Fig. 3: Simplified block diagram of the project. The QPSK modulator and demodulator with Costas phase-locked loop and DAC/ADC drivers are placed in FPGA. Also, the GNU Radio application prepares the ...

Eliminating software adjustments in circuits based on digital logic improves robustness and reduces cost for small-production-run series. This circuit is a cost-improved version of classical QPSK ...