Abstract: A method and apparatus is provided for deriving the direction of a received signal from a signal source using first and second orthogonally-mounted loop antennas and an omnidirectional antenna. In operation, output signals from each of the antennas are generated and repeatedly supplied to signal processing circuitry in a cyclical fashion as the receiver is rotated to locate the transmitter. The amplitudes of the output signals from the first and second loop antennas are then compared to determine whether the signal source is located in a null of the second loop antenna. If so, a null indication signal is generated. The phases of the output signals from the second loop antenna and the omnidirectional antenna are compared to determine whether the received signal is being received in a predetermined region of the second loop antenna. If so, an ambiguity indication signal is generated.

Abstract: A digitally-controlled quadrature signal generator is provided having a frequency synthesizer for receiving a digital input signal and in response thereto generating an output signal having a predetermined frequency. The output signal is split to produce an in-phase (I) signal and a quadrature-phase (Q) signal. A first table look-up memory is provided for generating a predetermined phase correction signal for use in cancelling any phase error in the quadrature-phase signal. A mixer receives the phase correction signal and the in-phase signal and in response thereto generates a phase error signal. The phase error signal is then added to the quadrature-phase signal to thereby cancel the undesirable phase error. Moreover, programmable attenuator circuits or limiter circuits are provided to limit the in-phase and quadrature-phase signals and thereby cancel any undesirable amplitude error components therein.

Abstract: A high power tunable filter, for use in a frequency hopping system, is described and includes a transmission line having an input for receiving a high power level input signal to be filtered, and an output. The filter includes a plurality of resonators, each parallel-coupled to the transmission line, and driven by an associated electronic tuning network. Each of the electronic tuning networks includes a plurality of tunable reactive elements and PIN diodes, each PIN diode connected to one of the tunable reactive elements to enable this diode to connect its associated tunable reactive element in and out of the tuning network, thereby controlling the resonant frequency of the resonator associated with the tuning network. An electronic control circuit is also provided for controlling the frequency of the tunable filter.

Abstract: A noise pulse rejection circuit for use in a pulse type time-of-arrival detection system is described. Preferably, the pulse type time-of-arrival detection system includes a precision distance measuring equipment (DME/P) receiver having a delay-attenuate-compare (DAC) detector. The DAC detector produces first time-of-arrival detector outputs due to receiver noise, and a second time-of-arrival detector output upon detection of a received DME pulse having a leading edge, each of the first time-of-arrival detector outputs having a substantially shorter period than the period of the second time-of-arrival detector output. The noise pulse rejection circuit preferably includes a monostable multivibrator, which is triggered by the first and second time-of-arrival detector outputs to generate a timing signal having first and second logic states, the timing signal normally changing from a first logic state to a second logic state after a predetermined time period "T".

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.

Abstract: A precision distance measuring equipment (DME/P) receiver for detecting an RF signal including at least one interrogation pulse is described. The DME/P receiver includes first and second signal processing channels. The first processing channel includes a wideband filter, of bandwidth BW1, for receiving the processed RF signal and in response thereto generating a wideband (FA) mode signal proportional to the logarithm thereof. The second signal processing channel includes a narrowband filter, of bandwidth BW2, for receiving the processed RF signal and in response thereto generating a narrowband (IA) mode signal proportional to the logarithm thereof, the bandwidth BW2 of the narrowband filter being within the bandwidth BW1 of the wideband filter.

Abstract: A pulse modulated amplifier is described comprising a power transistor having a grounded base, an emitter for receiving a drive signal to be amplified, and a collector for emitting a high frequency pulse, the power transistor operating over a substantially 360.degree. conduction angle variation during which the drive signal is amplified. The pulse modulated amplifier preferably includes a pulse modulator for generating a modulation drive voltage, and a current driver circuit responsive to the modulation drive voltage for generating a control current. The control current is applied to the emitter of the power transistor to control the output power of the emitted high frequency pulse. For a given drive signal the conduction angle of the power transistor is proportional to the control current, and for a given control current the conduction angle of the power transistor is inversely proportional to the drive signal.

