AM equalizer circuit for digital systems

专利名称：AM equalizer circuit for digital systems发明人：David N. Critchlow,Graham M. Avis,Sandra J.

Earlam,Karle J. Johnson,Bruce A.Smetana,Gregory L. Westling,EricPaneth,Moshe Yehushua

申请号：US07/256557申请日：19881012公开号：US04881240A公开日：191114

摘要：A digital wireless subscriber telephone unit for wireless connection with a basestation. The subscriber unit has a baseband processor which is coupled to storage devicefor the baseband functions. The baseband processor is direct access coupled to a modemprocessor whereby the two processors may communicate with each other. The modemprocessor generally acts as the master in the system, although lock-out circuit may beused in certain circumstances. The signal from the modem processor is converted to ananalog 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 amplifiedIF signal is combined with a signal generated by a synthesizer to provide an RF signal. Onthe basis of certain signals received from the base station, the baseband processorproduces initiating signals which determine whether the subscriber unit will be in thetransmit mode or the receive mode. In intervals between actuation of the system, atraining mode is used wherein a known signal from the modem processor is comparedwith a looped-back signal to produce correction constants to compensate for

undesirable variations in the IF, these constants being stored for use in correcting actualreceived signals. During demodulation, the modulated digital signals are fed to themodem 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 frequencycorrection circuit for minimization of errors and for production of a frequency correctionsignal which is used to correct any errors in the timing of the system and in the output ofthe synthesizer.

申请人：INTERNATIONAL MOBILE MACHINES CORPORATION

代理人：Arthur A. Jacobs,Edward W. Callan

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