Abstract: The object of the present invention is to provide a radio communication system capable of following change in fading. To attain the object, the transmitter in the radio communication system according to the present invention predicts the state of fading after the specified period of time based on the fading state signal indicative of state of fading at current time notified by the receiver, thereby amplifies the transmission signal in accordance with the predicted state of fading.

Abstract: Synchronizing a local timing unit to a central timing unit in a first switching system to determine the difference in timing between a connected external link and the local timing unit. This timing difference is then transmitted to the central timing unit which utilizes this information to adjust a frequency synthesizer that outputs the frequency of the external link to a second switching system. The local timing units are synchronized to the central timing unit via multiple timing paths set up through switching units within a switching network of the first switching system. The timing difference transmitted from the local timing unit is transmitted over a plurality of control paths through the switching units. Each switching unit switches one bit of data for each group of data being received on each of the external links connected to the first switching system. Any of the external links connected to the first switching system can be utilized to provide timing information for the second switching system.

Abstract: In a digital communication system for voice signals, a system and method for recovering the timing of a pseudo-random noise (PN) sequence used for direct-sequence spreading and despreading of the communicated signals. In one embodiment, a received signal is a time-division duplexing (TDD) or time-division multiple access (TDMA) signal, and a receiver performs a complete "sliding correlator" examination of the received signal in a fixed time by using the timing of the TDMA or TDD frames. This examination allows a rapid initial acquisition of the PN synchronization. In another embodiment of the receiver, the initially acquired PN phase is verified by reading a SYNC field from the received signal and by checking that shifting the receiver's local PN phase results in a degraded correlation between the local PN sequence and the received signal.

Abstract: An information transfer system includes a transmitter and a receiver for transferring information over a differential communication link. The transmitter circuit includes a plurality of gated driver circuits each associated with one of a plurality separate phases of a clock signal, all of the gated driver circuits having respective outputs connected to a differential driver. Each gated driver circuit receives at a respective input a respective one of a plurality of selected information signals and transmits it over the communication link in response to the associated clock signal phase.

Abstract: A transmission space diversity method which is effective also for a communication system wherein different carrier frequencies are used for transmission and reception is disclosed. Such reception space diversity control that a controlling signal from terminal station 10 is received by two antennas 1 and 2 and receivers 3 and 4 of a base station and the two received controlling signals are compared with each other by reception space diversity controlling signal generation circuit 6 and then that signal which exhibits a higher reception level is provided to switch circuit 8. Furthermore, the reception space diversity controlling signal is utilized for transmission space diversity control of antenna selection wherein the output of transmitter 5 is emitted by one of the antennas.

Abstract: A method and apparatus for carrying out synchronous co-division multiple access (SCDMA) communication of multiple channels of digital data over a shared transmission media such as a cable television system coaxial cable, a fiber optic or copper conductor telephone link, terrestial microwave, satellite link, local or wide area network, wireless including cellur network or some combination of these media using suitable interface circuitry. The system includes modems at remote units and a central unit to receive time division multiplexed digital data arranged into timeslots or channels and uses orthogonal codes to encode each channel of multiple data and spread the energy of each channel data over a frame of data transmitted in the code domain. Spreading the data this way makes the system less susceptible to impulse noise.

Abstract: A system and method for time division duplex communication over a single frequency band wherein guard time overhead is reduced by active adjustment of reverse link transmission timing as a function of round trip propagation time. A time frame is divided into a plurality of time slots, during each of which the base station transmits to a user station and the user station transmits to the base station. Communication is initiated by a round trip timing transaction. In response to a general polling message from the base station, a user station seeking to establish communication transmits a short reply message. The base station calculates the distance of the user station by measuring the propagation delay with respect to receipt of the reply message. The base station sends a timing adjustment command to the user station instructing the user station to advance or retard its timing according to the calculated distance, so as to minimize guard times between time slots.

