Abstract: Apparatus and method for digital frequency discrimination are provided that only require one sample per data symbol (e.g. one bit for BPSK or 2 bits for QPSK). This is accomplished by determining the difference between the carrier phase error on successive data symbols. The difference in phase error is then used as an approximation to the derivative of the phase error, which is the frequency error between the carrier and the local oscillator of the receiver. An important advantage of this apparatus and method is that they allow the maximum symbol rate to be processed by the receiver for a given digital technology. In other words, maximum symbol rate can now be equal to the maximum clock rate of the digital technology, if so desired by the user. In contrast, conventional digital frequency discriminators limit the maximum symbol rate to one-half or one-fourth of the maximum clock rate for a given digital technology.

Abstract: A QPSK demodulator that is smaller in size and lower in cost by restricting a storage capacity needed for a TAN.sup.-1 ROM to a minimum. Values of I and Q channel base band signals obtained by converting and quantizing a received signal are approximated to a nearest one of values on (2.sup.N-3 +1) segment lines represented by Q=(n/2.sup.N-3)I, where n=0, 1, . . . , 2.sup.N-3, with a phase accuracy of positive N bits. Data corresponding to the approximated segment line is previously stored in a TAN.sup.-1 ROM as phase arithmetic data. An address decoder converts each base band signal into an address. An arithmetic circuit obtains phase data, for obtaining a QPSK demodulated signal, by performing a predetermined arithmetic operation, which is commensurate with the size of I and Q channel base band signals, on phase arithmetic data stored in the TAN.sup.-1 ROM in association with the converted address.

Abstract: A method and apparatus for communicating with chaotic and other waveforms employs a filter for estimating a parameter that describes a property of a signal. The filter is constructed by defining a system that models the source of the signal. The system is partitioned into a first subsystem that contains the parameter and a second subsystem that does not contain the parameter, the second subsystem including a term that makes the second subsystem stable and synchronizable with the signal. The signal is introduced as input to the second subsystem and an element of the second subsystem is substituted into a corresponding element of the first subsystem, thereby generating a signal-activated subsystem. An integration factor is introduced to the signal-activated subsystem to cause the parameter to behave as a constant when the signal-activated subsystem with the integration factor is integrated with respect to time.

Abstract: A transformer. According to one embodiment, the planar transformer has a first winding, a first conducting surface adjacent to the first winding, a second winding and a second conducting surface adjacent to the second winding. The first conducting surface is coupled to a first ground and the second conducting surface is coupled to a second ground.

Abstract: An FM demodulator having two input terminals (11, 12), to which FM input signals having 90.degree. phase relation are applied, the said FM demodulator including a phase comparator (1) and a tunable, phase shifting circuit (2), the phase shifting circuit (2) being tuned by the FM demodulator output signal via a feedback path comprising a loop, filter. By adding a compensation filter (5) to the tuning control loop the phase shifting circuit is effectively cancelled from the tuning control loop, thereby making the tuning control loop independent of the bandwidth of the phase shifting circuit (2). Thus the bandwidth of the phase shifting circuit (2) can be reduced for threshold extension.

Abstract: A heterodyne receiver including a frequency discriminator adapted such that a signal to be subjected to frequency discrimination is divided into two signals and mixed together after one of the divided signals has been given a delay time, and additionally provided with a filter, of which a cutoff frequency is determined according to the delay time, disposed in the front stage. This results in both improvement of accuracy in frequency identification and expansion of the capture range.

Abstract: An information signal processing apparatus according to the present invention is arranged to receive as an input a frequency-modulated information signal having a predetermined frequency band, form a sample pulse signal by sampling the input frequency-modulated information signal in accordance with a clock signal having a first frequency which is selected so that a frequency which is 1/n times (n is a positive integer) a frequency of half the first frequency is positioned in a frequency band lower than the frequency band of the input frequency-modulated information signal and so that a frequency which is (n+1) times (n is a positive integer) the frequency of half the first frequency is positioned in a frequency band higher than the frequency band of the input frequency-modulated information signal, and demodulate the frequency-modulated information signal by performing computing processing of the formed sample pulse signal in accordance with the clock signal having the first frequency.

Abstract: A frequency demodulation circuit having an improved detection sensitivity is provided by forming an all-pass equalizer in a Quadrature-type demodulator capable of allowing a band covering at least a carrier frequency deviation to pass therethrough. The equalizer comprises a band-pass filter for detecting the frequency deviation of an inputted FM carrier signal, a gain-doubling amplifier and a substractor for performing subtraction between the signal inputted to the band-pass filter and the output of the amplifier. The operation of the circuit is such that a FM carrier signal is supplied to the band-pass filter through a phase shifter and to a phase comparator and the output of the substractor and the FM carrier signal are compared to each other by the phase comparator to thereby obtain a FM demodulated signal.

Abstract: An apparatus and method is provided of recovering a frequency modulated signal having a first component of the frequency modulated signal at a zero-RF spectral location and a second component of the frequency modulated signal at a zero-RF spectral location in quadrature relationship to the first component. The method includes the steps of: upconverting and summing the first and second components to produce a reference signal (100), time delaying the first and second components, upconverting and summing the delayed, upconverted first and second components to produce a delayed reference signal (101) in quadrature relationship to the reference signal; limiting the reference and delayed signal (102); and exclusive or-ing (103) the limited reference and limited delayed signal.

