Over the last eighty years, Single Sideband (SSB) has dominated voice transmissions on amateur radio, but using software-defined radios SSB has now moved into the CPU.
SSB works by transmitting a signal with one of the sidebands eliminated and leaving only the necessary audio frequency, with the other sideband being filtered away as unwanted.
Now, a new method has been created using SDR techniques and a combination of AM and FM to achieve polar modulation and generate SSB, this new method is more suited to narrow bandwidths.
The method was created by Georg DG6RS, and uses a simple design of an SI5351 clock generator providing the reference for an ADF4351 PLL and VCO, with a PE4302 digital attenuator, all driven from an STM32F103 microcontroller.
This new method creates I and Q streams from the incoming audio, generating a algorithm to create the phase and amplitude for polar modulation, which are in turn fed to the PLL and attenuator for FM and AM modulation to achieve SSB.