Abstract: A wrap back test system and method for providing local fault detection within a section of an integrated I/O interface core device on an integrated circuit is disclosed. The system and method of this invention is suitable for use in any I/O interface having both a transmitter and a receiver section. The wrap back of input test data, prior to reformatting for transmission, to the receiver's data alignment stage permits fault detection within the core of an integrated I/O interface. By illustration, in a serializer/deserializer I/O, the wrap back of alignment pattern encoded parallel data, prior to serialization, to the receiver's data alignment stage permits identifying faults in just this portion of the I/O transceiver. The wrap back test system and method of this invention permits fault isolation of within the boundaries of the I/O core and independent of external logic or testers.

Abstract: A synchronization message transmitting apparatus employs a synchronization message to synchronize a communication network. If an abnormality occurs in any part of the apparatus or on a clock in the apparatus, the apparatus detects the abnormality and prepares a synchronization message indicating that a frame to be transmitted must not be used for preparing a master clock. An opposite party that receives the frame with the synchronization message will not use the received frame for preparing a master clock.

Abstract: A method of communication between a master unit and a slave unit, including the steps of: sending at least a command byte from the master unit to the slave unit including data byte counter bits to be interpreted by the slave unit according to the following rule set; if said data byte counter bits belong to a first set, then said data byte counter bits contain information representing a number of associated data bytes, which is the expected number of data bytes; if said data byte counter bits belong to a second set, then said data byte counter bits contain information representing a number which must be decoded before the expected number of data bytes is obtained; receiving at least the command byte; interpreting the command byte; and receiving the number of data bytes required by the rule set.

Abstract: A method and system for time aligning a frame (60) in a communication network (10) involves the steps of; i) determining if a frame needs to be advanced at a BTS (14), and ii) sending a shortened synchronization pattern from the BSC (12). The BTS (14) then determines if a short or long synchronization pattern has been sent by determining (256) if the received data stream matches a long synchronization pattern and setting a first flag when they do match. If the received data stream does not match the long synchronization pattern and the first flag is set (264), the data stream is compared (266) to the short synchronization pattern. When they match a second flag is set (268).

Abstract: A system is disclosed for an adaptive rate voice system to provide improvements in coded operation over changing communication channel (50) conditions. This adaptive rate system efficiently determines optimal voice/channel coding rates , coding strategies and modulation/demodulation for optimum voice quality and intelligibility. A system state estimator (100), channel status estimator (110) and channel status monitor (120) provides feedback in the system to optimize the communication channel. The system maintains a continuous link despite changing channel conditions and minimizes delays through the system. Even though simple in design, it provides relatively low complexity and powerful channel coding operation. Operating conditions are thus extended for CDMA and portable communication systems. Voice intelligibility is preserved in extremely noisy or even hostile channel conditions.

Abstract: In a communications network, a network user communicates through a remote unit via at least one base station. The communications network includes a first mobile switching center for controlling communications through a first set of base stations and a second mobile switching center for controlling communications through a second set of base stations. The network also includes a service providing base station controlled by the first mobile switching center and providing service to a first transition coverage area using a first pseudorandom noise code. The first transition coverage area defines a boundary between a first system controlled by the first mobile switching center and a second system controlled by the second mobile switching center.

Abstract: In CDMA communications, a base station detects a difference between a reference phase of a spreading code and a phase of a received signal of each terminal station, and feeds a phase jump signal PJ-i representative of the phase difference back to each terminal station. After timing acquisition, the reception operation is performed using the reference phase, and a shift amount between the phase of a received signal and the reference phase is fed back to each terminal station as phase synchronization control information PC-i. Each terminal station coarsely adjusts the phase of the spreading code in accordance with the phase jump signal PJ-i, and thereafter finely adjusts the phase of its transmitting signal in accordance with the phase synchronization control information PC-i. It is therefore possible to synchronize the phases of the signals transmitted from terminal stations and received at the base station. Accordingly, an orthogonal code is used for spreading on the reverse links.

