/OpenHT-fpga

OpenHT FPGA design

Primary LanguageVerilogGNU General Public License v3.0GPL-3.0

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