International Mobile Machines Corporation

Interdigital Technology Corporation

Hughes Aircraft Company

Other

Hughes Electronics Corporation

International Mobile Machine Corporation

Moshe Yehushua

David N Critchlow

Graham M Avis

Karle J Johnson

Eric Paneth

Wade Lyle Heimbigner

Bruce A Smetana

Sandra J Earlam

Gregory L Westling

George Alan Wiley

Michael I Parr

John Ratzel

John L Watson

Graham N Avis

Phil Labarbera

Nancy Neigus

A FIR chip is used in a wireless subscriber unit. The subscriber unit includes a processor for transcoding an input signal to provide digital input symbols. A received output signal is demodulated. Digital output symbols are synthesized from the demodulated output signal processor and filtered digital input symbols are provided. An internal address decoder decodes to allow the processor to access internal functions of the FIR chip. A control and status register allows the processor to read the status of and control the internal functions of the FIR chip. A FIR filter filters the digital input symbols. A transmit timer controls timing which allows the processor to control the FIR filter. A receive timer generates timing signals for timing transcoding operations and synthesizing operations connected to the processor.

FIR chip for use in a wireless subscriber unit

A subscriber unit has a processor. The processor provides an output phase signal corresponding to a selected output digital frequency. A tuning register buffers the phase signal. A lookup table has two sets of predefined stored values pertaining to the amplitude of a signal for a single quadrant. The predefined stored values comprise coarse angle approximations and fine angle approximations. A sine and cosine generator receives the phase signal and generates sine and cosine waveforms utilizing amplitude values obtained from the lookup table. The phase signal includes phase data and specifies the quadrant and the algebraic sign of the phase data. The sine and cosine generator accessing the lookup table differently depending upon the quadrant and sine of the phase data, such that the lookup table provides an amplitude value from the sets of predefined stored values based on the phase data. A modulator combines the sine and cosine waveforms to produce the selected output digital frequency and modulates digital frequency.

Subscriber unit producing a modulated digital frequency

The present invention is a method and system for processing communication signals in a wireless telecommunication system having at least two subscriber units. The subscriber units communicate with each other through a selected band of radio frequencies over a plurality of radio frequency channels. The system generates a fixed based radio frequency signal and a digital intermediate frequency signal. The fixed based radio frequency signal and the digital intermediate frequency signal are then combined to produce a carrier signal which is communicated between the at least two subscribers.

Digital synthesizer

A subscriber unit for wireless communication with a base station in a wireless subscriber communication system includes a FIR chip, a DIF (digital intermediate frequency) chip, a single prccessor chip and a radio. The processor chip transcodes a digital voice input signal to provide digital input symbols; demodulates an output signal received from the base station to provide digital output symbols; and synthesizes a digital voice output signal from the digital output symbols. The FIR chip FIR filters the digital input symbols and generates timing signals for timing the transcoding and synthesizing operations in the processor chip. The DIF chip digitally synthesizes a digital intermediate frequency signal by direct digital synthesis (DDS) and modulates the digital intermediate frequency signal with the filtered input symbols to provide a modulated intermediate frequency input signal. The radio further processes the modulated input signal for transmission to the base station.

Control functions are integrated into the digital signal processing (DSP) chip functioning as the central processor unit (CPU) for the subscriber's cellular telephone unit, eliminating the microcontroller and other support chips. The integration provided is not a physical integration combining the DSP and microcontroller chips into a single chip architecture, but rather a logical (i.e., software) integration. A real time preemptive executive controls the execution of the different functions and the messaging between them. The amount of code that has to run on the DSP chip acting as the CPU is larger than the address space of the DSP chip, so the code memory is divided into banks with only one bank being activated at a time. It is the job of the real time executive to activate the banks as required to control the various functions.

Integrated control and signal processing in a cellular telephone

A subscriber unit for wireless communication with a base station in a wireless subscriber communication system includes a FIR chip, a DIF (digital intermediate frequency) chip, a single processor chip and a radio. The processor chip transcodes a digital voice input signal to provide digital input symbols; demodulates an output signal received from the base station to provide digital output symbols; and synthesizes a digital voice output signal from the digital output symbols. The FIR chip FIR filters the digital input symbols and generates timing signals for timing the transcoding and synthesizing operations in the processor chip. The DIF chip digitally synthesizes a digital intermediate frequency signal by direct digital synthesis (DDS) and modulates the digital intermediate frequency signal with the filtered input symbols to provide a modulated intermediate frequency input signal. The radio further processes the modulated input signal for transmission to the base station.

