Abstract: In a noise canceling method and an apparatus therefor which notices the colored noise looked macroscopically, positively cancels the dominant noise component in the low frequency band, shifts the S/N value to plus, and can extract the reception signal buried in the low frequency band and having a comparatively high level, a signal in which a time axis, an amplitude, and a phase are specified or a zero-point signal is inserted into a transmission signal by an inserter, a noise component is interpolated by using the specified signal or the zero-point signal by a noise canceler, and an originally transmitted signal is regenerated by subtracting the noise component from the reception signal.

Abstract: A PLL circuit that causes an internal oscillation signal to lock to an external input clock signal, and is capable of suppressing jitter. The PLL circuit includes a frequency dividing circuit for frequency-dividing an input clock signal; a voltage-controlled oscillator; a missing-pulse clock signal creation circuit for creating, based on an output signal of the voltage-controlled oscillator, a missing-pulse clock signal having a higher speed than that of an output signal of the frequency dividing circuit and having a periodic missing-pulse portion; a phase comparator circuit for sampling the output signal of the frequency dividing circuit by using the missing-pulse clock signal; a shift register for storing a change in the output signal of the phase comparator circuit; and a digital signal processing circuit for converting a value stored in the shift register into a phase difference, and for controlling the input voltage to the voltage-controlled oscillator based on the phase difference.

Abstract: A transmission system for transmitting a data signal with an analog passband signal through a analog transmission line. The data signal is transformed to a signal representing a descrete data signal point in a vector signal space. The analog passband signal is transformed to a base band signal, and the base band signal is superimposed on the signal representing a descrete data signal point. A signal representing the superimposed data signal point is modulated and transmitted through the analog transmission line. In a receiver, the data signal point is decided from the signal representing the superimposed data signal point, and the superimposed bass band signal is extracted by subtracting the decided result from the signal representing the superimposed data signal point. The base band signal is transformed to the analog passband signal. A portion of information carried by the analog passband signal may be converted to a digital signal, and the digital signal is multiplexed with the data signal.

Abstract: A radio network is composed of a plurality of communications chips. The communications areas of the communications chips overlap one another. A gateway connects the radio network to another network and manages the radio network. When a radio signal is transmitted from a terminal device, each communications chip generates and outputs a corresponding radio signal in order that the signal level of the radio signal becomes a prescribed level. In this way, radio signals transmitted from a terminal device are propagated all over the area of the radio network.

Abstract: A frequency modulation method and modem unit for a frequency modulation using a common filter which uses a large number of carrier frequencies include a frequency-shifting unit for subjecting an input data to a frequency shift corresponding to a binary data value, a filter for limiting an output obtained by the frequency-shifting unit to a common band, and a modulation unit for frequency-modulating an output obtained by the filter, by a carrier frequency having an intermediate value of the frequencies respectively corresponding to the binary data values.

Abstract: A frequency modulation method and modem unit for a frequency modulation using a common filter which uses a large number of carrier frequencies include a frequency-shifting unit for subjecting an input data to a frequency shift corresponding to a binary data value, a filter for limiting an output obtained by the frequency-shifting unit to a common band, and a modulation unit for frequency-modulating an output obtained by the filter, by a carrier frequency having an intermediate value of the frequencies respectively corresponding to the binary data values.

Abstract: A signal processing apparatus having a register unit with the number of bits required for signal processing, which is not larger than predetermined number of bits, and comprising a ROM which inputs, as an address signal, an output signal from the register unit or an input signal to the signal processing apparatus, and uses an input signal to the register unit as a part of an output signal from the ROM. This makes it possible to greatly reduce the cost of a system which executes complex processing yet requires a reduced number of bits in the input signals and a reduced number of bits for the register that is essentially required by reducing the amount of signal processing and the number of electric components, to greatly improve the quality of the apparatus accompanying the reduction in the number of electric components, and to cheaply increase the signal processing functions without decreasing the processing speed.

Abstract: A transmission system for transmitting a data signal with an analog passband signal through a analog transmission line. The data signal is transformed to a signal representing a descrete data signal point in a vector signal space. The analog passband signal is transformed to a base band signal, and the base band signal is superimposed on the signal representing a descrete data signal point. A signal representing the superimposed data signal point is modulated and transmitted through the analog transmission line. In a receiver, the data signal point is decided from the signal representing the superimposed data signal point, and the superimposed base band signal is extracted by subtracting the decided result from the signal representing the superimposed data signal point. The base band signal is transformed to the analog passband signal. A portion of information carried by the analog passband signal may be converted to a digital signal, and the digital signal is multiplexed with the data signal.

Abstract: An automatic gain control circuit includes a first portion which calculates a first error amount, and a second portion which calculates a second error amount. Both calculated error amount is sent to a determination module. Further, an integrator integrates an error amount, a difference between a power of an input signal and an average power of an eye pattern for example. The determination determines whether the integrated error amount exceeds a predetermined value or not, and output either of the first error amount and the second error amount based on the determination.

