Matches 1 - 27 out of 27


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5848129 Electronic billboard with telephone call-in control  
A conventional billboard for displaying a visual message is combined with a communication system for enabling a message related to the message displayed by the billboard to be transmitted from the...
5471534 Devices, systems and methods for composite signal decoding employing interpolation filter  
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...
4316058 Sound field transmission system surrounding a listener  
Systems for uniformly reproducing a sound field surrounding a listener are disclosed utilizing three channels of audio information signals. One channel provides signals representative of total...
4282401 System for transmission and reception of discrete four channel stereo  
A system for transmission and reception of discrete four channel stereo for utilizing a carrier frequency modulated in accordance with a modulation function of the form: f1 (t)=A+Bsin 2ωt+Ccos ...
4245352 Automated system for testing radio receivers  
An automated system for electronically testing the response and the quality of the output produced by radio receivers and the like is provided, wherein various tests including frequency response,...
4131851 Radio-signal receiver with plug-in modules  
A receiver for radio signals, comprising an r-f (radio-frequency) unit and an a-f (audio-frequency) unit, the circuit in the a-f unit being interrupted at certain points and the receiver being...
4075425 Multi-directional sound signal reproducing system  
The present invention is to increase the carrier level so as to improve the S/N ratio when the factor T93, TT or TQ is small in level. When the level is low, noises are apt to be offensive to a...
4061882 Quadrature multiplying four-channel demodulator  
A decoder is provided for a FM radio four-channel system having the usual 19 kHz pilot signal, a first subcarrier at 38 kHz, a second subcarrier in quadrature therewith, and another subcarrier at...
4037055 Stereophonic demodulator apparatus  
Stereophonic demodulator system for demodulating a stereophonic composite signal that includes a subcarrier frequency of at least 38 KHz, the apparatus including: a circuit for producing a 38 KHz...
4027107 Multiple channel FM stereo system  
A transmitter or a receiver processes four-channel stereo frequency-modulation information. The information represents four audio signals A, B, C and D that correspond to sources respectively...
4016366 Compatible stereophonic receiver  
A compatible stereophonic receiver capable of receiving a monaural signal, 2-channel stereophonic composite signal and multi-channel composite signal transmitted in the frequency modulated form,...
4013841 Four-channel stereo receiver  
A four-channel stereo receiver capable of making the four-channel indication, and automatically changing over the four-channel mode operation and the two-channel mode operation or muting the...
3991374 Controllable bandwidth IF filter circuit for radio receivers  
Controllable bandwidth IF filter circuit for radio receivers generally, but having particular application to quadraphonic radio receivers intended for use in a quadraphonic system that is...
3985964 4-Channel stereophonic demodulating system  
A 4-channel stereophonic demodulating system based on a switching mode, which comprises a plurality of switching means for demodulating a received 4-channel stereophonic composite signal under...
3980832 Decoder for four channel FM stereophonic composite signal having an Indicating signal wherein the indicating signal is detected and used in the decoding of the four channel composite signal  
A decoder is provided for four channel FM stereophonic composite signals including a first pilot signal, a main channel signal, a first sub-channel signal suppressed carrier amplitude modulated on...
3970788 Monaural and stereo compatible multidirectional sound matrixing  
Multidirectional source signals which are encoded in two monaural and stereo-compatible transmission channels with predetermined amplitude and phase relations indicative of source directions and...
3965302 Stereo signal demodulator in a four-channel stereo broadcast receiver  
Improvements in a stereo signal demodulator of a receiver in a four-channel stereo system, in which system upon transmitting four sound source signals (LF, LB, RF and RB) from one station, the...
3942126 Band-pass filter for frequency modulated signal transmission  
A band-pass filter comprises a delay circuit comprising a plurality of unit delay elements connected in cascade arrangement and receiving as input a signal including a frequency modulated signal...
3909539 Four-channel stereophonic demodulating system  
A four-channel stereophonic demodulating system having three switching circuits, the outputs of the first one of the switching circuits being applied to the second and third switching circuits...
3902018 Multiple channel FM stereo system employing AM vestigial sideband subcarrier modulation  
A quadraphonic FM system includes an encoder and a decoder for processing four-channel stereo information is disclosed. The information is represented by four audio signals LF, RF, LB and RB that...
3896269 Four channel stereophonic broadcasting system and receiving device  
A four channel broadcasting system of the instant invention utilizes an FM broadcasting wave of the pilot tone system having a main channel domain containing a first composite signal, a first...
3881063 System for selectively receiving either 4-channel or- 2-channel stereophonic broadcastings  
The invention relates to a system for selectively receiving either 4-channel 2-channel stereophonic broadcastings. The 4-channel signal is a composite of stereophonic signals comprising a main...
3836724 FOUR CHANNEL HEADPHONE  
An earphone for a four channel headphone has a filling material of light weight and good sound absorbing nature closely fitted inside a unit case. Two cylindrical or conical holes are provided in...
3822365 COMPATIBLE FOUR CHANNEL FM SYSTEM  
A four channel FM system is described. In one embodiment the usual 19 kHz pilot signal is employed to switch between front and rear information, while in another, a 76 kHz switching signal is...
3798377 FOUR CHANNEL FM DECODER UTILIZING A ONE-OF-FOUR DECODER  
A four channel FM system decoder wherein the usual 19 kHz pilot signal actuates a phase lock loop circuit, said phase lock loop circuit actuating a one-of-four decoder and quadraplex gate to switch...
3794779 HEADPHONES FOR REPRODUCING FOUR-CHANNEL SOUND  
Each headphone casing encloses forwardly and rearwardly extending, segregated, acoustic mixing chambers segregated by a generally vertical partition and opening inwardly through a common, generally...
3787629 APPARATUS FOR DISTINGUISHING BETWEEN VARIOUS FM BROADCAST MULTIPLEX TRANSMISSIONS  
A 38kHz flag subcarrier accompanying an FM multiplex transmission identifies whether such multiplex transmission includes two channel or surround stereophonic information. Apparatus to provide such...
Matches 1 - 27 out of 27