Improving the Accuracy of Digital Simulation of the Radio Signal Propagation Delay

Methods of reducing and completely eliminating of the characteristic discrete error of simulating a variable delay (range) of radio signal propagation is discussed in this article. The structure and parameters of hardware-in-the-loop (HIL) simulators, which is based on basic digital radio frequency memory (DRFM) technology are considered. Some possibilities of improving the FPGA implementation are suggested. One of the feature is the simultaneous realizing of a continuously variable delay and Doppler frequency shift by using a double-frequency synchronization of the input and output parts of the simulator. It is possible to change all main parameters of the simulation, including automatic adjustment to the modulation parameters of a radio signal. The proposed simulator is useful to perform a HIL simulation with finer verification of both receiver-transmitting microwave paths and signal processing algorithms of typical and cognitive communication and radar systems.