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8050412 |
Scaling adjustment to enhance stereo separation
A demodulator (10) converts television signals to video baseband signals and audio baseband signals including stereo signals representing a right channel signal value and a left channel signal...
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8045717 |
Stereo decoder and method for processing pilot signal
A stereo decoder and a method therefor are provided. The stereo decoder receives a MPX signal from an FM demodulator, and comprises a first auto-calibration circuit, a band-pass filter, a second...
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7961890 |
Multi-channel hierarchical audio coding with compact side information
A parametric representation of a multi-channel audio signal describes the spatial properties of the audio signal well with compact side information when a coherence information, describing the...
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7932775 |
Digital demodulation device and related method
A digital demodulation device for demodulating an amplitude modulation (AM) signal whose carrier has a first frequency includes: a processing circuit for performing first path digital processing...
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7894609 |
Stereo signal processing apparatus
Disclosed is a stereo signal processing apparatus, in particular for a digital BTSC television decoder, comprising a sub-channel signal processing section which comprises an input for inputting an...
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7639821 |
System and method for improved detection of AM signals
A software defined radio detects an amplitude modulated (AM) signal contained within a received signal. This detection involves first receiving a radio frequency (RF) signal that contains the AM...
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7558549 |
Method and system for rejecting single-sided leakage into an amplitude modulated (AM) channel
Aspects of the method and system for rejecting single sided leakage into an amplitude modulated channel may comprise an AM demodulator for demodulating a received composite broadcast signal's...
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7302011 |
Quadrature frequency doubling system
The frequency doubler of the present invention operates to provide an in-phase signal and a quadrature signal, each having a frequency equal to twice the frequency of a reference signal. The...
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7295631 |
Stereo demultiplexer
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...
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7043026 |
Method for removing AM neighboring interference and a circuit for the same
An AM neighboring interference removing method and circuit is provided which can select only a desired AM modulation wave even if an interference AM modulation wave is partially superposed upon the...
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6813359 |
Apparatus and method for minimizing multipath interference
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...
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6671494 |
Small, battery operated RF transmitter for portable audio devices for use with headphones with RF receiver
A portable FM stereo RF transmitter having an audio plug extending therefrom directly or via a cable and which mates with the earphone or output jack of an audio source such as a portable battery...
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6570500 |
Infra-sound surveillance system
The invention is a method for monitoring an environment by evaluating an infrasonic signal obtained from said environment. The method includes averaging said infrasonic signal (Vinfra) to provide...
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6459796 |
AM stereo receiver with reduced distortion
Left and right stereo audio information is reproduced from a compatible quadrature amplitude modulation (C-QUAM) broadcast using two separate modes of detection. In the first mode, a true C-QUAM...
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6406439 |
Phase lock evoked response audiometer
An evoked response audiometer method and apparatus in which a patient receives an auditory stimulus signal comprising a carrier frequency which is periodically amplitude modulated and frequency...
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6347146 |
Noise reducing
A noise reducing AM receiver has a receiving stage for receiving an AM signal of carrier frequency separated from that in an adjacent channel by a predetermined spacing and that may have a noise...
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6272226 |
Apparatus and method for masking audio signals in a signal distribution system
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...
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6111957 |
Apparatus and method for adjusting audio equipment in acoustic environments
The signal in each channel of a stereo is modulated at an inaudible frequency by a replica of the original signal. The modulated signal is broadcast into a room by a loudspeaker and is picked up by...
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6047170 |
Automatic squelch control for narrow band AM radio
An improved squelch circuit which utilizes a phase-locked-loop (PLL) arrangement to track the carrier signal and identify when audio communication should be curtailed. The lock detect circuit of...
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5915028 |
Amplitude demodulator
An amplitude demodulator for demodulating a quadrature-amplitude modulated stereo signal for radio receivers, where a digital intermediate-frequency signal is constructed from a received signal,...
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5784466 |
Co-channel interference detector
An interference detection assembly is disclosed for detecting interference generated from a plurality of signals received by a receiver having a single output signal, the interference detection...
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5706350 |
Stereophonic decoder
A compatible quadrature type AM sterophobic decoder including an enveolpe detector for providing a current output signal and a combination of a VCA and a synchronous detector for providing a...
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5668923 |
Voice messaging system and method making efficient use of orthogonal modulation components
A modulation scheme (600) useful in a voice paging system in which both of two orthogonal modulation components (500 and 510) are used to carry two halves of a single voice message destined for a...
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5561716 |
Demodulator
In a demodulator for a stereo signal transmitted by amplitude and phase modulation of a carrier, a phase signal and a quantity signal are formed. By multiplication of the quantity signal with the...
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5467399 |
Coherent signal generation in digital radio receiver
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...
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5359661 |
Out-of-lock detector for synchronous AM detection
An AM stereo receiver in which a synchronous in-phase signal is determined comprises a low pass filter circuit for determining an average DC value of the synchronous in-phase signal, a reference...
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5341431 |
AM stereo detection and audio processing apparatus
A synchronous AM detector and processor requiring a reduced number of external components and fewer integrated circuit pins comprises an audio processor having a first filter operation controlled...
