| 摘要 |
1,167,668. Radar. PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd. 26 April, 1968 [29 April, 1967], No. 19852/68. Heading H4D In a known radar system affording range and velocity data several pairs of correlators are fed with the received signal and delayed transmitted signals, correlator pair outputs are combined and applied to a threshold device, and a second delay circuit associated with phase-quadrature transmitted signals is utilized to eliminate undesired carrier phase variations # by using the identity cos<SP>2</SP># + sin<SP>2</SP># = 1; the phase-quadrature may be imposed to give a second received signal, the second delay circuit being eliminated. Band-pass filters are utilized for Doppler analysis and the ensuing disadvantages are outlined. According to the present invention local phase-quadrature oscillators D 1 ... D k . . . representing corresponding Doppler shifts, are employed. In one embodiment, delay circuits 1, 2 are fed with respective transmitted wave counterparts (at I.F.) R 1 , R 2 in phase quadrature, the summed outputs of correlator pairs A 11, B 11 &c. are applied to respective squarers Q, squared outputs are summed in devices T and threshold devices L are provided; a device L xj responds for a target range x# o , the jth device L x responding for a target velocity corresponding to frequency wdj. Digital operation may be utilized, a digital correlator incorporating NAND elements and a counter, Fig. 3 (not shown). In another embodiment a single delay circuit with phase-quadrature receiver outputs is utilized, Fig. 2 (not shown). The radar may employ any kind of amplitude or frequency modulation. |
