Abstract: A method includes a step of reading in the radio data signal and a radio data clock signal, a step of integrating a signal that is a function of the radio data signal and/or the radio data clock signal in order to determine an integral value curve, a step of decoding radio data signal information from the integral value curve, using the radio data clock signal and/or a phase position of the radio data signal, a step of ascertaining radio data signal quality information which represents the credibility of the decoded radio data signal information, using the radio data signal and/or the phase position of the radio data signal, and a step of providing the radio data signal information and the radio data signal quality information in order to provide a conditioned radio data signal.

Abstract: An audio system encodes and decodes audio captured by a microphone array system in the presence of wind noise. The encoder encodes the audio signal in a way that includes beamformed audio signal and a “hidden” representation of a non-beamformed audio signal. The hidden signal is produced by modulating the low frequency signal to a high frequency above the audible range. A decoder can then either output the beamformed audio signal or can use the hidden signal to generate a reduced wind noise audio signal that includes the non-beamformed audio in the low frequency range.

Abstract: Systems and methods of audio reproduction are described. In one embodiment, one or more processors can be configured, for example, to receive an L channel signal and an R channel signal, to combine the L channel signal and the R channel signal, to average the combined signal, to detect an impulse signal in the averaged signal, to multiply the impulse signal, to scale the multiplied impulse signal, and to add the scaled impulse signal to the averaged signal to form a resultant signal. Sound can be generated, for example, by speakers based on at least the resultant signal.

Abstract: Methods and systems for amplitude modulation in a parametric speaker system are provided that perform truncated double sideband (TDSB) frequency modulation of audio signal in which most of the processing is performed in the frequency domain, thus permitting use of fast processing techniques for amplitude modulation (AM) and filtering and reducing computation cost over time domain processing. A maximum envelope value of the time domain audio signal may be to the carrier signal in the frequency domain that avoids emitting the carrier signal when the input signal level is low or mute. The application of the envelope value may be smoothed to reduce discontinuity at input block boundaries.

Abstract: A receiving apparatus includes: a local oscillator to output first- and second-local-oscillator signals whose phases are orthogonal to each other; a mixer to output first- and second-intermediate-frequency signals; a first filter to allow a component from a desired signal to pass therethrough, and eliminate a component from an image signal having a frequency symmetrical with that of the desired signal, in the first- and second-intermediate-frequency signals; a second filter to allow a component from the image signal to pass therethrough, and eliminate a component from the desired signal, in the first- and second-intermediate-frequency signals; a comparator to compare levels between output signals of the first and second filters; and a control unit to switch a frequency of the first- and second-local-oscillator signals to a difference frequency between a frequency of the desired signal and the intermediate frequency or a sum frequency thereof, according to a comparison result of the comparator.

Abstract: The disclosed BTSC encoder includes a left high pass filter means; a matrix means for receiving the digital left and digital right filtered signals, and including means for summing the digital left and digital right filtered signals and thereby generating a digital sum signal, and including means for subtracting one of the digital left and digital right filtered signals from the other of the digital left and digital right filtered signals and thereby generating a digital difference signal; a difference channel processing means for digitally processing the digital difference signal; and a sum channel processing means for digitally processing the digital sum signal.

Abstract: The disclosed BTSC encoder includes a left high pass filter means for receiving a digital left channel audio signal and for digitally high pass filtering the digital left channel audio signal and thereby generating a digital left filtered signal; a right high pass filter means for receiving a digital right channel audio signal and for digitally high pass filtering the digital right channel audio signal and thereby generating a digital right filtered signal; a matrix means for receiving the digital left and digital right filtered signals, and including means for summing the digital left and digital right filtered signals and thereby generating a digital sum signal, and including means for subtracting one of the digital left and digital right filtered signals from the other of the digital left and digital right filtered signals and thereby generating a digital difference signal; a difference channel processing means for digitally processing the digital difference signal; and a sum channel processing means for d

Abstract: A feed-forward amplifier includes a main amplifier having input signals and amplified output signals and an error amplifier for amplifying distortion signals to be added to the amplified output signals of the main amplifier to produce an amplifier output. A pilot tone modulation and recovery circuit modulates a pilot tone to be coupled to the input signals of the main amplifier and recovers the pilot tone from the amplifier output. The pilot tone modulation and recovery circuit includes a digital filter and a signal source. The signal source is used to both modulate the pilot tone and control the digital filter for recovering the pilot tone.

