Tiny Ten DSP-Based HF Transceiver
7 comments
·March 2, 2025avidiax
01100011
After working at a company using SDRs, I realized that a well performing SDR is a lot more than an antenna, a DAC/ADC, amplifiers and a processor. You still have analog paths you need to worry about and for many applications those aren't going to cover your 1GHz range. You need to worry about noise, amplification, signal fidelity, etc. You still need a good portion of what makes up a traditional radio. Sure, there are narrowband, low power SDR xcvrs and xmitters but that's not the same thing.
That said, a long time ago I made a test fixture for a 6-bit, 12GHz DAC and it was cool to run it as an arbitrary waveform generator.
RF_Savage
The popular IC-7300 transceiver from Icom does that. Receiver samples the whole band and does downconversion in the digital domain (DDC) and same for the transmitter (DUC).
On the hobbyist side there is the TRX Wolf by UA3REO.
th0ma5
Sure, just do the Zeta SDR schematic in reverse, but like others have said you'd have to figure out the rest of the chain as well as a tone of filtering. I've transmitted with direct digital synth chips as well as rpitx which is literally bit-banging RF off of a pin on a raspberry pi with NTP sync even. Again, still had to do a lot of filtering, but with wsprrypi I was able to be heard one time in New Zealand from Ohio, USA without any amplification.
ale42
How much RF power is actually coming out from the RPi transmitter? A few mW?
th0ma5
Sure, just do the Zeta SDR schematic in reverse, but like others have said you'd have to figure out the rest of the chain as well as a ton of filtering. I've transmitted with direct digital synth chips as well as rpitx which is literally bit-banging RF off of a pin on a raspberry pi with NTP sync even. Again, still had to do a lot of filtering, but with wsprrypi I was able to be heard one time in New Zealand from Ohio, USA without any amplification.
mschuster91
> Again, still had to do a lot of filtering, but with wsprrypi I was able to be heard one time in New Zealand from Ohio, USA without any amplification.
Hope you got a QSL card out of that kind of DX effort. What antenna did you use?
I have been wondering if/when we could get a direct synthesis SDR transmitter. Obviously the amplifier and filter stages will have to be discrete & analog, but to me it seems more elegant that you can software define any radio signal below 1Ghz or so and pass it to an amplifier.
That doesn't detract from this project, which is quite an achievement for a single hobbier.