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    AUTOMATIC IF TANGENT LOCK CONTROL CIRCUIT
    33.
    发明专利
    AUTOMATIC IF TANGENT LOCK CONTROL CIRCUIT 未知

    公开(公告)号：GB2203908B

    公开(公告)日：1991-10-23

    申请号：GB8803777

    申请日：1988-02-18

    Applicant: MOTOROLA INC

    Inventor： ECKLUND LAWRENCE MARVIN

    IPC: H03J7/18 ,  H03D1/22 ,  H03J7/02 ,  H03J7/10 ,  H04B1/26

    Abstract: An improved radio receiver that maintains a stable predetermined IF frequency upon receipt of input carrier signals of differing frequencies. The IF signal (14) is processed through a signal demodulation unit (16) that includes a tangent processing unit (22) to yield a control signal that varies as a tangent function of both the demodulated IF signal and a reference signal from a reference oscillator (17). This control signal is used to control the frequency and phase of a reference signal (26) used by the IF stage (12) to center the IF signal with respect to the IF stage characteristics.

    TONE DETECTOR CIRCUIT
    37.
    发明专利
    TONE DETECTOR CIRCUIT 未知

    公开(公告)号：CA1176312A

    公开(公告)日：1984-10-16

    申请号：CA392870

    申请日：1981-12-21

    Applicant: MOTOROLA INC

    Inventor： ECKLUND LAWRENCE MARVIN

    IPC: H04L27/00 ,  H04B5/00 ,  H04H1/00 ,  H04H20/49 ,  H04H20/88 ,  H04Q9/10 ,  H04B1/16

    Abstract: A low frequency tone detector filters out higher frequencies, then a latching circuit locks on when a given number of low frequency cycles are detected which have at least a predetermined peak amplitude. Thereafter, only a second given number of missing or low amplitude cycles will reset the latch. The circuit is particularly suited to use with AM stereophonic signals where a low frequency tone is added to the difference channel for providing mono/stereo indication and mode switching. The circuit can also provide an early detect for use by a scanning circuit in a receiver.

    39.
    发明专利
    未知

    公开(公告)号：MX149709A

    公开(公告)日：1983-12-13

    申请号：MX18882081

    申请日：1981-08-20

    Applicant: MOTOROLA INC

    Inventor： ECKLUND LAWRENCE MARVIN

    IPC: H04B1/26 ,  H03J7/00 ,  H03J7/02 ,  H03J7/06 ,  H04B1/10

    Abstract: A mechanical radio receiver tuner with microphonics elimination circuitry is disclosed. During a mechanical tuning mode, the mechanical position of a movable tuning element provides an associated adjustable reactance which determines a control voltage for controlling the output of a voltage controlled oscillator (VCO) that serves as the local oscillator for a superheterodyne radio receiver. After initially selecting a channel frequency by adjusting the output of the VCO with the mechanically movable tuning element in the tuning mode, a switch means disconnects the movable tuning element from operative control of the local oscillator frequency and implements a locked tuning mode by providing the VCO with a control voltage related to the difference between the frequency of the output signal of a mixer stage and the center frequency of a fixed tuned narrow passband IF stage that follows the mixer. Preferably, this control voltage for the locked tuning mode is provided by a phase locked loop. When substantial changes in the reactance provided by the movable tuning element are sensed, the switching circuit reimplements the tuning mode so that the position of the mechanically movable element will once again control the output of the local oscillator. In this manner, minor changes in the mechanical position of the movable tuning element during the locked tuning mode have no effect on receiver tuning and therefore microphonics are substantially eliminated.

    40.
    发明专利
    未知

    公开(公告)号：BR8108811A

    公开(公告)日：1982-08-24

    申请号：BR8108811

    申请日：1981-07-29

    Applicant: MOTOROLA INC

    Inventor： ECKLUND LAWRENCE MARVIN

    IPC: H04B1/26 ,  H03J7/00 ,  H03J7/02 ,  H03J7/06 ,  H04B1/10

    Abstract: A mechanical radio receiver tuner with microphonics elimination circuitry is disclosed. During a mechanical tuning mode, the mechanical position of a movable tuning element provides an associated adjustable reactance which determines a control voltage for controlling the output of a voltage controlled oscillator (VCO) that serves as the local oscillator for a superheterodyne radio receiver. After initially selecting a channel frequency by adjusting the output of the VCO with the mechanically movable tuning element in the tuning mode, a switch means disconnects the movable tuning element from operative control of the local oscillator frequency and implements a locked tuning mode by providing the VCO with a control voltage related to the difference between the frequency of the output signal of a mixer stage and the center frequency of a fixed tuned narrow passband IF stage that follows the mixer. Preferably, this control voltage for the locked tuning mode is provided by a phase locked loop. When substantial changes in the reactance provided by the movable tuning element are sensed, the switching circuit reimplements the tuning mode so that the position of the mechanically movable element will once again control the output of the local oscillator. In this manner, minor changes in the mechanical position of the movable tuning element during the locked tuning mode have no effect on receiver tuning and therefore microphonics are substantially eliminated.

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