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 controller for a motor vehicle security system. The controller has a SAW device adapted to receive a signal and to generate a reply signal. A decoder is connected to the SAW device for decoding the reply signal. A comparator compares the reply signal to a previously stored value and an enabling device enables operation of the motor vehicle when the predetermined value and the decoded reply signal are successfully compared.

Abstract: A microwave data transmission apparatus adapted to transmit and receive information by microwaves, which the identification tag is made smaller in size and lighter in weight to considerably improve the convenience in setting operation for use in many applications, can be applied for the production control within the factory or the control for entering and leaving the room by a person having an identification tag.

Abstract: 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 from a memory in the passing responder. In one embodiment, the responder is equipped to receive data transmitted from a transmit station and to store the received data, for later recall, in a non-volatile, electrically erasable read/write memory.

Abstract: The antenna elements of the transponder of this invention are pierced with openings and thus have a general form of loops surrounding spaces devoid of any metallic elements. This arrangement diminishes the capacitance of the stray capacitor formed by the antenna elements and the body of the person carrying the transponder, thus improving the gain thereof. The invention is particularly applicable in the search for avalanche victims.

Abstract: A radar transponder comprising:a control circuit for controlling transmission and reception of signals in order to receive a receiving signal and transmit a definite answer signal,a video amplifier for amplifying the detection signal of the receiving signal, andan auxiliary video amplifier for amplifying the amplified output signal up to the level allowing the control circuit to be triggered,the radar transponder providinga video switch between the amplifier and auxiliary amplifier and switched in such a manner that a signal input to the auxiliary amplifier is broken only during the transmitting period of the answer signal by feeding back a positive potential pulse synchronized with the output signal from the control circuit and an input signal applied to the auxiliary amplifier is conducted except during the transmitting period of the answer signal, thereby delivering an output signal of the video amplifer to the auxiliary amplifier, andfurther, on respect, a pulse stretcher circuit between the control circu

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: Transponder reply rate limiting employing a circular memory queue to store the times of prior responses up to the limits of circular memory queue capacity. Separate circular memory queues contain the times of (1) long replies, and both (2) long or short replies. Each circular memory queue has a pointer and several offset indicators which are spaced from the pointer to the time entry positions at predetermined intervals according to corresponding preestablished criteria. After each transponder reply, the time of the reply is entered in the circular memory queue at a next pointer location. Eartimes, i.e., earliest allowable response times, are repeatedly determined and compared to time elapsed from a selected reference time. When the current time exceeds the eartime, for a given inquiry signal, a response signal is generated by the transponder electronics and is transmitted to the inquiring ground station. Eartimes are based upon predetermined criteria of allowable response rates in selected time periods.

Abstract: An improved vehicle or other object-tracking and location system, preferably, though not essentially, of national scope, wherein transponder or transceiver-equipped stolen or missing vehicles or other objects may be located and/or tracked, as by appropriately-equipped police direction/finding tracking vehicles, through homing-in on periodic transponder reply radio transmissions automatically activated by command activation signals broadcast on the same carrier frequency as the transponder reply signals and with encoded vehicle identification information that causes the intended vehicle transponder so to reply, and with provision for modifying the command signals to require an increased rate of periodic transponder reply signal transmission to assist homing-in on the selected vehicle.

Abstract: A reader transmits interrogating rf signals to a transponder including an antenna having a particular impedance. The signals received by the antenna are converted to a direct voltage which is introduced to a first terminal of a switch such as an emitter of a semi-conductor device having conductive and non-conductive states of operation. A second terminal of the switch, such as the base of the semi-conductor device, receives a voltage variable between first and second magnitudes in accordance with a pattern of binary 1's and 0's in a data source such as a read-only memory (ROM). This pattern of binary 1's and 0's is individual to an object identified by the transponder. The variable voltage on the base of the semi-conductor device causes the emitter-collector current of the semi-conductor device to vary between first and second amplitudes. When this current has the first amplitude, the impedance of the semi-conductor device and the ROM substantially matches the antenna impedance.

Abstract: The process for limiting traffic according to the invention comprises an AND input gate receiving the incident pulses representative of the interrogations of the system, its output being connected to an authorization output as well as to a counter which is itself connected to an adder and to a counter, the adder receiving from a memory criteria values, and its output being connected via a reference values memory to the comparator, the output of which is connected via a memory to the said AND gate.

