Abstract: Methods and apparatus for encoding and decoding information in broadcast or recorded segment signals are described. In certain embodiments, an audience monitoring system encodes identification information in the audio signal portion of a broadcast or recorded segment using spread spectrum encoding. A personal monitoring device receives an acoustically reproduced version of the broadcast or recorded signal via a microphone, decodes the identification information from the audio signal portion despite significant ambient noise, and stores this information, automatically providing a diary for the audience member which is later uploaded to a centralized facility. A separate monitoring device decodes additional information from the broadcast signal, which is matched with the audience diary information at the central facility.

Abstract: A transmitter for transmitting at least a first and a second main signal component is disclosed, having at least two input terminals for receiving the at least two input signals. The transmitter comprises multiplexer means for multiplexing the at least two input signals to a first input of matrixing means, and to an input of first bitrate reducing means. The first bitrate reducing means is for carrying out a data reduction step on the signal applied to its input and to supply a data reduced version to an output. Expansion means are present, having an input coupled to the first bitrate reducing means, for carrying out a data expansion on the data information applied to its input, so as to obtain a replica of the signal applied to the input of the bitrate reducing means at an output. Said output is coupled to a second input of the matrixing means. An output of the matrixing means is coupled to signal combination means via second bitrate reducing means.

Abstract: An audio apparatus having a plurality of modes as a karaoke reproduction to superimpose a sound signal from a microphone on an audio signal from a stereo sound source. A subtracting circuit is provided which obtains the difference between left and right channel signals from the sound source. A first changeover circuit selectively outputs the left and right channel signals to first and second terminals in a combination in accordance with a mode. A second changeover circuit is connected to the output of the subtracting circuit and to at least one of the left and right channel signals and selectively outputs a subtraction signal and a signal on the line to which the second changeover circuit is connected, to a third terminal. A third changeover circuit selectively outputs signals at the first, second and third terminals to fourth and fifth terminals according to the modes.

Abstract: Reproduction accuracy of, for example a digital stereo audio signal, is improved by transmitting sample data as sub-signals such as frequency subband signals. In one or more subbands, corresponding components such as left and right stereo channels are combined so that only one composite signal is transmitted per subband. An indicator signal is transmitted, indicating which subbands are combined. Scale factor signals for all subbands, and for the relative intensity of the respective subband signals which were combined, may also be transmitted. In the receiver a subband signal is derived for each channel from the composite signal, before synthesis of the full channel signals which will be reproduced.

Abstract: A protocol for transferring audio data and control/status data between audio functional units. The protocol involves multiplexing the audio data and control/status data. The multiplexed data is then transferred between a first audio unit and a second audio unit on two wires, each corresponding to the direction of data flow, and according to a clock rate and a synchronization pattern on third and fourth wires respectively.

Abstract: A method for incorporating future developments in video compression technology to migrate toward a better television system in a receiver-compatible manner. The invention uses enhancement data that can be combined with standard video data. Standard HDTV receivers will utilize standard video data, ignoring the enhancement data. More advanced HDTV receivers will combine the enhancement data with standard data. The television signal is transmitted in a format comprising a first set of bits that represents images at a first quality (e.g., first resolution) and that can be decoded to provide an output at the first resolution, and a second set of bits that represents enhancement information and that can be decoded and used in conjunction with the first set of bits to provide an output at a second resolution greater than the first resolution. The first set of bits is decoded according to a first decoding procedure to provide information representative of images at the first resolution.

Abstract: A five-channel perceptual audio compression system which encodes five matrixed channels switches among a fourteen encoding modes each utilizing a respective different set of matrixed channels. Six of the modes are for encoding the three front channels and eight of the modes are for encoding the two back channels. A number of the modes have as at least one of their respective matrixed channels a matrixed channel which is a function of a) one of the input channels or a sum or difference of two of them, and b) a predicted value of a).

