Motorola Corporation

James Michael Keba

Clinton C Powell, Ii

Stephen Rocco Carsello

Chun-Ye Susan Chang

Eric Thomas Eaton

Kazimierz Siwiak

Lu Chang

Jian-Cheng Huang

David R Petreye

Francis Robert Steel

Kenneth D Finlon

Arthur Gerald Herkert

James Rodney Webster

Lorenzo Ponce De Leon

Leon Jasinski

A symbol synchronizer (10) for use in a communication device. The symbol synchronizer (10) comprises a sampling circuit (100) which samples the demodulated signal at a plurality of sampling events for each symbol period to generate three sample values at each sampling event. An eye pattern detector circuit (200) generates eye pattern characteristic information based on the three sample values, and outputs a symbol pulse in response to detecting eye pattern characteristic information consistent with a symbol center. A synchronization noise mask circuit (400) filters symbol pulses that occur during a predetermined period of time after a first symbol pulse is detected for each symbol period. A synchronization adjust circuit (500) generates a synchronization pulse during each symbol period at a particular instant of time during the symbol period based on a history of the occurrences of symbol pulses for a current symbol period and for prior symbol periods.

Symbol synchronizer based on eye pattern characteristics having variable

A selective call receiver (800), including a receiver circuit (101) and a processor (810), is used for synchronizing an internal reference to symbol edges of a plurality of symbols in a multi-level radio signal transmitted by a radio communication system. To perform this function the processor (810) is adapted to cause the receiver circuit (101) to demodulate the multilevel radio signal to in-phase and quadrature signals (108, 106), convert the in-phase and quadrature signals (108, 106) to a sequence of state transitions representative of the plurality of symbols, detect at least one same state transition from the sequence of state transitions, and synchronize the internal reference to the at least one symbol edge of the plurality of symbols based on the at least one same state transition.

Method in a selective call receiver for synchronizing to a multi-level

A clock recovery circuit for recovering a symbol clock (226) includes a level decoder (210) for determining one of a plurality of received states of a demodulated signal (105) during each symbol period of the symbol clock (226). Each of the plurality of received states corresponds to one of at least two modulation levels. The level decoder (210) generates for each of the plurality of received states a sign signal (212) having transitions at central threshold transition times and a magnitude signal (211). An edge selector (220) determines selected central threshold transition times. A synchronizable clock (225) is synchronized by the selected central threshold transition times, resulting in a significant reduction of symbol clock (226) jitter.

Digital signal clock recovery

A communication device (400) with a polarization diversity antenna configuration, having a first antenna (410) with a first plane of polarization and a second antenna (412) with a second plane of polarization. Signal strength of a demodulated signal when the antenna switch (420) is coupled to one of the antennas (410, 412) is measured by a signal strength measuring circuit (440) to generate a short-term average signal power (SA) representing signal strength over a first predetermined number of symbol periods, a medium-term average signal power (MA) representing signal strength over a second predetermined number of symbol periods, and a long-term average signal power (LA) representing signal strength over a third predetermined number of symbol periods, greater than the second predetermined number of symbol periods and first predetermined number of symbol periods. Switching between antennas (410, 412) is made in response to differences between SA, MA and LA.

Communication device having antenna switch diversity, and method therefor

A data receiver (110) for processing multiple signals includes a receiving circuit (120) for demodulating at least first and second signals and a selector (125) coupled to the receiving circuit (120) for comparing the at least first and second signals to estimated peak and valley values. The selector (125) generates error values associated with the at least first and second signals and selects a data symbol associated with one of the estimated peak and valley values based on the error values. A timing circuit (140, 150) activates the selector (125) at predetermined times, and a controller (140) coupled to the selector (125) and the timing circuit (140, 150) recovers information in accordance with the data symbol and other data symbols.

Method and apparatus for detecting data symbols in a diversity

An apparatus and method for updating upper and lower thresholds in peak and valley systems. The apparatus includes comparators which determine which peaks or valleys are eligible for use in the calculation of upper or lower threshold levels. The comparators output the eligible peaks and valleys into statistical blocks that calculate the mean of the peaks and valleys as well as the deviation over a predetermined number of samples. Additional comparators compare either the mean deviation, standard deviation, or variance of the eligible peaks and valleys to predetermined deviation thresholds to determine whether the mean peak or mean valley should be used to calculate update thresholds. The apparatus further includes memory elements that store the mean peak or mean valley values used in the calculation of upper or lower thresholds.

Apparatus and method for updating thresholds for peak and valley systems

A communication system providing selective encoding of digital messages (408) comprising a plurality of transmitting devices (116) and a plurality of receiving devices (122). The transmitting devices (116) transmit an encoded address (404), encoded message vector (406) in a first portion of the message, and digital message (408) in a second portion of the message. The digital message (408) is encoded in the second portion of the message with an error correction code if the digital message is a data message (414), and without the overhead of an error correction code if the digital message (408) is a voice message (410). The receiving device (122) decodes the encoded address (404), encoded message vector (406), and digital message (408) transmitted by the transmitting devices (116) in the first and second portion of the message. The receiving device (122) determines the encoding method of the digital message (408) based on the message type received in the message vector (406), and thereafter decodes the digital message.

Method and apparatus for selectively encoding digital messages in a

A technique substantially reduces power consumption of a selective call radio (106) while the selective call radio (106) is in an inactivated state. During the inactivated state a power state of the selective call radio (106) is cycled at an inactivated duty cycle and a first selective call message having a selective call address of the selective call radio (106) is received and processed. An activation mode of the selective call radio (106) is set to an activated state during which the power state of the selective call radio (106) is cycled at an activated duty cycle. The activated duty cycle is substantially greater than the inactivated duty cycle. The activation mode of the selective call radio is set to the activated state in response to an activation command generated during the inactivated state.

Method and apparatus for reducing power consumption in a selective call

A method and apparatus improves the perceived quality of a voice message received in a radio signal by a radio communication receiver (108) having voice storage capability and operating in a fading signal environment. A monitor (203) repeatedly monitors (304) a received radio signal quality indication during intervals of reception of contiguous portions of the voice message, and a selective storage element (228) selectively stores (308) for later playback (404) only those portions of the voice message received during the intervals of reception having a radio signal quality indication higher than a predetermined threshold.

Method and apparatus for improving perceived quality of a stored voice

An acknowledge back (ack-back) pager is provided for use in a paging system including a central station which transmits a group of message signals to a group of ack-back pagers which are addressed as a group. The users of the group of addressed ack-back pagers indicate a response to their respective pagers thus providing ack-back data. The pagers in the group of addressed ack-back pagers then simultaneously transmit back to the central station their ack-back data on different frequency sub-bands, a different frequency sub-band being allocated to each of the pagers in the group. To accurately control the ack-back transmit frequency, the pager receives and down-converts the F.sub.RX signal thus producing a down-converted F.sub.C signal, the frequency of which is measured and stored. The pager selects which sub-band of a plurality of frequency sub-bands within a predetermined range of frequencies is to be used for transmission of the ack-back signal. The pager determines a frequency offset F.sub.D corresponding to the selected sub-band, such offset being with respect to a predetermined frequency within such range of frequencies. The pager generates an acknowledge back signal at a frequency (F.sub.C +F.sub.D)-F.sub.CTX and up-converts such signal to a transmit frequency F.sub.TX corresponding to said selected sub-band, F.sub.CTX being the frequency of a down-converted sample of the F.sub.TX signal.

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Wellington, FL, United States of America

James Michael Keba