Abstract: A wireless communication system allow two-full two-way communication among a net or loop of stations. Each station is in direct communication with another member of the net such that a logical communication loop is created about the net. Each station combines its received signal with its own audio signal for retransmission to the next member of the loop whereby audio from said station is passed in turn to each of the other loop members. Transmission frequency hopping is utilized to insure system privacy and minimize interference with or from other loops operating in the same area. The system dynamically reconfigures itself to allow for the addition or dropping of a station without breakdown of the loop.

Abstract: A communication system provides data packet timing alignment to facilitate soft handoff. A vocoder (315) transmits compressed voice frames to base-stations (130,131) along links (110,112) of variable length, .DELTA..sub.L. The .DELTA..sub.L translates to a delay .DELTA..sub.t in the air-frames to be transmitted by the base-stations (130,131). To compensate for the time delay .DELTA..sub.t, the communication system advances both sets of air-frames to be transmitted by base-stations (130,131) by at least .DELTA..sub.t so that skipping of frames, relative to an air-frame reference (300), during transmission does not occur.

Abstract: The synchronization process of the present invention filters the received signal with an adaptive band-pass filter (101) while buffering the received signal in memory (108). The energies of the input signal and the filtered signal are estimated (103 and 104) and the gain of the filter is adapted (105) based on the difference between the energies. The pole of the filter is adapted (102) to center the frequency of the input signal in the filter's pass-band. If a tone is detected (106), the length of the tone is determined (107) to ascertain if it is a frequency correction burst (FCB). If the tone detected is an FCB, the signal in the memory is also the FCB that is then filtered in the band-pass filter (101) and the difference between the frequency of this signal and 67.5 kHz is determined (109). This difference represents the frequency offset between the base station carrier frequency and that of the mobile radiotelephone, and can be fed into the local oscillating means to compensate for the frequency offset.

Abstract: A narrow band modulation UHF/Microwave communication system comprises a transmit/receive base station having a plurality of transmitter for transmitting information at respective UHF/Microwave channel frequencies to a plurality of remote transmit/receive stations, in which the transmitters at the base station are served in common by a single master oscillator and in which a single reference frequency signal is derived from the master oscillator at the base station and transmitted to all of said remote stations where it serves to provide for frequency locking of the oscillators at said stations to produce synchronization between the frequencies at the base station and the remote stations.

Abstract: A system (10) for operating a multiplicity of credit card reader-equipped cellular mobile radiotelephones (CMRs 12) as credit card paystations is disclosed. The CMRs (12) incorporate a remotely programmable unit (RPU 48) which controls credit card operation (1400, 1700) and which controls data communication sessions (1800, 1900, 2100) with a credit card (CC) host (26) and a remote programming (RP) host (24). The RPU (48) resides between a conventional control unit (CU 42) and a conventional transmit/receive unit (TRU 62) of a conventional CMR. The RPU (48) monitors messages (1200, 1300) transmitted from the CU (42) and from the TRU (62). The CMR (12) powers up in a locked state (1402), within which a credit card (88) may be read. The credit card is locally validated (1421) at CMR 12. If the validation is successful, the CMR (12) is unlocked so that a call may be placed.

Abstract: A synchronized broadcast network comprises a main transmitter transmitting an audio source signal to a plurality of receiver/transmitter units remote from each other and from the main transmitter, the receiver/transmitter units broadcasting the audio signal using frequency modulation. In the main transmitter the audio source signal is digitized by sampling it at a predetermined sampling frequency. A digitized signal representing the sampled audio signal is transmitted to the receiver/transmitter units. In each receiver/transmitter unit a reference signal representing the sampling frequency is derived from the received digitized signal and the received digitized signal is passed through a succession of digital processing stages including a stage in which a carrier derived from the reference signal is digitally modulated and a stage in which the result of the digital modulation is digital-to-analog converted.