Subscriber unit for wireless digital subscriber communication system

A subscriber unit for a wireless digital telephone system is disclosed. An equalizer for receiving I and Q samples is disclosed which is in the form. The I and Q samples are complex sample pairs provided at a frequency. The equalizer receives a training signal in the form of complex I and Q sample pairs. A training signal is affected by undesirable characteristics that might be present in the I and Q samples. A comparator compares the actual input training signal with the desired output to obtain a set of weighting coefficients for the equalizer to produce the desired output. A frequency correction circuit provides a corrected frequency signal for the frequency of the sample pairs from the weighting coefficients.

Subscriber unit for wireless digital telephone system

A cellular automated test set for testing cellular telephones consists of a RF interface coupled to an RF input/output of the cellular telephone and a transmitter-receiver coupled at an RF input/output of the transmitter-receiver to the RF interface. The transmitter-receiver transmits a first message signal to and receives a second message signal from the cellular telephone via the RF interface. The second message signal is generated by the cellular telephone in response to the first message signal. A data interface is coupled to a data port of the transmitter-receiver; and a processor is coupled to the data interface. The processor transmits a first data signal to and receives a second data signal from the transmitter-receiver via the data interface. The first message signal is generated in response to the first data signal and the second data signal is generated in response to the second message signal. In practice, the processor may be a personal computer system and the transmitter-receiver may be a modified cellular telephone programmed with a base station program.

Cellular automated test set

A digital cellular system (10) employs a decoder that decodes control messages encoded by a convolutional tail-biting encoding procedure. The control messages (57) contain 65 bits that are encoded in a 260 bit data frame (59). The decoder reads (112) the first x quadruple bits and writes them also at the end of the data frame bit stream. A Viterbi decoding algorithm (114) is applied to the modified bit stream for x plus 65 steps. A bit stream of (65+x) bits is selected (116) from a best value path and y first bits are discarded from the selected stream. The output decoded message (118) includes bits (y+1) through (y+65).

System and method for decoding tail-biting code especially applicable to

In a wireless digital telephone system, a circuit for determining in a subscriber unit whether a particular RF channel is of the type designated by the base station to be either a control channel or a voice channel and for determining whether the channel is in the transmit or receive mode; the circuit utilizing the duration of an AM hole to determine the type of the channel and utilizing a unique word for determining the mode.

A digital wireless subscriber telephone unit for wireless communication with a base station. An IF is used within the subscriber unit and base station which is combined with a carrier signal generated by a synthesizer for RF transmission between stations. In intervals between actuation of the system, a training mode is used wherein a known training signal is compared with a known values to produce correction coefficients to compensate for undesirable variations in timing and/or frequency, these constants being stored for use in correcting actual received signals. During demodulation, the modulated digital signals are fed to the modem processor in the form of time multiplexed I and Q samples and are demultiplexed. The demultiplexed I and Q samples are fed to an equalizer and frequency correction circuit for minimization of errors for production of a frequency correction signal based upon the correction coefficients which is used to correct any errors in the timing and frequency of the system.

Automatic adaptive equalizer

A digital wireless subscriber telephone unit for wireless connection with a base station. The subscriber unit has a baseband processor which is coupled to a storage for the baseband functions. The baseband processor is direct access coupled to a modem processor whereby the two processors may communicate with each other. The modem processor generally acts as the master in the system, although lock-out device may be used in certain circumstances. The signal from the modem processor is converted to an analog signal, which is subjected to deglitching, and the deglitched signal is then upconverted and filted to form an IF signal which is thereafter amplified. The amplified IF signal is combined with a signal generated by a synthesizer to provide an RF signal. On the basis of certain signals received from the base station, the baseband processor produces initiating signals which determine whether the subscriber unit will be in the transmit mode or the receive mode. In intervals between actuation of the system, a training mode is used wherein a known signal from the modem processor is compared with a looped-back signal to produce correction constants to compensate for undesirable variations of the IF, these constants being stored for use in correcting actual received signals. During demodulation, the modulated digital signals are fed to the modem processor in the form of time multiplexed I and Q samples and are demultiplexed. The demultiplexed I and Q samples are fed to an equalizer and frequency correction circuit for minimization of errors and for production of a frequency correction signal which is used to correct any errors in the timing of the system and in the output of the synthesizer.

Growing community of inventors

San Diego, CA, United States of America

Moshe Yehushua