Software and Hardware Design for DQPSK Signal Transmission and Reception System

This paper presents the software and hardware design of a DQPSK signal transmission and reception system. The system operates with an intermediate frequency of 70MHz and an information rate of 10Mbps. To achieve higher signal sampling rates, we implemented bandpass signal sampling technology, which allows selective sampling of specific frequency bands without requiring baseband conversion. In digital signal processing, we employed quadrature demodulation and modulation techniques using I/Q component separation to improve received signal quality. The system utilizes a 32-bit numerically controlled oscillator (NCO) for fine frequency resolution and 10-bit phase resolution, enabling precise carrier synchronization through phase accumulation algorithms. Additionally, we integrated an adaptive filter using LMS (Least Mean Squares) algorithm implementation to dynamically adjust filter coefficients, further enhancing system performance and stability. These design decisions ensure accurate and efficient signal transmission and reception while maintaining robust operation under varying channel conditions.