Abstract: In the present invention a method of re-establishing a wireless communication after a communication break is disclosed. Prior to the communication break, a base unit transmits to a remote unit a table of channels of communication to be used. The base unit also transmits a clock signal value to the remote unit. After a communication break, the remote unit continues to count the clock signals generated from a clock signal source internal thereto. The remote unit applies a function to the value of the clock signal to obtain an entry in the table. The channel of communication associated with the entry in the table is selected by the remote unit. The base unit continues to count the clock signals generated internal thereto. The base unit applies the same function as the function used by the remote unit to the value of the clock signal to obtain an entry in the table. The base unit selects the channel of communication associated with the entry in the table.

Abstract: A CDMA cellular radio-telephone system (FIG. 2) has switching systems (201) synchronized to public telephone network (100) timing signals (600), and radio telephones (203) and cell base stations (202) synchronized to a different clock (1000). Transmission delays between the cell base stations and the telephone network are variable. Switching systems include digital communications interfaces (264) to the telephone system, whose connections to the telephone system are synchronized to the telephone system, and whose connections to the cells are nominally also synchronized to the telephone system but whose processor (602) operates for each call within predefined windows (1302, 1402) of phase relationships to the operation of the cell that is handling the call, and occasionally adjusts (FIGS. 13-16) its phase relationships to the operation of the telephone system to achieve and maintain its operation within the predefined windows.

Abstract: A CDMA cellular radio-telephone system (FIG. 2) has switching systems (201) synchronized to public telephone network (100) timing signals (600), and radio telephones (203) and cell base stations (202) synchronized to different clock (1000). Transmission delays between the cell base stations and the telephone network are variable. Switching systems include digital communications interfaces (264) to the telephone system, whose connections to the telephone system are synchronized to the telephone system, and whose connections to the cells are nominally also synchronized to the telephone system but whose processor (602) operates for each call within predefined windows (1302, 1402) of phase relationships to the operation of the cell that is handling the call, and occasionally adjusts (FIGS. 13-16) its phase relationships to the operation of the telephone system to achieve and maintain its operation within the predefined windows.

Abstract: A transmitter/receiver apparatus includes a transmitter and a receiver. The transmitter includes an intermittent signal generator and an intermittent modulator. The intermittent signal generator generates an intermittent signal. The intermittent modulator outputs an intermittent modulated signal, as a radio signal, which is obtained by intermittently modulating a carrier on the basis of the intermittent signal. The receiver includes a synchronization determining circuit and a synchronization detector. The synchronization determining circuit has a receiving circuit for receiving the radio signal from the transmitter and outputting a demodulated signal and is designed to detect the presence/absence of the demodulated signal and output a determining signal.

Abstract: A radiotelephone system having a base unit and a plurality of subordinate units for carrying out radiocommunication between the base unit and the subordinate units. The base unit sends transmitting carriers to the subordinate units and gets receiving carriers from the subordinate units. The system includes a first frequency varying part for periodically shifting transmitting/receiving carrier frequencies of the base unit from a given frequency of one operating interval to another frequency of another operating interval. A first synchronizing signal part generates a synchronizing signal in synchronism with a time period determined from the shifting of the carrier frequencies. A second synchronizing signal part extracts a synchronizing signal from a receiving carrier signal received by each of the subordinate units.

Abstract: An improved method and apparatus for synchronizing a receiver oscillator with a transmitter oscillator is provided. The receiver is arranged with a counter driven by the receiver oscillator; and the transmitter is arranged with a counter driven by the transmitter oscillator. The transmitter sends a start signal to the receiver and simultaneously records the current reading of its counter. Later, the transmitter sends a stop signal to the receiver and simultaneously records the current reading of its counter. The transmitter then computes the elapsed count, and sends this value to the receiver as the "transmitter reading". Upon receipt of the start signal, the receiver records the current reading of its counter. Later, upon receipt of the stop signal, the receiver records the current reading of its counter, and then computes the elapsed count.

