Abstract: In an exemplary embodiment, a base station maintains RF communication with mobile units using a polling protocol which may communicate at a higher or lower data rate, depending on the channel conditions. The base station transmits a general polling message at the lower data rate, and, associated therewith, transmits a test pattern for evaluation by the mobile units. Upon receipt of the transmissions, the mobile units analyze the test pattern to determine whether communication at the higher data rate is possible. Based on the determination, the mobile units select the appropriate rate to transmit data messages. The test pattern can be associated with a query from a mobile unit having a message to send, or with a contention polling message from the base.

Abstract: A method for establishing a logical connection between a plurality of sites (101-110) and either a plurality of site controllers (112-115) or a switching center (117) in a radio communication system (100) may be accomplished in the following manner. A first site (101) is selected from a first pair of sites (101,104), wherein the geographical separation (119) between the first pair of sites (101, 104) exceeds the geographical separation between any other pair of sites. Upon selecting the first site (101 ), at least a second site (106, 108) is selected to form a group of selected sites (101,106-108). The group of selected sites (101,106-108) is assigned to a first site controller (112), or a first control portion (201) of the switching center (117), such that communication resources provided by the group of selected sites (101,106-108) can be accommodated by the assigned controller (112), or control portion (201).

Abstract: A mobile radio system includes fixed stations and mobile stations, a free channel for establishing connection to a mobile station being selected from a predetermined channel list for each fixed station. The individual station lists are initially assigned in a radio network planning phase. To adjust to changes in the system which only occur after it is in operation, the assignment of radio channels is modified on the basis of measured data obtained during actual operation of the system. In this way the system becomes self-adaptative.

Abstract: A wireless fully submersible transmitter includes the substantially water-resistant casing within which there is located an audio frequency circuit, a radio frequency circuit, antenna, and a rechargeable battery. A microphone is connected through the casing between the inside of the casing and a position external the casing. A receiver includes a squelch circuit to eliminate the volume when the transmitter is submersed within water such that the RF signal from the transmitter is lost. The transmitter is operable from outside of the casing by a switch which interacts with an operable reed switch on the inside of the casing. An antenna is located inside the casing using the circuit board as the ground.

Abstract: In a multiple site communication system, a method for determining when to hand off a communication that is occurring on one communication resource to another communication resource may be accomplished in the following manner. Once a communication unit is allocated a communication resource, it begins to monitor signal usabilities of the allocated communication resource and a predetermined set of alternate communication resources. A broadcast unit associated with the allocated communication resource also monitors the signal usability of the allocated communication resource. When the signal usability of the allocated communication resource is determined to be unfavorable by the communication unit or the broadcast unit, one of the alternate communication resources is selected based on calculated signal usability, such that the communication unit can continue the communication.

Abstract: The present invention relates to a device for correcting a frequency shift due to the Doppler effect in a transmission system. The device for correcting a frequency shift due to the Doppler effect is applicable to a transmission system in which a signal is transmitted in a transmission lobe between a transmitter and a receiver that are in relative motion. The frequency shift which is the difference between the frequency of the transmitted signal as measured at the receiver and as measured at the transmitter is presented as the sum of a center frequency characteristic of the transmission lobe plus a position frequency which is a function of the position of the receiver in the transmission lobe. The device includes means for tuning the receiver which has a tuning frequency such that said tuning frequency is equal to the sum of the transmitted frequency plus the center frequency.

Abstract: A system for combining AM and FM transmissions. In-band, On-channel, FM Digital Audio Broadcast (IBOC FM-DAB) allows simultaneous transmission of DAB and FM over existing FM allocations without interfering with conventional analog FM signals. The utility of existing FM spectrum allocations is therefore enhanced.