Abstract: A signal is transmitted from a first location to a remote second location where a target carrying a transponder is positioned. The transponder re-radiates the signal to the first location where it is received. A phase comparator generates from the transmitted and received signals a measurement of their phase difference which is functionally related to the distance between the first and second locations. In one embodiment, the transponder is a passive parametric oscillator, being powered by energy received from the transmitted signal, which generates and transmits a subharmonic of the transmitted signal.

Abstract: A marker for use in radio frequency electronic article surveillance systems where the marker contains an inductive-capacitive resonant circuit and is made reversibly deactivatable and reactivatable by the addition of a piece of magnetic material and means, such as a piece of permanently magnetizable material, for biasing the first material to prevent alternating fields induced therein from changing the magnetic state of that material, thereby preventing hysteresis losses from causing a lowering of the Q of the resonant circuit below the point of detection.

Abstract: A reader interrogates an object. The object has a tag with a data source such as a read-only memory (ROM) which produces an identifying sequence of binary 1's and 0's in an individual pattern and transmits these signals to the reader. Each "1" or "0" is converted to a plurality of signal cycles at first and second harmonic frequencies. For example, a "1" may be identified by two signal cycles at the second frequency (e.g. 40 kHz) and then one signal cycle at the first frequency (e.g. 20 kHz) and a "0" may be identified by a signal cycle at the first frequency and then two signal cycles at the second frequency. The transponder also produces a plurality of signal cycles in an individual code (different from any combination of "1's" and "0's") to indicate the end of the transmission of the signal cycles identifying the object and the start of another transmission.

Abstract: A "passive interrogator label system" (PILS) is disclosed with passive, SAW transponders which are capable of receiving an interrogation signal, processing this signal and transmitting a reply signal that is derived from the interrogation signal and contains encoded information. The SAW transducers employed in the transponders are operated at their third harmonic and comprise split fingers which reduce SAW reflections. These transducers are also shaped to increase their bandwidth and to reduce their capacitance. The bus bars connecting the transducers are formed of double thickness to reduce ohmic resistance losses and these bus bars as well as the transponder phase delay pads have two levels of serrations on their edges to substantially cancel reflections. SAW reflectors in the transponder are provided with shorts between successive fingers to reduce ohmic resistance losses and to render them less susceptible to fabrication errors.

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: Interrogator/receiver apparatus is disclosed for transmitting a first signal to, and receiving a second signal from a remote transponder. In the preferred embodiment, the transponder is a passive, surface acoustic wave device which receives the first signal, processes this signal and transmits, in reply, the second signal which includes a unique identification code. The interrogator/receiver apparatus includes (1) a common RF unit for generating the first (interrogation) signal and (2) a plurality of transmitter/receiver heads, each remote from, and coupled to the common signal generator, for transmitting the first signal to, and receiving the second signal from a transponder or transponders in its vicinity.

Abstract: The conventional way of achieving an identification, friend or foe (IFF) function for a moveable subject requires the subject to carry a transponder that emits a coded return when a radar pulse is received by its receiver. In the present invention, an IFF system is disclosed which departs from the conventional transponder method and employs no radio-frequency power source. Instead, it uses the scattering or reflecting properties of an antenna to modulate, in a distinctive manner, the radar return from a moveable subject. A binary sequence code generator modulates the impedance of a receiver antenna, with the reflected signal being detected and correlated with a synchronized code sequence at the radar.

Abstract: A radar responder for transmitting an electric wave signal which sweeps a predetermined frequency deviation width including the reception frequencies of the searcher's radar a plurality of times, responding to the pulse-modulated radar signal from the searcher's radar. The responder is provided with a high frequency FM modulator having said frequency deviation width, generates a radar responding signal which repeats said sweeps a predetermined number of times with a predetermined period, and a distinction signal for distinguishing individual radar responder which repeats said sweeps with said period in a predetermined pattern.

Abstract: In a transponder adapted to be attached to an object to be identified, an interrogator for interrogating the transponder utilizes an antenna system including first and second antennae with the first antenna being formed as a loop and the second antenna formed in a figure-8 configuration, and being coplanar with the first antenna. A source of power provides first and second transmission signals to the first and second antennae, respectively. A phase shift is introduced between the first and second transmission signals such that the first and second antennae create an electromagnetic interrogating field in a desired region with the electromagnetic field having a non-zero value at all points within the desired region for activating the transponder regardless of the orientation of the transponder. At least one of the two antennae may be arranged to function as a receiving antenna to receive signals emitted by the transponder.

