Abstract: The present invention relates to a wireless communication system having improved PLL circuits in the RF transmitter and receiver sections. The PLL circuits in the wireless communication system according to the present invention include time constant controllable filters. A series circuit of capacitor and resistor detects turn-on of the power switch for the PLL circuits to generate an output signal to be applied to the filters, thereby controlling the time constant of the filters in the PLL circuits to a lower value than normal for a given time after power-on of the PLL circuits.

Abstract: The present invention relates to a wireless communication system which suppresses the quantity of an electric power of a carrier wave consumed in communicating by a digital data as well as it can improve the communication quality. The wireless communication system according to the present invention includes at least a signal processing circuit section and a high frequency transmitter/receiver section and it comprises controlling the timing of modulation completion by the digital data signal with the transmitting timing of the modulation carrier wave supplied from the electric power amplification section of the high frequency transmitter/receiver section and a control circuit which controls the operation of the high frequency transmitter/receiver section in transmitting the modulation carrier wave on the basis of the preceded timing of the modulation completion.

Abstract: A method and a device for obtaining a data of tape thinness, in which a calculation is carried out by using information of the changing pulse period based on rotational speed of a tape reel in a take-up side or a supply side, and the number of revolutions of the tape reel and tape velocity. The tape thinness d is obtained by a formula, d=A.times.v.sub.0 (T.sub.T -T.sub.T0)/2.pi..times.n.sub.T, in which, in case of the tape reel in the take-up side, the pulse period of the tape reel is represented as T.sub.T, the initial pulse period of the tape reel is T.sub.T0, the counted number of revolutions of the tape reel from initial setting time is n.sub.T, tape velocity is v.sub.0, and a pole number of the tape reel is A.