Abstract: Systems, methods and apparatus are provided for conducting local wireless audio signal transmissions from a local audio signal source to a person within a local signal transmission area. In certain embodiments, the transmissions are conducted over the 900 MHz local transmission band to a portable receiver unit supported on the headband of a stereo headphone unit. The receiver unit serves to down convert the 900 MHz signal to a local frequency band which is received by an FM receiver of the receiver unit which serves to reproduce the audio signals therefrom which are, in turn, converted to acoustic signals by electroacoustic transducers of the headphone. A transmitter unit includes a ceramic resonator stabilized FM transmitter, as well a filter for suppressing high frequency noise in an audio modulation signal, a stereo audio multiplexing unit utilizing a 3fH subcarrier and an overmodulation detection unit.

Abstract: Systems, methods and apparatus are provided for conducting local wireless audio signal transmissions from a local audio signal source to a person within a local signal transmission area. In certain embodiments, the transmissions are conducted over the 900 MHz local transmission band to a portable receiver unit supported on the headband of a stereo headphone unit. The receiver unit serves to down convert the 900 MHz signal to a local frequency band which is received by an FM receiver of the receiver unit which serves to reproduce the audio signals therefrom which are, in turn, converted to acoustic signals by electroacoustic transducers of the headphone. A transmitter unit includes a ceramic resonator stabilized FM transmitter, as well a filter for suppressing high frequency noise in an audio modulation signal, a stereo audio multiplexing unit utilizing a 3f.sub.H subcarrier and an overmodulation detection unit.

Abstract: Systems, methods and apparatus are provided for conducting local wireless audio signal transmissions from a local audio signal source to a person within a local signal transmission area. In certain embodiments, the transmissions are conducted over the 900 MHz local transmission band to a portable receiver unit supported on the headband of a stereo headphone unit. The receiver unit serves to down convert the 900 MHz signal to a local frequency band which is received by an FM receiver of the receiver unit which serves to reproduce the audio signals therefrom which are, in turn, converted to acoustic signals by electroacoustic transducers of the headphone. A transmitter unit includes a ceramic resonator stabilized FM transmitter, as well a filter for suppressing high frequency noise in an audio modulation signal, a stereo audio multiplexing unit utilizing a 3f.sub.H subcarrier and an overmodulation detection unit.

Abstract: Systems, methods and devices are provided for remotely transmitting a control command to a device having a light sensor for receiving the control command in the form of a light energy signal. A radio frequency remote control signal is produced within an enclosure of a remote control unit (such as a hand-held remote control unit) and is radiated therefrom to a radio frequency receiver. The receiver converts the received signal to a light energy signal which it applies to the light sensor of the device to provide the command thereto.

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: An improved demagnetizer for the magnetic heads of a tape cassette recording and/or reproducing device. The device includes an intermediate gear which is rotated by either one of two hub gears engaging respective drive spindles of the recording and/or reproducing device. A push-pull rod has one end pivotally connected to an outer radial position of the intermediate gear and another end pivotally connected to a generator of an alternating magnetic field of constant intensity. Power is supplied from a battery to the generator of an alternating magnetic field upon closure of a power switch caused by motion of the magnetic head into the "play" position. Rotation of the intermediate gear causes the magnetic field generator to be cyclically and linearly reciprocated with respect to the head so as to produce a varying magnetic field at the head. A sensor senses when the magnetic field generator has been reciprocated to its farthest point from the head and a circuit counts the number of such sensings.

Abstract: This invention discloses a wireless compact disc stereo playback system for use in automobiles. An FM transmitter is employed which is connected at the output of a portable CD player, the FM transmitter thereby producing a stereo FM signal which is transmitted to be received by the automobile antenna. The automobile's FM system is tuned to play the output of the CD player through the FM radio system of the automobile. The output power of the FM transmitter and its bandwidth are selected so that the distance from the antenna to the FM transmitter will be sufficient to ensure effective sound production in standard automobiles and vans.

Abstract: A pulse width modulated DC to DC voltage converter for producing selectable differential output voltages. A feedback voltage and a selectable error voltage are fed back to the controller to control the pulse width by the difference between them. First and second power switches are respectively operable in response to first and second square wave signals output from the controller. The converter includes a center-tapped transformer having first and second output terminals. The outputs from the first and second output terminals are filtered and rectified into respective nominally positive and negative DC output voltages. A first selector switch for selectively connecting the nominally negative voltage output terminal to either a grounded bus or a negative bus is mechanically ganged to a second selector switch having a plurality of positions for selecting one of a plurality of predetermined error voltages.

Abstract: A wireless local transmission system includes a separate transmitter and receiver. The transmitter converts an audio signal and/or an audio and video signal into a modulated signal within the 902-928 MHz frequency band and transmits the modulated signal to the receiver which reconverts the modulated signal to a frequency band below 900 MHz for use by a radio or television receiver.