Overview
The COM-1801SOFT is a fairly generic PSK/APSK/QAM digital modem. It does not comply with any specific standard.
The generic VHDL source code is portable to most FPGAs.
- Modulations
- Multiple modulation types with 1 to 5 bits per symbol: BPSK, QPSK, 8-PSK, 16-QAM, 16-APSK, 32-APSK
- Symbol rate up to fclk/2 -1%, where fclk is the processing clock frequency. 32-bit precision
- 4-bit soft-decision demodulator output for interface to FEC decoders
- Framing structure for demodulator frequency acquisition and phase ambiguity removal
- Performance
- Near theoretical BER vs Eb/No: demod implementation loss < 0.5dB (QPSK)
- ±50ppm symbol timing tracking
- Carrier frequency acquisition: ±10% of symbol rate at the Eb/No threshold
- Acquisition threshold < -1dB Eb/No
- Built-in tools
- PRBS-11 pseudo-random test sequence
- BER tester
- AWGN generator
- Internal loopback mode
- Carrier frequency error measurement
- VHDL testbenches (back-to-back modem or stimulus file input)
- Matlab .m file for generating stimulus files for VHDL simulation of the demodulator and for end-to-end BER performance analysis at various signal to noise ratios
Documentation
Specifications
Complete VHDL/IP Core license agreement