Abstract: A process for the pseudo-synchronization of a time multiplexing communication network comprises the steps of measuring a time shift TM in reception by a mobile station of synchronization signals from first and second fixed stations, measuring the propagation times t1 and t2 of a synchronization signal between the fixed stations and the mobile station, and calculating the transmission time shift TR between the synchronization signals in accordance with the relationship TR=TM+t1 -t2. The pseudo-synchronization process can also be employed for geographically locating a mobile station.

Abstract: A digital radio communication system includes a plurality of cells for providing two-way digital radio communication. Each of the cells utilizes communication frames having at least one inbound communication slot and at least one outbound communication slot. The frames of each cell are of uniform length. At least some of the cells have different bit rates than other cells. Information about the contiguous cells is provided to the radios operating within a cell. The radio includes a memory for storing information on adjacent cells and the radio can evaluate the signal of adjacent cells for determining an appropriate cell for hand-off purposes.

Abstract: In a multisite radio frequency simulcasting transmission system involving microwave-multiplex distribution paths to several transmitting sites, each path including manually settable amplitude and time delay devices for equalization of the modulation in signal overlap areas among the various transmitter sites, an automatic simulcast alignment device is included in each distribution path whereby transmissions between a control point and each site transmitter are periodically tested and each path is compensated for amplitude and time delay variations to thus maintain equalized amplitude and time of arrival of the modulation in the transmitter site overlap areas. Thus, the instantaneous distribution of the FM modulation sidebands is maintained to be ideally identical in the signal overlap areas.

Abstract: Method and apparatus for ensuring synchronism among modules of a distributed digital system (DDS) to a master clock signal is disclosed. The master clock signal is distributed at a frequency f.sub.c /N, and circuitry associated with each module multiplies the distributed master clock signal by N to provide a desired sync frequency f.sub.c to each module.

Abstract: Method and apparatus for synchronizing radio transmitters in a paging network. A synchronization order of base stations is determined based in part upon the relative geographic locations of the stations, and is communicated to the base stations via a command signal transmitted by the paging network unit. A predetermined first base station transmits a synchronization signal to base stations to be synchronized. Subsequent sequences of synchronization signals may be transmitted from synchronized base stations until all base stations have been synchronized. The synchronization signals may be transmitted via radio waves, and the synchronization order is determined so as to minimize the number of synchronization sequences and maximize the number of base stations synchronized simultaneously in parallel. Transmitted synchronization signals are corrected to compensate for propagation delays caused by the distance between base stations and for delays which occur within an individual transceiver.

Abstract: Synchronization of a frequency hopping transceiver to a network by embedding synchronization codes in the pseudo-random frequency hopping transmission sequence. A receiver is implemented with a frequency detector and a correlator to generate a correlator signal in response to the synchronization codes in the pseudo-random frequency hopping transmission sequence. Detection of a peak in the correlator signal is indicative of synchronization of the receiver with the network. The network entry synchronization scheme is such that, when two transceivers A and B are communicating, a third unnetworked transceiver C extracts the hidden network entry code pattern from the A-B transmission in order to enter the network. As a part of the communication between the two transceivers A and B, transceiver A transmits a known pattern as a hidden part of the communication which allows transceiver C to enter the A-B network.

Abstract: A coherency generator for providing signals to control the time and phase coherency of data information signals in an overlap region of a simulcast system that comprises a control site and a plurality of remote broadcast sites. A channel card located at each remote site derives from the information signals a master clock signal for synchronizing the broadcast of data information on an RF carrier. At substantially regular intervals a transmit section of the coherency generator transmits a synchronization command signal after detecting a predetermined sequence of ones or zeros. A receive section of the coherency generator issues a reset pulse to the remote site channel card upon detecting a predetermined pattern of values of a preselected data bit, and following detection of the synchronization command pulse. The reset pulse clears the memory elements of the channel card, setting the phase of the clock signal.

Abstract: A method of configuring directional antennas to more fully radiate a geographic region serviced by a simulcast radio system can reduce the number of omni-directional antennas used by prior art methods. Directional antennas having significant differences between frontal and rearward radiated signal levels are used to provide large signal amplitude differences when signal phase differences in the simulcast coverage area become appreciable.