Abstract: A cooperative feedback system is provided for a compensation system associated with, for example, a transmitter or codes, for enabling the compensation system to improve the accuracy of digital signals transmitted to a digital network. The cooperative feedback system is particularly suited for providing feedback to a compensation system for correcting distortion resulting from rob bit signaling (RBS), digital loss, or other types of digital signal degradation. The cooperative feedback system includes a compensation selector in a transmitter (e.g., digital modem, analog modem, codec, etc.) that combines compensations with frames of digital data by way of an addition mechanism to produce modified digital data frames. The transmitter is configured to transmit the modified digital data frames into the digital network. A receiver (e.g., digital modem, analog modem, etc.

Abstract: The fitting of boundary buffers on the exit from a telecommunications network can greatly reduce the relative wander. Adaptive boundary buffers have a phase adjusting circuit, for determining the phase error between a recovered line clock and a recovered return clock from receiving equipment of a telecommunications system, the phase of the recovered return clock being advanced or retarded by the value of the phase error and the phase of the recovered line clock being retarded or advanced respectively by less than the value of the phase error, so as to produce a phase adjusted Output Line Clock.

Abstract: A method for performing timer synchronization between a first processor having a first timer and a second processor having a second timer is presented. The first processor issues to the second processor a first timer value corresponding to the current value of the first timer and the second timer compares the first timer value with a second timer value corresponding to the current value of the second timer. If the second timer value is less than the first timer value, the second processor increments the second timer value to a new second timer value equal to the first timer value. If the second timer value is greater than the first timer value, the second processor issues to the first processors the second timer value and the first processor adjusts the first timer value to be equal to the second timer value.

Abstract: In a discrete tone system, a base station receives a transmission burst from a remote unit being installed that includes delay compensation pilot tones that are uniformly spread throughout the transmission bandwidth. The arrival time transmission burst is not synchronized with the other remote units transmitting to the base station. The base station measures the phase delay of each tone and calculates the delay of the remote unit from the slope of the line of phase angle versus tone frequency. The base station transmits a signal to the remote unit that includes the magnitude and direction of the delay, which allows the remote unit to adapt the timing of its transmission to be synchronized with the other remote units.

Abstract: A coordinated system time is established for spatially separated components of an industrial control system using synchronizing messages transmitted over a communication link between those parts. Precisely coordinated actions may be obtained at separated components by the use of a time conditional command received by those components prior to a time of execution the command instructing the component to execute the command only when at execution time in the future has been reached. The coordinated system time may be used to time stamp received triggering events for use in coordinating subsequent actions based on those triggering events.

Abstract: In a discrete multitone spread spectrum system, a base station receives a transmission burst from a remote unit being installed that includes delay compensation pilot tones that are uniformly spread throughout the transmission bandwidth. The arrival time transmission burst is not synchronized with the other remote units transmitting to the base station. The base station measures the phase delay of each tone and calculates the delay of the remote unit from the slope of the line of phase angle versus tone frequency. The base station transmits a signal to the remote unit that includes the magnitude and direction of the delay, which allows the remote unit to adapt the timing of its transmission to be synchronized with the other remote units.

Abstract: A method for handoff of an analog connection within a cellular communication system which relies upon mobile station synchronization to a system time is disclosed herein. In order to reduce the acquisition time for a mobile station commencing operation in a digital mode, an estimate of master system time is transferred to the mobile station in analog mode before entering digital mode. The alignment operates within the protocols of existing analog systems, and hence requires only minimal changes in the mobile station. Time alignment may be initiated upon the base station sending to the mobile station a command to continually transmit a periodic signaling tone. The base station compares the phase of the signaling tone from the mobile station to a master system clock and determines an error signal. The base station notifies the mobile station to delay or advance in time the transmitted signaling tones based on the error signal.

Abstract: A radio communication network includes at least one mobile transceiver unit in communication with at least one base transceiver unit that facilitates communicate with at least one host computer for storage and manipulation of data collected by bar code scanners or other data collectors associated with the mobile transceiver units. The radio network implemented by the mobile transceivers and base transceivers adapts to compensate for the wide range of operating conditions by adjusting its operating parameters. Such operating parameters include: the length and frequency of spreading codes employed in direct-sequence spread spectrum communications; hop frame lengths, coding and interleaving in frequency-hopping spread spectrum communications; the method of source encoding used; and the data packet size in a data segmentation communication scheme.

