Abstract: A phase compensation circuit, for use with an FM reception system, includes a delay circuit and a control circuit. The delay circuit receives a composite input signal that exhibits a variable phase error and provides a plurality of selectable discrete delays. The control circuit is coupled to the delay circuit and receives a control signal whose value corresponds to the phase error associated with the composite input signal. The control circuit selects one of the plurality of selectable discrete delays responsive to the control signal, which is utilized to delay the composite input signal to provide a phase compensated composite output signal.

Abstract: A mobile weather band radio and method of tuning the radio to select a signal channel based on geographic position. The radio has a weather band tuner adjustable for a plurality of radio wave signal channels. A position indicative receiver is provided for receiving position indicative signals and determining a current position of the radio. A controller automatically tunes the tuner to a select signal channel based on the determined geographic region.

Abstract: A mobile weather band radio and method with dynamic geographic message updating. The radio has a weather band tuner for receiving weather band signals containing a message and a geographic identification code. A position indicative receiver is provided for receiving position indicative signals and determining a current position of the radio. Geographic identification codes and electronic map data are stored in memory for defining geographic regions corresponding to the geographic identification codes. A controller determines one of the geographic codes corresponding to the determined current position based on the position indicative signals, and further performs an operation, such as playing the message, when the determined geographic code corresponds to the received geographic code.

Abstract: A phase compensation circuit, for use with an FM reception system, includes a delay circuit and a control circuit. The delay circuit receives a composite input signal that exhibits a variable phase error and provides a plurality of selectable discrete delays. The control circuit is coupled to the delay circuit and receives a control signal whose value corresponds to the phase error associated with the composite input signal. The control circuit selects one of the plurality of selectable discrete delays responsive to the control signal, which is utilized to delay the composite input signal to provide a phase compensated composite output signal.

Abstract: A technique for the automatic alignment and tuning of the front end of a vehicle radio. A tuning voltage is applied to a multiplying digital-to-analog converter before being applied to a front end tuning circuitry of the radio. A tuning voltage antenna number is applied to the tuning voltage at the converter to scale the tuning voltage, and adjust the center frequency tuning of the front end. During alignment, the tuning voltage antenna number is used to modulate the tuning voltage around a mean by reprogramming the tuning voltage antenna number a few values higher and lower in sequence. This modulation of the antenna tuning voltage creates an AC modulation component on the signal strength indicator signal passing through the front end. The signal strength indicator signal is measured and compared to its value before the tuning voltage antenna number was changed.

Abstract: A technique for reducing FM intrusion in an AM section of an AM/FM receiver. In one embodiment, a first switch is provided between an FM tuner filter circuit and an AM tuner circuit. A second switch is provided between the FM tuner circuit and a reference potential. When the receiver is in an FM mode, the first switch is closed so that a tuning voltage can be applied to the FM tuner circuit, and the second switch is open to prevent the tuning voltage from being affected by the reference potential. When the receiver is switched to the AM mode, the first switch is open to prevent intermodulation product signals generated by the FM tuner circuit from reaching the AM tuner circuit, and the second switch is closed to connect the FM tuner circuit to the reference potential. By connecting the FM tuner circuit to the reference potential when the receiver is in the AM mode, the tuning of the FM tuner circuit is shifted out of the FM bandwidth, thus eliminating intermodulation products at the AM frequencies.