Motorola Corporation

Arvind S Arora

Niels Vinggaard

Alexander Wayne Hietala

John J Vaglica

Duane C Rabe

Charles Philipp Binzel

Oded Norman

Yoram Salant

Paul McAlinden

Patrick J Marry

Christopher F Bussan

Moshe Refaeli

Adam F Gould

Thomas Edward Oberhauser

Joseph F Thome

By employing AFC range extension, a high frequency communication device (,) can use a low cost, low accuracy crystal (,) in its reference oscillator (,). AFC range extension involves varying receive bandwidth of the communication device (,) to facilitate AFC or automatic frequency control. In particular, the receive bandwidth is set to a first, wide setting for AFC acquisition purposes (,). Frequency error associated with a received AFC signal is determined (,) and receive reception is adjusted (,) to reduce frequency error in the communication device (,). Once the frequency error is below a predetermined threshold (,), the receive bandwidth is set to a second setting different from the first setting for normal reception (,).

Method of and apparatus for automatic frequency control range extension

A communications system includes multiple processors (14, 16) and a protocol timer (18). The protocol timer (18) controls the timing of events in the communications system and operates autonomously after it is loaded with initial instructions by one of the multiple processors (14, 16). The protocol timer (18) utilizes a frame event table (50) and a macro event table (46, 48) to trigger events and to generate interrupts of the multiple processors (14, 16). By allowing the protocol timer (18) to operate autonomously, the processors (14, 16) are relieved of timing control, and can be powered down when not in use, thus reducing power consumption of the communications system. Also, by using the protocol timer (18) to control the timing of events, software related errors and interrupt latencies are reduced.

Data processing system having a protocol timer for autonomously

An error detector circuit (300) for a discrete receiver indicates bad frames of binary information signals which contain distorted bits of data in numbers so great as to prevent a convolutional decoder (738) from generating, accurately, a decoded signal. A variable threshold generator (440) generates a variable threshold level according to the signal quality estimate for the received signal. When bit errors are detected in numbers beyond the variable threshold or when a first preselected value of the signal quality of a received signal combined with the detected number of bit errors forms a signal beyond a second preselected value, a bad frame is indicated.

Error detector circuit for digital receiver using variable threshold

A method and associated circuitry for acquiring a channel of a set of frequency channels by a radio receiver. The radio receiver scans selected control channels and measures the power levels of signals generated upon the respective ones of the control channels and stores values. An attempt to effectuate a communication link with a transmitter which transmits a data signal upon one of the control channels is only attempted if the measured power level on such control channel increases beyond a certain amount. The tuning frequency of the tuning circuitry can be retuned when the tuning circuitry is initially tuned to receive a communication signal transmitted by a transmitter of a less-than-most desired network of transmitters according to a second embodiment.

Method and circuit for acquisition by a radio receiver

An error detector circuit, and an associated method, for a discrete receiver. The error detector circuit indicates bad frames of binary information signals which contain distorted bits of data in numbers so great as to prevent a convolutional decoder from generating, accurately, a decoded signal. When bit errors are detected in numbers beyond a first preselected value of the signal quality of a received signal combined with the detected number of bit errors forms a signal beyond a second preselected value, a bad frame is indicated.

Error detector circuit for receiver operative to receive

An error detection system for a discrete receiver. Sequences of bits together forming frames of information comprise the signal received by the discrete receiver. The signal is decoded by a convolutional decoder and is re-encoded by an encoder. Successive portions of nonoverlapping sets of adjacently positioned bits of the re-encoded signal formed by the encoder are compared with corresponding bits of a signal representative of the signal received by the receiver. When excessive numbers of the successive portions of the signals which are compared include bit dissimilarities, a bad frame indication is generated.

Error detection system

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. The boundaries of the FCB establish the time slot alignment of the TDMA structure being received from the base station.

Growing community of inventors

Arlington Heights, IL, United States of America

Arvind S Arora