Abstract: A method and apparatus for carrying out synchronous code division multiple access (SCDMA) communication of multiple channels of digital data over a shared transmission media. The system includes modems at remote units and a central unit to receive time division multiplexed digital data arranged into timeslots or channels and uses orthogonal codes to encode each channel of multiple data and spread the energy of each channel data over a frame of data transmitted in the code domain. Spreading the data this way makes the system less susceptible to impulse noise. Frames are synchronized as between remote and central units using a ranging scheme which is also useful in any other system transmitting data by frames in a distributed system where synchronizing the frames as between all units regardless of differences in propagation delays is necessary. Each frame in the SCDMA modulation scheme includes a gap or guardband containing no other data.

Abstract: A reconnection apparatus in a direct communication system between subsidiary radiotelephone units in which connection between the subsidiary radiotelephone units is forcedly disconnected when direct communication is carried out between the subsidiary radiotelephone units over a prescribed duration of a continuous connection, comprises detection means for detecting the passage of the prescribed duration of a continuous connection and informing the expiration of the prescribed duration of a continuous connection immediately before the prescribed duration of a continuous connection expires; judging means for judging whether there is a communication continuation instruction from the outside in response to the information from the detection means; storing means for storing at least information on the connection destination of the direct communication and information on connection between the subsidiary radiotelephone units when the judging means judges that there is the communication continuation instruction; and

Abstract: A method and apparatus for characterizing a communications link. An apparatus is disclosed for performing a series of tests that measure delay time, frequency response, background noise, frame error rate and sample slipping and repetition measurements. A signal generator generates a series of signal optimally selected for the particular test. The generated signal is transmitted through the communication system and then sent back through the system by a loop back element remotely placed. The return signal is then analyzed by a monitor means.

Abstract: A cooperative feedback system is provided for a compensation system associated with, for example, a transmitter or codec, for enabling the compensation system to improve the accuracy of digital signals transmitted to a digital network. The cooperative feedback system is particularly suited for providing feedback to a compensation system for correcting distortion resulting from rob bit signaling (RBS), digital loss, or other types of digital signal degradation. The cooperative feedback system includes a compensation selector in a transmitter (e.g., digital modem, analog modem, codec, etc.) that combines compensations with frames of digital data by way of an addition mechanism to produce modified digital data frames. The transmitter is configured to transmit the modified digital data frames into the digital network. A receiver (e.g., digital modem, analog modem, etc.

Abstract: A mobile telecommunication system power control loop includes a symbol error rate detector to detect a number of symbol errors induced during transmission, a summing node to subtract the output of the symbol error rate detector from a symbol error rate target, a multiplier to introduce an adjustment factor, and an integration element to sum the output of the multiplier with past outputs of the multiplier. The output of the integration element is a signal power to noise power ratio target which is used to control the transmission power of the mobile telecommunication system. In one embodiment the symbol error rate target is a constant or parameter set by the user. In another embodiment the symbol error rate target is adjusted automatically to maintain a constant frame error rate.

Abstract: To initiate communication, a first station generates a synchronization signal and sends the synchronization signal to a second station. When the second station detects the synchronization signal, the second station acquires synchronization and sends a synchronization-acquisition message back to the first station. The first station now reduces the power of the synchronization signal, while continuing to send the synchronization signal, and also begins sending a modulated data signal. The second station uses the synchronization signal to maintain synchronization for demodulating the data signal.

Abstract: A mobile station sends a speech signal to a radio base station or, in the absence of speech signals, sends back a sync signal from the radio base station. The radio base station detects whether the signal received from the mobile station is a speech signal or the sync signal it sent. If a speech signal is received, it performs usual processing for speech signals or, if the sync signal is received, judges the line quality according to this sync signal.

