Yes, should be possible.? Note this is for a homebrew version based on ESP32 processor, not the tinySA developed by Erik/Hugen.
The firmware already allows use of the main SA RF connection as a signal generator.? The frequency range will depend on the low pass filter components installed, typically up to 200/250MHz but it should be possible to design for higher cut off, say up to 350MHz, we have not tested that yet.? Output level can be adjusted using the attenuator and varying drive strengths from the SI4432.
The tracking generator based on two SI4432 should be capable of the same performance, and indeed adding a signal generator facility for the TG is already on the ToDo list.? Note that the frequency resolution of the SI4432 tranceiver module limits the resolution of the output frequency.? With a nominal 434MHz IF, the resolution is 156Hz below 46MHz output and 312Hz above that.? Not sure if that is good enough for your needs.? The oscillator in the SI4432 modules can also drift badly - not so bad given the resolution available, but could be a problem in certain cases.
Also currently there are no modulation options programmed in the firmware, though again this is planned.? AM is likely to be fairly crude!
There are options to improve performance - a TCXO could be used for example, different tranceiver modules such as SI4468 are available with finer frequency resolution (14.3Hz), or a suitable low phase noise clock generator ic could be selected.
Dave M0WID