Abstract: A television audio signal encoder includes a matrix that sums a left channel audio signal and a right channel audio signal to produce a sum signal. The matrix also subtracts one of the left and right audio signals from the other to produce a difference signal. The encoder also includes a configurable infinite impulse response digital filter that selectively uses one or more sets of filter coefficients to filter the difference signal. Each selectable set of filter coefficients is associated with a unique filtering application to prepare the difference signal for transmission.

Abstract: Utility data modulation is superimposed on a payload data modulator optical signal by exploiting spread spectrum techniques by virtue of one embodiment of the present invention. Utility data transmission rates of e.g., 200 Kbps, can be achieved without impairment to payload data transmission. The utility data modulated signal spectrum overlaps or is entirely within the payload data modulation spectrum, therefore, overcoming problems with optical amplifier gain control and pink noise.

Abstract: In a frequency modulator, a VCO oscillates at a frequency according to a voltage applied to an input terminal. A divider divides an output signal of the VCO. A phase comparator compares the output of the divider with a reference clock signal and outputs a voltage corresponding to a phase difference. A loop filter is provided on a path leading from an output terminal of the phase comparator to the input terminal of the VCO, and the loop filter removes a high-frequency component of an output voltage of the phase comparator. A terminal for inputting a modulation signal is provided in the loop filter, separately from a terminal connected with the path leading from the output terminal of the phase comparator to the input terminal of the VCO.

Abstract: A television audio signal encoder includes a matrix that sums a left channel audio signal and a right channel audio signal to produce a sum signal. The matrix also subtracts one of the left and right audio signals from the other to produce a difference signal. The encoder also includes a configurable infinite impulse response digital filter that selectively uses one or more sets of filter coefficients to filter the difference signal. Each selectable set of filter coefficients is associated with a unique filtering application to prepare the difference signal for transmission.

Abstract: A demodulator (10) converts television signals to video baseband signals and audio baseband signals including stereo signals representing a right channel signal value, a left channel signal value and a pilot signal having an amplitude. A DSP (60) recursively finds a coefficient value for scaling that keeps the pilot signal amplitude within a range of values, there by improving baseband signal quality, such as stereo separation of stereo signals within the baseband signals.

Abstract: A stereo demultiplexer is proposed which can be calculation power efficiently implemented in a DSP. Modern digital FM receivers exploit the information content in the in quadrature component of the modulated difference signal for a noise reduction. The proposed stereo demultiplexer derives the in phase component and the in quadrature component of the difference signal with a minimized number of sinus and cosinus calculations by first downconverting the modulated difference signal to a not synchronized complex baseband signal on basis of a fixed frequency, thereafter a complex sampling rate decimation unit sampling rate decimates the not synchronized complex baseband signal with a factor N and a second complex mixer synchronizes and coherent demodulates the sampling rate decimated not synchronized baseband signal on basis of a first complex carrier signal derived on basis of the pilot carrier signal and the fixed frequency.

Abstract: According to the invention, a circuit arrangement for gaining a 38 kHz stereo subcarrier and a 57 kHz RDS carrier for decoding a stereo signal comprised in a demodulated FM signal and/or an RDS signal comprised in a demodulated FM signal, having a simple structure with only one PLL and particularly only one voltage-controlled oscillator (2) is characterized in that the arrangement comprises a phase-locked loop with a loop filter (1), a voltage-controlled oscillator (2), a first phase detector (3) which receives a reference signal having a reference frequency, and a second phase detector (4), which receives the FM signal, the output signal of the voltage-controlled oscillator (2) being coupled to both phase detectors (3, 4) in a form divided down by means of dividers (6, 9; 10, 11), and the signal fed back to the second phase detector having a frequency of 19 kHz, in that dividers (9, 10, 12) are provided, by means of which the output signal of the voltage-controlled oscillator (2) is divided down and which su

Abstract: A method and apparatus for minimizing multipath interference for commercial FM signals which use SCA secondary signals in QAM format that includes tracking the time series of phase measurements of a received stereo pilot signal for determining the proper phase reference for demodulation of QAM signals at the center of the time series. Phase measurements of the pilot signal are tracked over a predetermined tracking period. The phase measurement is used to support demodulation of the QAM signal. The SCA secondary signals in QAM format transmitted on commercial FM have minimal multipath interference and Doppler interference by movement of transmitter and receiver (vehicular).

