OpenHT-fpga

OpenHT FPGA design - a complete Lattice Radiant project for the LIFCL-40-9SG72C.

Functionality

Generic modulators:

• frequency modulator
• amplitude modulator
• phase modulator
• single sideband (SSB)
• 16QAM (Gray-coded)
• arbitrary I/Q
• 32APSK

Generic demodulators:

• frequency demodulator
• amplitude demodulator
• phase demodulator
• single sideband (SSB)
• arbitrary constellation map

Other:

• I/Q raw sample access over SPI
• optional phase dither for the frequency/phase modulator
• Received Signal Strength Indicator (RSSI) estimation
• symbol recovery, clock sync

Supported modes

Analog: FM, AM, SSB, OOK (CW)
Digital: M17, FreeDV, crude "4FSK", SSTV, 16QAM, BPSK/QPSK/DQPSK, OFDM, AFSK, APRS

Note: automatic gain control (AGC) is done by the RF transceiver chip. Not all modes are yet implemented in the firmware.

Block diagram

Register map

The register map is listed in /docs/OpenHT_reg_map.pdf.

Gallery

Transmission

M17 (baseband via SPI)

SSB (USB) - FreeDV (baseband via SPI)

16QAM (unfiltered, internally generated, pseudorandom "staircase" baseband)

BPSK/QPSK (unfiltered, internally generated, pseudorandom "staircase" baseband)

Reception

M17