Radar detection and signal processing circuit
First Claim
1. A radar detection and signal processing circuit having a microwave frequency receiving antenna and a local oscillator where signals from each are fed into a first mixer, and in the presence of a signal being received by said antenna an intermediate frequency signal is fed from said first mixer to a second mixer together with a signal from a swept frequency oscillator, where the output from said second mixer is fed to a band pass filter so that for each sweep of said swept frequency oscillator a pair of signals of substantially predetermined time spacing appears at the output of band pass filter, and further comprising:
- a detector for frequency modulated intermediate frequency signals at the output of said band pass filter, said detector having at least a first output signal that is fed to two pairs of complimentary paired comparators, the outputs of which are set to low and high threshold levels;
where the first pair of complimentary comparators has a low threshold level output, and said output is examined by a microprocessor against a clock which divides each sweep period of said swept frequency oscillator into a plurality of time cells;
there being storage means for storing low threshold detection incidence information, so that the incidence of detected low threshold signals at a level above said low threshold level in a pair of spaced time cells over a first given number of consecutive sweeps causes an alarm;
and the second pair of complimentary comparators has a high threshold level output, and said output is examined by said microprocessor against said clock and plurality of time cells;
there being storage means for storing high threshold detection incidence information, so that the incidence of detected high threshold signals at a level above said high threshold level in a pair of spaced time cells over a second given number of consecutive sweeps causes an alarm;
and said first given number is greater than said second given number.
23 Assignments
0 Petitions
Accused Products
Abstract
Radar detection and signal processing circuits are provided where, following a front end having an RF and local oscillator mixer to an I.F., which is then further mixed against a signal from a swept frequency oscillator, in the presence of a microwave frequency signal, the output of a band pass filter goes to a detector for frequency modulated intermediate frequency signals, and that detector has at least a first output signal that is fed to two pairs of complementary paired comparators, the outputs of which are set to low and high threshold levels. The first pair of complementary comparators has a low threshold level output which is examined by a microprocessor for the incidence of detected low threshold signal in a number of spaced cells--as determined by a clock which divides the detector output into time cells of the sweep period of the swept oscillator. Signal processing is provided so that the incidence of signals in a pair of spaced cells over a given number of consecutive sweeps causes an alarm. Likewise, a high threshold output is examined so that the incidence of a detected high threshold signal in a pair of spaced cells over a different, lower number of consecutive sweeps, causes an alarm. The sensitivity of the circuit may adjust up or down according to the number of low threshold signals that are detected; or dynamically if too many low threshold signals are detected in a small group of time cells.
57 Citations
17 Claims
-
1. A radar detection and signal processing circuit having a microwave frequency receiving antenna and a local oscillator where signals from each are fed into a first mixer, and in the presence of a signal being received by said antenna an intermediate frequency signal is fed from said first mixer to a second mixer together with a signal from a swept frequency oscillator, where the output from said second mixer is fed to a band pass filter so that for each sweep of said swept frequency oscillator a pair of signals of substantially predetermined time spacing appears at the output of band pass filter, and further comprising:
-
a detector for frequency modulated intermediate frequency signals at the output of said band pass filter, said detector having at least a first output signal that is fed to two pairs of complimentary paired comparators, the outputs of which are set to low and high threshold levels; where the first pair of complimentary comparators has a low threshold level output, and said output is examined by a microprocessor against a clock which divides each sweep period of said swept frequency oscillator into a plurality of time cells;
there being storage means for storing low threshold detection incidence information, so that the incidence of detected low threshold signals at a level above said low threshold level in a pair of spaced time cells over a first given number of consecutive sweeps causes an alarm;and the second pair of complimentary comparators has a high threshold level output, and said output is examined by said microprocessor against said clock and plurality of time cells;
there being storage means for storing high threshold detection incidence information, so that the incidence of detected high threshold signals at a level above said high threshold level in a pair of spaced time cells over a second given number of consecutive sweeps causes an alarm;and said first given number is greater than said second given number. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
-
Specification