Abstract: In a transmission power control circuit which performs power amplification of a transmission signal to one of several predetermined levels in response to a control signal and outputs the amplified signal, bias voltage of the power amplifier circuit is set to the optimum in response to the output power of multiple levels, respectively. Since the bias voltage is set to the optimum, the power loss in the power amplifier circuit is decreased and the efficiency of the power amplifier circuit is improved.

Abstract: A shield construction for electrical devices which comprises a conductive thin film mounted at least one of the surface of electrical devices. The shield construction is connected with ground leads of a electrical devices or the ground plane of the circuit board. The shield construction prevents the radiation of undesired waves from the electrical devices. As a result, the deterioration of the receiving sensitivity and noise generation becomes negligibly small even in the weak electric field area.

Abstract: The electronic device housing employs unique temperature management functions. Thermally sensitive electronic components are thermally isolated from the environment and from temperature generating components provided within the housing through the use of an insulative case material. Furthermore, heat generating components are connected to the outside environment with a conductive thermal path which is isolated from the remaining components provided within the case, thereby efficiently transferring undesired heat to the environment without allowing the heat to substantially affect remaining components in the housing. The electronic device housing includes a case and a cover formed by molding using a synthetic resin, and a metallic layer formed on the surface of the case which cooperates with the cover to provide an electromagnetic shield for the case.

Abstract: A pocket transceiver can be, for example a portable wireless telephone apparatus small enough to be put into a pocket of a user. The apparatus operates at a low power level. The pocket transceiver as an independent unit only handles signals at a low power level and is suitable for communication over close range. The pocket transceiver can also be used as a telephone apparatus for communication over long range, such as a mobile transceiver in a vehicle, by being connected to an adapter, which includes a power amplifier and a power controller for selecting an output power level out of multiple levels in response to an instruction from a transmitting-receiving unit of the pocket transceiver.

Abstract: A voice of user is picked up by a microphone built in a sun visor of a vehicle. The output of microphone is frequency-modulated by an FM transmitter powered by a solar battery and transmitted through a transmitting antenna in a vehicle. The frequency-modulated radio signal is received and demodulated by a receiver with a receiving antenna. The received signal is further transmitted outside of the vehicle through a transceiver.

Abstract: A portable wireless communication apparatus of new type is provided. The apparatus is composed of a handset type substantially parallelopiped body which is to be used in combination with a battery pack in a portable mode and a support tray installed in a passenger car room for hand-free use. The top surface of the body is provided with a key operating section, a display section and a speaker. All of them are in the user's sight while the apparatus is being used in the hand-free mode. In the portable mode, on the other hand, all the user has to do is only take up the apparatus away from the tray after the key board operation, hold the receiving section against the ear and talk into the transmitting section without changing the grip.

Abstract: An aural transmitter device is improved by largely eliminating the amplification of ambient environmental noise. To this end, control may be effected in response to the difference between a smoothed, rectified output of an amplifier and a reference voltage, either with or without a high-pass filter for removing low frequency noise components.