Abstract: A device for achieving animal response that produces two output frequencies, one to soothe the animal and one to distress the animal. The frequency for distressing the animal is an oscillating frequency to cause further attention by the animal and to provide optimum operation of the sound-producing element. The oscillating frequency is created by producing a second frequency higher than the first frequency, and then oscillating this second frequency. Sound is produced by a piezoelectric element driven by these frequencies. Components are generally contained in an enclosure body, with push buttons for selecting a desired sound output penetrating this enclosure body for contact by a user of the device.

Abstract: A system for tracking articles or persons comprising a base unit for transmitting a series of ultrasonic signals and an alarm signal, a remote unit, removably attached to the article or person, for receiving the series of ultrasonic signals from the base unit and for transmitting an electromagnetic signal upon receipt of the ultrasonic signal from the base unit, and a monitoring unit for receiving the alarm signal.

Abstract: A radio frequency communication system utilizing a radiating transmission line for simultaneously communicating audio and video signals is disclosed. The video signals convey video information and the audio signals convey narrow band computer data or audio information. The communication system also provides several separate channels allowing simultaneous audio communication between a plurality of mobile stations. The communication system is intended to be used in environments where radio waves do not propagate well, such as in underground mines. The communication system comprises at least one amplification unit connected to the radiating transmission line for periodically amplifying the audio and video signals. The amplification units have a separate amplifier for amplifying each of the signals and each amplifier is connected to the transmission line in parallel. The amplifiers utilize transistors operating in the linear region.

Abstract: A radio frequency communication system utilizing a radiating transmission line is disclosed. During normal operation, a mobile communication unit near the radiating transmission line can communicate with other mobile communication units near the transmission line as well as with the base station. The communication system is redundant in that if a portion of the communication system fails such that communication signals cannot be communicated through the fault the communication system will continue to operate and communication signals from any mobile communication units near the radiating transmission line will be transmitted and received from the base station. The communication system is particularly suited for use in underground mines in which event the base station can be located at the surface, and the mobile communication units are generally located in the mine shafts.

Abstract: A pet containment system uses a transmitter for transmitting a series of electromagnetic signals, and a receiver removably attached to the pet for receiving the series of electromagnetic signals from the transmitter. The transmitter includes means for modulating the electromagnetic signals, means for transmitting the resulting non-random patterns of electromagnetic energy, and at least one transmitting antenna. The receiver includes at least one receiving antenna, means for comparing the signal level of the received electromagnetic signals from said transmitter with a predetermined level and for producing an electronic indication of a loss of signal, means for comparing the phase of the received electromagnetic signals from said transmitter with a reference phase and for producing an electronic indication of a loss of phase, means for producing a warning stimulus to the pet, and means for producing a control stimulus to the pet.

Abstract: A system for charging a rechargeable battery of a portable unit in a rack includes a detection circuit which detects the presence of the unit in the rack. The system has circuitry for transferring of energy from a supply circuit of the rack via a charging circuit of the unit to the battery. The transfer circuit is formed by an induction path which comprises a coil of the rack and a coil of the unit. The unit has a transmission circuit which, after placement of the unit in the rack, transmits a message via a wireless path, for example the induction path, to a control circuit of the rack, the control circuit being connected to the supply circuit. If the rack does not receive, or does not satisfactorily receive, a message expected upon placement of the unit in the rack, the control circuit controls the supply circuit so as to make the supply circuit select a higher transfer rate than normal for the purpose of transferring energy to the battery via the induction path.

Abstract: A pager system includes a transmitter with a control unit for selectively transmitting radio signals having specific pager codes, and a plurality of portable pager receivers each having its own electrical energy source and adapted to respond to a specific pager code. The pager system further includes a central unit coupled to the control unit. The central unit includes a comparing unit and is coupled to a first memory for storing information relating to the individual pager receivers, a second memory for storing reference data, a clock, and a presentation unit. The comparing unit compares the contents of the first and second memories for a specific receiver and clock data, and signals the transmitter when a code signal is needed. The presentation unit generates a warning signal in response to a code signal received from the transmitter.

Abstract: A system for detecting the presence in a compartment of a rack of a portable transmission unit of a number of portable transmission units, each being capable for transmitting or for receiving a signal containing an identification number assigned to the unit. All compartments of the rack or only compartments receiving or having received the units therein are scanned. The presence of a unit in a compartment is acknowledged by the unit after it has received a scanning signal, being identical for each scanned compartment, by providing a response signal comprising the identification number assigned to the unit. For each unit which is present, or until the actual scanning thereof was present, in a compartment a control circuit updates a datum, indicating the presence of the unit in a compartment, in a memory.

Abstract: System for transmitting alarm signals, comprising at least one portable transmitting unit and one central receiver, the transmitting unit comprising a control circuit which is connected to an activation device and a transmitting circuit, the control circuit activating the transmitting circuit when the activation device is energized in order to transmit an alarm signal and in order to re-activate the transmitting circuit for the re-transmission of the alarm signal after the elapse of a delay time, the delay time being different from a delay time of another transmitting unit, the transmitting unit having a memory for storing an identification code allocated to the transmitting unit, the central receiver comprising a processing system which is connected to a receiving circuit which is suitable for receiving an alarm signal and the processing circuit activating a signalling device, on receipt of an alarm signal, for the purpose of generating an attention signal, in which system the delay time is dependent on corr

Abstract: Portable unit, comprising a housing, a clip piece fixed to the housing by a hinge, and spring means which press the clip piece against the housing for forming a clip which is suitable for being clipped over an edge of a garment. The clip piece has an essentially L-shaped part with the hinge being fitted at a distance from one leg of the L-shaped part. The axis of the hinge runs essentially parallel to said one leg of the L-shaped part and such that the one leg extends past the hinge in the longitudinal direction of said one leg.