Abstract: A two-way ranging system in which deviations of transmit times of interrogation signals from a nominal transit time are determined at a transponder. These deviations are dependent upon the propagation conditions for interrogation and reply signals in the medium of propagation. A normally fixed delay is developed in the transponder. This fixed delay occurs between the reception of an interrogation signal and the transmission of a reply signal. This fixed delay is so shortened as to compensate for transit time deviations of the interrogation and reply signals.

Abstract: A small-size transmitting apparatus for search and rescue operation (SARTR) adapted to be worn by a user for emitting a microwave rescue signal upon a marine accident involving the user. The SARTR includes a power supply, a transmitter unit energizable by the power supply and having a microwave oscillator, a transmitting antenna receiving of a microwave output from the transmitter unit for emitting the microwave rescue signal, a case accommodating the power supply, the transmitter unit, and the transmitting antenna and attachable directly to the user's body, or mountable on clothing or the like worn by the user for being carried thereby, and a switch unit mounted in the case for controlling the emission of the microwave rescue signal.

Abstract: In a radar enhancing transponder, apparatus for determining the percent of modulation on a received signal and apparatus for determining the percent of modulation on a signal transmitted by the transponder, with means for comparing the percentages to develope an error signal which is used to control the modulation in the transponder so that the percent of modulation on the return signal remains the same as that on the received signal.

Abstract: An identification system to be used in association with a set of objects or persons whereby any member of the set may be automatically identified while the member is located within a predetermined interrogation zone, wherein the system has an oscillator and field coils by which an oscillating electromagnetic field is established in the interrogation zone, an identification tag associated with each member of the set of objects or persons, each tag having a core strip of magnetically responsive material of a type which abruptly reaches saturation at a predetermined level of magnetic field, an electromagnetic coil wrapped around the strip, a switch connected with the coil, electronic circuitry for controlling the opening and closing of the switch according to a sequence in timed relation to the half cycles of the electromagnetic field, which sequence defines an identification code for the tag, and a first antenna connected to the circuitry where the circuitry may be operated by power derived from the electromagn

Abstract: This transponder includes a dielectric support, an antenna and a covering layer. The central portion of the antenna forms a self induction loop which, together with the junction capacity of a non-linear component serving to close the loop, provides a circuit resonating at the frequency at which the transponder receives its energy. The antenna radiates energy at double this frequency which energy may be detected by a receiver.

Abstract: The invention concerns beacons associated to radars.It consists in modulating the re-emitted signal, in phase by the frequency of a vocal signal, and in amplitude by the envelope of this signal.It allows vocal transmission between such a signal and a Doppler radar.

Abstract: A passive transponder for use in an interrogation/transponder system comprises a substrate having a substrate surface defining a path of travel for surface acoustic waves; a launch transducer element arranged on the surface for converting interrogating signals into surface acoustic waves which propagate along the path of travel; a plurality of tap transducer elements arranged on the surface at spaced intervals along the path of travel for converting surface acoustic waves into respective output signals; and a circuit, connected to the tap transducer elements, for combining the output signals of these transducer elements to form reply signals. In order to control the delay time from transducer element to transducer element, one or more "delay pads" are provided on the substrate surface between these transducer elements.

Abstract: A passive transponder for use in an interrogation/transponder system comprises a substrate having a substrate surface defining a path of travel for surface acoustic waves; at least one transducer element arranged on the surface for converting between electrical energy and surface acoustic wave energy which propagates along the path of travel; and a circuit, connected to the transducer element(s), for supplying interrogating signals to the transducer element(s) and for receiving reply signals therefrom. In order to minimize insertion losses in the substrate, acoustic wave reflectors are provided to reflect the surface acoustic waves back towards the transducer element(s).

Abstract: A passive transponder for use in an interrogation/transponder system comprises a substrate having a substrate surface defining a path of travel for surface acoustic waves; a launch transducer element arranged on the surface for converting interrogating signals into surface acoustic waves which propagate along the path of travel; a plurality of tap transducer elements arranged on the surface at spaced intervals along the path of travel for converting surface acoustic waves into respective output signals; and a circuit, connected to the tap transducer elements, for combining the output signals of these transducer elements to form reply signals. In order to reduce the effect of spurious signals, the tap transducers are arranged both in series and in parallel with respect to the path of travel.