Abstract: A high-frequency signal output from an active radio transmitter is input to a phase comparator via a standby radio receiver. A transmitting data processing unit delays a frame data signal and a clock signal by a predetermined time and inputs them to the phase comparator. The phase comparator compares the phases of the two frame data signals and the two clock signals, and the delay time adjuster in the active radio transmitter adjusts the phases of the frame data signal and the clock signal input from the data processing unit so that the phases of both data signals and clock signals are coincident with each other. Similarly, the delay time adjuster in the standby radio transmitter adjusts the phases of the data signal and the clock signal input from the data processing unit. In this manner, the delay times (signal phases) of the active radio transmitter and the standby radio transmitter are automatically adjusted during the operation of a radio equipment.

Abstract: A system for self-calibrating a clock of a communication terminal for use with communication systems in which a central communication node generates time base correction signals for the terminal clock includes a terminal oscillator which generates an oscillator frequency that includes an error amount. An oscillator calibration filter generates a frequency error estimate amount. Circuitry is provided for subtracting the frequency error estimate amount generated by the calibration filter from the oscillator frequency error amount. Circuitry is provided for applying the time base correction signals to the calibration filter to thereby modify the frequency error estimate amount generated by the calibration filter based upon the time base correction signals generated by the communication central node.

Abstract: A facsimile communication system includes a transmitter for transmitting data in a state where a minimum value of a total amount of data to be transmitted for each scanning line is secured, the data for each block including image data, and a receiver for receiving the data transmitted from the transmitter.

Abstract: A data transmission system includes a polling modem and a central control unit that receives a response signal from a terminal. A data transmission central control unit performs polling type transmission to transmit an information data unit to the terminal that has requested the information data unit. The central control unit also performs loop type transmission to cyclically transmit information data units with their loop flags being set to the terminals in succession. The control portion in the terminals selects the transmission that requires the shortest waiting time.

Abstract: A system for full duplex real time two-way voice and data communication between a pair of computer terminal locations is disclosed. Analog voice signals are converted to digital form at one terminal location and those digital signals are interleaved with other digital information for transmission to the other terminal location. A value for the number of bytes, in a data packet is first established, and then values for the number of bytes and the location dedicated to the transmission of voice information, control information, and data transmission within such fixed size data packets is established. Thereafter, a sequence of data packets with synchronization bytes in the voice byte locations is transmitted from each computer terminal location and received by the other of the terminal location. Upon receipt thereof, an acknowledgement of the receipt is transmitted back to the originating location to indicate the establishment of synchronization between the two locations.

Abstract: Loss of synchronization between transmitter and receiver of a remote entry system is detected during the communication sequence between transmitter and receiver, by generating a checksum of the authentication code at the initiation of the communication sequence and comparing it with a checksum previously stored. If the checksums do not match an automatic resynchronization sequence is begun in which random numbers are generated by the transmitter and broadcast to the receiver for subsequent use as rolling code or linear feedback shift register variables.

Abstract: A transmitter transmits blocks to a receiver by means of frames formed of a locking row and data rows. It receives an acknowledgement from the receiver sent by the latter on recognizing a locking row. A block comprises control bits, data bits and adaptation bits. During a first phase preceding reception of the acknowledgement the transmitter transmits blocks in which the adaptation bits have been eliminated by means of short frames comprising an initial number of data rows. During a second phase following on from reception of the acknowledgement it transmits blocks incorporating the adaptation bits by means of complete frames comprising a final number of data rows which is greater than said initial number. The receiver includes an analyzer for determining if the blocks are conveyed by a short frame or by a complete frame in order to identify the nature of the blocks.

Abstract: A method and apparatus for negotiating service configuration in a digital communication system is disclosed. In an exemplary embodiment the service negotiation system is implemented in a wireless spread spectrum communication system. The service configuration comprises data rates, frame formats and types of services. Types of service may include speech encoding, facsimile or digital data services. Further described herein is a digital transmitter and receiver using the service negotiation system to provide service configuration mutually acceptable at both ends of a communication link.

