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    Radar receivers
    6.
    发明授权
    Radar receivers 失效
    雷达接收机

    公开(公告)号：US3108224A

    公开(公告)日：1963-10-22

    申请号：US5254660

    申请日：1960-08-29

    申请人： COSSOR LTD A C

    发明人： PETER BRADSELL

    IPC分类号： G01S13/95

    CPC分类号： G01S13/95 ,  Y02A90/18

    摘要： 894,974. Radar; non-linear circuits. COSSOR Ltd., A.C. Aug. 8, 1960 [Oct. 20, 1959], No. 35573/59. Classes 40(6) and 40(7). Relates to a superheterodyne radar receiver for a weather radar having an output/input amplitude characteristic which increases up to a turnover point X and then decreases to zero, e.g. as shown in Fig. 1a, so that a storm region is shown on a P.P.I. display as a bright patch with an inner dark patch corresponding to the most violent storm area. According to the present invention the I.F. stage is split into two separate amplifying channels coupled to respective detectors whose outputs are combined in opposition and the output/input characteristic of each channel is logarithmic, the slopes of the two characteristics being different and the threshold of the steeper characteristic being delayed relative to the other characteristic, e.g. as shown in Fig. lb. As shown in Fig. 2 each channel comprises a separate logarithmic amplifier 15, 17 having respective amplitude characteristics I and II, Fig. 1b, the delayed threshold of the amplifier 15 being controlled by a variable attenuator 14. If the threshold for the characteristic I of the amplifier 15 is displaced to the right beyond the point at which the amplifier 17 saturates then the resultant characteristic will have a flat top Fig. 5 (not shown). In another embodiment Fig. 3, one channel comprises a first amplifier 19 coupled to a detector 16 and the other channel comprises the first amplifier 19 in series with a second amplifier 20 and detector 18. The actual arrangement may be as shown in Fig. 4 when the amplifiers A, B, C and D, E, F correspond to amplifiers 19 and 20 respectively and the groups of detectors 21 and 22 correspond to detectors 16 and 18 respectively. Each of the stages A to F comprises a linear amplifier with a predetermined saturation level so that as the input increases stage F saturates first, then stage E and so on to give an overall logarithmic characteristic, the combined output from the detector 21 being negligible until the stage D saturates when the resultant output from the combining circuit 13 starts to decrease. The amplifiers 15 and 17 in Fig. 2 may be of the type shown in Fig. 4.