Abstract: A navigation guidance receiving system for use with a Doppler navigation beacon of the type comprising a commutated linear array for producing a simulated Doppler effect. The receiving system includes a wideband Doppler beat waveform information filter and measurement circuits. Means are also provided to gate the filter output synchronously to allow dissipation of the filter transient response. The result is reduced filter frequency "pulling" and reduced measurement error due to the effect of multipath signals having beat frequencies in the filter rejection band.

Abstract: A signal processing arrangement, particularly for Doppler ILS, giving complete scanning verification and tracking filter operation. Two commutated filters are driven by two voltage controlled oscillators whose roles are interchangeable. One filter is used solely for information signal tracking and the other solely for scanning. If the true signal is being tracked, the peak output from the scanning filter corresponds in amplitude and frequency to this signal and occurs at the same time as the frequency coincidence of the two oscillators. If the incorrect signal is being tracked, there is non-correspondance between the peak output and the signal being tracked. This is detected and the roles of the oscillators are interchanged, causing the oscillator which was scanning to reside on the correct signal and the other oscillator to adopt the scan program.

Abstract: Radio navigation receiver apparatus for operation with ground beacon equipment of the simulated Doppler type (having a commutated array).The receiver derives a beat between the received ground beacon (commutated) signals and a reference signal also from the ground beacon. Angular information is extracted from this beat signal. Means are included for determining the commutation times and scan reversals at the receiver location, so that the effect of phase transients can be ameliorated by discriminating against the received signal at these phase transient times.

Abstract: A frequency scan radar system is provided which scans in groups of nine contemporaneous beams which partially overlap in angular coverage in the plane of scan, such that any given target is illuminated by at least two of the beams. Receiving means separates echoes according to frequency (which relates to angle) in nine corresponding channels. Logic circuitry is employed to determine presence of signal in one or more channels. Bona fide echo signals occur in not less than two adjacent channels, whereas limited spectrum interference or jamming signals occur in only one channel. Video blanking means are controlled to blank out video corresponding to such single beam reception.