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Jacob R

Use of QVRT streams in GRC (gr-osmosdr)

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   I am writing an OOT GNURadio block that makes use of the osmocom sink/source project file modified for the WBT. I was reading last night like certain aspects of the API (raw high bandwidth qvrt streams) are only available in "WBT Service Apps". However, i am not developing apps using Service applications but directly inside the source code of the stream and source blocks. 

1.   I am allowed to access these high bandwidth streams from within gr-osmocom's (WBT) sink and sources?  These are of course to be added in a WBT GRC GUI app (subproject), not in a service app. Is this going to cause an issue with access to the data i need (high BW raw IQ)?

2.  What is the difference between the QVRT sink/source type and the WBT source type? These devices can be specified in gr-osmosdr - you can say "wbt=0" "wbt=1" "wbt=2" and i believe "qvrt=0"....  Is the "wbt=0" sink/source direct IQ data from the radio and the QVRT one a file sink/source? 

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You're right. We found a much easier way to accomplish this task. Basically, we made a WBT app that used a GRC flowchart with a gr-osmocom (wbt=0) block connected to a TCP Sink. Then on the FPGA we used a TCP source to grab the data, it will be processed by an FPGA to be an FFT data array that will be fed into a Graphical Sink.

The WBT Source block to TCP Sink made it very easy to test our code. On the client side we made a TCP source and set the output to a FFT.

 

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So far, the WBT A/B radios can be accessed through wbt=0 and wbt=1 for the source block.

The sink block supports the qvrt = 0 and qvrt=1 with the filename parameter set to file=filename to save data directly to a qvrt file. Live TX is still a work in progress.

An example parameter string for instantiating a sink saving to a qvrt file would be:

qvrt=0,file=/data/testfile.qvrt

An example of setting up Tuner A in a Source block would be:

wbt=0

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Also, as a side note - you should be able to use the gr-osmosdr WBT block in any place that you would normally be able to use a GNURadio block. Deployment of the application becomes more complex as you will have to gather up the dependant GNURadio shared object libraries for bundling in the wpk. 

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8 hours ago, PacManFan said:

Also, as a side note - you should be able to use the gr-osmosdr WBT block in any place that you would normally be able to use a GNURadio block. Deployment of the application becomes more complex as you will have to gather up the dependant GNURadio shared object libraries for bundling in the wpk. 

So if i were running GNURadio on another embedded device (Xilinx Zynq-7000, Ubuntu 14.04 armhf) the osmocom-WBT source block would still work if i compiled and installed it? I am working on FPGA acceleration

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I don't think compiling and installing this on an armhf system would work. The WBT API uses the shared memory of the WBT system. The WBT API is separate from the GNURadio osmocom source block I provided. Were you planning on using the FPGA to process raw I/Q samples?

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