Abstract: In direct communications between PHS terminals, each terminal detects an intermittent timing signal from a predetermined control channel of the base station. Based on the intermittent timing signal, a terminal intermittently exchanges signaling information with another terminal through an idle channel to establish synchronization therebetween. A calling-party terminal searches for an idle channel and intermittently transmits a control signal to a called-party terminal through the idle channel with intermittently supplying power to a transmitter. A called-party terminal intermittently transmits a response signal to the calling-party terminal through the idle channel. When receiving the response signal from the called-party terminal, synchronization of the calling-party terminal with the called-party terminal is established.

Abstract: The invention relates to a method of managing transmission errors between a base station and a transcoder, in a digital radiocommunications system for mobile stations, in which method the transcoder, in the presence of a transmission error, systematically inserts (29, 221, 228) an error message in a frame addressed to the base station without interrupting useful data transmission to the base station, and in which method the base station decides to interrupt data transmission to the transcoder (down direction) and generates an up-direction transmission interruption request when the transmission errors detected in the down direction and/or reported by an error message in the up direction satisfy predetermined conditions. In this way, all call-interruption decisions are centralized in the base station.

Abstract: A technique for reliable passage of handshaking information between a cellular modem and a land modem. Instead of bare transmission over a voice channel connection highly susceptible to signal fading and dropout, the initial modem handshaking exchange is instead FSK-encoded and broadcast using a network data signalling methodology already used to reliably pass signalling information between the base and registered mobiles. Automatic retransmission request signalling and transmission redundancy may be implemented to insure successful receipt at the receiving end of the radio link. Once received and verified, handshaking information is decoded and delivered to the destination modem in the appropriate format along cleaner fixed pathways. Reliable handshaking operations are contemplated whether the destination modem is a cellular modem registered in auto-answer mode (land-originated data call), or a land modem (mobile-originated data call).

Abstract: An improved method and apparatus for achieving ping-pong communication over a single channel comprises a circuit (located at each communication station) which adjusts the transmission frequencies of two or more communicating stations such that each communicating station is transmitting at the same frequency as the other communicating stations. Additionally, the circuit provides a time delay between data receipt and data transmission at a given station such that data is not transmitted from the given station when data is being received by the given station. In the preferred embodiment cross coupled phase-lock loops are employed and the delay provided is such that a data pulse is transmitted half way between the receipt of two consecutive data pulses.

Abstract: A communication system is simpler and conserves power by eliminating the need for a reference frequency oscillator in the transmitter circuit. In a battery operated transceiver of the present invention, the receiver portion includes a tracking oscillator. The tracking oscillator output is used to synchronize received data and as a reference frequency source for the transmitter. In a half duplex communication system a reply signal is transmitted while no command signal is being received. Therefore, the transceiver in such a system includes circuitry for maintaining the reference frequency during transmission. Thus, the frequency accuracy of the transmission is based on the frequency accuracy of the received command signal. The tracking oscillator in one embodiment includes a phase locked loop circuit having a voltage controlled oscillator (VCO), an up-down counter, and a digital to analog converter (DAC) for determining the VCO frequency.

Abstract: A system for the transmission of information between elements of a data processing complex and a method for establishing such a system. Two elements of a data processing system are connected by a physical link comprising multiple conductors attached to transceivers at channels in each data processing element. Once the transceivers have been synchronized, commands and responses are exchanged which ensure that all of the transceivers in a channel are connected to the same channel on the other end of the conductor. If the transceivers are considered configured an entry is made in a Configured-Transceiver table. A search is made of an Allowed-Operational-Link table which contains sets of transceivers which are allowed to become operational links. The set of transceivers thus found, is compared against the Configured-Transceiver-Table to verify that all of the members of the set have been configured. If a match is found, this set of transceivers becomes an Intended-Operational-Link.

Abstract: A network control system for eliminating a relative error among control signals transmitted from nodes provided in radio zones respectively, a mobil station moving among the radio zones, each of the nodes comprising: a relative error detecting unit for detecting a relative error between an after-controlled transmitting control signal to be transmitted to adjacent nodes and a received control signal from an adjacent node; and a control unit for controlling a before-controlled transmitting control signal in such a way that the relative error becomes zero so as to output the after-controlled transmitting control signal.

