This invention relates to modulation systems, and more particularly to broadband data modulation systems employing acousto-optical modulation elements.
The broadband data modulation system of the present invention is intended for the transmission of amplitude and frequency modulation (AM and FM) data with a bandwidth up to and greater than 500MHz. This system, as an example, may be employed to relay radar-type data with pulse bandwidths of up to and greater than 30MHz and pulse-to-pulse frequency diversity of up to and greater than 500MHz. The system of the present invention involves the multiple heterodyning of microwave signals with infrared or optical signals, hereinafter referred to as IR signals.
The system of the present invention is further related to the simulation of radar-type signals reflected from aircraft, missiles, chaff, rain, and any other general clutter which may be capable of causing signal reflections. Radar basic frequencies lie normally in a range between 1 and 18GHz, and the system of the present invention contemplates a combination of heterodyne-conversion and frequency division to frequencies and bandwidths which can be processed so as to simulate radar-to-target ranges, target signature, radial doppler, and the effects of space environment on radar signals. The system of the present invention is further intended to be employed under conditions wherein the complexity of the radar transmissions is too great to allow complete reforming of the radar signal based only on radar synchronizing pulses.