Re: packetized audio transmission using GMSK modulation

[Amir Hossein Aalipour]

Thank you for your reply.

The version 3.7.13.4 was recommended by Ettus website (though it had not been updated recently) but anyway if it can really cause such problems I have to update to v3.8.

Putting throttle in the flow graph didn't get any warning about "better not to use throttle when having a hardware in the flow graph" which I had seen before. But this time it gave the Gtk-warning below:

(top_block.py:2798): Gtk-WARNING **: 17:28:42.474: Negative content width -13 (allocation 1, extents 7x7) while allocating gadget (node button, owner GtkButton)

I don't have any idea about it but I ignored it because the song was played well. Anyway I removed throttle and this warning was also removed. That's ok thank you.

But the main problem is still here. I saw the waveforms of the input of the gmsk mod and output of gmsk demod and they were clearly not the same (the picture below). It seems that gmsk demod is producing an output with lower rate. From its documentation we have:"The output is a stream of bits packed 1 bit per byte (the LSB)" but I can't understand how I can convert it into the appropriate format so that "correlate access code" block can understand it. This block don't produce output and it is probably because it can't find the access code from the the output of gmsk demod (which is expected)

So now the question is why the formats of "gmsk mod" input and "gmsk demod" output are not the same? they have to be in the same format and have the same value, don't they?

Can you please give me a hint how to match the gmsk demod output to the input the "correlate access code" block needs?

Thank you very much.

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Amir Hossein Aalipour

MSc student of Electronics engineering
Department of Electrical Engineering
Sharif University of Technology

Mod_Demod_waveforms.png
Description: PNG image