International Mobile Machines Corporation

Interdigital Technology Corporation

International Mobile Machine Corporation

Sandra J Earlam

David N Critchlow

Karle J Johnson

Bruce A Smetana

Graham M Avis

Gregory L Westling

Eric Paneth

Moshe Yehushua

Graham N Avis

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

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 frequency synthesizer that generates two output signals at a set frequency apart from each other and in synchronization with each other. The output frequency is selected by a microprocessor and the set frequency difference between the two output signals is determined by a frequency divider and a voltage controlled oscillator.

Frequency synthesizer circuit

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.

Digital time-multiplexed quadrature frequency upconverter

An interpolator varies the sampling rate of a signal. The signal may comprise pairs of in-phase and quadrature components at a first rate which are serially input through a pair of memories connected in series. The serially connected memories operate at a second higher rate which is a multiple of the first rate. An output taps the signals being circulated by the serially connected memories which results in the output of a signal having the in-phase and quadrature components at the higher second rate.

Interpolator for varying a signal sampling rate

In a digital wireless subscriber telephone unit for wireless connection with a base station which includes a modem processor whose signal is converted to an analog signal which is then upconverted and filtered to form an IF signal, a deglitching circuit for removing glitch spikes occurring during the transition periods from digital signals to analog signals comprising a timing system, a detector for detecting the transistion periods in order to control the timing system, and a mixer coupled to the output of a D/A converter to mix a blanking signal from the timing system with the analog signal received from the D/A converter during the transistion periods, whereby the output of the mixer is returned to an intermediate reference level.

Deglitching means for digital communication systems

An analog to digital converter system utilizable in a wireless digital telephone network, the system comprising a circuit to produce an analog signal, and a circuit for amplifying this signal, mixing the amplified signal with a signal from a timing circuit and applying the output of the mixer to a sample and hold circuit; the output of the sample and hold circuit being then applied to an analog to digital converter, the output of which is applied to a FIFO, whose output is then available for further processing.

A digital wireless subscriber telephone unit for wireless connection with a base station. The subscriber unit has a baseband processor which is coupled to storage device 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 circuit 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 filtered 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 in 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. 2

Digital signals and frequency correction in a digital wireless system

A digital wireless subscriber telephone unit for wireless connection with a base station. The subscriber unit has a baseband processor which is coupled to storage device 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 circuit 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 filtered 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 in 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.

AM equalizer circuit for digital systems

A digital wireless subscriber telephone unit for wireless connection with a base station. The subscriber unit has baseband processor which is coupled to storage means 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 means 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 filtered 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 undersirable variations in the IF, these constants being stored for use in correcting actual received signals.

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San Diego, CA, United States of America

Sandra J Earlam