Abstract: A correlating filter includes a delay circuit which outputs a plurality of tap output signals TP1 to TPn having different delays. The correlating filter further includes a weighted adder circuit which weights the tap output signals, respectively, and adds the weighted tap output signals so as to derive a correlated output signal. A timing control circuit produces a control signal based on the correlated output signal from the weighted adder circuit. The control signal is high in level when the correlated output signal has a correlation peak. A power feed to the weighted adder circuit is achieved via a switching element. The switching element is only turned on when the control signal is high in level so as to enable the power feed to the weighted adder circuit. Thus, reduction in power consumption is achieved and the filter can be used in a portable radio device.

Abstract: A signal characterizer for performing functional transformations such as Fast Fourier Transforms (FFTs), which converts an input serial analog signal into a plurality of parallel discrete signals using an analog-type serial-to-parallel converter. The discrete signals are then supplied to the input terminals of butterfly operation circuits to process the parallel discrete signals into a plurality of transformed signals. A switch supplies the transformed signals to a serial signal output terminal. The switch is controlled by a controller so that the input signal sequence is converted to a serial signal sequence according to a predetermined order.

Abstract: A multi-user demodulator eliminates synchronization problems without interference cancellation. A threshold process is applied to a despread signal to extract each user's signal. The extracted signals are respread, and those respread signals other than a specifier user's signal are subtracted from the received signal to ideally extract the specific user's signal.

Abstract: A fast spread spectrum communication system is provided, having fewer circuits and requiring fewer PN codes to be assigned to a user. A series of digital data to be transmitted, is divided into 4-bit frames. The 4-bit data of each frame is divided into the first through fourth elements in a predetermined order. The first complex number is constructed by the first and second elements, and the second complex number is determined according to the value of the third and fourth elements. The spectrum of the data to be transmitted is spread by multiplying these complex numbers. Four matched filters despread a received signal by different combinations of PN codes stored in a receiver. The first through fourth elements are recovered according to the outputs of the matched filters.

Abstract: The present invention solves the conventional problems and has an object to provide a matched filter system of high process in speed, a small size and low electric power consumption. The matched filter circuits of each matched filter set is allocated different n combinations of M/n digits selected from the M length PN code sequence picking one out of every n digits, cyclically performs sampling every 1 chip time duration the input signals to be inputted to each set constructed by matched filter circuits by n sets each of which including n matched filter circuits, and calculates the sum of outputs of all matched filter circuits.

Abstract: The demodulator has a plurality of matched filters in parallel. Each matched filter has a different binary PN code, a plurality of sample holders, a plurality of multipliers, an adder, and a controller. The sample holders has a common input, a switch, a first capacitor, a first inverse amplifier with an output and an input connected to the common input through the switch and the capacitor, and a first feedback capacitor for feeding the output of the first inverse amplifier back to the input. Each multiplier has a first and second sub-multiplexers, one of sub-multiplexer selecting corresponding sample holder output and another sub-multiplexer selecting a reference voltage.

Abstract: There is disclosed an acceptable error detector for error correcting block codes, in which of received syndrome vectors S for the received word vectors Y available from the syndrome generator, the m.sub.e -bit received subsyndromes S(m.sub.e) formed by the same components as those of the m.sub.e -bit representative subsyndromes <S(m.sub.e)> uniquely corresponding to the vectors of all the acceptable error pattern with error bits equal to or less than the acceptable number e is applied as addresses into the redundant subsyndrome table memory. Since the stored data specified by the input address are (m-m.sub.e)-bit redundant subsyndromes <S(m-m.sub.e)> which are supposed to appear in the remaining portion of S(=<S>) when the number of error bits is equal to or less than e, the remaining (m-m.sub.e)-bit received subsyndromes S(m-m.sub.e) derived from the received word vector Y in the syndrome generator and the (m-m.sub.e)-bit redundant subsyndrome <S(m-m.sub.

Abstract: An intermittenceless switching system includes two speech path memories having sufficient capacity to store a single frame of data having a plurality of time slots. The incoming data is stored in one memory, while the outgoing data is read from the other memory. A control circuit continuously alternates the read/write functions between the two memories. A control memory is used to store switch control information. The system includes a buffer memory that is present between a data processor and the control memory to prevent switch operation during data transmission. The system also includes a monitoring circuit for detecting an indication bit signifying the presence or absence of data in the time slot.

Abstract: A mobile radio telecommunication system and method provide battery-saving receiving of mobile stations. The mobile station autonomously changes the period of intermittence according to the frequency of paging in order to reduce the power consumption of the mobile station. When there has not been paging processing for a fixed time, the mobile station autonomously prolongs the period of intermittence and reregisters a new period of intermittence. In case there has been paging processing, the mobile station shortens the period of intermittence. If blocking has occurred for paging from the cell site, the cell site incorporates blocking information into a broadcast signal, informs the mobile station of occurrence of blocking, and registers a new period of intermittence.

Abstract: A speech coding circuit is disclosed, which comprises a PCM encoder for converting an analog input into a digital output, and a speech coder with voice activity detector which encodes the digital output from the PCM encoder into speech coding data and detects whether the analog input is voice active or non-active, for each period, and then outputs a speech detection flag indicating whether the analog input is voice active or non-active. A power comparator compares the power of the analog input with a predetermined power threshold value and outputs a level detection flag indicating voice activity or non-activity, depending on whether the power of the analog input is greater or smaller than the power threshold value. A mode switch receives the level detection flag indicating voice activity or non-activity and applies to the PCM encoder and the speech coder a mode control signal which puts them into an activated mode or a sleep mode.

Abstract: A quaternary-level waveform generator in which a modulation wave prior to a band restriction (a quaternary-level square wave sequence) is separated into two binary-level square wave sequences and as waveform components prestored corresponding waveform component outputs after a predetermined band restriction are read out of a waveform component generating read-only memory and added to generate a desired quaternary-level waveform shaped by the band-restriction.

Abstract: A multi-level band-restricted waveform generator in which a modulation wave prior to band restriction (M-level signal sequence) is broken into elementary waveforms and a plurality (N-nary) of prestored waveform components corresponding to the elementary waveforms after predetermined band restrictions are read out of a read-only memory for generating waveform components and added to generate a desired multi-level band-restricted waveform.