Abstract: A transmitter and receiving apparatus from a headphone, comprising a demodulating circuit for demodulating a received broadcasting signal into multi-channel data, a modulating circuit for frequency-modulating each channel of the multi-channel data with a different carrier frequency, said carrier frequencies being selectable by the user to avoid local interference, and a transmitting circuit for transmitting output data from said modulating circuit externally. There is also provided a receiver for a radio headphone, comprising a data receiving circuit for receiving data transmitted from an external transmitting circuit, a demodulator for dividing the data received by said data receiving circuit into separate frequency channels, an envelope detecting circuit for detecting envelopes of respective channel data, and an output circuit for outputting an output signal from said envelope detecting circuit as an analog sound signal so as to allow a user to listen to noiseless sound through a headphone.

Abstract: A transmitter for transmitting at least two main signal components (L,R) includes a first data compression circuit (BRR1) for performing a data compression of a first of the main signal components, a data expansion circuit (DEQ) for performing a data expansion of the compressed signal component so as to obtain a replica of the first main signal component, and a matrixing circuit for combining the second main signal component with the replica of the first main signal component so as to obtain a combined signal (M'). A second data compression circuit (BRR2) performs a data compression of the combined signal (M') in response to a masking control signal. The output signals of the first and second data compression circuits are combined as a composite signal for transmission via a transmission medium, for example a record carrier. The invention also provide a receiver for such a transmitted composite signal. The transmitter may be adapted to provide for transmission of three individual signal components (L,R,C).

Abstract: Coding of high quality stereophonic audio signals is accomplished in a perceptual filterbank coder which exploits the interchannel redundancies and psychoacoustic. Using perceptual principles, switching between a normal and short window of input samples improve output signal quality for certain input signals, particularly those having a rapid attack. Switching is also accomplished between coding of left and right channels and so-called sum and difference channels in response to particular signal conditions.

Abstract: Receiver having an RF input for applying an RF input carrier thereto, which receiver is coupled to a phase-locked loop (PLL) whose signal path incorporates a phase detector, a loop filter, a controlled amplifier and a controlled oscillator, and a signal generator for generating a local auxiliary pilot and a pilot detector for detecting the local auxiliary pilot, a first input of which is coupled to the signal path of the PLL between an output of the phase detector and a control input of the controlled oscillator, a second input is coupled to an output of the signal generator and an output is coupled to a control input of the controlled amplifier via a selection device.

Abstract: A system for broadcasting audio music and broadcasting lyrics for display and highlighting substantially simultaneously with the occurrence of the lyrics in the accompanying audio music is provided. The system includes a audio music source that provides a data output and a analog audio signal output. A computer receives the data output by the music source and generates lyric text data and lyric timing commands. A subcarrier generator generates a subcarrier signal carrying the lyric text data and lyric timing commands. An FM transmitter broadcasts a composite signal that combines the analog output of the music source with the subcarrier signal. A lyric display unit receives the composite signal, separates and decodes the subcarrier signal and displays and highlights lyrics according the lyric text data and lyric timing commands decoded from the subcarrier signal.

Abstract: A teleconferencing system 100 is disclosed having a video camera for generating a video signal representative of a video image of a first station B. A microphone array 150, 160 is also provided in the first station for receiving a sound from one or more fixed non-overlapping volume zones 151, 152, 153, 154, 155, 156, 157, 158, 159, into which the first station is divided. The microphone array is also provided for generating a monochannel audio signal 170 representative of the received sound and a direction signal indicating, based on the sound received from each zone, from which of the volume zones the sound originated. The teleconferencing system also includes a display device 120A at a second station A for displaying a video image of the first station.

Abstract: A digital signal processing automotive audio system uses an analog audio source providing stereo output signals. One of the stereo signals is mixed to a distinct frequency band and summed with the other stereo signal to form a composite signal which can be digitized in a single analog-to-digital converter. Separate digital stereo signals are recovered using digital signal processing.

Abstract: A system is provided which transmits either analog or digital data signals over the air. The system includes including a transmitter and a receiver. The transmitter and receiver are arranged to transmit signals using a carrier signal having a high frequency such as in the range of 902-928 MHz. The transmitter and receiver are configured to provide for the transmission of two channels of stereophonic signals while maintaining high signal-to-noise ratios, good frequency response, and low distortion. To provide for the proper transmission of signals between transmitter 10 and receiver 12, these devices include oscillating circuits having ceramic resonators which provide a base frequency which is readily modulated to facilitate proper transmission of either analog or digital signals between the transmitter and receiver.

