Abstract: A cashless business transaction system (e.g., a vending system, a material tracking system, or a highway toll system) incorporates a method and apparatus for transmitting a digital information signal. A signal generator (311) generates a constant frequency signal. A phase modulator (305) varies the instantaneous phase of the constant frequency signal to represent digital information, thereby producing a phase modulated signal (325). A tuned resonant circuit (307) filters and averages the phase modulated signal to produce a simulated FM signal, and transmits the simulated FM signal via its antenna (309). One such business transaction system (e.g., a vending system) incorporates such a transmitter to facilitate transmission of billing information from a device located within a substantially electrically shielded environment.

Abstract: A system apparatus for controlling the whereabouts of an animal includes a receiver/stimulator unit affixed to the animal to selectively administer appropriate aversive stimuli effective to deter the animal from encroachment of boundaries in accordance with predetermined conditions based on radio signals received from at least one battery powered transmitter. The system may receive radio signals intermittently transmitted from the transmitter, the radio signals defining at least one boundary for the animal. The system then selectively administers the appropriate aversive stimuli in response to determining that at least one of the received radio signals satisfies one or more of the predetermined conditions.

Abstract: An apparatus for controlling the whereabouts of an animal is affixed to the animal and selectively administers appropriate aversive stimuli effective to deter the animal from encroachment of boundaries in accordance with predetermined conditions based on the coding and/or timing of radio signals received from at least one transmitter, which may include a wire loop. The apparatus receives radio signals intermittently transmitted from the transmitters, wherein the radio signals define at least one boundary for the animal. The apparatus then selectively administers the appropriate aversive stimuli in response to determining that at least one of the received radio signals satisfies one or more of the predetermined conditions.

Abstract: An RF signaling system and system for controlling the whereabouts of animals utilizing same functions, in a preferred embodiment, by efficiently establishing well-defined electronic boundaries using small, battery powered transmitters transmitting constant envelope RF signals in a near-field regime by repetitively delivering trains of brief, low duty cycle pulses of electrical energy to a resonant circuit which includes an antenna at a low RF carrier frequency corresponding to the resonant frequency of the circuit. During intervals between pulses, the resonant circuit is effectively isolated from the circuit delivering the pulses to minimize loading effects. Further energy efficiency is achieved by interposing inactive interals between at least some successive transmissions of the RF signals represented by the pulse trains. The RF signals emitted by the transmitters are digitally encoded as are those emitted from a wire loop coupled to an optional wire loop unit to define a wire loop boundary.

Abstract: A transmitter prepares digits for transmission, e.g. as spread spectrum data accompanying commercial radio, using code sequences having exactly zero cross-correlation. The code sequences include phased versions of the maximal length sequence, with an additional "0" bit appended to the end of each phased version. Information signals (which may be analog signals, or digital signals encoded as two or more analog levels) are transmitted by multiplying each information signal by one of the code sequences, and adding the resulting sequences together to form an output sequence for transmission. A receiver that recovers the information signals correlates the received sequence with each of the code sequences, producing results which are directly proportional to the information signals.

Abstract: An electromagnetic induction type hearing aid which comprises (1) an electromagnetic transmitter having an input for receiving a radiated acoustical signal and an output for radiating an alternating electromagnetic signal whose frequency components are determined by the input signal and (2) a wireless magnetostrictive vibrator of bimorph design and of biocompatible material and which is adapted to be surgically implanted on one of the bones of the ossicular chain in a spatial operative relationship to the transmitter output without the need for mechanical anchoring and without any components passing through the boundary of the middle ear of the user. The vibrator is further responsive to the electromagnetic signal radiated from the transmitter and vibrates the ossicular chain in response to such radiated electromagnetic signal to stimulate the inner ear to create the perception of sound to the user.

Abstract: The whereabouts of a pet or other animal are controlled using one or more transponders to established a boundary. The transponders receive an incident signal from a transmitter and generate a distinguishable return signal which, when the animal moves into proximity of the boundary, is received by a unit affixed to the animal to initiate application of an aversive stimulus which deters the animal from traversing the boundary. The transponders can be active or passive and can be located to establish either fixed or mobile boundaries.

Abstract: A line isolation monitor for detecting ground faults in isolated power systems by determining the potential personnel hazard current due to the complex ground fault impedances and a method for accomplishing the same. The total hazard current is determined by dividing the peak line voltage of the isolated power supply by the total impedance between ground and a common mode point, such as the center tap of the primary winding of the line isolation monitor transformer connected to the isolated power supply. This impedance is determined at line frequency by impressing a minute, phase-modulated, power line frequency test signal into the isolated power system and using an extremely selective, coherent filter to remove the signals in phase with the power line signal. The magnitude of the phase modulated test signal passed through the filter is related to the amount of fault impedance. Comparison of this test signal magnitude to the line voltage provides an indication of the total hazard current.

Abstract: A binary capacitor consists of a piston having a metallized band on its periphery. The piston is movable between first and second positions within a cylinder which carries two spaced metallized bands. One of the positions of the piston defines a position of maximum capacitance, i.e. where the band on the piston overlaps both of the cylinder bands. The second position of the piston defines a position of minimum capacitance; i.e. where the piston band clears at least one of the cylinder bands. The piston is latched in its stable minimum and maximum states by fixed permanent magnets located at the ends of the piston in combination with soft iron slugs at the ends of the cylinder. The piston is moved by appropriately energizing electromagnetic coils wound over the soft iron slugs on the cylinder.

Abstract: The high power (10-1000 W) modulated carrier of a noisy transmitter is attenuated and amplitude limited and is used to control a power oscillator which regenerates the carrier and modulations without the loss of power. The power oscillator is slaved in frequency to the amplitude limited and attenuated signal, and it follows any phase or frequency modulation present thereon. Noise components appearing on the original carrier fall outside of the information passband of the power oscillator loop and therefore are not reproduced. The noise free output from the power oscillator is then A.M. modulated prior to power amplication and transmission. The oscillator operates at relatively high power (1 watt) and is automatically digitally coarse tuned and analog fine tuned.