Abstract: A semiconductor optical device includes a substrate, an optical waveguide layer on the substrate and having well and barrier layers. The semiconductor optical device also includes an optical absorbing layer on the substrate and adjacent to the optical waveguide layer so that incident light having an incident wavelength &lgr;LD is guided into the optical absorbing layer. Each of the well layers has a wavelength &lgr;g corresponding to the band gap of the well layers and that is larger than the incident wavelength &lgr;LD. Also, the band gap energy between base levels of a conduction band and a valence band of the optical waveguide layer is larger than the energy of the incident light having the incident wavelength &lgr;LD.

Abstract: A feedback controller, embedded in an FM audio processor, that controls the “integrated multiplex power” to the requirements of ITU-R 412 (2.51) is disclosed. This regulation specifies the maximum power, which is the same as the power produced by a sinewave modulating the carrier ±19 kHz (where ±75 kHz is 100% peak modulation). The controller applies the square of the multiplex signal to an integrator. A constant is removed from the integrator; representing the maximum power threshold. The output of the integrator is sampled periodically with a sample-and-hold circuit. A second integrator receives the output of the sample-and-hold. The output of the second integrator circuit is added to the threshold setting of a compressor, which determines the average power output of the compressor. The output of the compressor is applied through a peak controller to the input of the multiplex coder, closing a feedback loop, which controls the integrated multiplex power to a preset threshold.

Abstract: An integrated circuit for decoding an analog audio signal includes a tuner that receives the analog audio signal and provides a sound intercarrier frequency signal. A digital demodulator receives and digitizes the sound intercarrier frequency signal to provide a digitized sound intercarrier frequency signal, and digitally demodulates the digitized sound intercarrier frequency signal to provide a digitized multichannel television sound (MTS) demodulated signal. A digital broadcast television system committee (BTSC) compatible decoder receives and decodes the digitized multichannel television sound (MTS) demodulated signal, and provides a summed (L+R) audio output signal and a difference (L−R) audio output signal.

Abstract: An apparatus and method is provided for transmitting “masked” stereo audio signals in a signal distribution network such as a cable television system within the bandwidth constraints of conventional frequency allocation schemes. In various embodiments, left and right stereo audio signal components (L+R and L−R) are used to amplitude modulate a carrier using independent sideband (ISB) modulation without the transmission of a pilot signal. A jamming signal or low bandwidth data signal may be transmitted in place of the normal pilot tone. Various aspects of the invention contemplate the use of Hilbert transforms to perform the ISB modulation and demodulation.

Abstract: A system (100) is provided wherein a primary radio signal and a redundant radio signal are transmitted from a transmitter subsystem (120) and received by a receiver subsystem (140). The output (112) of an audio source (110) is coupled to a modulator (160) for modulating a radio frequency signal (162) for coupling to a transmit antenna (172). A second output (114) of audio source (110) is coupled to a delay circuit (116), for adding a predetermined time delay thereto. The delayed audio source signal is coupled to a modulator (164) for modulating a second radio frequency signal (166) that is also coupled to the transmit antenna (172). The receiver subsystem (140) receives both the primary radio signal and the delayed redundant radio signal and couples each to a respective demodulator (180, 182). At least one demodulator (180) includes a circuit (181) for determining the degradation in the primary radio signal and provides a quality measurement output signal (186) to a blend control circuit (190).

Abstract: The disclosed BTSC encoder includes a left high pass filter means for receiving a digital left channel audio signal and for digitally high pass filtering the digital left channel audio signal and thereby generating a digital left filtered signal; a right high pass filter means for receiving a digital right channel audio signal and for digitally high pass filtering the digital right channel audio signal and thereby generating a digital right filtered signal; a matrix means for receiving the digital left and digital right filtered signals, and including means for summing the digital left and digital right filtered signals and thereby generating a digital sum signal, and including means for subtracting one of the digital left and digital right filtered signals from the other of the digital left and digital right filtered signals and thereby generating a digital difference signal; a difference channel processing means for digitally processing the digital difference signal; and a sum channel processing means for d

Abstract: A distributed pre-emphasis equalizer comprises a partial pre-emphasizer and a (50) microsecond pre-emphasizer. The partial pre-emphasizer receives an input signal and produces a partially pre-emphasized output signal. The (50) microsecond pre-emphasizer receives the partially pre-emphasized output signal from the partial pre-emphasizer and adds a (50) microsecond equalization to produce a pre-emphasized output signal equal to a standard (75) microsecond pre-emphasis curve. The distributed pre-emphasis equalizer allows an FM audio processor to produce only the "dulling" effect of a (50) microsecond pre-emphasis even when generating a (75) microsecond pre-emphasis curve. The distributed pre-emphasis equalizer also creates a pre-emphasizing method which is inherently compatible with both the (75) microsecond and (50) microsecond standards. Furthermore, the distributed pre-emphasis equalizer creates a pre-emphasizing method which is easily switchable between the (75) and (50) microsecond standards.