Abstract: A method and apparatus are provided for transmitting, receiving, and reproducing digital audio signals as discrete carriers similar to standard FM broadcast signals. An audio signal is digitized using, for example, adaptive delta modulation techniques. Several channels of audio information, such as left and right stereo channels and a second audio program ("SAP") channel can all be digitized and incorporated onto the digital broadcast signal carrier. The digitized audio signal may be modulated using multiphase modulation of the carrier of an FM broadcast band or cable television band signal. A plurality of audio channels may be digitized and transmitted over the airwaves, or over a cable transmission network. Channels of nondigitized audio channels may be interspersed with the digitized audio channels in the Fm broadcast band.

Abstract: Coding of high quality stereophonic audio signals is accomplished in a perceptual filterbank coder which exploits the interchannel redundancies and psychoacoustic. Using perceptual principles, switching between a normal and short window of input samples improve output signal quality for certain input signals, particularly those having a rapid attack. Switching is also accomplished between coding of left and right channels and so- called sum and difference channels in response to particular signal conditions. A number of new perceptually based techniques, including improved threshold determinations, result in high quality.

Abstract: A digital audio broadcasting system that is capable of providing a large number of high quality stereophonic channels to mobile receivers in an environment with severe multipath delay and fading. Optimum combination of frequency and time diversity to guarantee robust performance in the mobile channel, with its multipath delay and frequency-selective fading effects. The system is based upon a dynamic single channel per carrier assignment of each stereo channel to many carriers. Intersymbol interference degradations caused by multipath delay are mitigated via an adaptive equalizer in the receiver. This dynamic single channel per carrier system preserves the simplicity inherent in the single channel per carrier assignment while it incorporates the ability to address frequency-selective fading by providing substantial frequency diversity.

Abstract: A synchronized broadcast network comprises a main transmitter transmitting an audio source signal to a plurality of receiver/transmitter units remote from each other and from the main transmitter, the receiver/transmitter units broadcasting the audio signal using frequency modulation. In the main transmitter the audio source signal is digitized by sampling it at a predetermined sampling frequency. A digitized signal representing the sampled audio signal is transmitted to the receiver/transmitter units. In each receiver/transmitter unit a reference signal representing the sampling frequency is derived from the received digitized signal and the received digitized signal is passed through a succession of digital processing stages including a stage in which a carrier derived from the reference signal is digitally modulated and a stage in which the result of the digital modulation is digital-to-analog converted.

Abstract: An interface circuit (16, 44) is provided for communicating a plurality of demodulated digital audio values in a predetermined serial data bus protocol between a digital source (12) and a digital sink (46). Each of the plurality of digital audio values contains either left or right channel audio information and control values. The serial data bus protocol is formed by the interface circuit (16, 44) by transmitting a left channel information value of a predetermined demodulated digital audio value, a right channel information value of the predetermined demodulated digital audio value, and then a byte of control information formed from both the left and right channel control values.

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: Apparatus and methods are disclosed for providing text information which identifies audio program selections, such as musical selections, stored on a compact disk (CD). Digital identification numbers encoded on the disk are provided by a compact disk player to a digital processor having a memory storage device. The identification numbers include an album identification number, and the track number selected for play. The memory storage device has stored therein text data identifying a plurality of program selections, organized by album and track identification number. The identification signals provided by the CD player are used to address the proper identifying text data for the selection being played. The identifying text data may be organized for radio broadcast along with the musical selection, and a receiver is used to display the data in text form to identify the musical selection as it is being reproduced.

Abstract: A discrete parallel path modulation multiplexer for use in generating a composite baseband signal from separate left and right input signals. The composite baseband signal includes the sum of the left and right input signals and the product of the difference between the left and right input signals and a subcarrier. The composite baseband signal may also include a pilot subcarrier at one-half the frequency of the subcarrier. In one signal path, the multiplexer multiplies the right input signal by the function (1+sin (wt)) and in a second signal path the multiplexer multiplies the left input signal by the function (1-sin (wt)). The products are then combined to obtain the composite baseband signal. A pilot subcarrier may also be generated and included as part of the composite baseband signal.