Abstract: Method and apparatus for reducing or cancelling impulse noise from a signal containing noise. The desired noise-free signal is assumed to have a representative frequency .omega..sub.3, but may have a range of frequencies adjacent to this frequency, and is assumed to have substantially zero amplitude for all frequencies .omega.<.omega..sub.1 and/or for all frequencies .omega.>.omega..sub.2, where .omega..sub.1 <.omega..sub.3 <.omega..sub.2 or .omega..sub.1 <.omega..sub.2. An input (noisy) signal is filtered and analyzed in a narrow frequency region surrounding .omega.=.omega..sub.1 and/or a narrow frequency region surrounding .omega.=.omega..sub.2 to obtain one or two output signal components n.sub.1 (t) and/or n.sub.2 (t), respectively, that, ideally, contain no contribution from the desired signal. The input signal is also filtered and analyzed in a narrow frequency region surrounding .omega.=.omega..sub.3 to obtain an output signal s(t)+n.sub.3 (t) component including the desired signal s(t).

Abstract: In a speed-dependent hand over method for hierarchic cell structures, a finding is made to whether mobile stations have traversed a radio coverage domain of a micro cell within a time interval. When the mobile stations are still in the radio coverage domain with respect to the micro cell after the time interval, then a hand over for the appertaining mobile stations into the micro cell is requested.

Abstract: The frequency and power of transmissions in a mobile communication system, such as an air-to-ground telephony system, are stabilized without a priori knowledge of the system gain factors or frequency references. The ground station monitors the available channels and modifies a vacant channel broadcast message to provide information that the channel is available. In this way, the air terminals have knowledge of all available channels. The ground station transmits a pilot signal. Upon request by a user for a dial tone at the air terminal, the air terminal selects a vacant channel and scans for the pilot signal. The air terminal estimates a distance to the ground station and sets a power level of a seizing transmission based on the estimated distance. The air terminal also estimates a Doppler frequency shift of the selected channel due to the relative movement of the air terminal with respect to the ground station and sets a frequency of the seizing transmission based on the estimated Doppler frequency shift.

Abstract: An orbiting satellite-based telecommunication system for providing store and forwarding service by having a ground station, in response to an instruction from an orbiting satellite over a specific communication channel of the down link, supply transmit data to the orbiting satellite through an unused one of a plurality of communication channels of the up link in accordance with a packet protocol, and having the ground station in response to another instruction from the orbiting satellite through the down link, receive the transmit data from the orbiting satellite through an unused one of said plurality of communication channels in accordance with the protocol wherein said orbiting satellite is provided with a divider for dividing the frequency band of the up link into a plurality of subchannels on the basis of the Doppler shift amount due to variations in the distance between a terminal and the orbiting satellite; a demodulator for demodulating the transmit data on a subchannel-by-subchannel basis; and data p

Abstract: A hierarchical communication network includes primary, secondary, and tertiary communication systems. The primary system uses orbiting satellites as communication nodes and forms a pattern of cells that may cover the entire earth and that move over the earth. A given spectrum is divided among the cells in accordance with a reuse plan. Any number of secondary, terrestrial-based systems have secondary region areas of coverage that are substantially smaller than the distance to the orbits of the satellites used by the primary system. Secondary systems monitor the primary system to determine which channels of the spectrum are available for use in their secondary regions. Any number of tertiary, terrestrial-based systems reside within a secondary region and have tertiary region areas of coverage that are substantially confined within buildings. Tertiary systems use channels concurrently used by the primary system in the same area where their tertiary regions are located.

Abstract: On selecting as a selected channel at a base station in response to a channel assignment request one of transmission channels of a cellular mobile radio communication network when this channel is given a higher updated priority degree in accordance with an interference signal power received through this channel while such requests are not present and furthermore when a CIR of this channel is above a preselected CIR threshold level, the CIR threshold level is selected in dependency on the updated priority degrees given to the transmission channels. Preferably, the CIR threshold level is low and high if the updated priority degree of each channel is high and low at the base station, respectively.

