Motorola Corporation

Clifford D Leitch

Robert J Schwendeman

Kazimierz Siwiak

William J Kuznicki

Thomas V D'Amico

Sunil Satyamurti

Francis Robert Steel

Paul Edward Gorday

William J Ooms

Leon Jasinski

Philip P Macnak

Jose I Suarez

Rene M Delgado

Francis R Steel, Deceased

Lynne A Steel

A wireless communication system ( ) employing quadrature amplitude modulation techniques comprises a system controller ( ), at least one radio frequency base transmitter ( ), and at least one wireless communication device ( ). The system controller ( ) generates a downlink call ( ) for transmission between the radio frequency base transmitter ( ) and the wireless communication device ( ). Multiplexing an I-channel bit stream ( ) comprised of a first set of calls ( ) interleaved together and a Q-channel bit stream ( ) comprised of a second set of calls ( ) interleaved together generates the downlink call ( ). One wireless communication device demultiplexes the downlink call ( ) and processes the I-channel bit stream ( ). Another wireless communication device demultiplexes the downlink call ( ) and processes the Q-channel bit stream ( ).

Method and apparatus for communicating a call

A method for setting up a link for a call in a narrowband cellular communication system (100) includes, in a selective call radio (106), determining a transmitter identity and a signal quality (310, 315) of a strongest monitoring channel of a set of N monitoring channels, each of which has propagation characteristics that closely represent propagation characteristics of one of N groups of channels, and transmitting a report (330) of the transmitter identity and a signal quality of the strongest monitoring channel; and includes, in a system controller, receiving the report (405), choosing an available outbound resource (425, 430) in a first group of the N groups of channels, wherein the first group includes the strongest monitoring channel, and establishing the call (555) using the chosen available outbound resource at a bit rate that is a highest bit rate that is compatible with the signal quality.

Link setup method for a narrowband cellular communication system

A communication system (700) comprises a plurality of base sites (702-708) which include a first antenna (712) for transmitting a synchronous communication protocol such as a paging protocol and a second antenna (714) for transmitting a rotating phase signal. A communication device (250) takes the synchronous communication protocol and develops a reference signal (220) from the received protocol. The communication device (250) takes the reference signal (220) and the received rotating phase signal (214) and uses a phase detector (216) to produce a phase difference signal (232) which is substantially equal to the angle of the communication device (250) with respect to the particular base site (702-708) which transmitted the signals. In order to determine the location of the communication device at least two such phase difference signals (232), one phase difference signal from at least two different base sites is determined. In the preferred embodiment, the phase difference signals (232) are transmitted by the communication device (250) to a paging system controller (710) for calculation of the proximate location of the communication device (250).

Communication system and device having unit locating feature

A method and apparatus for time-scale modification of speech using a modified version of the Waveform Similarity based Overlap-Add technique (WSOLA) comprises the steps of storing a portion of an input speech signal in a memory, analyzing the portion of the input speech signal to determined at least one filtered pitch value, calculating an estimated pitch value (12) from the at least one filtered pitch value, determining a segment size (14) in response to the estimated pitch value (12), the segment size (14) having a value greater than the estimated pitch value (12), and time-scale compressing (18) the input speech signal in response to the segment size determined.

Communication system and method using a speaker dependent time-scaling

A digital transmission system for a selective call message communication network such as a paging network utilizes a quadrature amplitude modulation (QAM) transmitter (40) and receiver (42). The QAM transmitter (40) receives as a modulating input thereto, a message data encoded signal with a pilot carrier in a notch of the power spectrum of the signal. In order to generate the signal, the system generates a Hilbert transform of a wave-form representing message data to be transmitted. The Hilbert transform and message data waveform are combined to provide a positive frequency component and a negative frequency component. These frequency components are shifted apart and combined to provide a notch in which a DC component can be added to form a pilot carrier. A receiver of the system removes the pilot carrier from a received signal and shifts the positive and negative frequency components together to recover the message data.

Transmitter and receiver system and method utilizing a pilot carrier

A radio communication system (100) includes a system controller (102) for encoding data information to generate data messages which have periodic error protection at one or more burst error frequencies. The system controller (102) transmits one or more of the data messages to at least two transmitters (103) for simultaneous transmission of the one or more data messages. The first and second transmitters (103) have radio carrier frequencies which are offset by an offset frequency which is substantially equivalent to one of the one or more burst error frequencies. A selective call receiver (106) receives and decodes a radio signal including a data message having periodic burst errors at the offset frequency and wherein the data message includes encoding which provides substantial periodic burst error protection at the offset frequency.

Apparatus for encoding and decoding a digital radio signal

The present invention comprises a method for compressing a plurality of voice signals within a voice communication resource (see FIG. 6) having a given bandwidth within a voice communication system (100). The method comprises the steps of subchanneling the voice communication resource into a plurality of subchannels (441, 442, 443), placing a pair of the plurality of voice signals (401, 402) on a subchannel (441); modulating the pair of the plurality of voice signals (401, 402) about a pilot signal (581) within the subchannel (441) using single sideband modulation; and compressing the time of each of the voice signals (401, 402) within the plurality of subchannels (441, 442, 443), wherein these step provide a compressed voice signal.

