Abstract: A radar altimeter for determining altitude of an air vehicle with respect to ground comprises a digital sequencer for digitally modulating a first signal. A transmitter coupled to the digital sequencer transmits a radar signal including the modulated first signal toward the ground. A receiver receives a reflected radar signal from the ground. The received radar signal includes the modulated first signal. A digitizer coupled to the receiver generates digital samples of the modulated first signal. A digital signal processor coupled to the digitizer receives digital samples of the modulated first signal from the digitizer, demodulates the received digital samples, processes the demodulated digital samples and outputs altitude data based on the demodulated digital samples.

Abstract: A radar altimeter for determining altitude of an air vehicle comprises a transmitter for transmitting radar signals toward the ground. A first and a second antenna receive reflected radar signals from the ground. A signal processor is coupled to the first and the second antennas. The signal processor includes filter means for rejecting signals other than signals reflected from a selected ground swath. The signal processor determines the above ground level altitude of the air vehicle based on the radar signals output from the filter means. A phase ambiguity resolution means resolves phase ambiguities that arise due to multiple wavelength separation of the first and the second antenna. The signal processor also determines the horizontal position of the highest point in the selected ground swath.

Abstract: The apparatus has the capability to detect the distance between an aircraft and the ground and at the same time to the nearest point to the aircraft such as buildings or trees. The apparatus includes an altimeter, determining the nearest point, as well as a device for determining the distance to the second target.

Abstract: Aircraft position determination system includes a transmitter to transmit a signal, and two receivers to receive the transmitted signal reflected from the terrain below the aircraft, and a phase comparison apparatus operating from the two receiver's inputs. A processor determines position based on the output from the phase comparison apparatus.

Abstract: A low cost frequency modulated (FM) radar altimeter system with enhanced accuracy for continuously providing an altitude of a target, comprising a transmitter means for transmitting a carrier modulated output signal towards the target; a receiver means having an altitude output signal for receiving the carrier modulated output signal reflected from the target after a time delay, and for providing an open loop error correction means for correcting errors resulting from nonlinearities in the transmitter means and signal processing delay variations in the receiver means so that the altitude determined is accurate; a coupling means for directing a portion of the carrier modulated output signal to the receiver means, and searching means having a first output directed to the receiver means and a second output directed to the transmitter means and having a symmetrical search output signal with a slope, s.sub.

Abstract: A method and apparatus for determining an altitude for a radar fuze. The method includes the steps of receiving a return signal and transmitting a transmitted signal. The return signal and the transmitted signal are mixed and a mixed signal representing an altitude is responsively generated therefrom. The mixed signal is amplified to generate an amplified signal. The amplified signal is filtered to generate a filtered signal which is envelope detected to provide a detected signal responsive to the filtered signal. The detected signal is integrated responsively to the detected signal. The integrated signal level is compared against a track threshold reference signal and a track/no-track comparator signal is provided responsively to the integrated signal level and the track threshold reference signal. System timing is controlled by generating a plurality of control signals responsive to the track/no-track comparator signal and proportional to an altitude.

Abstract: A radar altimeter incorporates circuitry for automatically adjusting altitude readings for variations caused by altitude and temperature changes. Normal target tracking of the radar is intermittently interrupted and a calibration sequence is interjected. The current altitude and receiver AGC information at the time of each interruption is temporarily stored and a test is initiated in which a pseudo radar return at that altitude is introduced to the receiver. The receiver operates on the pseudo return as it would on an actual return. The transmit power is adjusted automatically for the correct signal level at the tracker. The resultant altitude measured for the pseudo return is compared to a known test altitude and any difference is stored away as a correction factor to be applied to the altitude reading which had been stored at the time that its operation had been interrupted to perform the calibration test.

Abstract: A pulse Doppler radar altimeter designed to resolve the ambiguous range problem associated with the use of a pulse repetition interval, which is less than the aircraft altitude, includes a radar transmitter configured to transmit first and second series of pulses where the first series has a pulse repetition interval slightly different from the pulse repetition interval of the second series. At a time when the first series is being transmitted, the receiver electronics including a range gate and a tracker searches for ground returns and positions the range gate in time coincidence with the detected ground return. Control then shifts so that the second series of pulses is transmitted and a determination is made whether overlap of the range gate with the ground return from the second series corresponds to the same altitude as when the first series was involved.

Abstract: An aircraft radar altimeter includes a programmed microcontroller which permits effective simultaneous tracking of at least two targets such that, for example, both ground and obstacles on the ground can be simultaneously tracked, thus avoiding crashes when the aircraft is operating at very low altitudes. The microcontroller is operatively coupled to the radar transmitter and to the receiver so that information relating to a first target can be stored away while a search and track operation is run on a second target. The information concerning a detected second target is likewise stored away and the microcontroller permits alternate tracking of the two targets with the stored information being used as the basis for establishing an initial position for a target when tracking of that target is resumed.

Abstract: The invention contemplates a capacitor-discharge ignition system which includes a particular low-resistance, low-inductance, wire-wound circuit element at the spark plug which is operative with the spark plug and with the rest of the ignition system to materially suppress RFI generated at the spark gap. In application to high-speed, high-power two-cycle engines, use of the invention does not adversely affect engine performance.

Abstract: A four cylinder, two-cycle internal combustion engine for an outboard motor includes a pair of energy storage power capacitors. An engine driven alternator produces a generally sine wave output voltage having one-half cycle connected to charge one capacitor and the opposite half-cycle connected to charge the second capacitor by a suitable diode steering network. The output voltage frequency is greater than the firing frequency and a plurality of voltage cycles provide for charging of the capacitors to the desired level. A separate trigger capacitor is provided. The trigger capacitor is coupled to be charged from the main alternator through a low impedance network and additionally from the main capacitor charging circuit through a high impedance network which may also function as a safety circuit means. Each capacitor is recharged by a plurality of half-cycles and during such period of engine revolution the alternate capacitor is being finally charged and discharged.