I have been playing around the USRP and would like to get an Idea how I
can transmit an FM signal in the FM Band. For example, I would like to
transmit a file (txt, jpeg, audio or anything) using in the FM band
88MHz-108MHz at a specific frequency.
I have looked at the nbfm_tx.py but it seems like I cannot generate a
valid audio-N.dat file that could be transmitted or in other words how
can we generate an audio-N.dat file from an .mp3 or .wav file? Also, can
any one explain that how we can use the nbfm_tx.py or any other method
to transmit something over an frequency in FM band?
I have been playing around the USRP and would like to get an Idea how I can transmit an FM signal in the FM Band. For example, I would like to transmit a file (txt, jpeg, audio or anything) using in the FM band 88MHz-108MHz at a specific frequency.
I have looked at the nbfm_tx.py but it seems like I cannot generate a valid audio-N.dat file that could be transmitted or in other words how can we generate an audio-N.dat file from an .mp3 or .wav file? Also, can any one explain that how we can use the nbfm_tx.py or any other method to transmit something over an frequency in FM band?
Using sox, it is pretty easy to write a mp3 wfm broadcasting system (I
have made one that broadcasts a mp3 playlist). The others are also
possible, but there are very many ways to transfer images or data over
the air.
Juha, you said you have built wfm broadcasting system. I am trying to
build one myself and would really appreciate some guidlines. I am new to
python and would like to use some built-in python modules and scripts
that gnuradio already has. If you could please give a start up point
I’ll be grateful.
Here is the quick hack that I wrote a while ago. It probably only
works with linux, and be sure that you have all the necessary programs
installed (check out README). Just stick some random wire antenna in
the sma port and you should hear music.
The original idea was to create a super WFM radio that would
simultaneously broadcast many stations (you can probably fit about
35-70 music streams in a 8 MHz bandwidth), so that you could chose
what mp3 playlist you want to listen to by tuning your fm radio. But I
have lost interest in doing this, as I rarely listen to even one
stream of music I suspect that a very fast disk, plenty of
processors and a buffered and queued filesource block would be needed
to make the super mp3 broadcast system possible. I am planning to
write the filesource block soon, but I will use it for another
project.
Hi Juha! Thank you so much for your tremendous help. I looked at your
code and using part of your fmradio.py code, wfm_tx.py and fm_tx4.py I
put together something similar and am now able to transmit using my
microphone and anything through my sound card. I am facing one problem,
when I received the sound in an FM Radio, it comes out funny as in the
pitch is low. So I tried changing the “audio_rate” and making it 50KHz,
which makes it sound better but not perfect and has clicking noises. I
believe the soundcard I am using (Creative SB Audiy2) has a sample rate
of 44100Hz I think. Might be 48000Hz. Either way, and I can’t make the
audio_rate close enough. I am basically just getting the packets from
the audio source and putting it in the code like below inside class
‘wfm_tx’:
I suspect that a very fast disk, plenty of