Voice compression method and apparatus in a communication system

A selective call receiver (105) for use in a selective call communication system (100) and a controller (206). The receiver (203) is for receiving and demodulating a digital signal which includes a predetermined sequence of A.times.N interleaved symbols representing a non-interleaved set of N tiers of symbols, each tier having A symbols, wherein A and N are positive integers. The controller (206) includes a deinterleaver (830) which reconstructs the non-interleaved set of N tiers of symbols from the demodulated signal, and a decoder (950) detects and corrects errors in the deinterleaved set of N tiers of symbols. The digital signal is transmitted simultaneously from two transmitters (103) having a difference frequency 1/P, and the symbols are transmitted at a rate of SPS symbols per second. The period of the difference frequency is given by P=(A.times.N)/SPS.

Method and apparatus for encoding and decoding a digital radio signal

A method and apparatus adaptively selects a communication strategy for communicating a message in a selective call radio communication system including a fixed portion (100) and a portable portion (101). The fixed portion (100) transmits (402) an alert signal to the portable portion (101), and awaits (404) an acknowledgment signal including a signal quality estimate from the portable portion (101). The portable portion (101) receives (602) the alert signal, and computes (604, 606) the signal quality estimate therefrom. The portable portion (101) then sends (608) the acknowledgment signal to the fixed portion (100). In response to the acknowledgment signal, the fixed portion (100) selects (407) a transmission strategy in accordance with the signal quality estimate. For compatibility, the transmission strategy requires a matching reception strategy in the portable portion (101). After sending the acknowledgment signal, the portable portion (101) selects (609) the matching reception strategy in accordance with the signal quality estimate sent in the acknowledgment signal without requiring further communication with the fixed portion (100).

Method and apparatus for adaptively selecting a communication strategy

An amplitude modulator circuit, having an input for receiving an input information signal and an output for providing an output signal, which is proportional to the input signal. The amplitude modulator circuit comprises at least two pass devices for amplifying the input information signal to produce the output signal and applying it to a load. The amplitude modulator circuit further comprises at least two voltage supplies for applying a plurality of supply voltages (at least some of which have different voltages) to the pass devices. The amplitude modulator circuit also includes a driver circuit having an input for receiving the input signal, and at least two driver outputs for driving the pass devices. The driver circuit activates the pass device having the lowest supply voltage that is sufficient to supply the required voltage to the load.

Amplitude modulator circuit having multiple power supplies

A dual mode communication receiver a receiver for receiving information transmitted in a first and second modulation format on a common channel, a first demodulator for detecting information transmitted in the first modulation format, and a second demodulator, responsive to the information detected in the first modulation format, for detecting information transmitted in the second modulation format. A power conservation circuit is also provided for selectively supplying power to the first and second demodulators for enabling the detecting of the information transmitted in the first modulation format and the second modulation format, respectively.

Dual mode receiver having battery saving capability

A transmitter for transmitting digital information to a communication receiver employing a post detection low pass filter having a predetermined filter transfer function comprises a memory, a pulse recovery circuit, and a transmitter section. The memory stores an optimized electric pulse which is defined by the combination of an electric pulse exhibiting minimum intersymbol interference characteristics and the reciprocal transfer function of the predetermined post detection low pass filter transfer function of the communication receiver. The pulse recovery circuit recovers the optimized electric pulse from the memory, and generates a sequence of optimized electric pulses corresponding to the digital information to be transmitted. The digital information to be transmitted is then transmitted by the transmitter section.

Spectrally efficient digital FM modulated transmitter

A paging terminal for transmitting address and variable length message signals to a plurality of remotely located acknowledge back and non-acknowledge back pagers, each having a unique address, includes an input for accepting variable length messages to be sent to a group of M pagers within the plurality of pagers, wherein M is an integer number. A controller orders the acknowledge back pager addresses for transmisison prior to the transmission of addresses for the non-acknowledge back pagers. A transmitter sequentially transmits the ordered addresses corresponding to the group of M pagers as an address batch during a first time period, and sequentially transmits the variable length messages for the group of pagers in a message batch including end of message markers delimiting an associated variable length message during a second time period subsequent to the first time period. The messages of the message batch are transmitted in a predetermined order bearing a known relationship to the order in which the addresses of the address batch were transmitted.

Acknowledge back paging system having the capability of matching

A method is described for transmitting digital data with minimum splatter and for recovering the same with a conventional frequency modulated (FM) receiver to obtain data having minimum intersymbol interference. The method utilizes an optimized prototype pulse which has been predistorted to match the inverse characteristics of the post detection low pass filter in a conventional FM receiver. When the optimized electric pulse is received and processed by the post detection low pass filter of the conventional FM receiver, a pulse shape exhibiting minimal intersymbol interference is produced.

Spectrally efficient digital FM modulation system

A transmitter, with an inphase input for receiving an inphase baseband input signal, and a quadrature input for receiving a quadrature baseband input signal, comprises a modulator, coupled to the inphase and quadrature inputs, for modulating the inphase and quadrature baseband signals to provide a modulated radio-frequency signal and a linear amplifier, coupled to the modulator, for amplifying the modulated radio-frequency signal to produce an output signal. Oscillation detector means are coupled to receive the output signal, for detecting oscillation, and for producing an error signal as a result of the oscillation. The transmitter also comprises means for reducing the open loop gain of the feedback loop, disposed between the inphase and quadrature inputs and the modulator. The means for reducing the open loop gain reduces the open loop gain of the transmitter to less than one, in response to the error signal.

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Coral Springs, FL, United States of America

Clifford D Leitch