Abstract: A method and apparatus for efficiently monitoring a plurality of radio channels in a data communication system in which mobile message receiving devices are programmed to receive messages on a plurality of channels by selecting a group of channels for scanning, based upon detection of signal activity in the radio channels.

Abstract: A radio paging network transmits non-paging data, such as facsimile images, to lap top computer receivers by formatting the data into a series of packets and interleaving these packets, on a space available basis, into the paging signal.

Abstract: A method of allowing use of small, low-power communication systems (20) within the coverage area (11) of larger trunked communication systems. A low-power communication system re-uses the same communication resources used by the larger trunked system whenever sufficient distance exists between large system communication units and the low power system so as to avoid interference. Large system communication units may also be constructed to operate in a dual mode format so as to transmit and receive in a low power mode and on re-used resources, whenever near a low power system or to transmit and receive in a high power mode whenever else necessary.

Abstract: With cordless telephones it is a known fact that each pair of radio stations has m radio channels out of n possible radio channels in common. During a test cycle the mobile unit examines only the common radio channels. Consequently, the test period required for testing only the common channels is shorter than the time necessary for testing all channels. If, by chance, all common channels are busy or if such a situation is the result of a malfunctioning, establishing a link between the base unit and the mobile unit is no longer possible. In the proposed embodiment of a cordless telephone, reliably establishing a link is guaranteed in that in a first test phase the common channels and in a second test phase all n radio channels are tested. A field of application of the invention is the cordless telephone.

Abstract: An improved communication system (10) includes a plurality of transceivers (A, B, C, D, etc.) adapted to communicate with one another via a common communication path. Each transceiver has its own unique identity code. The invention provides a cable (11) for temporarily enabling the mutual exchanging of identity codes between only two of the transceivers so as to establish a dedicated pair. Each transceiver has memory (12) for receiving and storing the identity code of the other transceiver of the pair, and for purging any previously-stored identity code. Each transceiver is arranged to identify all communications transmitted by it as having originated from it, and as being addressed to the other transceiver of the pair. Each transceiver is also arranged to accept communications only if addressed to it and if identified as having originated from the other transceiver of the pair.

Abstract: A radio based communication system comprises a base station (1) and one or more remote stations (2) each incorporating a radio transmitter and receiver to support communication between the base station and each remote station on a down link and between each remote station and the base station on an up link. Each link comprises a plurality of frames of fixed length divided into a fixed number of slots. The base station includes a base control which transmits control data in a general control slot (GC) in each frame of the down link so as to identify to each remote station a down-setup slot (DSU) in each frame of the down link in which the base station (1) is to announce the transmission of data for it and identify at least one down-transfer slot (DTR) in the frame of the down link in which the data is to be transmitted. The control data further identifies an acknowledgement slot (ACK) in each frame of the down link and an up-setup slot (USU) divided into sub-slots (1/4) in each frame of the up link.

Abstract: A radio paging network transmits non-paging data, such as facsimile images, to lap top computer receivers by formatting the data into a series of packets and interleaving these packets, on a space available basis, into the paging signal.

Abstract: A simple self-oscillating mixer circuit is provided, suitable for forming with an antenna (21) the complete front end of an inexpensive short-range FMCW radar. A modulating signal (40), e.g. from a sweep generator (44), is applied to a control terminal (14) to sweep the RF output (R) of the self-oscillating mixer SOM (10). A cancellation circuit (6 to 9) is connected between the control terminal (14) and an IF output line (13) to remove a corresponding modulation (41) which occurs on the IF line (13) and so to generate a substantially demodulated IF output signal (I). Advantageously a grounded-source MESFET in a feed-back network forms the SOM (10) and has the IF output line (13) taken from its gate. In this case the IF modulation (41) is inverted with respect to the modulating signal (40), and so the cancellation is achieved by adding the modulating signal (40) to the modulated IF output signal (41), e.g. via a resistor network 6 to 8.

Abstract: In a wireless communication system between a base unit and a remote unit, the base unit transmits periodically a sync signal in a first selected time period in a selected frequency channel. The remote unit scans the frequency channels to detect the sync signal. The remote unit transmits a response signal in the selected frequency channel. The response signal is transmitted in a second selected time period different from the first selected time period. In addition, the remote unit transmits a first control signal encoded by a first code in the selected frequency channel in a third selected time period, different from the first and second selected time periods, containing a set of functional capabilities of the remote unit. The base unit receives and decodes the first control signal to derive the set of functional capabilities of the remote unit and compares it to its own set of functional capabilities to determine a common set of functional capabilities.

Abstract: In a transparent tone-in-band (TTIB) single-sideband-modulated communication system used to communicate digital data; to compensate for variations due, eg, to doppler shift of the pilot tone in the received signal, during the sweep of the frequency of a local oscillator used to tune the receiver, the output of a narrow band filter is monitored for the presence of the expected pilot tone. When the pilot tone appears to be present, the sweep is interrupted and the error rate of the demodulated digital signal is tested, the sweep being resumed if an excessive error rate is encountered.

Abstract: When a first paging network system terminal determines that a pager is not within the coverage area of that network system, a paging message is automatically transmitted from another paging network system terminal. The pager wearer can advise the first paging network system terminal of his travel to another paging network system coverage area or the first paging network system terminal forwards the paging message to a predesignated alternate paging network system terminal.

Abstract: The process consists in:using at least one transceiver station to search for a set of usable frequencies,transmitting the set of usable frequencies to the other transceivers in the networkand performing the communication transfers in frequency hopping in the set of usable frequencies communicated to all the transceivers in the network.

