Prairiecomm, Inc.

Freescale Semiconductor,inc.

Other

Freescale Semiconductors Inc.

Wayne H Bradley

John W Diehl

James L Porter

Lindo St Angel

Dien N Nguyen

Peter A Tomasi

Tong Zhao

Michael J Schellinger

A code division multiple access (CDMA) receiver detects, de-scrambles, and de-spreads multiple channels that utilize different binary codes. The processing that is common to all channels can be performed once thus saving gate count and power consumption.

Multicode receiver

A receiver () comprises a non-equalizing demodulator (), an equalizing demodulator () and an output control selector (). The non-equalizing demodulator () receives a modulated signal () and demodulates the modulated signal () to produce a first digital bit stream (). The equalizing demodulator () receives the modulated signal () and equalizes and demodulates the modulated signal () to produce a second digital bit stream (). The output control selector (), coupled to the non-equalizing demodulator () and the equalizing demodulator (), selectively delivers a first one of the first digital bit stream () and the second digital bit stream () for at least a predetermined period of time () before selectively delivering a second one of the first digital bit stream () and the second digital bit stream () responsive to a predetermined decision criterion (e.g., bit error rate). The first one of the first digital bit stream () and the second digital bit stream () is different from the second one of the first digital bit stream () and the second digital bit stream ().

Receiver having equalizing demodulator and a non-equalizing demodulator and method for controlling the same

A code division multiple access (CDMA) receiver detects the presence of differently formatted signals (e.g., global system for mobile communications (GSM) signals) by programming a CDMA searcher co-processor, which includes a digital filter, with tap weights that correlate with a known sequence within the differently formatted signals. If the tap weights correlate to a received signal, the receiver produces an indication that a differently formatted signal is present. Once differently formatted signals are detected, specific hardware and/or software may be implemented to receive and process the differently formatted signals.

Signal detection using a CDMA receiver

A blind rate determination system generates syndromes for a received symbol stream and, based on the syndromes, calculates a confidence metric associated with possible data rates. The confidence metrics are compared to one another and to a threshold and the data rate associated with the best confidence metric is selected as the data rate at which the symbol stream was encoded.

Blind rate determination

A receiver generates two metrics, one that is used to control the gain of an amplifier and the other that is used to determine the presence of narrowband interference, such as IMD. The two metrics may represent analog-to-digital converter (A/D) saturation and average signal strength, either of which may be used to control gain or to detect the presence of narrowband interference.

Receiver having gain control and narrowband interference detection

A digital filter includes a number of coefficient generators that are clocked by a clock having a frequency including an undesired component. The coefficient generators, which each have a number of states, are communicatively coupled to multipliers that receive incoming signals and multiply the incoming signals by coefficients produced by the coefficient generators. Based on the magnitude of the undesired coefficient, certain states of the coefficient generators may be repeated or skipped to adjust the time and frequency domain of the output from the digital filter.

Digital filter having an upsampler operational at a fractional clock rate

A frame synchronizer for use in a receiver that receives an encoded signal from a transmitter includes a conjugation unit, a delay unit and multiplier coupled together to process the encoded signal. The multiplier multiplies either the received encoded signal by a conjugated, delayed version of the received encoded signal or multiplies a conjugated version of the received encoded signal by a delayed version of the received encoded signal to produce a first product signal. A further multiplier multiplies the first product signal with a locally-stored signal to generate a second product signal. An accumulator accumulates the second product signal over a plurality of bit times to generate an accumulated signal having a magnitude representing a time synchronization offset between the receiver and the transmitter and phase representing a frequency synchronization offset between the receiver and the transmitter. A synchronization correction unit generates a time offset correction and a frequency offset correction from the accumulated signal and these corrections are used to correct offsets between the receiver and the transmitter.

Frame synchronizer

A method and apparatus reduces current consumption of a mobile communication unit, such as a cellular or mobile telephone that communicates with a base station by disabling a temperature controlled crystal oscillator and a code generator while the mobile communication unit is in a sleep mode of operation, thereby reducing the sleep mode current consumed by the mobile communication unit. Prior to entering sleep mode, the mobile communications unit stores the state of the code generator and disables the temperature controlled crystal oscillator. Upon waking from sleep mode, the mobile communication unit calculates what the state of its code generator would have been if its temperature controlled crystal oscillator had not been disabled, and uses this calculated state to achieve synchronization with a code generator in the base station.

Method and apparatus for reducing current consumption

A demodulation subsystem includes an equalizing demodulator and a non-equalization demodulator, each of which receive a baseband signal, and an output control selector that selects the output of one of the equalizing demodulator and the non-equalizing demodulator based on a bit error rate of the signal.

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West Chicago, IL, United States of America

Wayne H Bradley