Abstract: Automatic switching circuitry for processing input signals of more than one frequency, incorporating information for the derivation of one or more audio channels. The circuitry, including a selectively variable bandpass device, may be one of several values corresponding to the frequency of a input signal. A demultiplexing device is provided to apply a demultiplexing operation on signals output from the bandpass device, with a control logic monitoring the demultiplexing device to determine if a demultiplexing operation has been achieved, and instructing the selection of another value for the bandpass device if no demultiplexing operation was achieved for a given value of the bandpass device.

Abstract: A multisound signal demodulator IC has a demodulator for demodulating L+R and L-R signals from a composite input signal and for producing a third signal M when it is present in the composite signal, a matrix circuit for producing L and R signals from the L+R and L-R signals, a pair of changeover switches for supplying either the L and R signals or the M signal to first and second output terminals, and a third changeover switch for supplying either the L+R or M signals to a third output terminal. The generation of the changeover devices are controlled by signals supplied to external control terminals. The IC is adapted for use in both television receviers and VTR's and is adaptable to use with different methods of multisound transmissions.

Abstract: A device comprised of separate transmitter and receiver sections, which converts an audio signal into an FM signal, transmits the FM signal over AC power lines, and reconverts the FM signal into an audio signal, which can then be outputted to loudspeakers or other devices. By transmitting the signal over AC lines, no long wires are needed to connect remote loudspeakers or other devices to the source of the audio signal.

Abstract: A device comprised of separate transmitter and receiver sections, which converts an audio signal into an F.M. signal, transmits the F.M. signal over A.C. power lines, and reconverts the F.M. signal into an audio signal, which can then be outputted to loudspeakers or other devices. By transmitting the signal over A.C. lines, no long wires are needed to connect remote loudspeakers or other devices to the source of the audio signal.

Abstract: A decoder for use in an FM stereo broadcasting system in which the usual difference signal S and a compressed version S' of the difference signal are transmitted, automatically selects on a continuous basis for de-matrixing with the received sum signal M either an attenuated signal S' or the usual difference signal S based on the protocol that the attenuated signal S' is always selected unless the usual difference signal S is higher in level than a predetermined threshold potential related to the signal level at the knee of the expansion characteristic. The decoder eliminates the need for the relatively expensive analog variable gain amplifier used in prior art decoders and is less sensitive to time constant errors and errors due to multipath distortions.

Abstract: A method and a circuit arrangement for receiving frequency-modulated stereo multiplex signals is disclosed in which the channel to be received is converted to the zero IF using negative feedback for reducing the frequency deviation in the IF band. The conversion takes place in a quadrature converter stage, and adjacent-channel selectivity is provided by low-pass filtering the two outputs of the quadrature converter stage, with the slopes of the selectivity characteristics of the two low-pass filters being relatively slight and lying partly in the zero IF band. The amount of the average attenuation of the frequency-modulated stereo subcarrier signal is equal to the amount of the reduction of the frequency deviation of the frequency-modulated main-channel signal. The negative-feedback signal is the demodulated main-channel signal, the amount of negative feedback being determined by an amplifier in the negative-feedback path.

Abstract: Dematrixing circuit of the switched-capacitor type for dual channel TV stereo sound signals comprising first and second signal inputs (I.sub.1, I.sub.2) for applying a stereo sum signal ##EQU1## thereto and one of the two left and right stereo signals (for example, R), the amplitude of said latter stereo signal being twice as high as that of each of the two stereo signals in the stereo sum signal, and comprising first and second signal outputs (O.sub.1, O.sub.2) for supplying a dematrixed stereo signal. In order to provide the possibility of a correct dematrixing of the stereo signal (L), which is not separately available, with a minimum number of circuit elements and to simultaneously avoid through-connections from the two signal inputs (I.sub.1, I.sub.2) at one end and the two signal outputs (O.sub.1, O.sub.2) at the other end, the dematrixing circuit according to the invention comprises first and second capacitors (C.sub.1, C.sub.2) each being arranged between an input switch (S.sub.i1, S.sub.

Abstract: A multivoice signal switching circuit is incorporated in a circuit for demodulating a multivoice signal containing a main channel signal, a first subchannel signal, and a second subchannel signal, the latter two signals being treated for noise reduction. The demodulating circuit comprises a first circuit for extracting a main channel signal from the multivoice signal, a second circuit for extracting a first subchannel signal from the multivoice signal, and a third circuit for extracting a second subchannel signal. The above switching circuit receives the first and second subchannel signals and selectively outputs one of the two subchannel signals, to a decoder where the original signal is restored from the noise reduction treated signal. This signal is fed to an output circuit means together with the outputs of the first circuit, so that an audio signal is reproduced.

Abstract: A digital television receiver circuit filters and demodulates a signal contained in the input signal of the television receiver and frequency-modulated with at least one audio signal. The only A/D converter required in the circuit is the converter for changing the video signal from analog to digital form. The circuit uses digital filters, a digital mixer, decimation stages and a digital frequency demodulator stage to separate the audio signal from the composite video signal.

