Storing the RF-Output data

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Yazeed
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Joined: Tue Jan 30, 2024 6:22 pm

Storing the RF-Output data

Post by Yazeed » Wed Apr 17, 2024 2:40 pm

Hello everybody, I would like to ask a question regarding the stream of data from the RedPitaya to the computer.

For my application, I am sampling environmental noise, from one RF input of the Redpitaya STEMlab 125-14, on every rising edge of a 1 MHz signal at the second RF input and then generating a random signal (high or low voltages) accordingly at the RF output.

My goal now is to also send the random signal (the low and high voltages) that I generated to my PC (or even the RedPitaya SD) as it will be later needed for post-processing.
I successfully modified the averager example (http://antonpotocnik.com/?p=514765) and I can read the random signal from Python, however, I would need a continuous stream and not just a single measurement.

I tried to look into the streaming feature (https://redpitaya.readthedocs.io/en/lat ... aming.html), but unfortunately, it doesn’t work as the files that I saved are empty.

In the best-case scenario, I would also leverage this stream of data the other way around, generating the random signal at the RF output starting from a bitstring stored on my computer.

Any help would be really appreciated.
Thanks

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redpitaya
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Joined: Wed Mar 26, 2014 7:04 pm

Re: Storing the RF-Output data

Post by redpitaya » Thu Apr 18, 2024 9:57 am

Hello Yazeed,

The streaming application sends the data in packages. Unless a package is full it will not be received at the other end. The minimum package sizes are written here: https://redpitaya.readthedocs.io/en/lat ... #streaming

The intended functionality will most likely require a change in the FPGA. The Streaming application loads and expects the "stream_app" FPGA project. Perhaps you can try modifying that one to also include the averager and then stream it at the wanted data rate.

Currently, we have not yet made the output streaming feature - the problem is that to generate a precise output you need a lot of data points. From our attempts, we were able to generate signals up to 1 kHz that were OK. Anything more was not rendered OK, which is the reason we decided to delay the project. If it is just a bitstring streamed at 1 Msps (1-bit data), then you should be able to achieve the stream by modifying the current Streaming application. Keep in mind that the streaming application has an internal pipeline limitation of 20 MB/s (input data to computer). Streaming to the SD card is slower (10 MB/s).

Otherwise, the intended functionality is possible with Red Pitaya.
I hope this helps.

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