Abstract: A base station of a CDMA communication system includes a transmission de-correlator for eliminating interferences between communication channels of a downlink. The transmission de-correlator has a memory storing a set of data representative of the products of transmission information bits for the respective channels, and the sums of the products of the spread code data sequences for the respective channels, and the elements of an inverse matrix with respect to a predetermined matrix of a cross-correlation between the spread code data sequences for the respective channels. The sums correspond to additions of the products along a direction of columns or to additions of the products along a direction of rows of the inverse matrix. A counting device is operative for causing the memory to sequentially output the data therefrom. An adder serves to calculate a sum of the data outputted from the memory.

Abstract: Radio zones 2a through 2d are each assigned radio frequency channels of the number corresponding to the zone traffic, one frequency f1 of the radio frequency channel is assigned in common to all radio zones, and radio channels of the same frequency are assigned spectrum spreading codes different for each zone. A mobile station is provided with two correlators 14 and 15. If the received signal level lowers when the mobile station stays in the radio zone 2a and is in conversation over the channel of a frequency f2, the mobile station once switches the communication to a channel of the common frequency f1 and continues the communication using one of the correlators, while at the same time the mobile station scans spectrum spreading codes for control channels of the respective radio zones by the other correlator for measuring the received signal levels of the control channels and determines a destination radio zone which provides the maximum received signal level.

Abstract: In order to change a subscriber alert mode of a radio pager from an audible alert mode to an inaudible alert mode, a normally open function switch is depressed while the radio pager operates in the audible alert mode. The function switch is subsequently depressed. Following this, a timer is set to count up to a predetermined time period. A pager display exhibits a silent time duration for which the pager will operate in the inaudible alert mode if the timer counts up the predetermined time period. Subsequently, another timer is set to count up to a predetermined time period if the function switch is released. Thereafter, if the second timer counts up the second predetermined time period and if the function switch remains released, the radio pager is set to operate in the inaudible alert mode for the set silent time duration.

Abstract: A received signal of a control channel of each cell is despread by each spreading code in a correlation detector. The received level of the despread output in a window, including its peak, is measured in a level measuring part and an interference signal level outside the window is also measured. In a control part the difference or ratio between the measured received level and the interference signal level is obtained as a comparison signal for each spreading code, and the comparison signal is compared in terms of magnitude to thereby determine the visited cell of a mobile station.

Abstract: A dielectric plate 21 can be mounted on a housing 11 in such a manner that it is slidably retracted into the housing. A strip antenna element of an electrical length approximately equal to a quarter wavelength is formed on one side of the dielectric plate along one marginal edge thereof, and an antenna element 23 composed of a straight conductor portion 23a and a coil 23b connected at one end thereto is formed on the dielectric plate 21 just above the strip antenna element 22. The electrical length of the antenna element 23 is also equal to a quarter wavelength. A parallel twin-lead type feeder of a length nearly equal to the quarter wavelength is also formed on the dielectric plate 21 in parallel to the strip antenna element 22. The feeder 26 is connected at one end to inner ends of the antenna elements 22 and 23 and at the other end to a feeder 27 via contact pieces 29a and 29b. The feeder 27 is connected directly to a radio circuit 12 in the housing 11.

Abstract: For supply to first and second feedforward distortion compensating circuits 33(1), 33(2) connected in parallel, a two-divider 31 divides into signals of a common phase and a common amplitude an input or composite radio frequency signal supplied to an input terminal 11. The composite radio frequency signal collectively has a plurality of radio frequency signals of different frequencies. A two-combiner 35 combines component outputs of the feedforward circuits in inphase as an amplified output signal which is supplied to an output terminal 13. In general, N feedforward circuits (N being an integer not less than two) are connected in parallel and are supplied with the input radio frequency signal through an N-divider. Component outputs of the feedforward circuits are combined in inphase as the output signal by an N-combiner. Alternatively, the input radio frequency signal is divided into signals of a predetermined phase difference and of a common amplitude by the N-divider.

Abstract: In the selection of a control channel of a mobile station in a radio zone to which some control channels are assigned as communication channels, the receiving levels of the control channels are sequentially measured and control channel candidates are selected. A check is made to see if a control signal can correctly be received in each of the selected control channel candidates, and if not, the number of signal reception failures in that channel is incremented by 1 in a memory used by the mobile rotation. A channel in which the number of signal reception failures has reached a predetermined value M (an integer equal to or greater than 1) is excluded from the group of control channel candidates, and the other selected control channel candidates are similarly checked to determine whether or not the reception of the control signal is possible in each of them.

Abstract: A method of handover and route diversity in a mobile radio communication which is less time consuming and capable of improving the frequency spectrum utilization efficiency and securing the high quality of service regardless of the moving speed of the mobile station. In the method, a loop transmission line by which each base station is connected with neighboring base stations is provided; a handover information is transmitted through the loop transmission line, where the handover information is relayed by each base station from one of the neighboring base stations to another one of the neighboring base station; and the handover of a communication of a mobile station from one traffic channel of one base station to an idle traffic channel of another base station is carried out by using the handover information transmitted through the loop transmission line. The method can also be applied to a route diversity reception.

