Did You Know...
...that Kleenex tissue was originally designed to be a gas mask filter? It was developed at the beginning of World War I to replace cotton, which was then in short supply as a surgical dressing.
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| Number | Title | Issue Date |
| 4932006 | Process for signal transmission without electric connection through a conducting wall, the hull of a ship for example, and a device for implementing same A process is provided for transmitting a signal, without material connection, through a conducting wall which may be a ship's hull, to external user apparatus. A current supplied by a generator and whose intensity is proportional to the amplitude of the s... | 06/05/1990 |
| 4918737 | Hearing aid with wireless remote control A hearing aid has a housing which can be worn at the head, such as in or behind the ear, and which contains the basic electrical and acoustic elements of the hearing aid. The housing has a portion adapted for introduction into the auditory canal, and a co... | 04/17/1990 |
| 4912471 | Interrogator-responder communication system An interrogator-responder communication system in which responders are carried by vehicles (such as railroad vehicles) travelling along a route and in which an interrogating station situated along the route operates each passing responder to recall data f... | 03/27/1990 |
| 4908869 | Induction-based assistive listening system A multiple-loop magnetic induction system for improving communication with the hearing-impaired or to people in general who wish to listen privately to speech or music while being in the company of others or at a public location. The invention uses a part... | 03/13/1990 |
| 4879755 | Medium frequency mine communication system A method for using an underground mine communication system to effect minewide communication and an intrinsically safe current limiter circuit for insuring that electrical equipment in the system will not cause incendiary conditions. The underground mine ... | 11/07/1989 |
| 4868887 | Cable-car with information transmission via the cable A terminal station of an aerial rope transport installation is equipped with a generator (26) of a high-frequency signal modulated in amplitude by the information to be transmitted. This generator (26) is coupled to the looped rope (10) by a transformer (... | 09/19/1989 |
| 4864633 | Inductive device for the rapid exchange of data between two data carriers An inductive device is provided for the rapid data exchange between two data carriers, more particularly between a fixed station and a movable carrier, usable in industrial process automation systems an automatic tuning circuit is provided for maintaining... | 09/05/1989 |
| 4833337 | Inductive coupled power system An inductive coupled power system has a transmission circuit with a dual primary comprising two conductor loops. First segments of the loops extend through an area served by the system adjacent each other and second segments of the loops extend through th... | 05/23/1989 |
| 4833338 | Ferroresonant regulator for inductively coupled power distribution system A ferroresonant regulator for use in an inductively coupled high frequency power distribution system. A constant current resonant power source, comprising a sine wave oscillator (12), an amplitude controlled amplifier (16), a power amplifier (20), and an ... | 05/23/1989 |
| 4829500 | Portable wireless sound reproduction system A portable wireless sound reproduction system includes a first portable housing having a sound signal receiving circuit and controls for processing the sound signal into two signals for transmission by two separate sound signal transmitters located in the... | 05/09/1989 |
| 4792965 | Oscillator system for detecting a selected one of a plurality of tuned circuits The system of the present invention allows transmission of information and data across a gap, for example, from the steering wheel of an automobile to the steering column, without any physical connection between the information source and the information ... | 12/20/1988 |
| 4792796 | Electronic alarm apparatus In electronic alarm apparatus for monitoring the presence or absence of objects within a given area, a transmitter attachable to an object, a shift register for storing a digital identification code, and an electronic circuit including a time delay circui... | 12/20/1988 |
| 4777652 | Radio communication systems for underground mines A radio communications system operational within the medium frequency range for underground mine communications, coupling MF carrier signals into existing conductive channels extending to within the mine and devices within the mine and coupled to the cond... | 10/11/1988 |
| 4763340 | Capacitive coupling type data transmission circuit for portable electronic apparatus A capacitive type coupling data transmission system for portable electronic apparatus is comprised of an input circuit, a capacitance changing circuit, a transmitting circuit capacitively coupled to, a receiving circuit, and a detecting circuit for detect... | 08/09/1988 |
| 4750206 | Adapter for TV stereo, SAP and auxiliary signals An adapter is provided for use with a television receiver to detect and decode stereophonic audio signals, SAP signals or auxiliary signals that may be transmitted with the composite television signals. The adapter includes an IF input that is physically ... | 06/07/1988 |
| 4747158 | Cordless communications system A cordless communications system wherein transmission is made and received via magnetic lines of induction comprises a base station and at least one mobile station wherein the base station receives and transmits voice or data signals at different frequenc... | 05/24/1988 |
| 4736452 | Core coupled transmitter/receiver loops for connectorless entertainment systems A method and apparatus for interconnecting passenger entertainment service units to the aircraft system through connectorless inductive couplers. Couplers are arranged along the seat track as desired without limitation on seat spacing or location.... | 04/05/1988 |
| 4712250 | Tape player adapter for car radio A portable stereo cassette tape player is connected to an FM automobile radio through an adapter having an input plug which is inserted into the audio signal output terminal of the tape player and an output plug which is inserted into the cigarette lighte... | 12/08/1987 |
| 4685133 | Wireless audio transmission system A system for wirelessly transmitting stereo audio from a source such as a tape player to a removed location. The output signal-carrying wires from the source are connected to a coupler unit adapted to removably hold an FM band stereo broadcast microphone/... | 08/04/1987 |
| 4675648 | Passive signal coupler between power distribution systems for the transmission of data signals over the power lines A passive signal coupler transfers data signals being transmitted over AC power lines from a first AC power distribution system to a second AC power distribution system. Each leg of the passive signal coupler coupled to a phase of the power line voltage i... | 06/23/1987 |
