BladeRF2.0 wont stop transmitting with GNUradio sink

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o8ko8k
Posts: 2
Joined: Tue May 10, 2022 7:57 pm

BladeRF2.0 wont stop transmitting with GNUradio sink

Post by o8ko8k »

UPDATE: After waiting 5 days or so for this post to get approved, I kludged a work around together. When the PTT button is not pressed, I set tx gain to minimum and move the center frequency out of band, works great!

I have a flowgraph where the BladeRF2.0 is supposed to transmit an FM signal from a microphone which is routed through push to talk QT GUI switch. 1. When the flowgraph starts up, there is no transmit from the bladeRF2.0 as expected.
2. After the push to talk button is depressed, audio flows to the gr-osmoSDR sink block and FM RF is present as expected.
3. Once the push to talk switch is deactivated, a QT audio sink debug block confirms the audio stream is no longer reaching the input side of the RF sink block, yet the transmitter stays transmitting w/ no carrier (this does not happen when the gr-osmoSDR sink block is changed to use the USRP device instead, in the case of the USRP, the transmitter shuts down as expected).
4. Upon exit from the gnuradio companion flowgraph application, the bladeRF2.0 hardware continues to transmit a carrier till power is removed (again unlike the USRP device).

Conclusion:
1. The BladeRF device behaves differently to the same flowgraph stimulus than the USRP.
2. The BladeRF device does not stop transmitting after it is commanded to do so until power is removed (provided the aforementioned stimulus; Under other conditions, this may not happen, further experimentation will be required)

Question:
1. Is the BladeRF acting as expected?
2. Does the BladeRF need different stimulus than the USRP in order to turn the transmitter off, then on again, then off again ect?
3. Or is there bug in the BladeRF gr-osmoSDR, or BladeRF driver that is causing this?

Thanks,
o8ko8k
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