Abstract: A remotely controllable message broadcast system includes a Central Programming Station, and many Remote Message Transmitters and repeaters. The Central Programming Station includes a library of broadcast messages and a set of Remote Message Transmitter programming instructions. A transmitter in the Central Programming Station transmits selected broadcast messages from the library and selected Remote Message Transmitter programming instructions from the set to all the Remote Message Transmitters over a wide area transmission network such as a licensed radio link. The transmitted instructions may include global instructions which apply to all Remote Message Transmitters and unique (addressable) programming commands which apply to an individual one of the Remote Message Transmitters. Each Remote Message Transmitter selectively stores received broadcast messages and programming instructions based on whether it is a global instruction or a unique addressable command for that particular Remote Message Transmitter.

Abstract: A broadcast digital sound processing system includes an ISA (Industry Standard Architecture) bus compatible personal computer with a hard disk drive and a sound processor board installed in an expansion slot of the computer. The board includes a stereo input, analog to digital converter (ADC) and a stereo set of digital to analog converters (DAC's) interfaced to a digital signal processor (DSP) chip. A stereophonic audio signal is converted to digital data by the ADC and communicated to the computer by the DSP chip through a two port record first-in/first-out (FIFO) buffer for storage on the disk. A program is played back by communicating a program data file through a two port playback FIFO buffer to the DSP and from thee to the DAC's for reconstruction to a stereo set of analog signals. The reconstructed audio signals may then be used as a modulating signal for radio broadcasting.

Abstract: Method and apparatus are provided for transmitting, receiving, and reproducing digital audio signals as discrete carriers similar to standard FM broadcast signals. An audio signal is digitized using, for example, adaptive delta modulation techniques. Several channels of audio information, such as left and right stereo channels and a second audio program ("SAP") channel can all be digitized and incorporated onto the digital broadcast signal carrier. The digitized audio signal may be modulated using multiphase modulation of the carrier of an FM broadcast band signal. A plurality of audio channels may be digitized and transmitted over the airwaves, or over a cable transmission network. Channels of nondigitized audio channels may be interspersed with the digitized audio channels. Source material for the digitized audio channels may be provided to a cable headend over the cable transmission network outside the FM band, and rebroadcast over the cable transmission network in the FM band.

Abstract: For a digital/analog master control desk for audio signals, it is proposed to sum the analog channel signals, possibly while simultaneously processing them. Forming the analog broadcast signal, this sum is added to a further channel signal A.sub.n which is formed of the analog-converted sum of the digital channel signals. A digital signal D.sub.n obtained from the digital-converted sum of the analog channel signals is added to the sum of the digital channel signals, resulting in a digital broadcast signal which has the same modulation content as the analog broadcast signal.

Abstract: A packet data generator for generating complementary packet data which are added to information data for packet transmission via a high speed PCM transmission line. The packet data generator includes first and second memories for storing the complementary packet data; an address counter for counting an address at the timing of a synchronization signal of the high speed PCM transmission line; a multiplexer for changing the connection of the first and second memories; and a synchronization circuit for outputting a switching signal to the multiplexer in synchro with an output from the address counter. Since two memories are provided, while one memory is used for supplying complementary packet data at the data transmission speed, the other memory can be used for storing new complementary packet data at the CPU processing speed. The new complementary packet data are supplied by switching from the one memory to the other memory in synchro with a synchronization signal of the high speed PCM transmission line.

Abstract: A digital signal is received in which synchronization data is inserted at a predetermined period and in which a timing signal is synchronism with the synchronization data is developed from a digitally modulated input digital signal. A circuit generates detection signals indicative of a sampling frequency of the input digital signal on the basis of the synchronization data. A first window generating circuit generates signals of different frequency based on stable clock signals and uses the detecting signals to select one of the signals as a first reference signal. A second window generating circuit generates a second signal in synchronism with the synchronization data on the basis of an output signal from a phase-locked loop.

