Sperry Corporation

Sperry Rand Corporation

Anro Engineering, Inc.

Other

Unisys Corporation

Multispectral Solutions, Inc.

Gerald F Ross

Richard M Mara

Kenneth W Robbins

Harry M Cronson

Basrur R Rao

David Lamensdorf

Kenneth W Rollins

Robert J Fontana

Alexander M Nicolson

Prentis B Drew

Michael E Hinkley

Werner Lerchenmueller

A filter which highly attenuates CW signals within specified frequency bands while allowing baseband pulses to pass therethrough with relatively low attenuation is provided. The filter comprises a main transmission line and stub transmission lines that are coupled in parallel relationship with the main transmission line. Each of the stub transmission lines is terminated with a short circuit or other appropriate impedance and is of such a length that a pulse coupled thereto from the main transmission line and reflected from the terminating impedance will arrive at the coupling plane with the main transmission line after the pulse propagating on the main transmission line has completely passed the coupling plane, thus eliminating the possibility of cancellation of any portion of the propagating pulse. The length, spacing and terminating impedance of each of the stub transmission lines is selected to provide stop bands for CW signals so that a pulse is coupled to the output terminals of the filter that is substantially free of CW interfering signals that may exist at the input terminals thereof.

Anti-jam apparatus for baseband radar systems

An Ultra Wideband (UWB) short-range radar system is used for the detection of targets in clutter. Examples of targets on the ground include human walkers, crawlers and runners, and vehicles. The UWB sensor can also be used to detect small approaching boats in different levels of sea clutter or airborne targets like hang gliders. One of the primary differences between this device and other UWB radar sensors is the manner in which the bias on the threshold detector is set as well as the logic circuitry used to find targets in clutter while maintaining a low false alarm rate. The processing is designed to detect targets in varying degrees of clutter automatically. There may be no front panel controls other than an ON-OFF switch. The system is lightweight, low-cost, and can be easily installed in minutes.

Quick response perimeter intrusion detection sensor

A safety device is used to protect golfers located in blind areas of a golf course from balls being driven, for example, off the tee. The safety device is manually activated by a push-button switch once the golfers enter the blind area. The switch initiates a low current drain, high-intensity, strobe light blinking at a 1 Hz rate that is visible from both the tee and blind areas even in bright sunshine. An electronic timer deactivates the strobe after N minutes. A wireless transmitter link located outside the blind area can be used to recycle the timer prior to the elapsed time (minutes) for those golfers who play more quickly.

Golf course electronic safety device

A batteryless sensor includes either a micro miniature generator/gear train or a piezoelectric crystal to convert a movement of a door or window to an ersatz V.sub.cc transient power supply to radiate a coded RF signal to a receiver, a distance away. The receiver may monitor a multiplicity of sensors to identify a source of an intrusion.

Batteryless sensor used in security applications

An Ultra-Wideband (UWB) transmitter array consists of N individual transmitters coupled to a reference cw oscillator. Each of the N transmitters generates a waveform consisting of a number of cycles of a nominal carrier frequency of f.sub.0. The duration of the amplitude spectrum of the envelope of each signal is T. The transmitters are arranged in close proximity to form a multipole moment and are precisely synchronized to each other and delayed appropriately so that the resulting amplitude spectrum of the envelope of the transmitter array is due to a pulse duration of NT seconds. This reduces the overall signal bandwidth by a factor of N, at the same time increasing the radiated energy by a factor of N.

Efficiently decreasing the bandwidth and increasing the radiated energy

A four-terminal network in tandem with a tunnel diode (TD) threshold receiver currently used in radar or communications improves its sensitivity. Previous inventors have shown that the temperature and sensitivity properties of a conventional TD threshold device used for detecting very short duration bursts of microwave energy would be enhanced by appropriately biasing the TD by a current derived from the thermal noise; the current sets the TD operating point. The magnitude of the current is determined by a constant false alarm rate (CFAR) feedback loop. The subject invention recognizes that a TD changes states (i.e., a detection event) when the area under the current vs. time curve or the charge passing through the device exceeds a prescribed number of picocoulombs. To maximize the charge and improve detection, a form of superheterodyne conversion is introduced to convert the oscillatory short pulse microwave signal received by an antenna to a monopolar baseband signal. This is done by mixing the incoming signal with a CW carrier whose frequency is precisely chosen so that the resulting beat frequency is one-half of an rf cycle for the given duration of the microwave burst. This maximizes the charge available to trigger the TD. Proper gain and filtering is provided in the adjunct four-terminal network to establish minimum noise figure and appropriate gain to drive the TD held in a CFAR loop. It is shown both mathematically and experimentally that the subject invention can increase the receiver sensitivity by a factor of 20 dB or greater over the prior art. Proper microwave gain is provided to establish the noise figure prior to mixing in the added four-terminal network and a bandpass filter is employed to discard frequency components and the gain of a wideband IF (e.g., 0-500 MGz) is selected to appropriately drive the TD.