Abstract: A device for testing an amplifier. A plurality of PN modulators are provided corresponding to a plurality of oscillators at stages preceding or following them, or fluctuation is given to division ratios at the oscillators. Since each of n carriers combined by a combiner contains phase fluctuation, the possibility that the peaks will overlap each other or that the carriers having opposite phases will negate each other is very low. The peak power in signals supplied to the amplifier to be tested is unlikely to vary, enabling accurate evaluation or testing.

Abstract: In a power amplifying apparatus which has a high-frequency power divider and combiner and two to four parallel-operated power amplifiers, in which a change is made in the number of the parallel-operated power amplifiers so as to adjust output power, there are provided a power dividing circuit D.sub.1 having a transmission line Wd.sub.51 serving as an impedance transformer set in such a manner that the power loss is minimized by assigning an intermediate number 3 between 2 and 4 both of which indicate the number of divisions, and having four output terminals, and a power combining circuit S.sub.1 having a transmission line Ws.sub.51 serving as an impedance transformer set in such a manner that the power loss is minimized by assigning the intermediate number 3 indicative of the number of combinations, and having four input terminals.

Abstract: In a mobile communication system in which the service area is covered with a plurality of location registration areas each having a plurality of cells each relating to a specific base station, each location registration area has a plurality of groups so that the cells belonging to any group overlaps partly with the cells of other groups, but do not completely coincide with cells of other groups, and each mobile station belongs to one of said groups. When a mobile station moves beyond the border of location registration areas, the location updating for the mobile station is carried out at the cell in which the mobile station stays. In that case, as the mobile stations are classified into a plurality of groups, the traffic in each cell for location updating is dispersed to many cells, and the maximum traffic density for location updating per cell is reduced. So, the number of control channels in the system for location updating may be reduced.

Abstract: A control circuit for an automatically controlled feed forward nonlinear distortion compensation amplifier. The control circuit controls a distortion detection loop and a distortion removal loop. The distortion detection loop is a loop for feeding forward input to a main amplifier into a first directional coupler. The distortion removal loop is a loop for feeding forward distortion elements into a second directional coupler. The main amplifier is preceded by a variable attenuator and a variable phase shifter. A variable attenuator and a variable phase shifter are also located in a feed forward path to the second directional coupler. The control circuit controls the variable attenuator and the variable phase shifter preceding the main amplifier for detecting the distortion elements. The control circuit controls the variable attenuator and the variable phase shifter located in the feed forward path to the second directional coupler for removing the distortion elements.

Abstract: In a receiver comprising a receiver filter (12) with a frequency attenuation band and a pilot oscillator (25) for generating a pilot oscillation signal with a pilot frequency in the frequency attenuation band, a coupler (26) couples the pilot oscillation signal and a filtered receiver signal of the receiver filter to form a coupled signal. A low noise amplifier (13) amplifies the coupled signal into an amplified signal which comprises an amplified receiver signal component derived from the filtered receiver signal and an amplified pilot oscillation signal component derived from the pilot oscillation signal. A branching filter (27) branches the amplified signal into the amplified receiver signal component and the amplified pilot oscillation signal. A pilot signal component detector unit (28) detects the amplified pilot oscillation signal component to produce a direct pilot signal.

Abstract: A modulus counter counts first clock pulses to modulus M and outputs the count value as an m-bit reference signal, M being an integer. A latch circuit samples and holds the reference signal in response to a trigger signal generated by a trigger signal generator in synchronism with an input signal. A high-speed counter is supplied with second clock pulses of a frequency higher than that of the first clock pulses and starts counting the second clock pulses in response to the trigger signal and stops the counting in response to a first one of the first clock pulses immediately thereafter. A data processor converts the n-bit count value of the high-speed counter to n-bit data corresponding to a phase fraction of a phase quantization step in the latch, combines the n-bit data as low-order bits with m-bit data from the latch and outputs the combined data as phase difference data.

Abstract: A quadrature amplitude modulator capable of avoiding compensating the linear distortions completely and accurately by a simple configuration. The modulator includes a level signal generation unit for generating level signal for the modulated wave, and a parameter generation unit for determining appropriate values of linear transformation parameters of the linear transformation to be applied to the in-phase and quadrature amplitude input signals according to the level signal. In this modulator, the linear transformation parameters are determined sequentially in such an order that the linear transformation parameters for a DC off-set are determined first, then the linear transformation parameter for an amplitude balance is determined next while compensating distortion due to the DC off-set, and then the linear transformation parameter for an orthogonal phase relationship is determined while compensating distortions due to the DC off-set and the amplitude balance.