Abstract: A transmitter system for transmitting coded message signals on a plurality of channels of which at least one channel to be assigned to each of a plurality of geographical areas. The coded message signals include channel identification information and message information being transmitted in a sequence of coded transmission slots on each of the plurality of channels. The sequence of coded transmission slots are transmitted offset in time such that a particular transmission slot is not substantially simultaneously transmitted on any of the plurality of channels.A receiver capable of receiving the coded message signals during a predetermined coded transmission slot being transmitted on the plurality of channels is also described.

Abstract: A global communications system is described having terrestrial transmitters for transmitting coded message signals in each of a plurality of geographic areas. The global communication system further includes at least one satellite transmitter for transmitting the coded messages signals in each of a plurality of global geographic areas. The coded message signals transmissions include channel identification codewords identifying the terrestrial channels and the satellite channel. The terretrial channel is selected for operation when the channel identification codeword received matches a first predetermined channel identification codeword. The satellite channel is selected for operation when the channel identification codeword does not match the first predetermined channel identification codeword. When the satellite channel is selected the terrestrial channel is periodically reselected to enable decoding the channel identification codeword received on the terrestrial channel.

Abstract: A scanning radio reciever for a wide area paging system which interconnects conventional radio common carriers (RCC) for broadcasting page information. A plurality of RCC's in each geographical area served by the paging system of the invention are connected to a local page processor. The local page processor processes incoming page information and transfers the information to an available RCC for broadcast in the local area. If broadcast of the page information is also desired in a remote geographical area, a copy of the page information is transferred to a central page processor for distribution to the selected remote geographical area for broadcast. The paging receiver is designed so that it scans the frequency of a plurality of RCCs. Thus, the same receiver may be used to receive pages from more than one RCC.

Abstract: A method and apparatus for directing mobile stations in a cellular mobile radio system to different sets of control channels, depending on whether the land system and the mobile stations have digital capabilities. The mobile stations operate to initially scan the same primary set of control channels and to read one of them, and to make a determination, based on the value of certain bits transmitted over the control channel and also the digital capabilities of the type of mobile station involved, whether to continue operation on the primary set of control channels, or whether to scan and read any secondary set of control channels. If a mobile station with digital capabilities decides to scan the secondary set of control channels, but does not find such channels, the mobile station determines that there are no secondary sets of control channels. In this case, if the mobile has analog capabilities, the mobile station will return to scanning the primary set of control channels.

Abstract: An autodyne receiver comprises a plurality of tuning circuits for tuning a high frequency signal in linkage motion thereof and, in particular, a negative impedance converter connected to at least one of the tuning circuits to cancel apparent parallel resistance of the tuning circuit. Since the resistance of the tuning circuit is cancelled, the sharpness of the tuning circuit can be improved, thus allowing the use of a stable tuning circuit having a low sharpness without use of positive feedback. The gain of the negative impedance converter is constant irrespective of signal frequency and the tuning sharpness increases in proportion to signal frequency. Thus, the selectivity of the receiver is constant irrespective of received signal frequency.

Abstract: The invention relates to a high frequency mixer stage comprising a field-effect transistor tetrode having two gate electrodes, with one gate electrode being supplied with the high frequency input signal. According to the invention, the mixer stage becomes a frequency changer by means of inductive load at the second gate electrode of the tetrode.

Abstract: The millimeter and submillimeter wavelength oscillator includes a Gunn diode coupled to a hole in a ferrite image waveguide in such a way that a portion of the waveguide acts as a resonant cavity, and oscillation results. A coil surrounding the portion of the waveguide has a variable dc current applied to it to variably magnetize the waveguide and hence correspondingly vary the oscillator frequency. By applying an RF signal to the Gunn diode, the oscillator frequency can be mixed with the RF to yield heterodyne or intermediate frequencies.

Abstract: A frequency converter comprises a frequency converting circuit, and filters which are input and output functional with respect to the frequency converting circuit for passing input and output frequency waves respectively and which have different passing frequency bands. A single terminal is provided for the frequency converter, through which reception of the input frequency wave to the input functional filter and delivery of the output frequency wave from the output functional filter are effected.

Abstract: In a self-oscillating mixing stage for FM radio receivers, comprising a transistor producing the oscillator signal and to whose emitter circuit the high-frequency signal is coupled and from whose collector circuit the intermediate-frequency signal is coupled out, the transistor being operated in the grounded-collector circuit mode to produce the oscillator signal and in the grounded-base circuit mode to process the high-frequency and intermediate-frequency signals.

Abstract: A self-oscillating mixer circuit to operate mainly at SHF band comprises a single-gate FET and a micro strip line. The gate or source terminal of the FET is connected to a radio frequency signal input line. A feedback path is provided between the drain terminal and the gate or source terminal. An intermediate frequency output line is connected to the drain electrode of the FET. A dielectric resonator is coupled to the radio frequency signal input line to improve the stability of an oscillator frequency and to suppress leakage of a local oscillator signal.

Abstract: A self-mixing antenna-mixer millimeter wave receiver has the local oscillator and the mixer combined in one single unit, using a Gunn diode (or other device) placed at the center of a spiral antenna and proper voltage applied, so that the diode becomes an oscillator. At the same time the diode will function as a mixer for the input signals received by the spiral antenna. The IF frequency from the mixer can be amplified and detected for further processing. Only a dc power supply is required to feed the diode at the center of the antenna.