Recipetion/Transmision of QPSK wavefrom with USRP E3xx fails + blocks not found in Simulink

I am trying to run the example "Recipetion of a QPSK Waveform Using USRP E3xx" together with "Transmission of a QPSK Waveform Using USRP E3xx" using a USRP E312 and a loopback cable between its Tx and Rx ports. Initially the recieved signal was decoded into a similar message as in the following image:

Following the suggested troubleshooting steps and using burst mode, the message now appears as following:

It was observed that the only LED blinking the whole time is the TRX-B LED. There is also some ambiguity regarding mapping of the used port on the USRP and the channel mapping parameter of the transmiiter and reciever blocks.

Please also note that when I try to do an example with the E3xx transmitter or reciver block from scratch, I am unable to find the blocks in simulink. I understood from this link of the E3xx Transmitter block that it should be found under Communications Toolbox Support Package for USRP Embedded Series Radio / E3xx, however I couldn't find this support package under simulink.

Anyone faced similar issues and was able to solve it?

Answer 1

[James Hopkins]

Hi Menna,

Thanks for your question.

I suspect that you may be running into some performance issues, particularly if you are running both simulink models from the same host computer. I suggest you try using this script in place of the transmitter model: https://www.mathworks.com/help/supportpkg/usrpembeddedseriesradio/ug/repeated-transmission-of-a-qpsk-waveform-using-usrp-e3xx.html

This will reduce the amount you are streaming from host computer to radio.

If this does not solve the issue, there is an optional output port on the receiver which flags overflow. This can be enabled through the block parameters menu:

The LED activity you describe is as expected.

Finally, the issues you've had finding the blocks relate to a known issue which will be fixed in a future release. For now, you can use type "e3xxlib" into the Matlab command window. This will open a Simulink model with the tx and rx blocks, you can then copy these into your own model.

I hope this helps.