Abstract: A device useful in personal digital cellular (PDC) mobile telecommunications. The device is formed of an application specific integrated circuit (ASIC) chip and a digital signal processor (DSP) chip. The ASIC at least converts between digital modulated signals and analog ones. The DSP chip at least digitally modulates and demodulates the digital modulated and demodulated signals, digitally processes the demodulated signals to and from speech and control channel signals and performs vector sum excited linear prediction (VSELP) compression and decompression.

Abstract: An accessory voice operated unit for a cellular telephone is disclosed. The accessory unit includes a speech signal input/output unit, a voice recognition unit and a processing unit. The voice recognition unit recognizes trained words within the speech signal and the processing unit has telephone numbers associated with the trained words. The processing unit provides standard telephony dialing signals when a trained word has been recognized, wherein the dialing signals correspond to the telephone number associated with the recognized trained word. The accessory unit also includes a hands-free conversation unit which provides hands-free conversation. The processing unit connects the input/output unit to the voice recognition unit during a dialing mode after which, during a conversation mode, the processing unit connects the input/output unit to the hands-free conversation unit.

Abstract: A demodulator is described which includes a hard limiter, reference generator and a phase determiner. The hard limiter produces a binary phase-modulated signal from an analog phase modulated input signal having a first frequency. The reference generator provides a binary reference signal having a second frequency generally equivalent to the first frequency. The phase determiner is operative during a sampling period and determines the phase between the phase-modulated and the reference binary signals during the sampling period.