Long range police radar warning receiver

Claim 2

A police radar warning receiver comprising: IF signal means for producing an IF sweep pattern as an oscillator signal is swept in frequency between a first frequency and a second frequency in response to mixing of received RF signals in at least one band of police radar signal frequencies with said swept oscillator signal; FM discriminator means responsive to IF signal means for producing an FM sweep pattern corresponding to FM demodulation of said IF sweep pattern as said IF sweep pattern is produced; sampler means for repeatedly sampling at sample intervals said FM sweep pattern as it is produced whereby to produce a series of digital sample words each associated with a respective sample interval; correlator means for correlating each digital sample word as it is produced with a plurality of proceeding said digital sample words and a complex correlator function whereby to provide a series of complex digital correlator words each associated with a respective sample interval; averager means for accumulating for each of at least a plurality of said sample intervals, an average of the complex digital correlator word produced each sweep and associated with a said sample interval over a plurality of sweeps of the oscillator signal whereby to produce a series of averager words each associated with a respective one of said plurality of sample intervals; alarm enable means responsive to said averager means for providing an alarm enable if, after a given sweep of the oscillator signal, an averager word meets at least a first criterion whereby to indicate receipt of a police radar signal.

Claim 3

The police radar warning receiver of claim 1 further comprising digital filter means between said sampler means and said correlator means whereby to filter each said digital sample word before it is correlated by said correlator means.

Claim 4

The police radar warning receiver of claim 2, said digital filter means being a low pass filter.

Claim 5

The police radar warning receiver of claim 2, said digital filter means being a band pass filter.

Claim 6

The police radar warning receiver of claim 2, said digital filter means being at least a second order recursive infinite impulse response filter.

Claim 7

The police radar warning receiver of claim 1 including means for storing a first set of index numbers associated with a plurality of the averager words meeting the first criterion after a first sweep of the oscillator signal, means for obtaining a second set of index numbers associated with a plurality of the averager words meeting the first criterion after a second sweep of the oscillator signal, and means for permitting provision of said alarm enable whenever the second set of index numbers corresponds in a predetermined manner to the first set of index numbers whereby to reduce likelihood of false alarms.

Claim 8

The police radar warning receiver of claim 1, said averager words each being complex.

Claim 9

A police radar warning receiver comprising: IF signal means for producing an IF sweep pattern as an oscillator signal is swept in frequency between a first frequency and a second frequency in response to mixing of received RF signals in at least one band of police radar signal frequencies with said swept oscillator signal; FM discriminator means responsive to IF signal means for producing an FM sweep pattern corresponding to FM demodulation of said IF sweep pattern as said IF sweep pattern is produced; sampler means for repeatedly sampling at sample intervals said FM sweep pattern as it is produced whereby to produce a series of digital sample words each associated with a respective sample interval; correlator means for correlating each digital sample word as it is produced with a plurality of proceeding said digital sample words and a complex correlator function whereby to provide a series of complex digital correlator words each associated with a respective sample interval; digital filter means responsive to said correlator means to produce a filter complex correlator word for each complex correlator word; decimator means responsive to said digital filter means for decimating said filter complex correlator words to produce a series of decimator words, each said decimator word associated with a group of said sample intervals; averager means for accumulating for each of at least a plurality of said sample interval groups an average of the decimator word produced each sweep and associated with a said sample interval group of a plurality of sweeps of the oscillator signal whereby to produce a series of averager words each associated with a respective one of said plurality of sample interval groups; alarm enable means responsive to said averager means for providing an alarm enable if, after a given sweep of the oscillator signal, an averager word meets at least a first criterion whereby to indicate receipt of a police radar signal.

Claim 10

A police radar warning receiver comprising: IF signal means for producing an IF sweep pattern as an oscillator signal is swept in frequency between a first frequency and a second frequency in response to mixing of received RF signals in at least one band of police radar signal frequencies with said swept oscillator signal; FM discriminator means responsive to IF signal means for producing an FM sweep pattern corresponding to FM demodulation of said IF sweep pattern as said IF sweep pattern is produced; sampler means for repeatedly sampling at sample intervals said FM sweep pattern as it is produced whereby to produce a series of digital sample words each associated with a respective sample interval; correlator means for correlating each digital sample word as it is produced with a plurality of proceeding said digital sample words and a complex correlator function whereby to provide a series of complex digital correlator words each associated with a respective sample interval; digital filter means responsive to said correlator means to produce a filter complex correlator word for each complex correlator word; decimator means responsive to said digital filter means for decimating said filter complex correlator words to produce a series of decimator words, each said decimator word associated with a group of said sample intervals; averager means for accumulating for each of at least a plurality of said sample interval groups an average of the decimator word produced each sweep and associated with a said sample interval group of a plurality of sweeps of the oscillator signal whereby to produce a series of averager words each associated with a respective one of said plurality of sample interval groups; alarm enable means responsive to said averager means for providing an alarm enable if, after a given sweep of the oscillator signal, an averager word meets at least a first criterion whereby to indicate receipt of a police radar signal.

Claim 11

The police radar warning receiver of claim 8, said digital filter means being a low pass filter.

Claim 12

The police radar warning receiver of claim 8, said digital filter means being at least a second order recursive infinite impulse response filter.

Claim 13

The police radar warning receiver of claim 8, further comprising second digital filter means between said sampler means and said correlator means whereby to filter each said digital sample word before it is correlated by said correlator means.

Claim 14

The police radar warning receiver of claim 11, said second digital filter means being a low pass filter.

Claim 15

The police radar warning receiver of claim 11, said second digital filter means being a band pass filter.

Claim 16

The police radar warning receiver of claim 11, said second digital filter means being at least a second order recursive infinite impulse response filter.

Claim 17

The police radar warning receiver of claim 8, said averager words each being complex.

Claim 18

The police radar warning receiver of claim 8 including means for storing a first set of index numbers associated with a plurality of the averager words meeting the first criterion after a first sweep of the oscillator signal, means for obtaining a second set of index numbers associated with a plurality of the averager words meeting the first criterion after a second sweep of the oscillator signal, and means for permitting provision of said alarm enable whenever the second set of index numbers corresponds in a predetermined manner to the first set of index numbers whereby to reduce likelihood of false alarms.

Claim 21

The method of claim 17 further comprising digitally filtering each said digital sample word before it is correlated.

Claim 22

The method of claim 17 further comprising storing a first set of index numbers associated with a plurality of the averager words meeting the first criterion after a first sweep of the oscillator signal, obtaining a second set of index numbers associated with a plurality of the averager words meeting the first criterion after a second sweep of the oscillator signal, and permitting provision of said alarm enable whenever the second set of index numbers correspond in a predetermined manner to the first set of index numbers whereby to reduce likelihood of false alarms.

Claim 25

The method of claim 20 further comprising digitally filtering each said digital sample word before it is correlated.

Claim 26

The method of claim 20 further comprising storing a first set of index numbers associated with a plurality of the averager words meeting the first criterion after a first sweep of the oscillator signal, obtaining a second set of index numbers associated with a plurality of the averager words meeting the first criterion after a second sweep of the oscillator signal, and permitting provision of said alarm enable whenever the second set of index numbers correspond in a predetermined manner to the first set of index numbers whereby to reduce likelihood of false alarms.