Abstract: An improved identification system that employs a novel radio frequency (RF) transponder. The RF transponder comprises a plurality of integrated circuit transponder chips, an RF transmit antenna coupled to an RF output of each of the transponder chips, and a sensor coupled to each of the plurality of transponder chips. A sensor switch is coupled between each of the transponder chips and the RF transmit antenna. The plurality of transponder chips may be individually programmed with different information, or identical information except for one bit. A code reader is coupled to an RF receive antenna for processing data transmitted by the transponder. The transponder is used to transfer information to the code reader relating to an item to which the sensor or transponder is coupled and the condition of the sensor switch. Transmission is accomplished by way of an RF communications link using the RF transmit and receive antennas.

Abstract: A method for interrogating remote transponders having the steps of: sending an RF interrogation pulse from an interrogator (10), receiving by a first and second transponder (12,12a) the RF interrogation pulse, and establishing in a resonant circuit (130) of each of the transponders (12,12a) an oscillation, the oscillation being established by the coupling of signal energy from the RF interrogation pulse into the resonant circuit (130). After the RF interrogation pulse ends, the first transponder (12) senses the termination of the pulse and initiates a first RF response having a selected duration. A second RF response from the second transponder (12a) will also be detected in the first transponder (12) whose response will be affected by this second RF response.

Abstract: A multi-interrogator transponder arrangement is disclosed. The transponder arrangement comprises a first interrogation unit (10) comprising a first wireless datacom transceiver (19) which transmits at least one RF interrogation signal. The arrangement also comprises a second interrogation unit (16) comprising a second wireless datacom transceiver which is in wireless communication with the first wireless datacom transceiver 19. The arrangement still further comprises a responder unit (12) which upon receipt of the RF interrogation signal transmits data stored therein back to the first interrogation unit 10 in the form of a responsive RF communication, the responder unit (12) comprising a responder unit energy accumulator (136) which stores energy contained in the RF interrogation signal. Other devices, systems and methods are also disclosed.

Abstract: A method and system is provided for communicating permanent or semi-permanent information to a transponder (14) from an interrogator (12), preferably operated by a toll agency or other authorized entity. This permanent or semi-permanent information is communicated by means of special instructions valid only during a special mode or maintenance mode which is entered by transmitting a special access code to the transponder (14) from the authorized interrogator (12). The transponder (14) will preferably acknowledge to the authorized interrogator (12) that it is, in fact, operating in the maintenance mode so the interrogator (12) can transmit the special instructions in confidence.

Abstract: A system for secure communications between first and second locations where he first location measures the location of the second location. The first location then codes that measured location along with a random reply channel code for communications from the second location to the first location. The first location then transmits the two codes to the second location which decodes the two signals. The second location then measures it's own location and compares it with the received location. The newly measured location is coded and transmitted to the first station on the randomly selected reply channel.

Abstract: An system is provided which, in one embodiment, utilizes an identification unit to identify the contents of a container and to transmit a coded identification signal to a remote receiver unit, thereby allowing emergency personnel or other interested persons to ascertain the contents of the container at an accident site. The identification unit includes a sensor positioned within the storage cavity of the container to detect whether a predetermined unsafe temperature or pressure condition exists therein. If the condition is detected, a coded identification signal, which may be in 8-bit binary form, is generated and transmitted. In an alternate embodiment, the identification unit is modified to answer an interrogation signal transmitted by a remote interrogation device when the interrogation signal corresponds to the material stored in the associated container.

Abstract: A monitoring system determines the presence of the person or persons to be monitored within a well-defined area or areas using one or more portable remote devices which are in two-way communication contact with a base unit. The base unit is connected to a telephone line to enable communication with a monitoring service. The base unit and remote unit incorporate spread spectrum communication technology which permits a high transmit power level. The effectiveness of the monitoring system does not depend on radio signal strength, but instead, operates using a radio ranging method that measures the time it takes for a security-coded signal to be transmitted to and returned from the remote device. The remote device also includes a mechanism for sounding an audible out-of-range warning alarm in the event that the person being monitored exceeds the house arrest boundaries.