Abstract: The disclosed BTSC encoder includes a left high pass filter means for receiving a digital left channel audio signal and for digitally high pass filtering the digital left channel audio signal and thereby generating a digital left filtered signal; a right high pass filter means for receiving a digital right channel audio signal and for digitally high pass filtering the digital right channel audio signal and thereby generating a digital right filtered signal; a matrix means for receiving the digital left and digital right filtered signals, and including means for summing the digital left and digital right filtered signals and thereby generating a digital sum signal, and including means for subtracting one of the digital left and digital right filtered signals from the other of the digital left and digital right filtered signals and thereby generating a digital difference signal; a difference channel processing means for digitally processing the digital difference signal; and a sum channel processing means for d

Abstract: An apparatus for detecting a pilot signal. A phase detector detects a phase difference between a filtered amplitude-modulated pilot signal and a frequency divided signal, and a low pass filter low-pass-filters the phase difference. A voltage-controlled oscillator outputs a clock signal having a frequency determined by an output signal of the low-pass filter and outputs the clock signal having the frequency determined by an oscillation control signal. A (1/N) frequency divider divides the switching signal and outputs the (1/N) divided signal as a frequency divided signal, and an envelope detector detects an envelope of the filtered amplitude-modulated pilot signal and outputs the detected envelope as the pilot signal. The frequency of the pilot signal has information used to discriminate a broadcasting state. Therefore, the manufacturing cost and the number of pins in an integrated circuit can both be reduced.

Abstract: The method for obtaining the quality signal includes multiplying a digital multiplex signal (MPX) by respective reference carrier signals mutually phase shifted by 90.degree. to each other, but otherwise equal, to form a pair of mixed signals (Imr1,Imr2); multiplying the mixed signals (Imr1, Imr2) by respective correction signals (G38c,G38s) to form a pair of corrected mixed signal (Ims1,Ims2); separately multiplying the digital multiplex signal (MPX) by each of two reference pilot signals mutually shifted in phase by 90.degree.

Abstract: The VCR (video cassette recorder) inserts an index signal into a video signal at the time of recording, when information which will later become inaccurate at the time of playback is included in the video signal. The index signal prevents the VCR from using the inaccurate data at the time of playback. Further, tile VCR displays a message automatically when the broadcast signal selected by the user has no second audio signal, thereby allowing the user to grasp the reason why the receiver is producing no sound. Further, the main audio signal may be selected automatically, instead of the second audio signal, allowing the VCR to produce the sound.

Abstract: In a circuit for deriving at least one quality signal that is dependent on the quality of a received signal, where the received signal is demodulated, a first auxiliary signal which is dependent on the field strength, and a second or further auxiliary signal, are derived from the demodulated signal. The auxiliary signal and the second or further auxiliary signal are combined to derive the quality signal.

Abstract: A pilot signal detection circuit comprises: a PLL circuit for generating a reference signal whose frequency is same as and phase-synchronized with a carrier of a pilot signal extracted from broadcasting waves; a sync-detector for sync-detecting the carrier by using the reference signal; a frequency signal generator for generating a first pair of signals having a frequency assigned to sound multiplex broadcasting and a phase difference of 90 degrees and a second pair of signals having a frequency assigned to stereophonic broadcasting and a phase difference of 90 degrees; multiplies for multiplying the signal output from the sync detector by the output signals from the frequency signal generator; squaring circuits for squaring the output signals from the multipliers; LPFs for filtering the output signals from the squaring circuits; an adder for adding the outputs of the LPFs, and a detector for detecting the pilot signal by comparing the output of the adder with a predetermined reference level.

