Abstract: In accordance with the present invention, there is provided a method and apparatus for detecting a moving speed of a mobile terminal in a mobile communication utilizing time division multiple access system, wherein a measurement is made for a variation in delay of a burst radiowave received from the mobile terminal with reference to a transmission burst signal before a calculation of a moving speed of the mobile terminal is made on the basis of the measured variation in the delay.

Abstract: A radio frequency FET amplifier has an FET which commonly amplifies a plurality of radio frequency signals and a bias power supplying circuit which varies bias power supplied to the FET according to the number of inputted radio frequency signals. A DC/DC converter controls supply voltage according to control voltage corresponding to the number of inputted radio frequency signals, thus generating a converter output voltage proportional to the control voltage. A constant current circuit supplies drain voltage substantially equal to the voltage to the drain terminal of the FET and also supplies gate voltage to the gate terminal of the FET so as to hold the drain current therein substantially constant. Power consumption is reduced depending on changes in the number of inputted radio frequency signals, while suppressing variations of harmonic distortion component peak level and frequency characteristics.

Abstract: An apparatus for measuring an electric field of an incoming signal implemented in a mobile communication system is disclosed. The apparatus comprises heterodyne receiver for heterodyning the incoming signal with a local signal to detect electric field information of the incoming signal, a local oscillator provided with phase-locked loop circuit, wherein the local oscillator produces a local signal through the phase-locked loop when receiving a first selection signal, and the local oscillator, when receiving a second signal, produces a local signal having a frequency which varies in accordance with a prescribed voltage change, and a controller which provides a first selection signal to the local oscillator when a normal measurement of the electric field is to be effected and provides a second selection signal to the local oscillator when a rapid measurement of the electric field is required.

Abstract: An optical micro cell transmission system comprising a radio base station, at least one optical interface section connected to the radio base station, and an optical forward base station connected to the optical interface section via optical fibers for transmitting and receiving signals through an antenna, and being flexible for the variation of an amplifier due to a change in temperature or a change in the length of an optical segment, and also being available for detecting faults in the optical forward base station is provided. Pilot signal generators 30, 51 are provided for generating pilot signals. For a transmitted signal 11, a coupler 21 in the optical interface section convolutes a pilot signal P.sub.D, and a demodulator 48 in an optical forward base station detects the level of the pilot signal P.sub.D and controls a downward signal amplifier 42 according to the result of detection.

Abstract: A high frequency signal detecting circuit capable of smoothing a mean power in each time slot and performing rapid response during transition time. A detector detects the envelope of a radio frequency signal whose power level may change depending on the time slot. In response to a control signal, a filter narrows the pass band in the data field of each time slot and broadens it in the transition field of the same. The output of the detector is applied to the filter. The detecting circuit, therefore, produces an output which is smoothed in the data field without regard to the content of data and which responds to a change in the power level sharply in the transition field.

Abstract: Switching circuitry incorporated in a system including a plurality of signal processing circuits having an identical function. The circuitry has a selector and a controller which replace, in response to alarm signals from individual signal processing circuits, the processing timing of a failed signal processing circuit with that of another signal processing circuit which is normal.

Abstract: The present invention provides an output level control circuit for a transmitter of an automobile telephone system which can output a transmission output signal of an output level indicated by a level setting signal with a high degree of accuracy. First and second level control circuits function for a low-level side and a high-level side, respectively, of the detection output of a detection circuit and perform weighting such that the outputs vary with linearity relative to the output signal of the amplifier. A control signal generation circuit causes a selection circuit to select a first or second error signal of a first or second comparison circuit, respectively. The first and second comparison circuits receive the output of the first or second level control circuit, respectively, and these control circuits process the detection output corresponding to the output level of the output signal of the amplifier indicated by a level setting signal.

Abstract: For use in amplifying an input signal having an input electric power in response to an amplification control signal to produce an output signal having an amplified electric power and a desired waveform, a power amplifying circuit comprises a reference signal generator (22) for generating a reference signal with a predetermined waveform which defines the desired waveform. A multiplier (23) multiplies the reference signal and a power control signal produced by a power control signal generator (21) to produce a level control signal. A comparator (17) compares the level control signal and a detection signal produced by a detector (14) to produce an error signal. A driver (18) drives a power amplifier (11) based on the error signal.

Abstract: A detector for detecting changes in the output level of an amplifier included in, for example, a mobile communication signal. A first detecting circuit produces a detected voltage having linearity against low output levels of the amplifier. A second detecting circuit produces a detected voltage which is linear against high output levels of the amplifier. The detected voltages from the first and second detecting circuits are mixed by a mixer in a predetermined ratio. Even when the output level of the amplifier changes over a broad dynamic range, the detector detects the changes with accuracy.

Abstract: In a signal control apparatus for controlling an apparatus input signal to produce an apparatus output signal, a signal producing circuit (11) produces a reference signal in accordance with a plurality of original waveform signals generated by first and second generating circuits (31, 32). The reference signal is compared by a comparing circuit (13) with an output waveform signal which is produced by a detecting circuit (12) dependent on the apparatus output signal. The comparing circuit produces a difference signal representative of a difference between the reference signal and the output waveform signal. Under control of the difference signal, an amplifier (14) processes the apparatus input signal into the apparatus output signal.

Abstract: An output waveform control circuit for a time division multiple access system (TDMA), including a second driving circuit which sends a control signal to the power amplifier in accordance with a signal outputted by the comparator circuit. Thus, by controlling the operating voltage of the power amplifier simultaneously with the control of the level input signal from the input level control circuit, the output characteristic of the power amplifier, including a class C or the like amplifier having a non-linear input/output characteristic, is prevented from varying abruptly, and the output waveform of the power amplifier is so controlled as to have gently sloped leading and trailing edges.