Re: Making a VLF SSB receiver

Hi Julian,

the audio source is set to a sample rate of 48 kHz. So, you're either already
bandpass-subsampling and forgot to mention, or you can't represent frequencies higher than
24 kHz with your digitizer in this setting. Can't tell you which – your physical setup
isn't part of your flowgraph :)

So, please do specify your question a bit more: What's your digitizing system, which rates
do you plan to work at, and show spectra (using the screenshot functionality of your OS)
of what you get, and if possible, a sketch of what you want.

Best regards,
Marcus

On 19.07.24 15:46, Julian Aranguren wrote:
> Hi everyone !
>
> Long story short, in the context of a broader project I am attempting to recreate on
> GNUradio an SSB receiver for VLF, meant to function with an ultrasonic hydrophone. The
> goal here is to demodulate everything between 20 and 40khz (or higher, with a similar
> bandwidth) down to between 0 and 20. Basically the same as a bat detector or a
> surface-diver communication device.
>
> A few colleagues and I made a flowgraph by copying and adapting the SSB receiver from the
> GNUradio tutorial (https://wiki.gnuradio.org/index.php/Simulation_example:_Single_Sideband_transceiver#The_Weaver_method_of_SSB_demodulation <https://wiki.gnuradio.org/index.php/Simulation_example:_Single_Sideband_transceiver#The_Weaver_method_of_SSB_demodulation>). It works, but it doesn't really do what we exactly want and we are struggling to get it to work that way, as we're unfamiliar with some of the GNUradio terminology and online tutorials tend to be unclear.
>
> How would you change the flowgraph to work the way we seek to ? I noticed in particular
> that this version has a fine tuning option which we believe to be superfluous (with a
> 17.5khz carrier), and a 16khz carrier.
>
> Thanks a lot !