Abstract: To obtain a mobile telephone with remote-controlling capability easily available as a remote-controller. Various remote control codes for predetermined various controlling operations on target equipment are associated with a plurality of operation buttons of an operation unit of a mobile telephone in a one-to-one relationship, and stored in memory of the mobile telephone. When an operation button is depressed, a control unit of the mobile telephone reads a remote control code associated with the depressed button from the memory, and transmits it to the target equipment using an infrared emission unit.

Abstract: A portable telephone set includes a demodulating circuit which demodulates a signal from a base station to output a demodulated signal. A first signal processing unit amplifies the demodulated signal to output a first amplified signal. An earphone converts the first amplified signal into a sound. A microphone converts a sound into a signal. A second signal processing unit amplifies the signal from the microphone to output a second amplified signal. A modulating circuit modulates the second amplified signal to output a modulated signal. A volume control unit increases the amplification degrees of the signal processing units in accordance with the user's selection. A band limiting circuit limits to the voice band the sound input through the microphone. An S/N determining circuit compares the level of the signal from the microphone and the level of a signal from the band limiting circuit.

Abstract: A false-synchronization detection device comprises an up-down counter which counts down a predetermined amount of clocks when codes of phase changes at former and latter halves of a symbol interval are different, and counts up a different predetermined amount of clocks, which is less than the previous one, when codes of phase changes at former and latter halves of the symbol interval are the same. Thus, the false-synchronization detection device is capable of recognizing false-synchronization of symbol timing when the count value falls as far as the predetermined value.

Abstract: A frequency stabilization circuit includes a local oscillator, a mixer, a level comparator, a frequency comparator, and a controller. The local oscillator outputs a local oscillation signal in accordance with a control voltage. The mixer converts a received radio frequency signal into an intermediate frequency signal using the local oscillation signal from the local oscillator. The level comparator compares a DC voltage corresponding to the intermediate frequency signal from the mixer with a reference voltage to determine whether the reception electric field level of the radio frequency signal is high or low. The frequency comparator compares the frequency of the intermediate frequency signal from the mixer with the frequency of the reference signal to output frequency difference information. The frequency comparator outputs previous frequency difference information when the comparison result of the level comparator indicates a decrease in reception electric field level.

Abstract: In a diversity receiver, each of first and second diversity branches includes an antenna and a high-frequency amplifier coupled thereto. A diversity decision circuit is coupled to the outputs of the amplifiers to generate a switching control signal identifying one of the outputs of the diversity branches having a higher field intensity value. A power switching circuit is provided for coupling a voltage source to one of the amplifiers according to the switching control signal so that power supply to the other amplifier is cut off.

Abstract: In a radio pager, the front end of the pager is powered by a battery. A decoder processes an incoming signal received by the front end and generates a first or a second signal when it is in an active state or an inactive state, respectively. A high duty-ratio pulse signal or a low duty-ratio pulse signal is generated in response to the first and second signals from the decoder, respectively. A voltage inducing circuit is connected across the terminals of the battery to respond to the high duty-ratio and low duty-ratio pulse signals by allowing a current to periodically pass through an inductor for a varying duration proportional to the duty ratio of either of the pulse signals to cause a voltage higher than the battery voltage to be induced in the inductor. A capacitor coupled to the inductor stores DC energy proportional to the duration of the current and supplies power to the decoder.