Abstract: A method and circuit arrangement identifies the presence or absence of known frequencies in an input signal composed of a plurality of frequencies, whereby a frequency generator controlled by a reference frequency generates four switch signals having frequencies dependent upon the frequency to be identified and having a phase difference of 90.degree. and respectively one switch signal is mixed with the input signal in a respective mixer. The respective mixer products of two mixers are additively combined and are filtered through a respective filter for filtering AC components out, and the DC voltage component contained in the respective mixer product given the presence of the known frequency is evaluated with respect to the amplitude.

Abstract: An apparatus for delaying a sub-aural (i.e., subchannel) signal in a television receiver of a sound multiplex system is provided, which is capable of outputting the sub-aural signal later than the main aural signal by a predetermined time interval. The apparatus is provided with a delaying circuit including an input clock generator, an output clock generator, an A/D converter for converting the output signal of a band-pass filter into a digital signal by setting down the input clock signal from the input clock signal generator at a sampling frequency, a memory for storing the output of the A/D converter, a D/A converter for converting the output signal of the memory into an analog signal by setting down the output clock signal from the output clock signal generator at a sampling frequency, and an output holding section for holding the output signal of the D/A converter by synchronizing the output signal of the D/A converter with the output signal from the output clock generator.

Abstract: In studio, stage or field applications, high fidelity audio signals are transmitted to a remote processor in digital form in order to solve the problems of audio degradation, cross talk, ground loops and multi-cable problems associated with the analog transmission of multiple channels of audio over long distances. In one embodiment a TDM/FDM multiplexing system is utilized with increased bandwidth and dynamic range compared to data and telephone multiplexing systems to accommodate high fidelity requirements. In an embodiment involving a distributed system, multiple MUX and DEMUX modules are coupled in a distributive fashion along a light-weight transmission line, in which each of the modules is assigned a predetermined transmission frequency and with each of the modules having a number of audio inputs which are time-multiplexed for that particular MUX module and frequency.

Abstract: A stereophonic audio system including a device for providing a stereophonic signal, such as an audio receiver. An infrared transmitter connected to the receiver converts the audio signal to an infrared signal to be radiated throughout a signal area. Within this signal area is disposed a pair of loudspeakers, each selecting a separate portion of the infrared signal, converting that one portion of the infrared signal to an audible sound signal, and radiating the sound throughout a listening area. Each loudspeaker includes a filter for selecting the one infrared signal which applies to it. The transmitter includes a plug engageable with a headphone jack of the receiver for electrically connecting the transmitter to the receiver and an infrared diode array for radiating the signal within the signal area.

Abstract: An improved FMX sterophonic broadcast receiver provided with countermeasures against transient noises, which includes a level detection circuit for detecting level of a detected stereo difference signal, and a level control circuit for controlling level of an expanded stereo difference signal according to an output signal of the level detection circuit. By the above arrangement of the present invention, since it is so arranged to cause the level control circuit to function when the degree of modulation becomes large so as to control the level of the stereo difference signal to be low, a level difference is produced between the stereo sum signal and the stereo difference signal for deterioration of the stereo separation degree upon matrixing at a matrix circuit for reduction of noises accordingly.

Abstract: A system for transmitting and receiving digitalized audio signals, particularly via satellites, wherein data sequences are arranged in timely succession within frames, wherein before transmission, the digitalized audio signal is converted to a digital signal representing the momentary frequency spectrum and, during subsequent coding of the digital audio signal to be transmitted, portions of this transformed signal are given different weights on the basis of psychoacoustic laws with respect to the accuracy of their representation.

Abstract: A stereo coding system is described in which 7 kHZ bandwidth sum (L+R) and difference (L-R) signals are converted to digital form (11 and 12). The difference signal is then bandlimited (13) to 2 kHZ and downsampled (14) to 4K samples/sec prior to being encoded (16), and the sum signal is encoded (15); both are then multiplexed together (17) prior to transmission. After reception, the signal is demultiplexed (19) and the difference signal is decoded (20) upsampled (21) to its original bit rate and filtered to prevent aliasing (22), and the sum signal is delayed in a digital buffer (28) and decoded (24) prior to both being converted back to analogue form (23 and 25). The delay introduced by the digital buffer (28) equalizes the excess delay introduced into the difference signal.

