Abstract:
The present invention provides a path-diversity system featuring a small-size phase compensating circuit. This circuit calculates a compensating coefficient according to the signals of a pilot block or a pair of pilot blocks surrounding an information block, and then compensates information signals thereafter by the calculated compensating coefficient.
Abstract:
A complex multiplication circuit of a calculation formula equivalent but different from the usual formula.The calculation formula is as follows:Pr={x(a+b)-b(x+y)} equivalent to (ax-by)Pi={y(a-b)+b(x+y)} equivalent to (ay+bx)Here,Input signal: x+jyMultiplier:a+jbMultiplication result:Pr+jPi.
Abstract:
A computational circuit for a multi-value addition comprising a parallel adder, an output adder, a quantizing portion and a logic conversion portion. Addition circuits in the above adders and thresholding circuits in the above quantizing portion consist of voltage-driven circuits including capacitive couplings.
Abstract:
This invention reduces electric power consumption of a CDMA communication system receiver while it is in the wait mode. A received spread spectrum signal is demodulated in multiplication means into baseband signals Ri and Rq, and inputted into a complex matched filter. This filter is intermittently driven by supply voltage control means to perform acquisition of received signals. When an electric power calculation circuit detects the output of the filter to reach a peak equal to or greater than a predetermined value, the received signals undergo acquisition by controlling n number of correlators 26-1 to 26-n to work by a correlator controlling circuit. Moreover, de-spreading is performed. The outputs from each correlator 46-1 to 26-n are given to a RAKE combiner and demodulated by the RAKE by a combining and demodulating circuit.
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:
A matched filter with reduced electric power consumption is disclosed. The matched filter circuit power consumption is reduced by stopping the electric power supply to an unnecessary circuit since input signal is partially sampled just after an acquisition. Since the spreading code is 1 bit data string, the input signal sampled and held is branched out into the signal groups "1" and "-1" by a multiplexer. The signals in each groups are added in parallel by a capacitive coupling, and the electric power is supplied in the circuit intermittently.
Abstract:
The present invention has an object to provide an inverted amplifying circuit with improved accuracy of output and reduced electric power consumption. In an inverted amplifying circuit according to the present invention, a MOS switch is connected between pMOS and nMOS of a CMOS inverter and between balancing resistances. The MOS switch is opened when the inverted amplifying circuit does not work.
Abstract:
A matched filter having a set of registers to successively store a digital voltage. The matched filter includes a cumulative shift register, a number of exclusive-or circuits, and an analog adder. The cumulative shift register has a number of stages in which each stage has one bit corresponding to the shift register. The exclusive-or circuits each perform an exclusive-or function on each bit of the digital data and the one bit coefficient while the analog adder sums outputs from the exclusive-or circuits.
Abstract:
An analog to digital converter comprises a differential input portion that receives an input voltage and a reference voltage and has a first and second output terminals, a positive feedback portion connected to said first and second output terminals, a buffer if CMOSFETs connected at its input to the first output terminal, a second buffer connected at its input to the second output terminal, and a comparison circuit including a first switching portion connected between the first and second output terminals for connecting and disconnecting the first and second output terminals in response to a comparison clock signal. The comparison circuit is connected at its output to the first or second buffer. The input voltage and the reference voltage are compared when said switching portion changes from the connecting condition to the disconnecting condition in response to the comparison clock signal.
Abstract:
An output of analog complex matched filter is simplified to be a one dimensional signal such as electrical power. Multi-path detection is performed by the simplified signal. The output of the matched filter is received and processed only when peaks occur in the one dimensional signal.