Abstract: A system for wirelessly transmitting stereo audio from a source such as a tape player to a removed location. The output signal-carrying wires from the source are connected to a coupler unit adapted to removably hold an FM band stereo broadcast microphone/transmitter. The audio output signal is coupled to the microphone/transmitter which, in turn, transmits the audio signal to an FM stereo receiver at the remote location where it is then rebroadcast for listening. In one embodiment, the coupler unit acoustically couples the signal to the microphone. In a second embodiment, the coupler unit inductively couples the signal to the microphone.

Abstract: A stereo demodulator capable of demodulating a composite signal without performing a switching operation is disclosed. A subcarrier generating circuit generates a square wave subcarrier signal V1 of 38 KHz which is in turn converted into a triangular wave subcarrier signal V4 of 38 KHz synchronized with the square wave subcarrier signal V1. The composite signal is converted into a current signal i which is then amplified by a voltage-controlled amplifier whose gain varies in accordance with the triangular wave subcarrier signal V4 applied thereto as a control voltage. Since the voltage-controlled amplifier is of such a type that the gain thereof logarithmically varies in accordance with the control voltage, the composite signal is amplified by a gain which varies substantially sinusoidally in accordance with the triangular wave subcarrier signal V4. As an output of the voltage-controlled amplifier is in the form of a pair of currents i.sub.R and i.sub.

Abstract: A television stereo adapter is provided for use with a television receiver to detect and decode stereophonic audio signals that may be transmitted with the composite television signals. The adapter includes an IF pick-up that is physically separate from the television receiver for picking up spurious IF audio signals that normally are generated by the television receiver. A stereo detector is coupled to the IF pick-up for detecting from the IF audio signals monophonic and stereophonic components that are transmitted with the composite television signals. The detected components are decoded into left-channel and right-channel audio signals; and these left-channel and right-channel signals are adapted to drive sound transducers, such as loudspeakers. Optionally, the left-channel and right-channel audio signals are amplified by gain-controlled amplifiers whose gains are a function of the output sound level of the television receiver.

Abstract: A method for recording and reproducing multiplex information in which two subcarriers of the same frequency are modulated by two respective subchannel signals. The modulated signals are added to two main channel signals to produce two corresponding sum signals. Two main carriers of different frequencies are then modulated with the two sum signals. Information is recorded on a storage medium in response to the frequency-modulated signals. For reproduction of the recorded information, the main carriers are extracted and separated in frequency, and then detected by separate frequency detecting means. A selected one of two detected outputs from the frequency detecting means is supplied at a time to a common subchannel demodulating means.

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: FM-receiver including a frequency-locked loop (2-14), which loop includes, successively connected, a voltage controlled oscillator (8), a mixer circuit (2) connected to an aerial input, an IF-portion comprising an IF-filter (9), an FM-detector (4), a loop filter (5) and a loop amplifier (6) for adjusting the transfer characteristic of the frequency locked loop (2-14), which loop amplifier (6) is connected to a control input of the voltage-controlled oscillator (8) for a feedback of the modulation signal of the received FM-signal. The loop filter (5) comprises a first low-pass filter (14). The FM-receiver being realizable in integrated circuit form and suitable for processing FM-stereo signals. The receiver is at least comparable to conventional FM-stereo receivers as regards selectivity, harmonic distortion and stability, the conventional FM-stereo receivers not being realizable in integrated circuit form.

Abstract: An FM receiver comprising a 90 degree phase shifter 21 of the FM signal and a first multiplier 22 for multiplying the FM signal and the phase shifted signal to produce a main signal L+R and a second multiplier 6 for multiplying the FM signal, the phase shifted signal and a subcarrier wave of 38 kHz to produce a sub-signal L-R.

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: A pulse position modulated (PPM) signal is derived from an input FM signal, and first and second switching signals are derived which are opposite in phase and correspond to alternating half cycles of the PPM signal. First and second opposite phase subcarrier signals are derived synchronized to the pilot signal in the input FM signal, and various combinations of the switching and subcarrier signals are multiplied together and the multiplication products combined to obtain left and right channel outputs.

Abstract: A system for time-period modulating (TPM) a subcarrier in accordance with the amplitude of an input signal includes generating a ramp signal of constant slope, comparing the ramp signal with the input signal, and resetting the ramp signal when the ramp signal reaches the input signal. Each time the ramp signal is reset, a clock pulse is counted. These clock pulses are counted in cyclic groups of N. After each clock pulse is counted, the then attained count is converted to a value of a sinusoid about some reference. The values for each of N counts define one sinusoidal cycle of the modulated subcarrier. Converting these values to voltage levels produces a sinusoidal stepwave which has a period linearly proportional to the amplitude of the input signal at the time.

Abstract: An output matrix adapted to receive an L+R signal component (made up of the sum of L and R stereo components) and an L-R signal component, and to combine these in a manner to produce a separate L output and a separate R output, with certain modifications to the outputs. The higher frequency portion of the L-R signal is passed through a detector which, in turn, causes a leading edge amplifier to transmit to the matrix only those signal portions where there is a relatively abrupt change of amplitude, these being the signal portions which contain the main stereo information which gives the directional information. Also, the L+R signal component, in addition to being transmitted directly to the matrix, is directed through time delay means to produce a time delayed L+R signal component that is also transmitted to the matrix, so as to provide what are called "ambient" to the output of the matrix.