Abstract: A transceiver includes a transmitter and a homodyne receiver, wherein the receiver is used to process both antenna-received and antenna-reflected signals. Thus, during a receive mode, for example, the receiver downconverts antenna-received signals to baseband signals, which are then processed to recover receive signal information. Then, during a transmit mode for example, antenna-reflected transmit signals are fed back to the receiver, which is retuned to the desired transmit frequency, and thus downconverts the reflected transmit signals to baseband signals. These baseband signals are then processed to obtain a characterization of impedance mismatch between the transceiver's transmitter and the associated antenna. An adjustable matching network disposed in the transmit signal path thus may be adjusted based on the characterization to reduce the mismatch.

Abstract: A method of broadcasting commercial FM services in a digital format in at least one bitstream comprises time-division multiplexing the bitstream(s) into one or more channels comprising a data frame, and frequency modulating the data frames around a single carrier frequency into a commercial FM broadcast signal. The modulation may comprise GMSK or 8-PSK, and multiple data frame types may be interleaved. The signal is transmitted on a commercial FM broadcast station such that substantially the entire spectrum of the transmission comprises the digital data frames. The bit rate(s) of the digital bitstream(s) may be monitored, and the bitstream(s) may be reallocated to channels in the data frames based on changes in the bit rate(s). Analog and digital formats may be broadcast simultaneously on non-adjacent commercial FM broadcast carrier channels. A receiver is operative to extract and decode content from a digital format FM broadcast signal.

Abstract: A transceiver includes a transmitter and a homodyne receiver, wherein the receiver is used to process both antenna-received and antenna-reflected signals. Thus, during a receive mode, for example, the receiver downconverts antenna-received signals to baseband signals, which are then processed to recover receive signal information. Then, during a transmit mode for example, antenna-reflected transmit signals are fed back to the receiver, which is retuned to the desired transmit frequency, and thus downconverts the reflected transmit signals to baseband signals. These baseband signals are then processed to obtain a characterization of impedance mismatch between the transceiver's transmitter and the associated antenna. An adjustable matching network disposed in the transmit signal path thus may be adjusted based on the characterization to reduce the mismatch.

Abstract: A method of broadcasting commercial FM services in a digital format in at least one bitstream comprises time-division multiplexing the bitstream(s) into one or more channels comprising a data frame, and frequency modulating the data frames around a single carrier frequency into a commercial FM broadcast signal. The modulation may comprise GMSK or 8-PSK, and multiple data frame types may be interleaved. The signal is transmitted on a commercial FM broadcast station such that substantially the entire spectrum of the transmission comprises the digital data frames. The bit rate(s) of the digital bitstream(s) may be monitored, and the bitstream(s) may be reallocated to channels in the data frames based on changes in the bit rate(s). Analog and digital formats may be broadcast simultaneously on non-adjacent commercial FM broadcast carrier channels. A receiver is operative to extract and decode content from a digital format FM broadcast signal.

Abstract: A mobile radio telephone having a simplified architecture including a reduced number of integrated circuits and a reduced number of RF connections. A dual band, dual mode mobile phone can be constructed using either a single crystal reference oscillator or two crystals such that alternative symbol rates, channel spacings, or transmit/receive duplex spacings can be achieved.

Abstract: A mobile radio telephone having a simplified architecture including a reduced number of integrated circuits and a reduced number of RF connections. A dual band, dual mode mobile phone can be constructed using either a single crystal reference oscillator or two crystals such that alternative symbol rates, channel spacings, or transmit/receive duplex spacings can be achieved.

Abstract: A spring member internally mounted within an electronic device, such as a radiotelephone, serves both as a mechanical device for urging a flip cover to an open position and as an antenna for receiving and/or transmitting wireless communications signals.

Abstract: A mobile radio telephone having a minimized tuning bandwidth, based on limiting intermediate frequencies at the highest and lowest expected receive frequencies in each band. A dual band, dual mode mobile phone can be constructed which maintains or improves intermodulation performance using fewer battery cells without additional circuitry.

Abstract: A simplified structure is disclosed for a dual-band, double-conversion superheterodyne receiver. All mixer-injection signals are generated by combining the outputs of two phase-locked frequency synthesizers driven by a single reference oscillator. The output of one synthesizer injects the receiver's second mixer, which converts signals from the first intermediate frequency to the second intermediate frequency. The output of the other synthesizer has two uses: (1) it provides first mixer injection needed to tune the receiver to a primary band, and (2) it is mixed with the output of the first synthesizer to provide the first mixer injection needed to tune the receiver to an alternate band.

Abstract: A communications apparatus for coupling a transmitter and receiver for duplex transmission is disclosed. The apparatus comprises a transmitter with a transmit power amplifier, a receiver with a receive filter, and a circulator with a plurality of ports, wherein the transmit power amplifier is connected to a first port of the circulator and the receiver filter is connected to a second port of the circulator. An antenna is demountably connected to a third port of the circulator. A switch alternately connects a load and the receiver to the second port of the circulator, wherein the receiver is connected to the second port of the circulator during reception of signals and the load is connected to the second port of the circulator during transmission so as to absorb power reflected by the antenna.

Abstract: A high dynamic range receiver IF system using limited dynamic range IF filters is disclosed. A variable gain amplifier amplifies a first IF signal. The amplified first IF signal is then applied to an image suppression mixer for suppressing an image component of the amplified first IF signal to provide adequate image suppression for a radio system, wherein the image suppression mixer outputting an image suppressed second IF signal. An active bandpass filter then filters the unwanted components from the second IF signal. The filtered signal is then hard limited in a limiting amplifier which outputs a limited IF signal. A logarithmic detector then provides a received signal strength indicator.

Abstract: Reduction of transmitter exciter chain generated noise from the receive bank of a portable/hand-held duplex transceiver is achieved using a high output power, low-noise voltage-controlled-oscillator (VCO) in the transmitter exciter chain. Using this high-power, low-noise oscillator as the RF source in the transmitter exciter chain precludes the need for the conventional buffer/driver amlplifier stage and an associated inter-stage noise filter. Elimination of buffer/driver stage components and bulky inter-stage noise filter components allows complete integration of transmitter exciter chain components resulting in reduced size and cost.

Abstract: A novel circuit architecture is disclosed for achieving audio, tone, and digital data signal modulation in a full duplex radio transceiver. A single signal source is utilized to generate both transmitted carrier and receiver local oscillator injection signals. Yet the architecture is such that the transmitted data does not appear at the receiver's discriminator output--while a "side tone" of transmitted audio does so appear. The audio to be transmitted is used to frequency modulate a VCO and provide the receiver first mixer injection signal as well as a "carrier" input to a phase modulator. The data/tone signals are on the other hand, combined and integrated in a complex waveform and input to control the phase modulator. The resulting FM (data/tone and voice) output from the phase modulator is then input to a conventional duplexed r.f. transmitter.

Abstract: An oscillator is controlled so that it produces the correct frequency in the transmitting condition, and so that it produces a slightly different frequency in the receiving condition. This is achieved by a circuit which supplies a first control voltage to the oscillator for transmitting and which supplies a second and different control voltage to the oscillator for receiving. This second and different control voltage causes the oscillator frequency in the receiving condition to be different so that there is no interference to or improper operation of a repeater system. The circuit also prevents any modulation signals from reaching the oscillator in the receiving condition, thus preventing false signals or other problems.