Abstract: A network control system for controlling a plurality of nodes respectively corresponding to, and provided in, a plurality of radio zones. Each node has a corresponding base station, where a mobil station travels among the plurality of radio zones and communicates with the base station of a respective node when travelling in a radio zone corresponding to the respective node. Each base station transmits a transmission signal for the corresponding node to adjacent nodes, receives transmission signals transmitted from the base stations of adjacent nodes and spatially filters the received transmission signals.

Abstract: A method for providing a standard coordinated time throughout spatially separated functional modules of an industrial controller employs a module operating as a time-master which transmits a coordinated time value to various dependent modules through communication modules. The particular time-master is determined by an arbitration process among potential masters which examines a time quality value, indicating the precision of the time-master's clock, and incorporated in the transmitted synchronization signal. Upon the loss of a master or the introduction of a new master, mastership is reallocated so that the master time value is provided from that module having the best time quality. Offset caused by "ripple through" of the time value through communication modules is minimized by summing to that time value as it traverses a communication module with a time quantity measuring the processing time of the communication module.

Abstract: A set of phases defining an `address` and a `spreading key` is selected. These are employed in determining a preamble waveform and a traffic waveform. The preamble carrier waveform is a sum of a set of tones each offset by its phase, whereas the traffic carrier waveform is the product of these same offset tones. The tones have frequencies which are geometrically increasing multiples of a fundamental frequency. The phases and magnitudes of the preamble and traffic carrier waveforms are determined and prestored in a transmit and receive unit storage device. An inverse discrete Fourier Transform unit (IDFT) in the transmit unit receives the phase preamble offsets and magnitudes from the storage unit and creates a preamble carrier signal transmitted to the receive unit which determines if the phases match those which it is to listen to. If not, the following message is ignored; if they are, the following message is despread and decoded.

Abstract: A method of mobile station synchronization to a system time, wherein the time alignment is attained while the mobile station operates in analog mode. The mobile stations transmits a periodic signal, each period of which has a leading edge. The base station detects the leading edge of the periodic signal and compares it to an indication of system time. The base station generates an error message for the mobile station indicating an update to the phase of the periodic signal. When the mobile station and the base station are time aligned, the base station may send a message indicating the absolute time at some future leading edge of the periodic signal thereby eliminating ambiguities of time due to the finite time required to receive the message.

Abstract: A spread spectrum communication system for performing spread spectrum communication by superimposing a pseudo noise signal on a transmitted signal. The system comprises traffic detecting means for detecting the traffic of the transmitted signal, and means for changing the clock frequency of the pseudo noise signal in accordance with the output from the traffic detecting means. The system may alternatively comprise transmission quality determining means for determining the transmission quality of the received signal, and means for changing the clock frequency of the pseudo noise signal in accordance with the transmission quality determined by the transmission quality determining means. In operation, the system offers improved S/N ratios where traffic is high or transmission quality is low, saves power where traffic is low or transmission quality is high and ensures large margins of power control precision for mobile stations near the upper limit of the system's line capacity.

Abstract: Apparatus useful for communicating digital data using a steady stream of pulses which achieve very high ratios of bit rate per occupied bandwidth using digital signal synthesis techniques to produce a stream of constant phase tone pulses having exceptional spectral compactness. An optimal pulse is formed having either no sidelobe energy in the frequency spectrum and few to no sidelobes in the time domain, or no sidelobes in the time domain and minimal sidelobe energy in the frequency spectrum. Each optimal pulse has a specially shaped, non-constant amplitude envelope. The embodiment having no sidelobes in the time domain uses both a pulse envelope corresponding to a Dolph-Chebyshev function and more than one frequency of tones with offset timing of overlapping tone pulses so that their envelopes go to zero at different times. The invention is particularly well suited for single sideband radio communication at frequencies below 30 MHz.