Westinghouse Electric Corporation

Thermo King Corporation

United States of America As Represented by the Secretary of the Air Force

David K Davies

Anastasios P Goutzoulis

John M Zomp

Peter J Chantry

Anastosios P Goutzoulis

Casey J Coppock

A system for signalling the presence of selected ion species in a gaseous sample of an ion mobility sensor, having a unidirectional field provided between first and second electrodes positioned a selected distance apart. An ionization source generates ions in the sensor and a trigger controller allows ions to enter the region between the first and second electrodes at a time t.sub.1. The ions then arrive at the second electrode at a time t.sub.2. A transimpedance amplifier converts the ion charges to voltage signals. The presence of selected ion species is determined by circuitry that is activated by the trigger controller at t.sub.2. The species are preferably analyzed by directing the amplifier output to an analog to digital converter and then to a digital signal processor. The ions may alternatively be analyzed by generating a logic pulse representing a selected ion species when the amplifier output exceeds a preset value. An alarm signal is output when the logic pulse is coincident at an AND gate with a logic pulse representing the species' travel time from the first electrode to the second electrode.

Practical implementations for ion mobility sensor

An improved phased array radar system has a plurality of bias binary fiber optic delay lines each connected between the transmit/receive cells and at least one of signal input means and signal processing means. A plurality of electronic binary delay lines are connected to at least one of the signal input means and the signal processing means and each bias binary fiber optic delay line.

Hybrid electronic-fiberoptic system for phased array antennas

An ion mobility sensor for obtaining measurements of concentrations of constituents of multicomponent gaseous samples. The sensor having an ionization region into which the sample is entered connected to a drift region, the regions being separated by a grid electrode. A first electrode is disposed at an end of the ionization region opposite to the grid electrode. A collector electrode is provided at an end of the drift region opposite to the grid electrode and DC voltages are applied by the electrodes so as to create a unidirectional field across the sensor. A pulse of UV light is directed toward the grid electrode. A voltage pulse of selected magnitude is superimposed at the first electrode within the pulse width of the UV pulse. Ions characteristic of the sample travel through the grid electrode, across the drift region to the collector electrode. The electrical output in accordance with any ions received at the collector electrode is then measured.

Pulsed ionization ion mobility sensor

A system for compensating for changes in pressure and temperature in an ion mobility sensor has first and second electrodes positioned a selected distance apart, with a unidirectional electric drift field provided between the electrodes. An ionization source generates ions in the sensor and a trigger controller allows ions to enter the region between the first and second electrodes at a time t.sub.1. A time t.sub.2 at which a selected ion species travels to one of the first and second electrodes is measured and a time to amplitude converter generates a voltage signal proportional to the difference between t.sub.1 and t.sub.2, representing the actual travel time of the ion species. A feedback control circuit adjusts the drift field and either the voltage pulse (in pulsed ionization) or the shutter voltage (in continuous ionization) by an amount proportional to the difference between the actual travel time voltage and a voltage proportional to a reference travel time of the selected ion species at a known pressure and temperature.

Automatic compensation for ion mobility sensor

A fiberoptic delay line architecture for generating multiple replicas of an input RF signal with variable replica-to-replica time resolution is provided in which the required hardware is kept to a minimum. A series of cascaded binary fiberoptic segment delay lines is used in which each cascaded binary fiberoptic segment delay line has an equal and defined number of segments but variable minimum time resolution. The minimum time resolution of each cascaded binary fiberoptic segment delay line increases by a multiple of two compared to the prior cascaded binary fiberoptic segment delay line. In this manner, the required number of segments and switches increases in a log.sub.2 .times.log.sub.2 relationship as the number of desired replicas and possible replica-to-replica delay values increases.

Fiberoptic delay line for generating replicas of an RF signal with

A wavelength-coded binary fiberoptic delay line apparatus for time steering of array antennas having a plurality of delay line units serially connected to each other to provide a plurality of delay signals. Signal detecting/converting units which are connected respectively between adjacent delay line units wavelength-code the delay signals passing between the delay line units. The input signal to each delay line unit is separated into two signals one of which is connected to the output of that delay line unit.

Wavelength-coded binary fiberoptic delay line apparatus for time

A fiberoptic-coupled free-space variable delay line is provided wherein the phase adjustment of the signal can be accurately set. A microscope-objective lens collimates a signal beam which is received by a focusing lens. The focusing lens is provided on an adjustable carrier to allow one to accurately adjust the distance travelled by the collimated signal base and thereby accurately adjust the off-set. A plurality of these variable delay lines can be arranged to form a multiplexer. If the threads on each drive rod moving a carrier are different, the carrier can be adjusted to accommodate changes in frequency of the signal.

Optical variable delay line and variable-frequency fiber-optic

An opto-electronic XOR gate includes a pair of diode type light sources connected back to back in parallel by a pair of input leads to which first and second electronic logic signals are applied. With only one logic signal in the high state, one of the diode-type light sources is forward biased while the other is reverse biased. With both logic signals high or low neither diode-type light source emits. A two to one fiber optic combiner (FOC) provides a single optical output which is on only when only one electrical signal is high. If an electronic output is desired, a single photodetector converts the output of the FOC to an electronic logic signal. For performing the exclusive OR operation on optical input signals, a pair of photodetectors and buffer amplifiers and connected to the input leads. For 10 to 12 GHz switching speeds laser diodes are used as the diode-type light sources. When lower switching speeds are satisfactory, light emitting diodes can be used as the diode-type light sources.

Opto-electrical exclusive or logic gates

Pseudorandom pulse code generators utilize XOR gates constructed of a pair of back to back parallel connected laser diodes, and fiber optic delay lines connecting the XOR gates to generate PN code sequences with tens of Gbits/s data rates. The single tap generator uses a fiber optic line of a length representing a selected number of delay stages connected to the optical output of the XOR gate and with optical splitters at the end of the delay line and at a selected delay stage feeding back optical signals to the optical inputs of the XOR gate to produce the PN sequence at the end of the delay line. Multi-tap generators utilize additional electro-optical XOR gates connected in serial-parallel, or preferably in a converging cascade arrangement to feed back pulses to the delay line. A syncopated PN code generator uses the electro-optical XOR gates to multiplex codes generated by syncopated pairs of relatively slow electronic shift register code generators with the required phase shifting provided by diffeence in the lengths of the optic fibers connected successive stages of XOR gates.

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Churchill Borough, PA, United States of America

David K Davies