Abstract: A pilot signal detection circuit receives a supply of a pilot signal produced by frequency-modulation of a predetermined third frequency carrier signal by a first discrimination signal of a first frequency and a second discrimination signal of a second frequency, and makes a discrimination between the first discrimination signal and the second discrimination signal by whether a signal detected is of the first frequency or of the second frequency. The pilot signal detection circuit is constituted by first and second multiplying and filtering stages. The first multiplying and filtering stage includes first and second multipliers and first and second low-pass filters. The first and second multipliers multiply the pilot signal respectively with the first reference signal and the second reference signal, and produce respectively first and second multiplied signals.

Abstract: An FM stereo radio data-system receiver has a front end including an FM discriminator that produces a composite signal composed of an AM stereo signal, including a 19 KHz pilot, and an AM digital-data signal. A dual-bandwidth phase locked loop (PLL) locks onto the pilot and serves both, as the decoder of the stereo portion of the composite signal, and as a generator of a strong stable 38 KHz carrier for use in regenerating the bit rate clock signal and for decoding the data-symbol signal of the digital-data portion of the composite signal. Advantages include economy of circuitry, a simpler and less costly high pass filter, and greater reliability in the decoding of the data signal.

Abstract: Radio receivers which scan through a predetermined band of the radio spectrum, in a station-seeking mode, must independently detect whether the currently tuned frequency is the central frequency of the transmitting station and whether this transmitter provides a signal whose strength is sufficient, i.e. whose strength exceeds a predetermined threshold value. Once these two conditions are satisfied, the radio generates a "stop" signal which terminates the station-seeking mode, i.e. keeps the tuning circuit set to the frequency which provided the sufficiently strong signal. The present invention provides an unusually simple way to determine whether these two conditions are satisfied, by using a Finite-Impulse-Response digital filter (2) to extract a d.c. component of the demodulated signal (MPX), for comparison (6) with a predetermined maximum value, and by filtering (10) a field strength signal (FST), for comparison (11) with a predetermined minimum value.

Abstract: A stereo and dual audio signal identifying circuit including an FM detector receiving a second intermediate frequency signal, a bandpass filter, an AM detector. The circuit further including an amplifier having a first input receiving an output signal from the AM detector, and a second input receiving a signal derived from a series connected resistor and DC-filtering capacitor connected between the second input and ground, and having a feedback resistor connected between the second amplifier input and the amplifier. The amplifier drives a second stage of the circuit including a voltage controlled oscillator, a phase detector and a low-pass filter. The particular disposition of the DC-filtering capacitor within the circuit allows the capacitor to be externally connected to a single pin in an IC package incorporating the circuit.

Abstract: A device and method for composite signal decoding is provided in which an analog-to-digital converter (15) digitizes an incoming FM composite signal. The digitized signal is filtered by an interpolator (13) which uses filter coefficients developed as a function of a sampled pilot signal's phase without synchronizing the decoder sample rate to the pilot signal to reconstruct the composite signal at points Where the pilot signal phase is a multiple of 45.degree..

Abstract: A digital radio receiver generates coherent signals for synchronous detection without use of a phase-locked loop by employing an adaptive notch filter to cancel the desired signal. The cancelling signal is employed as the coherent signal for synchronous detection. The invention obtains faster locking to the desired signal, a wider capture range, and more efficient software coding in a digital signal processing receiver.

Abstract: In a circuit for decoding a multiplex signal in a stereo receiver, where the multiplex signal contains a composite signal (L+R) in the base band, a subcarrier modulated with a difference signal (L-R), and a pilot signal with half the frequency of the subcarrier, the multiplex signal in digital form is multiplied (2, 3) by a reference carrier generated with a sampling clock signal (14) produced in the radio receiver, where the reference carrier is present in two phase positions shifted 90.degree. with respect to each other. The mix or product signals resulting from this multiplication are multiplied (4, 5) by one correction signal each, thus forming corrected mix signals. The corrected mix signals are added (6) and supplied to a matrix circuit (8, 9), together with the composite signal, to create respective stereo audio channel signals (L, R).

Abstract: A stereo signal demodulator circuit demodulates a stereo signal by using a PLL circuit including a voltage-controlled oscillator (VCO) for generating a first oscillation signal and a second oscillation signal having a phase different from that of the first oscillation signal by 90.degree.. The voltage-controlled oscillator circuit includes a first amplifier for outputting a signal whose phase is different from that of an input signal by 90.degree., a second amplifier for outputting a signal whose phase is different from that of an input signal by 90.degree., and a third amplifier for outputting a signal whose phase is different from that of an input signal by 180.degree.. The first, second and third amplifiers are connected in series so that an output signal of the third amplifier is different, in phase, from the input signal of the first amplifier by 360.degree.

