaeho wrote:

Hello. I am using Ubuntu 15.04 now.
I have a question about transceiver_OQPSK.py source code.
I success to run this source code on USRP X300.
The thing that i want to do next is changing frequency
automatically(randomly).
Originally, this code choose frequency using radio button GUI to change
frequency.
But, i hope to change frequency automatically without any GUI working.
For example, if I run this code, then frequency is changed periodically and
have random value.

Which block should I use to change value automatically in GRC 
or how can i modify in python code.

Please give me advice.
Thank you



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