# PYNQ + RFSOC qpsk/bpsk message transmission fail

**URL:** <https://discuss.pynq.io/t/pynq-rfsoc-qpsk-bpsk-message-transmission-fail/8772>\
**Category:** Support\
**Created:** [September 23, 2025, 6:32am UTC](https://discuss.pynq.io/t/pynq-rfsoc-qpsk-bpsk-message-transmission-fail/8772 "2025-09-23T06:32:54Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![vrb](https://avatars.discourse-cdn.com/v4/letter/v/46a35a/32.png) [@vrb](https://discuss.pynq.io/u/vrb)\
**Post date:** [September 23, 2025, 6:32am UTC](https://discuss.pynq.io/t/pynq-rfsoc-qpsk-bpsk-message-transmission-fail/8772/1 "2025-09-23T06:32:54Z")

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hi @marioruiz I am using a custom board based on the ZCU216. On this board, I am trying to run the QPSK/BPSK flow that I obtained from the provided link [GitHub - strath-sdr/rfsoc\_radio: PYNQ example of using the RFSoC as a QPSK/BPSK radio transceiver.](https://github.com/strath-sdr/rfsoc_radio) . The transmitter and receiver visualization windows display waveforms correctly, but when I send a message through the transmitter terminal, nothing appears on the receiver terminal.Please look into it.

 ![image](https://us1.discourse-cdn.com/flex019/uploads/pynq1/original/2X/a/a79516663ff4d7ee5b2aa55bd2c4d5d4ec1673a8.png)

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**Author:** ![vrb](https://avatars.discourse-cdn.com/v4/letter/v/46a35a/32.png) [@vrb](https://discuss.pynq.io/u/vrb)\
**Post date:** [September 24, 2025, 1:22pm UTC](https://discuss.pynq.io/t/pynq-rfsoc-qpsk-bpsk-message-transmission-fail/8772/2 "2025-09-24T13:22:21Z")

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hi @marioruiz @joshgoldsmith any updates ?

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**Author:** ![joshgoldsmith](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.pynq.io/joshgoldsmith/32/5347_2.png) [@joshgoldsmith](https://discuss.pynq.io/u/joshgoldsmith)\
**Post date:** [September 25, 2025, 12:29pm UTC](https://discuss.pynq.io/t/pynq-rfsoc-qpsk-bpsk-message-transmission-fail/8772/3 "2025-09-25T12:29:15Z")

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Hi @vrb

What have you tried so far to debug this issue?

Based on your description, there are myriad possibilities of what the issue could be, so I would start by narrowing them down. For example: Do other overlays work on the your image? Could it be a physical issue with your custom board? Do you have any working design with the custom board? Can you do basic PYNQ operations (e.g. MMIO, DMA transfers, etc.).

I would also suggest reaching out to StrathSDR who are the creators of the radio transmitter repo.

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**Author:** ![vrb](https://avatars.discourse-cdn.com/v4/letter/v/46a35a/32.png) [@vrb](https://discuss.pynq.io/u/vrb)\
**Post date:** [September 30, 2025, 10:28am UTC](https://discuss.pynq.io/t/pynq-rfsoc-qpsk-bpsk-message-transmission-fail/8772/4 "2025-09-30T10:28:12Z")

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Hi @davidnorthcote @joshgoldsmith , We have done DMA tutorial which was available on git hub repository. It was working properly. We don’t think it’s an hardware issue either. With this radio design we are facing issue at message transmission part.

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**Author:** ![joshgoldsmith](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.pynq.io/joshgoldsmith/32/5347_2.png) [@joshgoldsmith](https://discuss.pynq.io/u/joshgoldsmith)\
**Post date:** [September 30, 2025, 1:34pm UTC](https://discuss.pynq.io/t/pynq-rfsoc-qpsk-bpsk-message-transmission-fail/8772/5 "2025-09-30T13:34:06Z")

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I would suggest trying another one of the StrathSDR designs to make sure the RF part of your device is working as expected. If you are using a custom board, you will need to rebuild the designs for your specific board-specs.

> **[University of Strathclyde - Software Defined Radio Research Laboratory](https://github.com/strath-sdr)**
>
> University of Strathclyde - Software Defined Radio Research Laboratory has 20 repositories available. Follow their code on GitHub.