Improved Timing Synchronization Algorithm for Linear Modulation Signals

Vector signal analysis module needs digital down-conversion, low-pass filtering, matching filtering, timing synchronization, carrier synchronization, equalization and so on. Among them, timing synchronization is the key of vector signal analysis. Timing synchronization in traditional linear modulation formats uses the Gardner timing Error detector (GA-TED). The algorithm has large self-noise when faced with non-constant mode modulation schemes, such as multi-base quadrature amplitude modulation (MQAM), or when the roll-down factor is small. Therefore, GA- TED is modified in this paper so that it can produce correct timing error detection results for all linear modulation formats. The convergence accuracy of timing synchronization is improved by adding pre-filter for small roll-down factor and non-constant modulus format. Finally, the loop filter is improved to improve the convergence speed while ensuring the convergence accuracy. The algorithm is simulated and verified in MATLAB platform, and it can support linear modulation formats such as roll-down factor from 0.1 to 1, QPSK and 256QAM. The experimental results show that the modulated 256QAM signal with SNR of 40dB can be demodulated successfully, and the EVM is less than 0.2%, with high precision and fast speed.