Abstract: In a cellular radio system having a two layer cell structure comprised by macrocells (1) overlaying microcells (2), handover occurs only via the macrocell layer. Thus when the quality of a call handled by a microcell (2) deteriorates below predetermined criteria the call is handed up rapidly to the umbrella macrocell and is only handed back down to a microcell when the handset has been in that microcell for a predetermined time and the quality of the link thereto exceeds predefined criteria.

Abstract: A phase-locked-loop circuit for a radio transceiver operative to transmit and to receive modulated signals during nonconcurrent time periods. During time periods in which the radio transceiver is to generate and to transmit a modulated signal, the phase-locked-loop circuit is connected to the transmitter portion of the transceiver. During time periods in which the radio transceiver is to receive a modulated signal, the phase-locked-loop circuit is connected to the receiver portion of the transceiver. A switch, preferably comprised of a multiplexer, alternately connects the phase-locked-loop with the transmitter portion and the receiver portion of the transceiver.

Abstract: A private mobile radio transmission system comprising a plurality of geographically spaced base stations (BS) defining a plurality of overlapping service areas (SA). The base stations are coupled for example by land-line communication links (CL) to a system controller (SC). Mobile stations (MS) equipped with simplex two-way radios are free to roam through the service areas. In order to be able to make a call with or via a base station it is necessary for the mobile station to be registered with the base station concerned. Details of the registration are stored by the mobile station concerned and the base station.

Abstract: A selective call receiver transmission system for transmitting a message to at least one selected selective call receiver of a plurality of selective call receivers comprises a transmitter for transmitting information including the message thereto. At least one satellite receives the information and transmits the message to the selective call receiver and subsequently retransmits the message from a different location to the selective call receiver.

Abstract: A television conference system in which video and audio information generated in each hall are transmitted and reproduced in the other hall and further in which a plurality of personal terminals having at least a keyboard, or other information input device, and a monitor are provided in the first and second conference halls so that the attendees can transmit and receive personal electronic messages from one terminal to another in each hall.

Abstract: In a cellular radio system including a plurality of cells (e.g. cell sectors or micro cells) (4, 5, 8, 9, 10, 11) each normally using a respective channel for interference reduction purposes, a number of the cells are arranged in groups (6) and in the event of a cell associated with equipment moving within a group (6), all cells (4, 5, 8, 9, 10, 11) of that group use a common channel whereby to facilitate handover between them.

Abstract: In a radio transceiver (100), an IF stage (110) is formed on a single substrate. A balanced or image rejection mixer (204) having two pairs of inputs and a pair of outputs is integrated on an IC substrate (202). Disposed on the IC substrate are SAW transformers (210, 212 and 214) which provide a desired phase transformation. The SAW transformers comprise piezoelectric layers (228) and metallization layers (230) which are suitably patterned to provide the desired phase transformation and frequency selectivity.

Abstract: Automatic gain control of a communications receiver is provided by including a filter in the upper end thereof having a frequency pass-band which slopes off at each end and can be controllably shifted in a direction and by an amount determined by a control voltage which corresponds to the output signal level. As a result of such shifting of the frequency band relative to the frequency of a received signal, the filter provides adequate gain reduction even for unduly strong received signals and with less signal distortion and lower power consumption than occurs with AGC circuits which operate by changing the bias of a gain control amplifier. If the receiver employs a PLL with a voltage-controlled oscillator, the VCO control signal can be combined with the gain control voltage so as to control the center frequency of the filter pass-band as well as the amount by which it is shifted in order to provide gain control.

Abstract: A portable electronic equipment having a clip and an exchange panel which is adapted to be selectively fitted in a fitting groove formed on the rear surface of a housing incorporating a battery, a radio communication circuit, memory and the like, the clip or the exchange panel being releasably locked in the fitting groove, whereby the portable electronic equipment can be carried by being hooked on a belt or a pocket or clothes worn by a person with the use of the clip while it is held in a handbag or a pocket with the clip being removed and replaced with the exchange panel

Abstract: A radio circuit (10) provides for the selection of a mode of operation for the radio in response to sensing an external accessory (22, 22') including a speaker or an earpiece being connected to the radio circuit.

Abstract: For setting up LOS radio links between mobile calling transmitting/receiving stations and other mobile or stationary remote transmitting/receiving stations in a predetermined operating area, especially in the frequency range above 1 GHz, every mobile station is provided with an electronic memory with an associated processor. The memory stores the respective geographical and topographical data of the operating area. Prior to the setting-up of a radio link, the transmission loss between the stations is calculated in accordance with known model calculations on the basis of the geographical and topographical data stored in the memory by inputting into the processor the current location data of the calling station and the remote station.

