Abstract:

The accuracy in the radar ranging and speed application depends on the high precision of the time. High precision delay design, based on conventional finite impulse response (FIR) filtering, the required number of filter order is too high, and the filtering treatment is slower and more complicated. In order to speed up filtering and save hardware resources, this paper proposes a high precision delay design by combining digital interpolation with polyphase filtering. The FIR filter coefficient vector is reordered by the precision of time delay, and the polyphase filter is selected to filter the sampling data according to the size of the delay amount, so as to realize the high-precision delay less than the integer times of sampling period, which has the characteristics of fast filtering speed and high delay precision.The simulation results show that the proposed polyphase filter scheme can realize high precision delay by analyzing the phase of delay signal. With the field programmable gate array (FPGA) platform, the delay accuracy can be as low as 0.509 ns when the clock frequency is 245.76 MHz.

Key words: range and speed measurement, delay simulation, polyphase filtering, field programmable gate array (FPGA)