Frequency Offset Estimation In HF/VHF Communication And FPGA Implement

Because of the high attenuation and low signal-to-noise ratio characteristics of HF/VHF meteor burst channel and ionosphere scatter channel, the length of spread spectrum sequences needs to been increased to guarantee the performance of the systems, which means the effect of frequency offset on system performance aggravates. So the research on frequency offset estimation and correction has important significance on performance improvement.The main contributions of the thesis are as follows: firstly, by comparing and analyzing several representative frequency offset estimation algorithms, both theory analysis and computer simulations show that the Partial Match Filter-Fast Fourier Transform (PMF-FFT) method is more suitable for hardware realization of HF/VHF low power spectral density communication system. Then, hardware realization scheme of system is illuminated. The FPGA design using top-down and modularization method is implemented on the chip of Altera's Cyclone III EP3C55 with VHDL. Finally, the results of transmission test in laboratory show that by estimating the frequency offset and compensating the long spread spectrum code with the residual frequency offset, the corresponding performance of receiver is improved significantly.