Re: help request with simple live mic tx

[Marcus Müller]

Hi Stefano,

no need to thank me for patience, you're doing cool stuff! (but please, 
always keep the mailing list in CC:, as there are multiple people who 
can help you!)

The aO means "audio device is overflowing", which means you're not 
getting the data away from the audio source quickly enough. I'm at a 
different computer without GNU Radio on it right now, so I can't check 
your file, but:

1. Make sure your audio source is set to a sampling rate it actually 
supports. In my experience, 48000 and 44100 Hz are good bets.
2. Make sure your RF transmitter (i.e. your HackRF) is set to a sampling 
rate it actually supports
3. Make sure all decimating / interpolating steps between these to work out.

For example: if your audio sampling rate is 48000, and your HackRF rate 
is 960000 Hz (I don't know whether that is supported!), then you need to 
achieve an interpolation by 20 in between. Now, it could be that you 
have an FM modulator with an audio rate = 48000 and output (quadrature) 
rate = 96000, then you need another interpolation by 10 (using a 
"rational resampler" block).

Hope this helps!
Marcus

On 3/30/21 1:29 PM, Stefano Zorzanello wrote:
> thank you very much Marcus, I'm working on it, I just have copied the 
> file, but the original link is this 
> http://gareth.codes/hackrf-transmit/ 
> <http://gareth.codes/hackrf-transmit/>
>
> and I was just trying to substitute the .wav file with an input mic... 
> I keep on working... but anyway, once cut the [short to float] I get 
> the following lines:
>
> Generating: '/home/pi/Desktop/SDR STUFF/top_block.py'
>
> Executing: /usr/bin/python3 -u /home/pi/Desktop/SDR STUFF/top_block.py
>
> libEGL warning: DRI2: failed to authenticate
> qt5ct: using qt5ct plugin
> gr-osmosdr 0.2.0.0 (0.2.0) gnuradio 3.8.2.0
> built-in sink types: uhd hackrf soapy redpitaya file
> [INFO] [UHD] linux; GNU C++ version 8.3.0; Boost_106700; 
> UHD_3.15.0.0-0-7a3f1516
> Using HackRF One with firmware 2017.02.1
> gr::log :INFO: audio source - Audio source arch: alsa
> len(interp_taps) = 952
> aOaOaOaOaOaOaOaOaOaOaOaOaOaOaOaOaOaOaOaOaOaOaOaOaOaOaOaOaOaOaOaOaOaOaOaOaOaOaOaOaOaOaOaOaOaOaOaOaOaOaOaOaOaOaOaOaOaOaO 
>
> >>> Done
>
> what should I change on the graph?
>
> Thank you very much for your patience.
>
> Stefano
>
>
>
>
> Il 30/03/2021 08:23, Marcus Müller ha scritto:
> > Why are you doing short to float, if the output of the audio source 
> > is already float?
> >
> >
> > On 30.03.21 01:47, Stefano Zorzanello wrote:
> > > Dear list,
> > >
> > > as a newbie I ask you for your help with the attached file. For a 
> > > sound-installation
> > > purpose I'd like to transmit a weak signal, which is generated live, 
> > > over a particular FM
> > > frequency. In my attempt based on a grc file found here
> > > https://wiki.gnuradio.org/index.php/Simulation_example:_AM_transmitter_and_receiver 
> > >
> > > <https://wiki.gnuradio.org/index.php/Simulation_example:_AM_transmitter_and_receiver> 
> > > I
> > > get errors even if I change the vector lenght to 2 of [short to 
> > > float] and [multiply
> > > const] blocks, and I don't know what values to change in order to 
> > > make it work.
> > >
> > > Any help is greatly appreciated,
> > >
> > > thank you
> > >
> > > stefano
> > >
> > > system:
> > >
> > > HackRF one
> > >
> > > Raspberrypi + usb card for input
> > >
> > > GRC 3.8.2.0