| 4669109 | Telephone apparatus with a fixed telephone station coupled to a mobile and detachable handset A telephone apparatus, such as a public telephone, in which a voice and tone signals transmitting medium between a fixed station connected to a telephone line and a handset detachable from the station is free of disturbance. A modulation circuit for trans... | 05/26/1987 |
| 4652857 | Method and apparatus for transmitting wide-bandwidth frequency signals from mines and other power restricted environments A method and apparatus for transmitting and receiving messages by electromagnetic induction in a power restricted environment is disclosed in which the message bandwidth is narrowed prior to transmission and restored to its original breadth upon reception... | 03/24/1987 |
| 4633495 | TV stereo adapter A television stereo adapter is provided for use with a television receiver to detect and decode stereophonic audio signals that may be transmitted with the composite television signals. The adapter includes an IF pick-up that is physically separate from t... | 12/30/1986 |
| 4600829 | Electronic proximity identification and recognition system with isolated two-way coupling An electronic proximity identification and recognition system. The identification and recognition sections are physically separate from one another, but inductively coupled to one another by two-way coupling. The identification section and recognition sec... | 07/15/1986 |
| 4555792 | Transmitter for transmitting an FSK-modulated signal A transmitter for transmitting FSK-modulated signals by way of an inductive aerial. A large frequency deviation, such as with FFSK-modulated signals, and a high transmission rate may cause the occurrence of a non-constant envelope. Electronic equipment ar... | 11/26/1985 |
| 4542532 | Dual-antenna transceiver A magnetic-field, noise-cancelling transceiver is provided by a dual-coil antenna circuit. In the receive mode, two identical coils, connected in series opposition, cancel noise signals common to both coils and receive desired signals present at only one ... | 09/17/1985 |
| 4507646 | Radio communication system A paging system for use in a limited area such as an office, a factory building, a hotel, or other public building wherein the existing electrical supply network is used as the antenna of either the transmitter or the receiver. The electrical supply netwo... | 03/26/1985 |
| 4476574 | Radio frequency communication system utilizing radiating transmission lines A radio communication system for use in tunnels, mines, buildings or other shielded locations in which a pair of radiating transmission lines (30), (31) extend through such location in spaced coextensive relation to each other. Each transmission line (30)... | 10/09/1984 |
| 4462113 | Cordless transmitting and receiving apparatus A cordless transmitting and receiving apparatus which is capable of providing transmitting and receiving between a key transmitting and receiving apparatus such as a telephone and a portable remote transmitting and receiving apparatus and in which a trans... | 07/24/1984 |
| 4441210 | Transcutaneous signal transmission system and methods Greater positioning tolerance is permitted in inductively coupled transmitter and receiver tuned circuits by achieving critical coupling therebetween. Critical coupling at a predetermined distance is obtained by selecting the appropriate quality, Q, of th... | 04/03/1984 |
| 4428078 | Wireless audio passenger entertainment system (WAPES) A wireless aircraft passenger entertainment system utilizing simultaneous transmission of low frequency signals for power supply rectification and radio frequency signals for information demodulation between transmission lines parallel with seat tracks in... | 01/24/1984 |
| 4409590 | Building security, communication and control system A system for providing perimeter security, intra-building communication and control functions, utilizes a pair of single wire loops placed about the periphery of the building, and spaced from one another. At least one facilities unit, for fire detection, ... | 10/11/1983 |
| 4357497 | System for enhancing auditory stimulation and the like A plurality of the carrier signals are modulated by signals in the audio frequency bands. The carrier signals are transmitted to a receiver having one or more independent channels for receiving and demodulating the transmitted signals. The detected signal... | 11/02/1982 |
| 4334315 | Wireless transmitting and receiving systems including ear microphones A wireless transmitting and receiving system includes an ear microphone of the vibration pick-up type for picking up bone-conducted voice signals through an external auditory ear canal wall of a wearer. A portable case is disposed adjacent the wearer's ea... | 06/08/1982 |
| 4307466 | Audio system for drive-in theaters A drive-in theater having an array of predesignated parking spaces and a central audio output device for generating a carrierless audio signal. Interface devices are located at the spaces and connected in parallel to the output device. Each interface devi... | 12/22/1981 |
| 4291289 | Shielded surface wave transmission line A surface wave transmission line enclosed in a dielectric shield and supported within the enclosure at a predetermined distance from the base of the enclosure. The enclosure being constructed such that the surface wave transmission line may be in close pr... | 09/22/1981 |
| 4284856 | Multi-frequency system and method for enhancing auditory stimulation and the like A plurality of carrier signals are modulated by pulses corresponding to signals in audio frequency bands. The carrier signals are transmitted to a receiver having independent channels for receiving and demodulating the transmitted signals. The detected pu... | 08/18/1981 |
| 4239940 | Carrier current communications system A plurality of transmitters and receivers arranged for carrier current communications are generally placed throughout a large building. The transmitters and receivers are coupled to selected portions of the power distribution system. The selected portions... | 12/16/1980 |
| 4213122 | Intrusion detection system An intrusion detection system utilizes a radio frequency radiative system whose near electromagnetic field is monitored by receiving devices which respond, in a measurable way, to any disturbance of the near electromagnetic field by physical intrusion.... | 07/15/1980 |
| 4136338 | Perimeter alarm apparatus A perimeter alarm apparatus includes a loop of wire to be placed around an area to be guarded and electrical circuitry connected with the loop for detecting the absence of a signal imposed on the loop. The signal imposed on the loop is produced by a sendi... | 01/23/1979 |