Abstract: A radio communication apparatus used for both digital communications and analog communications is disclosed which comprises a digital signal processor DSP (4) which processes many kinds of digital signals according to a plurality of signal procedures (55,56,57,58) stored in the ROM (5). In the present invention, since the radio communication apparatus processes many kinds of procedures (55,56,57,58) stored in the ROM (5), the size of the apparatus becomes small and weight becomes light.

Abstract: A method of recovering a frequency modulated signal wherein the frequency modulated information signal is sampled at a rate less than the Nyquist sampling rate, following which the under sampled signal can be demodulated to extract the original information signal.

Abstract: A method and apparatus for extracting information from human speech are dislosed. A speech signal is received into a bank of bandpass filters and the instantaneous amplitude modulation and frequency modulation of each harmonic in the speech waveform is determined. A logarithm of the instantaneous frequency of the speech fundamental frequency is determined, for example, by computing a weighted average of the frequency modulations of the harmonics. An output signal is formed having the logarithm of the frequency of the thus determined speech fundamental and the logarithms of the amplitude modulation for the ten lowest frequency speech harmonics and/or the speech envelope.

Abstract: In an FM demodulator which is used in a video tape recorder and in which the linearity of input/output signals is not easily assured to increase a demodulation enable frequency, an FM signal is supplied to the base of a first transistor constituting a first differential amplifier, and a constant voltage is input to the base of a second transistor. A constant voltage is applied to the base of a third transistor constituting a second differential amplifier, and an FM signal having a phase opposite to the FM signal supplied to the first transistor is supplied to the base of a fourth transistor. A capacitor is connected between the emitters of the first and second transistors and the emitters of the third and fourth transistors. A first constant current circuit is arranged between the emitters of the first and second transistors, and a second constant current circuit having a current value twice that of the first constant current circuit is arranged between the emitters of the third and fourth transistors.

Abstract: A system and method for encoding and decoding a frequency-shift keyed data signal for transmission over a non-ideal communications channel that utilizes phase-coherently combined halfwave segments of sinewaves with a finite number of different frequencies and equal amplitudes. A stream of data characters is encoded into a transmit sequence {S(n)} of positive numbers which defines an ac signal of halfwave segments of sinewaves of fixed, preselected amplitude. The ac signal encoding the stream of data characters is transmitted over the communications channel and received as a perturbed ac signal. The received signal is identified by consecutively determining the time durations between peak values or between zero crossings of each segment yielding a receive sequence {E(n)} of positive numbers. All or parts of this receive sequence are then compared with each of a set of preselected, stored sequences, each representing a stream of none, one or more data characters.

Abstract: A signal processing circuit utilizes a convolver correlating a reference carrier signal with a received signal. The correlator output is detected and then demodulated to output the signal information originally present on the carrier. For a conventional AM signal the reference carrier signal is applied at a frequency offset from the AM center frequency. When the carrier is an FM signal, the reference signal is applied at a frequency equal to the center frequency of the FM signal. Similar procedures are followed for a spread-modulated AM signal, and the reference signal is modulated with a suitably timed-reverse replica of the pseudo-noise code. A similar procedure is used to process spread-spectrum frequency shift keyed FM signals.

Abstract: The disclosed decoder (14) produces an output signal when a receiver (12) signal contains frequencies that are sequentially within a predetermined passband surrounding detection frequencies f.sub.1 and f.sub.2. The receiver signal is mixed at exclusive-OR logic gates (52, 54) with cophase reference signals R1 and R2, which are produced by a reference tone generator (18) and have a frequency f.sub.r that corresponds to the desired tone detection frequency f.sub.1 and f.sub.2 and a phase difference of 90.degree.. The outputs of gates (52, 54) are applied to low pass filters (56, 58), which produce outputs having a frequency .DELTA.f equal to the absolute value of the difference between the input and reference frequencies f.sub.i and f.sub.r, provided that .DELTA.f is below the filter's cutoff frequency f.sub.c1.

Abstract: An FM demodulator circuit uses an oscillator to provide a switch control signal synchronized to an FM signal, and a current supply to provide differentially alternating currents at first and second outputs flowing through a commutator circuit to the first and second outputs of the FM demodulator circuit. The commutator circuit is responsive to the switch control signal for alternately switching the first and second outputs of the current supply between the first and second outputs of the FM demodulator circuit thereby providing an alternating current flowing in the first and second outputs of the FM demodulator circuit which has an average value over each half cycle of the switch control signal proportional to the deviation of the frequency of the FM signal from the free-running frequency of the oscillator.

Abstract: Intermediate frequency signals are produced by mixing with an oscillator voltage and subsequently filtered and demodulated. The oscillator voltage or the resonance frequency of the filter or filters are followed up by a control voltage derived from the demodulated signal corresponding to the intermediate frequency. The perturbatory phase modulator occurring as a result of the control lag is compensated by opposite-phase phase-modulation which is superimposed on the intermediate frequency. In this, the phase modulation is achieved by a phase modulator which is connected with the output of a demodulator by a matching circuit. Another possibility for achieving phase modulation of the intermeidate frequency is to modulate the oscillator of the mixing stage.