Abstract: An RF pulse transmitter, for use in precision distance measuring equipment (DME/P) of a microwave landing system, includes appropriate circuitry to correct for incidental phase modulation (IPM). The pulse transmitter includes a modulation circuit for generating an RF pulse having a pulse peak. A reference phase control circuit is provided to generate a reference signal. A phase detector receives the RF pulse and the reference signal and in response thereto generates a phase error signal. The reference phase control circuit includes appropriate circuitry for adjusting the phase of the reference signal applied to the phase detector to thereby drive the phase error signal to a predetermined value at the pulse peak. A pre-distortion circuit generates a pre-modeled correction signal pulse for use in correcting for incidental phase modulation (IPM).

Abstract: A leveling jack mounted on the frame of a vehicle with a horizontal stowed position and a vertical actuated position, including, a pair of telescoping tubular members, telescoping between open and closed position, a ball screw actuator including a ball member and a screw member supported within the tubular members and with one of the tubular members attached to the ball member for producing telescope movement of the one tubular member relative to the other tubular member in accordance with longitudinal movement of the ball member, a drive spindle coupled to the screw member for providing rotational movement of the screw member to produce longitudinal movement of the ball member, a motor and associated gear train coupled to the drive spindle and with the gear train providing a substantial reduction of speed of rotation of the drive spindle, an outer housing for mounting on the frame of the vehicle and with the tubular members, ballscrew actuator, drive spindle and motor and gear train forming a pivotable porti

Abstract: The problem of recurrent solder joint failure in spiral antennas is solved by the present invention through the use of resistive/capacitive contacts. Specifically, an electrical connector is provided for connecting opposed conductors disposed on a stripline, to a spiral antenna having a pair of dipole conductors disposed on a substrate. The connector includes a housing having a base, and a sidewall for supporting the substrate. A center post having first and second ends, and a cylindrical aperture, is mounted in the housing. The substrate is secured to the first end of the center post, the second end thereof secured to the base of the housing. A stripline contact snubber is supported in an end of the cylindrical aperture adjacent the substrate and receives the stripline. To ensure RF continuity between the stripline conductors and the dipole conductors, one or more mechanically compliant, leaf spring resistive/capacitive contacts are provided.

Abstract: A method of communicating data in a multinodal peer network communication system is disclosed in which the data is transmitted in accordance with an established priority scheme. The method uses two techniques to ensure that higher priority data is transmitted before lower priority data. In one technique, decreasing priority time-windows are established by each node of the system following the end of a transmission on a shared transmission medium. Subsequently, data is transmitted when the priority of the data matches or exceeds the priority of the time-window. In the other technique, data collisions on the shared medium are resolved by use of the priority time-window technique in combination with the use of a pseudo-random back-off timer.

Abstract: An efficient look-up table encoder for encoding k bit information words with linear error correcting block codes is provided comprising a plurality of read-only memories having 2.sup.x.sbsp.1, 2.sup.x.sbsp.2, . . . , and 2.sup.x.sbsp.i address locations, respectively, where x.sub.1 +x.sub.2 + . . . x.sub.i =k. Each of the read-only memories receives a portion of a k bit information word that serves to address a respective location therein, thereby mapping the portion of the k bit information word into an output word stored at the location. Corresponding bits of output words from the plurality of read-only memories are mod-2 summed by n-k exclusive-OR gates to generate a parity word associated with the information word. For systematic encoding, the parity word is then appended to the information word to form a codeword uniquely associated with the information word. This encoding scheme obviates look-up tables having 2.sup.k x(n-k) storage locations.

Abstract: The use of delay modulation (or "Miller") phase coding to encode transmitted data is disclosed in a multinodal, peer network communication system. The use of delay modulation provides bandwidth compression and reduces the direct current (dc) voltage component of transmitted data. In addition, the delay modulation provides a unipolar communication in which the transmitted waveform contains both data and synchronization information and error detection capabilities.

Abstract: A video camera image with a motion induced blurring component is corrected by measuring the motion of the video camera by orthogonally mounted rate gyros each producing a signal that varies with camera motion along a defined axis relative to the bore sight of the camera. The video camera signal with the motion induced blurring component is processed into a Fourier transform which is combined with a video deblurring signal. Motion output signals of the rate gyros are processed in a Fourier transform computed Wiener filter to produce the video deblurring signal which is combined with the Fourier transform of the video camera signal. This combination signal is then processed in an inverse Fourier transform and converted into an analog signal for input to a video display monitor. This input signal to the video display monitor is motion corrected and produces a video display corrected for motion of the video camera.