Abstract: A headset amplifier, adapted for use with a voltage source such as a battery, includes a time-out-timer circuit for deactivating the headset amplifier after a first predetermined period of time and for reactivating the amplifier in response to a signal fed to an input port of the time-out-timer circuit.

Abstract: A digital radio receiver generates coherent signals for synchronous detection without use of a phase-locked loop by employing an adaptive notch filter to cancel the desired signal. The cancelling signal is employed as the coherent signal for synchronous detection. The invention obtains faster locking to the desired signal, a wider capture range, and more efficient software coding in a digital signal processing receiver.

Abstract: A transmission apparatus and method for transmitting stereo multiplexed audio signals from a received television signal having a horizontal frequency f.sub.H are provided. Right and left channel audio signals obtained by demodulation from the received television signal are added to form a first combined audio signal. The same signals are subtracted to form a second combined audio signal. A subcarrier is modulated with one of the first and second combined audio signals, the subcarrier having a frequency substantially equal to 3f.sub.H to form a subcarrier modulated audio signal. The other of the first and second combined audio signals is combined with the subcarrier suppressed signal to form a stereo multiplexed audio signal, and the stereo multiplexed audio signal is transmitted.

Abstract: A stereo/multivoice recording and reproducing apparatus used for a high fidelity video tape recorder comprises a multi-channel television system (MTS) decoder for demodulating stereo and multivoice signals included in an IF signal supplied from a tuner, a high fidelity audio processor for frequency-modulating the stereo signal output from a MTS decoder, left and right channel heads for recording the stereo signal frequency-modulated in the high fidelity audio processor, a second audio processor for amplifying the multivoice signal from the MTS decoder, and a third audio head for recording the multivoice signal amplified in the second audio processor. According to one aspect of the invention, the apparatus can simultaneously record stereo and multivoice signal and selectively reproduce one of the stereo signal and the multivoice signal.

Abstract: A radio broadcasting system for a composite signal consisting of a frequency modulated (fm) analog signal and a multicarrier modulated digital signal is provided which is resistive to multipath degradation. The fm signal and the digital multicarrier modulated signal are fully coherent. The digital signal uses a plurality of carriers having a maximum amplitude at least 20 dB below the unmodulated fm signal. The multicarrier modulated signal is phase locked to a recovered analog fm pilot tone in the composite baseband spectrum of the fm signal which is at least 20 dB above the multicarrier modulated signal, which enables rapid and reliable acquisition of signal for coherent detection. In a specific embodiment the multicarrier modulated signal is a synthesized vector-modulated signal which is a quadrature phase shift keyed (QPSK) modulated set of synthesized carriers each occupying 9.5 kHz of spectrum replicated twenty-one times within a 199.5 kHz bandwidth with no more than two bits per vector.

Abstract: A receiver having a signal path incorporating a tuner, a demodulator circuit for supplying a stereo multiplex signal having a baseband stereo sum signal (L+R), a 19 kHz stereo pilot and a stereo difference signal (L-R) which is double sideband amplitude-modulated on a suppressed 38 kHz subcarrier, a sampler for converting an analog signal into a time-discrete signal and a stereo decoder for time-division multiplex decoding of a time-discrete stereo multiplex signal into time-discrete left and right stereo signals. In order to realize an effective selection of the stereo multiplex signal by an easily integrable low-pass filter, the stereo decoder includes a time-discrete halfband low-pass filter circuit having a finite impulse response, with a transition band which is substantially located in the frequency range of said modulated stereo difference signal and with a half-value transfer which is located at the frequency of said 38 kHz stereo subcarrier.

Abstract: Apparatus for demodulating information signals frequency-modulated on an RF carrier signal carrying spectral components within the audio frequency range, a pilot carrier signal having an imparted phase shift from the phase of the transmitted pilot carrier signal, and amplitude-modulated spectral components having another imparted phase shift in a subcarrier channel frequency range above the audio frequency range. The apparatus includes a demodulator for demodulating the frequency-modulated information signals to provide a detected composite signal which includes a detected pilot carrier characterized by an imparted phase shift due to the effects of multipath reception, and detected amplitude modulated spectral components exhibiting another multipath induced phase shift.