Abstract: In a cellular mobile telephone system serving a plurality of cells, each of the cells being assigned a unique standby channel, the mobile station is assigned several standby channels and a system identifier identifying the system. The standby channels are scanned and one of the scanned channels having a highest signal level is selected. If there is a match between the system identifier of the selected standby channel and the system identifier of the mobile station, the mobile station is ready to originate or receive a call. If there is no originating or incoming call, the identifier of a call setup channel specified by the standby channel is stored into a different location of a memory. Otherwise, the identifiers stored in the memory are scanned, and one of the scanned call setup channels is selected.

Abstract: The present disclosure includes a discussion of a Subscriber Identification Module (SIM) chip card reader (201). In the preferred embodiment, the SIM chip card reader is integrated into and sealed to a radiotelephone. A battery (105) for the radiotelephone (103) retains the SIM chip card (401) in the SIM chip card reader (201) while the radiotelephone (103) is operating. The SIM chip card reader (201) also includes a ejector knob (405) for removing the SIM chip card (401) from the SIM chip card reader (201).

Abstract: A system for two way communication under shallow water or between a swimmer and observer comprising a transceiver, a wire for conducting electrical signals connected to the transceiver, a watertight transducer housing that curvedly conforms to human heads incorporating a speaker/microphone transducer in watertight connection with the wire, an adjustable strap connected to the transducer housing so that it may be attached to a portion of a human body, and a hollow acoustic transmission tube in watertight connection with the transducer housing for sound transmission to an earplug which is inserted into a human ear.

Abstract: The dual mode power amplifier apparatus of the present invention is comprised of a number of power amplifiers (101-103) coupled to a voltage convertor (104) through their collector supply lines. A mode select line (105) is connected to the voltage convertor (104) to select a digital or analog mode. The preferred embodiment of the present invention is used in a hybrid digital/analog radiotelephone. In the digital mode, the voltage convertor (104) is turned off and the voltage convertor (104) supply voltage is allowed through to the collectors of the power amplifiers (101-103). This permits the power amplifiers (101-103) to operate with optimum linearity in a digital transmission environment. In an analog environment, the voltage convertor (104) is on and supplying a reduced voltage to the power amplifiers (101-103) allowing more efficient operation in this mode.

Abstract: A battery saving apparatus selectively supplies power to each receiver function of a battery powered communication receiver at predetermined time intervals prior to and continuing therefrom for enabling the reception of the coded message signals with each receiver function being powered only as long as is required for each receiver function to stabilize prior to the reception of the coded message signals.

Abstract: A radiotelephone system comprised of a radiotelephone-pair suitably intercoupled theretogether to permit transfer of data, such as NAM information, therebetween. A first of the radiotelephone-pair comprises a radiotelephone of conventional construction. A second radiotelephone of the radiotelephone-pair comprises a radiotelephone having circuitry to transmit efficiently an information signal upon a cellular, communication system of increased capacity. The data sequence contained in the first radiotelephone is transferred to the second radiotelephone to permit a communication link to be formed between the second radiotelephone and a cellular, communication network.

Abstract: Device for dispatching video and/or audio signals to several receivers. A typical installation has a main television receiver (1), optically coupled to a video recorder (2), and a standard antenna (4) for video and/or audio signal reception. A distributor (5) transmits these signals to the main receiver and to at least one auxiliary television receiver (7), and is coupled to at least one additional source (912) of baseband video and/or audio signals, which is independent of the reception antenna. The device has a dispatcher unit (14) which receives the antenna signals and transmits them to the main receiver directly, or through the video recorder, and receives the baseband video and/or audio signals from the independent source.

Abstract: A method of communicating data from a first location to a second location employing a vector quantization data compression technique that allows users to select the reproduction quality of the transmitted vector quantized data. According to the method, data is encoded (compressed) from the last level of a first tree search vector quantization codebook at the first location. A second tree search vector quantization codebook is provided at the second location having a number of levels equal to or less than the number of levels in the first codebook. The reproduction quality of the transmitted vector quantized data is a function of the number of levels in the second codebook.

Abstract: An off premises CATV system is disclosed. A headend transmits programming including pay-per-view programming and a cable distribution system distributes the programming. An off premises unit is coupled to the cable distribution system for supplying the programming to at least one subscriber. A subscriber terminal is coupled to the off premises unit over a communication link. The subscriber terminal including an input device for inputting subscriber-supplied signals indicative of a pay-per-view event to generate a message. A transmitter responsive to the subscriber-supplied signals transmits the message to the off premises unit over the communication link. The message is transmitted at a plurality of random times within a predetermined period of time.