Abstract: Disclosed is a system and method which protects a transponder or tag (14) from being enabled or awakened by spurious RF energy. A modulation detector (64) is provided which detects a modulation signal that is superimposed upon an RF modulation from an interrogator (12). Preferably this superimposed modulation is of a low frequency, below those typically existing as Electro-Magnetic Interference (EMI), such that the transponder (14) is less likely to be erroneously activated by an unintended RF signal. Upon reception of an RF interrogation having the proper modulation superimposed thereupon, the modulation detector (64) is operable to awaken other circuitry within the transponder (14) such that the transponder (14) is then operable to communicate with the interrogator (12).

Abstract: An interrogation unit which has a control circuit and an RF oscillator is described. The interrogation unit further has a transmitter which receives the output of the RF oscillator and transmits at least one RF interrogation pulse of a first frequency for interrogating the responder unit, causing the responder unit to return read data in the form of a RF response. Also in the interrogation unit is a switch for disabling the output of said transmitter and enabling reception of the RF response upon termination of the RF interrogation signal. The interrogation unit still further has a receiver for receiving the RF response upon termination of the RF interrogation pulse and an interrogation unit demodulator for demodulation of the read data from said RF response.

Abstract: An RF identification system having an interrogator operable to send RF interrogations to a transponder and to receive RF responses from the transponder. The interrogator is in electrical communication with a closed slot antenna. The closed slot antenna is formed by an an outer virtual magnetic loop and an inner virtual magnetic loop such that the antenna has a superior magnetic field when compared to a balanced double loop antenna with an equal area and a superior far-field noise suppression when compared to the single loop antenna. The antenna receives said RF responses from the transponder and provides said RF responses to said interrogator. Other devices, systems and methods are also disclosed.

Abstract: A hand-portable position locating radio has a geolocation (e.g. GPS) receiver providing local position and timing information from geolocation means (e.g. GPS or IRIDIUM satellites) and a local transceiver for sending local position and other information to a communication system (e.g., an IRIDIUM or MILSAT satellite). A data processor coupled to the local transceiver and receiver controls operation of the device, including storing local position information and separating signals broadcast by the communication system into those intended or not intended for the device. The radio prepares an emergency access message which it sends to the satellite communication system in a manner to insure rapid detection of the emergency signal and allocation of a clear channel and time slot for further communication.

Abstract: Systems are provided to derive a value of barometric pressure at a defined location in the atmosphere at a computed geometric height. By using the geometric height in a look-up table of pressure/height values representing a standard atmospheric profile, atmospheric deviation data indicative of the difference between measured and reference pressures at that atmospheric location (C) is derived. Ground-based interrogators (10,20) located at spaced positions are used to initiate response signals from airborne transponders commonly installed in transient aircraft (C). Using resulting range data based on round-trip timing differences in signals sent to (12,16) and received from (16,14) the airborne transponder (C), geometric analysis and computation is used (18) to determine the geometric height of the transponder representing a specific atmospheric location.

Abstract: A method for storing the life data of complicated products, primarily different types of automotive product, particularly cars, by the contactless transmission of information between a transmitter/receiver unit and a transponder. The transmitter/receiver unit includes one or more oscillators, transmitter and receiver antennas, a modulator and a detection circuit, and the transponder includes a transmitter/receiver antenna, a modulator and a detection circuit. The transponder is intended to accompany the product during its manufacture and to also accompany the finished product.

Abstract: A system including a first station (1) known as a beacon and at least one second station (2) known as a badge, each station having a transmission channel with an antenna and a reception channel with an antenna.To allow multiplex exchanges, using simultaneous transmission and reception, the two antennas (6, 11) (13, 15) in any given station are decoupled by cross-polarization but antennas which communicate with each other (6, 13) (11, 15) have compatible polarization.Applications to identification systems using microwave transmission.

Abstract: A transponder system comprising an interrogating source of HF electromagnetic radiation, and a plurality of transponders which each include a token reader unit to receive a removable token, e.g., a smart card, including onboard data processing capability. The transponders, or a group of transponders, are each arranged when interrogated to transmit a unique HF response modulated by information taken upon the token.