Abstract: A digital signal transmitting system includes a plurality of digital signal reproducers, each outputting a digital data signal to be time-division multiplexed; a digital signal multiplexer supplied with a frame synchronizing signal, a service bit signal and the output digital signals from the reproducers and for producing a block data signal including the frame synchronizing signal, the service bit signal and a plurality of slot data bits arranged with the digital data signals, each one bit within a multiple-frame, in which the service bit signal is indicative of the transmission mode and the slot data associated with each of the plurality of digital data signals being transmitted.

Abstract: A digital audio transmission system which is compatible with common carrier digital hierarchy systems converts two channels of analog data, such as precision stereo audio, into high resolution digital data words sampled at a high frequency. The data words are parity checked with the addition of one bit and divided into odd and even bit words for each channel. The bit words are time domain multiplexed into a common carrier frame with separate words for the parity bits and alternating channel data consisting of an odd and an even bit word. Each bit word is checked for all zeros and modified accordingly to assure that ones density and consecutive zero restraints are achieved. The resulting common carrier frames are transmitted over the appropriate common carrier cross-connects to a receiver which decodes the frames, recovering the bit and parity words. The bit words are recombined into data words and checked for parity.

Abstract: A MOSFET analog signal squaring circuit is disclosed. A first MOSFET has a source electrode coupled to a bias voltage source, a gate electrode coupled to an input terminal, and a drain electrode coupled to an output terminal. A signal inverter is also coupled to the input terminal. A second MOSFET has a source electrode coupled to the bias voltage source, gate electrode coupled to the signal inverter, and a drain electrode coupled to the output terminal. A load impedance is coupled between the output terminal and a supply voltage source.

Abstract: A broadcast center delivers each program in digital form and assembles the digital signals of the programs to constitute a digital multiplex which is conveyed to reception points by radio links or by cables. A program is selected by searching for coinicidence between a user-specified number and a channel number in the digital multiplex. The receiver device comprises an input circuit (1), a synchronization word finding cirucit (2), a bit counter (4), a channel counter (5), a comparator (7), a keyboard (8), first (11) and second (10) registers, a parity check register (13), and a digital to analog converter (14).

Abstract: A volume control circuit for a BTSC multi-channel signal includes a trap for the SAP frequency components, a pair of delay lines and a combiner circuit forming a transversal equalizer for shaping a frequency response characteristic that attenuates stereo L+R low frequency components more than L-R mid-frequency components, a pilot frequency trap and a resistance controlled inverting amplifier, all for producing a variable frequency response in a first path. A fixed frequency response, complementary to that at minimum attenuation in the first path, is provided in a second path, the outputs of the two paths being combined to produce an overall frequency response that is variable from unity across the frequency band to a response corresponding to that in the second path.

Abstract: An apparatus and method are provided for receiving and reproducing stereo television sound. A transmitted television signal is received that contains a first component comprising the sum of first and second stereophonically related audio signals and a second component comprising the difference between the first and second stereophonically related audio signals. The first and second components are converted to produce a first sound carrier centered at a first intermediate frequency and a second sound carrier centered at a second intermediate frequency. The first component is detected from the first sound carrier at the first intermediate frequency. The second component is detected from the second sound carrier at the second intermediate frequency. The detected first and second components are combined to produce a left channel audio output and a right channel audio output.

Abstract: A processing section for a television receiver for processing stereo/dual sound signals having a first sound carrier modulated by a first sound signal, and a second sound carrier modulated both by a second sound signal and by a pilot signal which, in turn, is modulated by a stereo/dual sound identifying signal. The processing section does not require a reference frequency from the synchronizing or intermediate frequency portion of the television receiver for recovering the pilot signal, but, rather, uses the pilot signal to control an oscillator in a phase-locked loop which loop is used to generate a signal for down-converting the frequency range of at least the modulated second sound carrier thereby obviating the need for expensive, precision filtering components.