Abstract: A modem connected to a radio which compensates for the characteristics of the radio side to make them suitable for data transmission without changing the characteristics of the radio and thereby increase the transmission speed. Therefore, a transmission side modem is provided with a deemphasis filter for compensating for the characteristics of a preemphasis filter of the radio transmitter, and a receiving side modem is provided with an emphasis filter for compensating for the characteristics of the deemphasis filter of the radio receiver so as to compensate for the characteristics of the radio. Further, in the signal constellation when selecting a signal point of input data, redundant signal points are added to the outside of the constellation to enable emphasis of the in-phase components of the preceding and succeeding signal points.

Abstract: A limiter is connected with the output of a PLL to limit the amplitude of the output from the PLL. The output from limiter is supplied to a voltage-controlled oscillator (VCXO). The limiter determines the difference between the input signal and the output signal. If the difference exceeds a predetermined value, the change in the output from the limiter is limited to the predetermined value. If the difference does not exceed the predetermined value, the change in the output is considered to be a difference value.

Abstract: A bandpass filter 51 extracts a Nyquist tone signal from an input signal, and a power calculation unit 52 checks the level of the extracted tone signal. A line equalizer control unit 53 controls a line equalizer 42 based on the level of the calculated tone signal. If the level of the tone signal fluctuates beyond a prescribed range, a level adjustment circuit compulsory activation control unit 54 compulsorily activates the line equalizer control unit 53, and if it is judged from the level of the tone signal that the apparatus is in a normal communication state, the level adjustment circuit compulsory activation control unit 54 nullifies the compulsory activation of the line equalizer control unit 53.

Abstract: A transmitter has a power calculation unit for calculating the power of a signal. A maximum value detection circuit determines a maximum value of an output of the power calculation unit, and a floating point transformation circuit changes an output of the maximum value detection circuit into a floating point representation. A significant bit extracting circuit extracts significant bits from an output of the floating point transformation circuit and outputs the significant bits as the transmitting signal.

Abstract: A signal processing apparatus having a register unit with the number of bits required for signal processing, which is not larger than predetermined number of bits, and comprising a ROM which inputs, as an address signal, an output signal from the register unit or an input signal to the signal processing apparatus, and uses an input signal to the register unit as a part of an output signal from the ROM. This makes it possible to greatly reduce the cost of a system which executes complex processing yet requires a reduced number of bits in the input signals and a reduced number of bits for the register that is essentially required by reducing the amount of signal processing and the number of electric components, to greatly improve the quality of the apparatus accompanying the reduction in the number of electric components, and to cheaply increase the signal processing functions without decreasing the processing speed.

Abstract: A transfer process in which, an original vector signal is precoded to an intermediately-precoded vector signal, and the extended modulo operation is performed when the intermediately-precoded vector signal is located outside a predetermined extended-modulo limit area, and the precoded vector signal is transferred through a system having a predetermined filtering characteristic. From the transferred vector signal, the original vector signal is detected, based on a relationship between the vector components of the original vector signal and the transferred vector signal.

Abstract: A preceding apparatus for calculating a difference between an inputted signal point and an output signal obtained one timing before and outputting the difference has a position information judging unit for judging which position on a vector plane the output signal obtained one timing before is located in, and a signal point selecting storage for outputting any signal point among a plurality of signal points generated correspondingly to a signal point inputted from the outside with a result of the judgement fed form the position information judging unit nd the signal point inputted from the outside as an address, thereby decreasing the number of cycles required by a DSP process and realizing a precoder process in a degree achieved hitherto.

Abstract: Disclosed is a modulation method in which the frequency band of a transmission signal, consisting of signal points generated at a given modulation rate in accordance with transmission data, is shifted by a desired frequency shift amount, and which is capable of lowering carrier frequency without increasing the amount of computation.

Abstract: In a modem signal transmitting/receiving system which includes a modem signal transmitter and a modem signal receiver connected to each other via a transmission line, a modem signal transmitter is suitable to transmit by multiplexing an analog signal such as audio and a modem carrier with digital data. Analog signals and digital data can be multiplex-transmitted at a high rate by effectively using an analog signal line. The modem signal transmitter includes a modem transmitting unit, an analog/digital converting unit which converts an analog signal into a digital signal, a demodulating unit which demodulates the digital signal with a predetermined carrier frequency signal, a decimation processing filter which decimates the demodulated signal and a deciding unit which decides a coordinate on a two-dimensional plane for the output from the decimation processing filter and then inputs the decision result to the modem transmitting unit.

Abstract: A transfer process in which, an original vector signal is precoded to an intermediately-precoded vector signal, and the extended modulo operation is performed when the intermediately-precoded vector signal is located outside a predetermined extended-modulo limit area, and the precoded vector signal is transferred through a system having a predetermined filtering characteristic. From the transferred vector signal, the original vector signal is detected, based on a relationship between the vector components of the original vector signal and the transferred vector signal.

Abstract: The invention provides a training method for a non-Nyquist transmission system and a training data transmission apparatus for a non-Nyquist transmission system by which initialization processing of a reception section can be performed with certainty even where a non-Nyquist transmission system is employed.