Abstract: Method and apparatus for measurement of the velocity of a moving target (20) in radio frequencies. From the measurement station (10) and from the target station (20), radio signals (S.sub.1,S.sub.2) are transmitted that are in different frequency ranges, as compared with each other, so that the receivers at the measurement station (10) and at the target station (20) are not subjected to interference. The radio signals (S.sub.1,S.sub.2) are received at stations (20,10) opposite to their transmission stations (10,20). The oscillator of the target station (20) is locked with the frequency transmitted by the measurement station (10) by means of a phase-locked loop (PLL). The frequency of said oscillator is passed to the transmitter part of the target station (20). The signal (S.sub.2) transmitted by the target station (20) is received at the measurement station (10). The Doppler shift (fd) of the frequency of the signal (S.sub.

Abstract: A detachable IC card applicable to a portable data processing device referred to as an "electronic organizer" is disclosed. The IC card is formed of microstrip lines formed on a dielectric substrate. An antenna receives an externally applied unmodulated carrier signal and guides the received signal to microstrip lines for impedance conversion. Cathode potential of a diode is varied in response to a data signal outputted from a CPU, so that the barrier capacitance of the diode varies. Accordingly, the carrier is reflected according to the data signal and radiated toward the electronic organizer main body through the antenna. An oscillator for data transmission is not required in the IC card, so that an internal battery having a large capacitance is not required, either. As a result, without increasing the size and weight of the device, radio transmission of data from the IC card can be accomplished.

Abstract: The monitoring assembly (10) monitors the location of mobile objects (12), i.e., personnel, within a structure (18). The object (12) carries a transponder (14) which periodically transmits status signals and receives command signals relating to audio control. Transceivers (16) are fixed at locations about the structure (18) for receiving the status signal producing the location signals, and transmitting commands to the transponders. The transmissions and reception occur during prescribed time windows. A controller (20) is connected to each transceiver (16) and monitors the location of transponders (14) and communication therethrough. The transponders (14) have audio capability of producing audio messages directly to the person thereof.

Abstract: A covert radar response system suitable for use with an illuminating coherent radar system having a moving target indicator subsystem shifts the phase and/or frequency of a retroreflected beam to transmit a message to the illuminating system that is not detectable by other observers in the vicinity.

Abstract: An interrogator-transponder system in which multiple vehicle mounted transponders which may be closely spaced in distance and moving at similar velocities, respond with a coherent identification code signal that is displaced in frequency from the interrogation signal by an amount that is identical for each transponder. The response signal spacings in time (Pulse repetition intervals) are different for each transponder but are always multiples of the pulse repetition interval of the interrogation signal. A coherent reference for the received transponder codes is obtained by combining the coherent interrogation signal with a coherent reference that is substantially identical in frequency to the displacement frequency of the transponder response signal.Means are provided in the interrogation device to determine the velocity of each transponder and its range with respect to the interrogator and to identify vehicles with inoperative transponders.

Abstract: A communication system for use in an area having a human environment delimited from below by a floor and from above by an overhead environment substantially clear of human presence. The communication system includes a first information source operative to independently generate first information; a plurality of second information sources, each operative to independently generate second information; a plurality of controllers, each coupled to the first information source and arranged in the overhead environment, for producing a substantially downwardly directed communication beam at a prescribed carrier frequency, imparting the first information to the beam, receiving a reradiated version of the beam and detecting therefrom the second information, the controllers being arranged such that the beams substantially contiguously irradiate a region of said human environment; and a plurality of communicators, each coupled to one of the second information sources and arranged in the human environment.

Abstract: A ranging method for measuring the flight distance of a flight object is implemented by means of a simple system construction. The ranging method is also capable of continuing ranging even if an interruption occurs in data transmission. The ranging method comprises the steps of inserting ranging pulses in a telemeter signal transmitted from a transmitting apparatus provided on the flight object, separating and extracting a ranging pulse from a telemeter signal received by a receiving apparatus provided on the ground side, obtaining a time difference between the ranging pulse and a reference clock signal generated in the receiving apparatus on the basis of a time reference equal to that of the transmitting apparatus (clock signal periods t1 and t2 of both time references are equal), and calculating the flight distance.