Coherent processing tunnel diode ultra wideband receiver

A batteryless sensor includes a small and concealed permanent magnet motor which operates as a generator to convert rotational or translational energy to an ersatz Vcc transient power supply via a mechanical arrangement to radiate a coded VHF oscillator signal to a repeater or central processing unit located as far as one mile from the sensor. The receiver is able to monitor a multiplicity of sensor units over a given time period.

This invention describes a high voltage, very short pulse, microwave radiating source using low-cost components, and capable of operating at high pulse repetition frequencies (prf). The source is activated by an ordinary video trigger commensurate with driving TTL logic. A trigger will cause a chain of N (where N may be 12 or greater) avalanche transistors connected in a Marx generator configuration to threshold resulting in a 1,200 volt or greater baseband pulse having a rise time of less than 100 ps and a duration of about 3 ns driving the input port of a dipole antenna. The dipole is excited by a balun. This invention achieves very short pulse duration broadband microwave radiation at pulse repetition frequencies as high as 30 kHz or greater.

Short pulse microwave source with a high PRF and low power drain

Short pulse microwave source with a high prf and low power drain

A transmitter array includes a number of individual transmitters, each contributing a series of short microwave pulses each consisting of only several cycles to make up an RF pulse in the far field. Apparatus for closed loop synchronizing the pulses from each transmitter in order to maximize the amplitude of the RF pulse includes a Voltage Control Oscillator which provides a continuous wave (CW) reference to each transmitter and includes apparatus for dividing the CW down to feed a series of timers in each transmitter, each timer having a means for setting the time and duration of firing and providing an output signal synchronously related to the CW. A dual polarity peak detector fine tunes the individual transmitters via closed loop feedback to compensate for any thermal drift. A novel time delay vs. voltage transducer is used to achieve closed loop synchronization. Short term pulse jitter is significantly reduced by overtriggering the avalanche transistor. Beam steering is accomplished by simply adjusting a regulated DC voltage at each radiating source in the array. The end result is a low cost means for forming a time steered array of short pulse microwave sources.

Synchronization of very short pulse microwave signals for array

A system for transmitting and receiving very wide instantaneous bandwidth signals. Synchronized short pulse generators are positioned at the feed location of each element of a linear array of short capped monopole antennas to sequentially excite the antenna elements which are spaced in accordance with the sequential interval to provide a beam in the desired direction and space. Reflections of the radiated short pulses are received by a feed monopole backed by a reflecting monopole and coupled to a short pulse receiver through a duplexing switch.

Antennas for wide bandwidth signals

A baseband receiver with a range gate interval in the order of nanoseconds. A tunnel diode, set to the low level state, is coupled across the output terminals of a bridge that is balanced in the absence of a received signal, during the range gate interval. Signals received by an antenna are coupled to a tunnel diode in an arm of the bridge causing it to change from its low level state to its high level state thereby unbalancing the bridge and establishing a voltage at the output terminals of the bridge that fires the tunnel diode coupled thereacross.

Narrow range gate baseband receiver

A method and apparatus for detecting a short pulse signal in the presence of an interfering jamming signal wherein the jamming signal is utilized as the local oscillator in a diode mixer when it is received at a sufficiently high level for efficiently mixing with a short pulse signal. When the received jamming level is insufficient to act as a local oscillator, an internal local oscillator signal is coupled to the diode to maintain an efficient mixing operation.

Baseband detector with anti-jam capability

A docking system for positioning a vehicle relative to a selective location employs a baseband communication link between the vehicle and the selected location. Transmitters located at specific points at the selective location are activated upon command from the docking vehicle and synchronized with reference signals radiated therefrom. Time delays between the arrival of each signal radiated by the transmitter and the initiation of a reference signal are determined to establish measures to the different points at the selected location. These measures are then processed to provide relative positioning information.

Baseband radar docking system

Electromagnetic pulses of substantially nanosecond duration are transmitted from a merge location along transmission lines paralleling merging guideways to be incident to reflecting or repeating apparatus on vehicles approaching the merge. Coupling of the reflecting or repeating apparatus to the transmission line is such that sufficient electromagnetic energy is returned from the n.sup.th vehicle to the merge location for detection and processing thereafter. The returned signals are used to calculate, for each vehicle, the distance from the merge location and the approach speed.

Growing community of inventors

Lexington, MA, United States of America

Gerald F Ross