Abstract: A noise pulse rejection circuit for use in a pulse type time-of-arrival detection system is described. Preferably, the pulse type time-of-arrival detection system includes a precision distance measuring equipment (DME/P) receiver having a delay-attenuate-compare (DAC) detector. The DAC detector produces first time-of-arrival detector outputs due to receiver noise, and a second time-of-arrival detector output upon detection of a received DME pulse having a leading edge, each of the first time-of-arrival detector outputs having a substantially shorter period than the period of the second time-of-arrival detector output. The noise pulse rejection circuit preferably includes a monostable multivibrator, which is triggered by the first and second time-of-arrival detector outputs to generate a timing signal having first and second logic states, the timing signal normally changing from a first logic state to a second logic state after a predetermined time period "T".

Abstract: The present invention describes a method and apparatus for determining the noise power ratio (NPR) of a unit under test (UUT). According to the method, a frequency domain representation of a desired test spectrum is generated by prompting an operator to input selected parameters to a general purpose digital computer. The desired test spectrum includes a notch of predetermined depth. The frequency domain representation is transformed into an input signal sequence by an inverse Fast Fourier Transform algorithm, the sequence defining a time domain representation thereof. The input signal sequence is then applied to the unit under test. An output signal sequence defining a time domain representation of a measured test spectrum is received from the unit under test and transformed back into a frequency domain representation. This frequency domain representation includes a notch whose depth is normalized in dB to determine the noise power ratio of the unit under test.

Abstract: A surface acoustic wave (SAW) convolver is provided for use in a communication system in which a received signal incorporates a mixed pseudonoise (PN) code sequence and narrowband information signal phase-modulated thereon according to a minimum shift keying (MSK) modulation scheme. The convolver includes a piezoelectric substrate capable of propagating acoustic wave signals on the top surface thereof, and a first transducer formed on the top surface for receiving the received signal and in response thereto generating acoustic surface waves along a first direction thereof. A second transducer is also formed on the top surface for receiving a reference signal and in response thereto generating acoustic surface waves along a second direction thereof, the reference signal incorporating the PN code sequence phase-modulated thereon according to a bi-phase shift keying (BPSK) modulation scheme. A BPSK-MSK converter integrally-formed on the substrate produces the reference signal in MSK form.

Abstract: A frequency synthesizer circuit of the phase-locked loop type for receiving a reference signal and generating in response thereto a plurality of local oscillator (LO) output signals is provided. The synthesizer includes a varactor-controlled oscillator having one or more hyperabrupt varactor tuning diodes for providing an octave bandwidth phase-locked loop output RF, and a plurality of series-connected emitter-coupled logic (ECL) circuits connected to the output of the varactor-controlled oscillator for generating a plurality of local oscillator output signals RF/N, where N=2.sup.x, x=1, 2, 3 . . . . The frequency synthesizer also includes a programmable frequency divider in the feedback loop thereof for reducing the frequency of the phase-locked loop output signal RF by a selectable factor.

Abstract: A dipole phase shifter for use in a phased array antenna includes an insulating substrate having first and second sides. A dipole element having first and second conductive dipole arms is formed on the first side of the insulating substrate and a PIN/NIP diode pair is mounted on the second side of the insulating substrate and electrically-connected to the first and second dipole arms, respectively. A coaxial RF transmission line having a center conductor extending through the insulating substrate connects an input signal to the phase shifter. Quarter-wave transformers are connected between the center conductor and the diodes to compensate for the forward and reverse bias reactances thereof. The first and second dipole arms serve as groundplanes for the quarter-wave transformers. The center conductor also serves as a common bias line which allows forward biasing of one diode and, simultaneously, reverse biasing of the other diode.

Abstract: A method of communicating is disclosed in which the receiving device acknowledges the receipt of a valid transmission and awaits the receipt of an abort message from the transmitting device before accepting the transmitted data. The transmitting device awaits the receipt of a valid acknowledgement and, if it fails to receive such an acknowledgement within a predetermined time-period, transmits an abort message to the receiving device. In multinodal, peer network communication systems, the acknowledgement and abort message may be transmitted during brief, dedicated time-periods following the transmission of data.