Abstract: An antenna system for mounting in a roadway comprised of an electrically lossy material. The antenna system has a reflector trough shield filled with a solid dielectric. An antenna, preferably comprised of coaxial cable, is positioned in the reflector trough, which prevents electromagnetic waves radiated by the antenna from being lost into the roadway.

Abstract: A communication system includes a base station, called a "Controller" and one or more remote or satellite stations, each called a "Communicator". The controller arbitrates, controls and communicates with the communicators which are in range to receive its transmissions. The communicators receiving a particular controller's transmission form a network for that controller for the period in which reception occurs. The controller is the only generator of electromagnetic radiation which it modulates with information relating to its own identity, transactions it undertakes and information it transfers. Each communicator modulates and re-radiates the received transmission using back-scatter. Back-scatter re-radiation keeps the communicator design simple and allows for very sensitive receiver design in the controller. In operation, the controller initiates communication with each communicator by establishing, through a handshake exchange, the unique communications channel it will maintain with that communicator.

Abstract: An identification system to identify objects from a remote interrogation station may be used with moving objects such as railroad cars. The system remotely programs and stores information on an object and remotely retrieves information from the object. An information and identity storage device is located on the object and at least one interrogation station is located remotely from the object.

Abstract: The device is an IFF Authentication System for sending and receiving of coded intelligence. So as to reduce an alien's chances of using the intelligence transmitted, the system uses a clock to provide signals for additional encipherment or scrambling of the coded intelligence. The clock is easily synchronized and provides continuously changing code encipherment for maximum protection and is connected into the system at a variety of predetermined places depending on the componential design of the particular system being used.

Abstract: The present invention pertains to a radiowave relay station in which image information or the like is transmitted by a helicopter from a first station to a second station. A direction finding device is provided which detects the direction of a transmitting source, i.e., a first station. The direction finding device calculates the vertical directional angle .phi. representing the direction of an incoming radiowave which is transmitted from the first station. This direction finding device allows the helicopter performing a relay function to fly rapidly to a contact point with the first station, i.e., in a vicinity of the first station. The direction finding device may also provide information to control an antenna driving portion for adjusting a receiving antenna located on the helicopter.

Abstract: The subject invention relates to a system for identifying, for writing data into and reading data out of electronic tags which may be attached to moving and moveable objects. An interrogator sends an RF signal to a remote tag, the signal including data intended to be received and stored in the tag. The tag backscatter-modulates the received signal with data temporarily and permanently stored in the tag, including data indicating the identity of the object to which the tag is attached. The interrogator has the capability of (1) recognizing the identity of the tagged object from the returned backscatter-modulated signal and (2) transmitting data to the tag only if it has data to be transmitted to that particular tagged object. This permits data to be selectively transmitted to a tag and received and stored by that tag only after the tag has been identified as a correct one to receive that data.

Abstract: A radar system operating by the line-of-sight method requires an accurate measurement of the relative position of at least two objects. By sending out coded radar transmission pulses, control data are transmitted to a guided flying body in a radar beam, which sends back an echo signal to the receiver via a transponder. In order to measure the passive signal and the transponder echo signal in the radar beam as accurately as possible, common reception channels are provided for both echo signals containing, inter alia, arrangements to equalize the dynamic levels of the echo signals. The returned transponder echo signal corresponds with respect to coding and bandwidth to the transmission pulses originally generated in the transmitter and that are phase-coded but not provided with the control code.

Abstract: An identification system to identify objects from a remote interrogation station may be used with moving objects such as railroad cars. The system remotely programs and stores information on an object and remotely retrieves information from the object. An information and identity storage device is located on the object and at least one interrogation station is located remotely from the object.

Abstract: A moving object discriminating system is arranged so that a signal transmitted from an interrogator is received by a responder where the signal received is processed at a control circuit, the processed signal is phase-modified by own stored data of the responder and returned to the interrogator as an answer signal, and the interrogator discriminates the moving object as based on the answer signal. The responder is thereby sufficiently minimized in size for achieving as improved mountability of the responder with respect to the moving object to be discriminated.