Abstract: A compatible multivoice broadcasting receiver is disclosed which can receive both Korean multivoice broadcasting and American multivoice broadcasting and commonly process the one-carrier component (L+R) of Korean multivoice broadcasting and the main channel signal (L+R) of American multivoice broadcasting. In addition to the existing multivoice broadcasting receiver, the multivoice broadcasting receiver further comprises a buffer section that operates the outputs L+R signal detector, L-R and SAP signal detector, and the L-R and pilot signal detector selectively under the control of a buffer driving section, the buffer driving section operating a buffer section, an analog switch section for switching the signal transmission according to the output signal from the buffer driving section, and a matrix section for matrix-operating the output signals from the buffer section according to the output signal from the analog switch section and for outputting the left channel signal and the right channel signal.

Abstract: In stereo receivers with digital decoding pulse generation, interference by the harmonics of the digital switching signal with signals in adjacent channels or with carrier signals in the sideband lead to faults that can be perceived in the audible range as chirping. An integrated stereo decoder with digital decoding pulse generation is described in which the low-harmonic, step-like switching signal consecutively assumes within a period and relative to the amplitude the values (1+.sqroot.2).sup.-1, 1, (1+.sqroot.2).sup.-1, -(1+.sqroot.2).sup.-1, -1, -(1+.sqroot.2).sup.-1, with the .+-.(1+.sqroot.2).sup.-1 values each persisting for an eighth of the period and the .+-.1 values a quarter of the period. Furthermore, an integrated circuit array for generation of this low-harmonic oscillation is described.

Abstract: In order to permit three-component (left, right and back) audio signals (LS, RS, BS) to be conveyed by a three-channel (left, right and mono) transmission system and still permit stereo and mono compatibility, the signals are encoded so that the three channels carry LS-1/2BS, RS-1/2BS and LS+RS+BS, respectively. Upon receipt, the signals can be decoded back to LS, RS and BS respectively. In a mono receiver without such a decoder, the signal LS+RS+BS on the mono channel is employed, and in a stereo receiver the signals LS-1/2BS and RS-1/2BS on the stereo channels are employed.

Abstract: A system which enables transmission of a standard composite stereo sound signal, made up of baseband, subcarrier band and pilot signals, from a first location to a second location while requiring only a relatively low bit rate for the transmission link. The standard composite stereo signal is synchronously sampled at a first location at rate F.sub.s twice the subcarrier frequency F.sub.c (four times the pilot frequency F.sub.p), and the sampled signal transmitted over the link along with appropriate synchronizing signals. At the second location, a signal processor separates the received signal into a first signal related to one stereo channel signal (e.g. R) and a second signal representative of the other stereo channel (e.g. L), determines the proper scale for the pilot signal, and regenerates the original standard composite stereo sound signal by combining the L-related and R-related signals with the pilot scale signals in appropriate proportions and with appropriate filtering.

Abstract: A stereo demodulator of a matrix system comprises: a first amplifier (23, 24, 25) for negative feedback amplification of a stereophonic composite signal, a first voltage-current converter (26) for detecting a current-form stereophonic sum signal responsive to a voltage output of the first amplifier, a non-inversion amplifier (27) for negative feedback non-inversion amplification of the stereophonic composite signal, an inversion amplifier (28) for negative feedback inversion amplification of the stereophonic composite signal, a second voltage-current converter (29, 38) for outputting a first current-form stereophonic subchannel signal responsive to a voltage output of the non-inversion amplifier (27), a third voltage-current converter (30, 39) for supplying a current-form signal stereophonic subchannel signal responsive to a voltage output from the inversion amplifier (28), a difference signal demodulator (31) for providing stereophonic difference signals of opposite phases in the form of current signals from

Abstract: A composite stereo signal comprised of a modulated signal modulated by a sum signal which is the sum of left and right channel audio signals and a difference signal which is the difference between the left and right channel audio signals, and a pilot signal synchronized with the modulated signal, has the left and right channel audio signals demodulated therefrom by a stereo multiplex demodulator that includes a phase-locked loop (PLL) circuit for forming a sine wave signal synchronized with the pilot signal and having a frequency equal to a subcarrier frequency of the modulated signal, and a multiplying circuit for multiplying the composite stereo signal and the sine wave signal to generate the demodulated left and right channel audio signals.