Abstract: A TC controlled RF signal detecting circuitry (211) used in the output power control circuit of a TDMA RF signal power amplifier includes positive coefficient current source (303) producing current I+ having a positive TC, negative coefficient current source (305) producing current I- having a negative TC, and current mirror (301) for summing currents I+ and I- to produce substantially identical compensated mirror currents Im1 and Im2. Anti-clamping current mirror (309) mirrors current Im2 to produce compensated currents Ia1 and Ia2, which are applied to and bias a Schottky diode coupled in series to a resistor network in each leg of diode detector (311). Each leg of diode detector (311) has a positive TC, which is substantially offset by the negative TC of compensated currents Ia1 and Ia2.

Abstract: A mixer is provided having a mixing element, an input signal port for incoming signals at a frequency f.sub.IN, a local oscillator signal port for signals from a local oscillator having a fundamental frequency f.sub.LO, and an output port from which the resultant frequency may be taken. Means are provided to impose a DC component of bias voltage across the mixing element at one of three levels. The mixer is such that it has a pair of conduction threshold voltages which are substantially symmetrical above and below zero volts, beyond which the mixing element will be conductive at least when a signal from the local oscillator is imposed on it. The signal from the local oscillator has substantially sinusoidal voltage waveform, with a peak-to-peak voltage which is greater than the voltage difference between the pair of conduction threshold voltages.

Abstract: The mobile radio system includes a plurality of power amplifier modules having discrete power levels, a common transceiver module and a plurality of control head modules having different control functions. Selected ones of the power amplifiers and control heads are electrically and mechanically coupled to opposite ends of the transceiver. In one form, the control head may be remotely mounted and electrically coupled to the selected power amplifier. A common bracket is used to mount a radio having selected ones of the power amplifiers coupled to the transceiver with a selected control head. In a further embodiment, a receptacle having electrical fittings at its rear end and an opening at its opposite end receives the radio through its open end with the electrical connections being automatically coupled to one another upon final seating of the radio in the receptacle. The radio includes a handle which forms a latch for releasably securing the radio in the receptacle.

Abstract: A method (200) and apparatus (100)is provided for a radio having adjustable operating parameters to adjust at least one such adjustable operating parameter based on the current location of the radio. Operating parameters which may be so adjusted include, but are not limited to, the following: transmitting power, operating channel, operating band, modulation type, modulation index, frequency deviation, squelch setting, channel spacing, control channel (for trunked communications), noise blanker characteristic, and receive bandwidth. In another embodiment, transmissions by the radio can be inhibited as a function of the location when it is determined that the location is within a hazard area.

Abstract: A digital mobile radio communication apparatus having a speech signal testing function and a data transmitting and receiving function. A pair of terminals are selectively used as speech signal test terminals or data transmit and receive terminals via switches.

Abstract: A method and apparatus for recognizing broadcast information, the method including the steps of receiving a set of broadcast information; converting the set of broadcast information into a frequency representation of the set of broadcast information; dividing the frequency representation into a predetermined number of frequency segments, each frequency segment representing one of the frequency bands associated with the semitones of the music scale; forming an array, wherein the number of elements in the array correspond to the predetermined number of frequency segments, and wherein each frequency segment with a value greater than a threshold value is represented by binary 1 and all other frequency segments are represented by binary 0; comparing the array to a set of reference arrays, each reference array representing a previously identified unit of information; determining, based on the comparison, whether the set of broadcast information is the same as any of the previously identified units of broadcast info

Abstract: The wireless shipboard data coupler allows transmission of data through steel ship bulkheads and submarine pressure hulls without the need for special wiring penetrations. Shipboard sensing data with a 1.0 MHz current is injected into the steel plating adjacent to a ships bulkhead, or onto the pressure hull at any penetration providing an electrical path or discontinuity to the opposing side of the bulkhead or pressure hull through the use of copper-plated, threaded electrodes. The injected current flows as a surface, or "skin effect" current between the electrodes and in an indirect, spread, pattern wrapping around the edge of the penetration. This produces a pattern of surface currents on the opposite side of the ships bulkhead or submarine pressure hull. As the injected current is modulated, the data is received on the other side of the bulkhead or pressure hull using coupling loops to sensing the electrical field generated by the surface currents.