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5261004 |
Noise blanking circuit for AM stero
An AM stereo input signal is processed by an envelope detector, an in-phase detector and a quadrature phase detector to yield outputs which may carry short noise impulses. Each output is low pass...
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5253298 |
Reducing audible noise in stereo receiving
A receiver for receiving a stereophonic signal with upper and lower sidebands carrying a modulating signal includes independent sideband circuitry for providing upper and lower sideband signals....
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5239699 |
AM-FM combined stereo receiver
An improved AM-FM combined stereo receiver is provided having a single processor for removing, in the FM mode, arctangent distortion, and in the AM mode, to process the phase term from arctangent...
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5222144 |
Digital quadrature radio receiver with two-step processing
A digital signal processing (DSP) radio receiver employs a conventional analog RF tuner to produce an analog intermediate frequency. The receiver performs DSP functions of digitally sampling the...
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5151939 |
Adaptive audio processor for AM stereo signals
An adaptive audio processor for stereo AM broadcast signals includes independent signal processing paths. Each path has a variable lowpass filter and a matrix and variable Q 10 kHz notch filter to...
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5050237 |
Radio receiver having automatic bandwidth control during tuning
In this radio receiver, the charge on a capacitor (14) controls the bandwidth of filters in the receiver's audio circuits. When tuning the radio, a bandwidth control circuit (13) forces this...
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5023909 |
Multi-system AM stereo receiver having preferred mode of operation
Stereo decoders for use in AM stereo receivers are disclosed which have two different modes of operation, one of which suffers adverse effects from the presence of co-channel interference and...
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5014316 |
Compatible quadrature amplitude modulation detector system
An audio detector circuit forms L+R and L-R audio signals from an intermediate frequency compatible quadrature amplitude modulated signal in the form (1+L+R)cos(fct+φ) where φ contains phase m...
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5008939 |
AM noise reducing
A receiver for receiving an amplitude modulated signal with upper and lower sidebands, comprising: an independent sideband decoder for providing demodulated upper and lower sideband audio signals,...
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RE33381 |
Multiple system AM stereo receiver and pilot signal detector
A stereo receiver is described which is capable of receiving any two or more of the five currently proposed AM stereo system broadcast signals. The multisystem receiver includes circuitry which is...
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4955072 |
Method of generating an amplitude-modulated ISB transmission signal and apparatus for carrying out the method
In the case of a method for the generation of an amplitude-modulated ISB transmission signal from different AF signal (NF1,2), the signal vectors are split into signal components (x1,y1 and x2,y2,...
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4944011 |
Circuit for controlling operator indicators in an AM stereo receiver
Disclosed is a circuit for controlling the activation of a stereo indicator and a tune indicator in an AM stereo receiver. In the preferred embodiment, a pilot tone detector is employed to...
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4903329 |
Clamping circuit for a PLL tuning system
An AM Stereo receiver is described which includes an AGC having an output which indicates whether the received signal has significantly decreased in level and having a clamping circuit for...
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4887297 |
Apparatus for processing stereo signals and universal AM stereo receivers incorporating such apparatus
Multi-system or "universal" AM stereo receivers are provided which require no switching of the receiver's stereo decoder circuitry regardless of which AM stereo system signal is being received. In...
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4872207 |
Automatic IF tangent lock control circuit
An improved radio receiver that maintains a stable predetermined IF frequency upon receipt of input carrier signals of differing frequencies. The IF signal (14) is processed through a signal...
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4866779 |
Adaptive AM audio processor
An audio processor for adaptively rejecting undesired noise and interference in an audio input which includes a variable Q, 10 kHz switched capacitor notch filter. The Q of the notch filter is...
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4845750 |
Multiple function control circuit for an AM stereo receiver
In an AM stereophonic receiver a voltage is developed in response to negative overmodulation in the received signal, to detection of a pilot tone, to detection of a minimum or no signal strength...
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4815141 |
Apparatus and methods for removing unwanted components from a communications signal
A tuner includes circuitry for conditioning an audio signal including (i) a pilot signal canceller, (ii) a noise limiter, (iii) a notch filter, and (iv) a de-emphasizer; as well as an attenuator...
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4757539 |
Apparatus and method for decoding an AM stereo broadcasting signal of an independent sideband system
In an AM stereo receiving apparatus for decoding an AM stereo broadcasting signal of an ISB system, an envelope detecting circuit 6 detects an output of an intermediate frequency amplifying circuit...
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4747141 |
AM stereo signal decoder
A simplified stereo signal decoder is disclosed for use in an AM stereo receiver which receives composite AM stereo broadcast signals comprising a radio frequency carrier wave having amplitude...
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4716590 |
AM stereo transmission method and apparatus
This invention discloses an AM stereo transmission method characterized in that when left and right audio signals L and R are transmitted as an AM stereo signal which is represented by S=A...
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4712241 |
Broadcast signal detected indication system
In a radio having an in phase multiplier (A) for providing an in phase detected signal, a detection unit for receiving this signal and for determining whether this signal includes any negative...
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4707856 |
AM stereo receiver
An AM stereo receiver applicable to receive AM signals containing ID signals which represent different AM stereo systems. The AM stereo receiver includes an IF circuit for generating an IF signal...
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