A multi-band microwave detector includes an antenna, a plurality of reception systems connected to the antenna in a parallel arrangement, a judgement circuit for judging whether or not a microwave signal detected by the reception systems is a detection target microwave signal, an alarm circuit for outputting an alarm when the judgement circuit judges the detected microwave signal to be a detection target microwave signal, wherein each reception system is constructed from a superheterodyne reception circuit having a prescribed intermediate frequency that is mutually different from the intermediate frequencies of all the other reception systems, and wherein all the reception systems are operated simultaneously during one detection cycle.

In a channelized receiver there is dual pulse present detection in which an RF signal is converted to a digital word and there are dual digital thresholds, each digital threshold having a programmable standard for determining when a pulse is present after said pulse has exceeded the particular threshold value and for determining which pulse will be reported based on which pulse arrived first. The invention also involves arbitration between adjacent channels in a channelized receiver to determine which signals are real and which signals represent spill-over energy from signals in adjacent channels and also including arbitration between spatial sectors to determine which signals are real and which signal represents spill-over energy from adjacent sectors.

A pseudo-noise-modulated spread spectrum is irradiated undirectedly--or, encoded by different modulation, into mutually displaced spatial sectors--and the energy (20) received after reflection at a potential target (13) is cross-correlated, using the pseudo-noise code which is predetermined at the transmission end, in order to provide a spherical monitoring effect which is continuous but which cannot be located in respect of its origin, to provide a warning in particular for marine craft, land vehicles and aircraft against an attacking guided missile as the target (13) to be repelled, and in order to be able to transfer to a target tracker (12) distance and speed information obtained from the correlation product, with the alarm signal, if the alarm sensor (11) is not itself also used as the tracking sensor.

A method to optimize a mixer (20) includes setting a DC bias current (24) at a predetermined level correlated to an RF frequency or band of interest, and varying the power output (32) of a local oscillator (36) until the DC voltage (66) of the mixer (20) is at a predetermined voltage. The setting for the local oscillator (36) is then stored, such as in volatile RAM (60), for use during normal operation of the receiver (10) to produce IF signals (40) correlated to the RF frequencies or band or interest. The process may be implemented on power-up of the receiver and/or periodically during use thereof in the field to reoptimize the mixer (20), and may be undertaken with different predetermined currents and voltages for different RF frequencies and/or bands.

A system and method is provided for detecting emitter signals and for determining a scan strategy for a receiver system that receives such emitter signals. However, it is possible that the scan strategy is not realizable because of capacity constraints within the receiver system itself. One embodiment of the invention provides a method for detecting and correcting such a situation.