Abstract: An identification system to identify objects from a remote interrogation station may be used with moving objects such as railroad cars. The system remotely programs and stores information on an object and remotely retrieves information from the object. An information and identity storage device is located on the object and at least one interrogation station is located remotely from the object.

Abstract: The IFF system uses basic identification codes which are transmitted between an interrogator and a responder. The basic codes are chosen in dependence upon the time and position of the interrogator or responder at the time of choice. In one version of the system, the lifetime of a code is less than or equal to the propagation time of a radio signal for a given maximum range between the interrogator or responder. Interactive interrogation may also take place using codes chosen in the same way as the basic codes. Local information may also be transmitted between the interrogator and transponder. An example of apparatus for performing these operations transmits basic or other codes together with a time code defining the time of production of the basic or other codes. It is not essential to transmit a time code in some circumstances. Position and time information may be gained from an external communications system.

Abstract: Pulse position coding is used to transmit several channels of data from a ground radar transmitter to a receiver in an airborne, remotely-piloted vehicle. The system is designed to ignore interfering pulses, especially those which are synchronized with the transmitter's PRF, by combining a number of noise reduction devices. These include the redundant transmission of address and channel information, the transmission of true and complemented data, the tracking of channels transmitted in a predetermined order, developing an interference count to recognize synchronous pulses, comparing data received for a given channel with data subsequently received for that channel, the use of windows around the expected positions of pulses, and the use of parity. There is also a novel programming arrangement which enables several programs to be stored in a reduced amount of memory space.

Abstract: A vehicle locating system (VLS) comprises a large number, for example, several million, vehicle-mounted transmitters and several benchmark transmitters; first, second and third signal relay stations and a central processing station at which the transmitter locations are determined, the central station being connected by conventional links to subscriber stations. One hundred microsecond-long RF signals are transmitted by each transmitter in a non-synchronized, mutually random manner. Each signal comprises a 20 microsecond synchronization symbol followed by six, four bit transmitter indentification symbols, each of ten microseconds length. Following the indentification symbols are 10 microsecond message and processing symbols. The control station includes correlation means for correlating the synchronization symbols on each relayed signal against stored data to identify the beginnings of the signals.

Abstract: An arrangement is disclosed for coupling electrical energy into and/or out of a surface acoustic wave (SAW) device, such as a transponder. The SAW device has two input/output terminals electrically connected to at least one transducer for converting between electrical energy and SAW energy. Such transducer presents to the terminals a prescribed capacitance in the frequency range of operation. An inductive loop, formed by at least one turn of an electrical conductor, is connected to the two input/output terminals of the SAW device. The inductance of the loop is made substantially equal to the prescribed capacitance at the frequency range of operation, thus forming a resonant circuit with the SAW device. The loop also forms a protective DC short circuit across the two terminals, preventing build-up of static electricity. The inductive loop is inductively coupled to an antenna capable of receiving and/or transmitting radiation in the frequency range of operation.

Abstract: An aerial survey method to determine ground contours establishes a reference plane to which all contour measurements are referred. The reference plane intersects a rotating beam optical radar unit which includes a receiving antenna. The antenna receives signal waves emanating from the aircraft to measure the relative height of the aircraft with respect to the reference plane. A survey track along the ground for the aircraft is determined and the position of the aircraft along the track is continuously measured. The aircraft is flown continuously along the track and repeated altitude measurements of the aircraft are made. The relative height of the aircraft with respect to the reference plane, the altitude of the aircraft above the ground and the position of the aircraft along the survey track are correlated to determine the ground contours.

Abstract: A remote sensing transponder system is disclosed including apparatus for sensing gamma radiation levels proximate thereto, generating a signal indicative of the sensed radiation level, and transmitting an RF Signal modulated with the generated signal to a remote receiver in response to an interrogation signal from the receiver. The transponder further includes a pressure sensing device for sensing overpressure shockwaves such as caused by a nuclear blast and further modulating the transmitted RF Signal to indicate the detection of such a shockwave.