Abstract: Methods and apparatus are provided for operating a radar system to provide a thunderstorm image to a pilot. The method comprises using one or more radar scans depending upon the aircraft altitude, a single upward tilted scan at or below a datum level of about 15,000±3000 feet wherein a clutter free storm image may be obtained and two scans above the datum level; a first upward tilting scan to determine, clutter free, a storm head perimeter and a second lower tilting scan for the storm body with ground clutter. The perimeter is used to discard return echoes from the second scan that lie outside the perimeter or an expansion thereof and retain those lying on or within the perimeter. The result is presented to the pilot. Optionally, the thunderstorm image is graded from center to edge so as to indicate weaker echo intensity near the edge.

Abstract: An aircraft guidance system uses radar imaging to verify airport and runway location and provide navigation updates. The system is applicable to flight operations in low visibility conditions.

Abstract: An aircraft guidance system uses radar imaging to verify airport and runway location and provide navigation updates. The system is applicable to flight operations in low visibility conditions.

Abstract: An aircraft guidance system uses radar imaging to verify airport and runway location and provide navigation updates. The system is applicable to flight operations in low visibility conditions.

Abstract: A radar based terrain and obstacle detection device for aircraft detects obstacles and terrain ahead of the aircraft. An alert is sounded if the obstacle or terrain is above a clearance plane positioned ahead of the aircraft.

Abstract: A method and apparatus for improving resolution of targets in a monopulse radar beam.

Abstract: The invention comprises a weather radar system in which a magnetron transmitter is controlled in frequency by injecting therein a low power locking signal from a stable frequency source. Frequency lock between the source and the magnetron is maintained without requiring injection signals of excessive power by an automatic frequency control (AFC). The AFC determines the frequency and phase error between the injection signal and the magnetron output and adjusts the frequency of the source so as always to be within a narrow band of frequencies centered about the natural frequency of the magnetron. Over the long term, therefore, the frequency of the source will vary by an amount equal to the change in the natural frequency of the magnetron occurring during that time. Over the short term, however, the difference in frequency between the injection signal and the magnetron output is zero, while the phase difference is less than 90.degree..

Abstract: A digital automatic frequency control for a pulse-type radar receiver having a voltage controlled local oscillator. A first digital number is generated and converted to a first analog voltage for coarse control of the local oscillator frequency. The first digital number is varied during the time output from the radar transmitter is present at the receiver mixer. The first digital number is varied causing sweep of the local oscillator frequency. When the difference frequency output from the mixer is at a value to cause output from the receiver intermediate frequency amplifier of a predetermined level, variation of the first digital number is halted, providing a coarsely tuned local oscillator frequency. A second digital number is then generated, converted to a second analog voltage which is combined with the first analog voltage. The second digital number is varied to cause the local oscillator frequency to be sidestepped above and below the coarsely tuned frequency.