A wideband linear FM ramp generator for the long-range imaging radar

A long-range imaging radar (LRIR) installed at the Haystack Observatory in Westford, Mass., operating at X band, is designed to acquire and characterize satellites out to synchronous range and beyond. A 1-GHz bandwidth linear FM pulse with a fixed pulse duration of about 250 microseconds, transmitted at repetition frequencies up to 1600 Hz, is used. A description is presented of the ramp generator which produces the wideband signal employed. The correlation processing technique which permits the use of the employed high (250,000) time-bandwidth-product signal is also discussed. It is pointed out that the LRIR wideband generator is used for the generation of both the transmitted waveform and the range-dependent correlation ramp. Between ramps, the voltage controlled oscillator is phase locked to the 6-GHz CW reference. A graph shows the compressed pulse shape as obtained by actual radar operation against a point target at a range of about 1000 km, following non-real-time processing of the recorded digital data.