Abstract: A paging receiver (10) is disclosed which is compatible with transmissions from analog or digital paging transmitters. The paging receiver has a command structure which permits it to be dynamically programmable to change its functionality including programming of the channel frequencies which the paging receiver is to receive. The programmability of the channel frequencies permits the paging receiver to be used for making national, regional, remote area, local area, and sublocal area pages, and pages to a group in the local area and to switch from channel frequencies which are heavily used during peak paging times to lesser used channels. The paging receiver transmits the paging receiver identification code digits in an order of increasing significance which significantly lessens power consumption for all paging receivers tuned to a particular frequency for determining if a page is to be received which prolongs paging receiver battery life.

Abstract: A semiconductor integrated circuit for a radio comprises: a front end circuit block (1) including at least an oscillation circuit (1b) and a mixing circuit (1c), for converting an RF signal to an IF signal; and an IF amplifying circuit block (2) for amplifying the IF signal and limiting an amplitude thereof, and the front end circuit block (1) is covered with shield electrodes (17, 17a, 17b, 17c) connected to a predetermined potential.

Abstract: A frequency modulator utilizing a frequency synthesizer is disclosed. The modulator is especially useful in a mobile radio communication apparatus. The synthesizer includes a phase locked loop made up of a voltage controlled oscillator (VCO), a programmable frequency divider, a phase comparator, a second frequency divider, a reference oscillator, and a low-pass filter. When a channel control signal is input to the programmable frequency divider, the modulator sensitivity of the voltage controlled oscillator is undesirably deviated according to the channel selection. An increase of the modulator sensitivity due to an increase of the oscillation frequency is compensated for by adding a simple FET to the VCO bias circuit. A control voltage from the phase locked loop is applied to both the voltage controlled oscillator and its bias circuit.

Abstract: An image suppression harmonic frequency converter capable of operating in any microwave range is described. Frequency conversion is obtained by making use of a local frequency which is half that of a conventional converter. In particular, the radiofrequency reception signal is converted into an intermediate frequency signal with suppression of the converted image band. Similarly, the intermediate frequency signal to be transmitted is converted into a single side band radiofrequency transmission signal. The converter comprises two harmonic mixers, a first inquadrature radiofrequency hybrid coupler, a second in-quadrature intermediate frequency hybrid coupler, two appropriate duplexer filters, two low-pass filters, two matching circuits, and two decoupling circuits.

Abstract: Undesired signals detected by a main antenna are cancelled by corresponding interference cancelling signals. The output of the main antenna is frequency converted to IF region and decomposed into first and second main baseband components. Decision circuits are provided for making a decision on whether each of the first and second main baseband components exceeds each of multiple thresholds and produces multibit codes as well as error signals. Auxiliary antennas respectively detect the undesired signals and feed auxiliary frequency converters for translating the frequency of the respective outputs of the auxiliary antennas to the intermediate frequency. Auxiliary quadrature demodulators are provided for respectively decomposing the output of each auxiliary frequency converter into first and second auxiliary baseband components. Correlations are detected between the first auxiliary baseband components and the first error signal and between the second auxiliary baseband component and the second error signal.