A digital high-frequency multipath propagation simulator

A digital h.f. multipath propagation simulator is described which can be applied to communications receiver and modulation techniques evaluation and operator training. It can also be applied to a variety of applications in the high-frequency field where programmable and repeatable ionospheric conditions require simulation. Simultaneous communications paths are simulated, four of which exhibit independent delays, Doppler shifts, Rayleigh fade and phase variations and attenuation consistent with ionospheric reflection (skywave) paths.