Hi everyone, I've been finally able to (successfully) test an all digital, Gnuradio based implementation of a TX path on QO-100.
The idea was to build some Gnuradio Flows that could be run on a Raspberry PI and that implemented different transmission modes, using an UDP source as signal source so that the whole thing could be used remotely via wifi from another computer.
The HW used is a Raspberry PI 3 rev. B, connected to an HackRF One board cascaded with a 2.4GHz preamplifier and finally the ubiquitous Chinese 4W Wifi amplifier.
A build of Gnuradio 3.8 has been built on the Raspberry in order to achieve the max performance possibile on that architecture.
Everything worked nicely and I could work the TX remotely by sending characters via UDP and have them transmitted as CW, PSK31 and QPSK31. HackRF One is equipped with TCXO so frequency was very stable, which is fundamental and assured perfect reception.
Code for the tested flows is here : https://github.com/matteo-campanella/gnuradio-flows
More modes are coming - now testing voice single sideband modulation using gsm vocoders, looks promising!!!
This is the picture of the hardware assembly:
73 de Matteo iz2eeq