Communications: directive radio wave systems and devices (e.g. – Testing or calibrating of radar system
Patent
1989-11-15
1990-11-13
Tarcza, Thomas H.
Communications: directive radio wave systems and devices (e.g.,
Testing or calibrating of radar system
342194, G01S 1332
Patent
active
049705199
ABSTRACT:
A CW radar comprises a substantially continuously operable transmitter (10) and receiver (16,18,20), signal operating means (12,14) for radiating the transmitter signal and for receiving at least the return signal and a reflected power canceller (RPC) circuit (26, 28 and 30) for cancelling leakage signals in a signal path from the signal operating means to the receiver. The receiver front end comprises quadrature related mixers (18,20) which supply intermediate frequency signals (I.sub.1 and Q.sub.1) to a low frequency control loop (32, 34, 36) which supplies at least a pair of control signals (I.sub.c, Q.sub.c) to a four quadrant vector modulator (28) in the RPC circuit. In order to be able to optimize the cancellation of phase as well as amplitude, the control circuit loop includes means for suynthesizing control vectors (I.sub.1 -I.sub.1, Q.sub.1 and -Q.sub.1) from the outputs of the quadrature related mixers (18,20). Selecting means selects a pair of quadrature related control vectors from those control vectors synthesized on the basis of minimizing leakage in the outputs of the quadrature related mixers (18,20). The selected control vectors (I.sub.c, Q.sub.c) are applied to the four quadrant vector modulator (28) which preferably comprises a pair of analogue driven biphase modulators (56,58- FIG. 4 (not shown)). In an alternative embodiment (FIG. 7) the four quadrant vector modulator comprises four voltage controlled attenuators to which respective control vectors (I.sub.c, -I.sub.c, Q.sub.c and -Q.sub.c).
REFERENCES:
patent: 2147810 (1939-02-01), Alford
patent: 2453169 (1948-11-01), Varian
patent: 2520553 (1950-08-01), Lawson
patent: 3735402 (1973-05-01), Mosher
patent: 4682175 (1987-07-01), Lazarus
Minnis Brian J.
Stove Andrew G.
Hellner Mark
Kraus Robert J.
Tarcza Thomas H.
U.S. Philips Corporation
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