Hello All
I have a basic/beginner question.
I am using mkfifo to pipe output from a C++ application to a GRC script using a
named pipe.
I'm using C++ code that another student wrote and I am not too keen on making
difficult changes to it. In mode 1, it outputs a waveform in double values in
the range of +1 and -1 (just like a .WAV file but with no header). In mode 2,
an auxiliary function converts from doubles to shorts in the range of -32768 to
32767.
I can get mode 2 to work with my GRC script by reading the file as short, then
converting to float so that I can apply resampling and the feed it to the USRP
(the resampling function won't work with shorts). This works great and I see
the proper waveform output on the USRP, but it seems awkward to convert from
double to short in C++, then short to float in GRC.
Next I tried with mode 1 with doubles. In my GRC script I read the file in as
float, and then I multiply by (2^15)-1 since the doubles range is from +1 to
-1. I get output from the USRP using this, but the waveform doesn't look right
at all.
Is it even possible to read a file with double values using a GRC generated
script and the gr_file_source block? Or is there something else I am doing
wrong?
Thanks...Tom
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