Abstract: A compression/expansion device is adapted to compress and expand gains of additive and subtractive signals at each level of at least two audio signals, characterized in that each audio signal or any one of the additive and subtractive signals is compressed at the compressing side and expanded at the expanding side depending on the level of the additive signal.

Abstract: Arrangement for receiving TV signals containing left and right stereo sound signals, a first sound carrier being frequency-modulated by the sum signal (L+R) of the two stereo sound signals and the second carrier being frequency-modulated by twice the right stereo sound signal (2R), comprising a first FM-demodulator for demodulating the sum signal from the first sound carrier and a second FM-demodulator for demodulating twice the right stereo sound signal from the second sound carrier, a matrix circuit for deriving at least the left stereo sound signal from the sum signal and twice the right stereo sound signal and a left and right sound channel for the respective left and right stereo sound signals, the possibility of a simple mono-stereo signal control being obtained such as it is already known for prior art stereo radio receivers in addition to an advantageous noise distribution over the left and the right stereo sound channels.

Abstract: System for routing stereo radio frequency signals over alternate audio channels in response to detection of an interference in one of the stereo signals. The system delays the radio signals during which time it detects whether an interference has corrupted one of the radio signals. If a corruption has occured, the system switches the non-corrupted signal to an active one of the audio channels so that the interference is prevented from being reproduced prior to reaching an audio output.

Abstract: Apparatus for demodulating a multiplexed sound signal comprised of a first sound signal formed by the sum of a left channel signal and a right channel signal in a first language, a second sound signal formed by the difference of the left channel signal and the right channel signal, and a third sound signal in a second language, comprising a single demodulation circuit for producing either the second sound signal or third sound signal in response to the multiplexed sound signal; a selector switch for selectively changing the center frequency of the demodulation circuit to control the latter to produce either the second sound signal or third sound signal in response to the multiplexed sound signal; a matrix circuit for producing a stereo sound signal in response to the first and second sound signals; a pair of output terminals; and a switch device for supplying the third sound signal as a second language monaural sound signal from the demodulation circuit to one output terminal when the selector switch controls

Abstract: Apparatus for demodulating a multiplexed sound signal comprised of a first sound signal formed by the sum of a first channel signal and a second channel signal, a second sound signal formed by the difference of the first channel signal and the second channel signal, and a third sound signal formed by the sum of a third channel signal and a fourth channel signal, includes a pair of loudspeakers; a first switch device for supplying a monaural sound signal or a stereo sound signal to the loudspeakers; a matrix circuit for producing a first stereo sound signal in a first language or a second stereo sound signal in a second language in response to the second sound signal and the first sound signal or third sound signal, respectively, and for supplying the respective first stereo sound signal or the second stereo sound signal to the first switch device; and a second switch device for selectively supplying the first sound signal or the third sound signal to the matrix circuit or to the first switch device as a first

Abstract: Circuit arrangement for receiving two modulating signals, more specifically for television, particularly for the transmission of stereo signals or dual channel independent sound signals, each of the two modulating signal being conveyed through respective variable amplifiers, the gain of the amplifiers being adjustable in the opposite current directions for an optimum dematrixing of the stereo signal and being switchable by a factor of 2 for the reception of dual channel independent sound signals.

Abstract: An FM broadcast band demodulator and stereo decoder which can be connected to an existing frequency modulated, or FM broadcast tuner or receiver. The unit includes four basic sections; FM demodulation, stereo decoding, audio amplification, and tuning error detection. The FM demodulation is done by an integrated circuit directly coupled to a second integrated circuit which performs the stereo decoding function. The function output signals of the second integrated circuit are re-centered to a direct current or d-c level of zero by voltage dividers and amplified by operational amplifiers to drive a load. The tuning error indicator is connected between the first and second integrated circuits and nullifies the d-c components from the output signal of the first integrated circuit before integrating the output signal to remove the audio portion and leave only an average d-c component. The remaining d-c signal is amplified and applied through a bridge rectifier to a light emitting diode or LED.