Radar altimeter
First Claim
1. A radar system on an aircraft, the system comprising:
- an antenna for outputting and receiving a radar signal;
a circulator in signal communication with the antenna;
a receiver for receiving the radar signal via the circulator; and
a transmitter for generating a radar signal, the transmitter comprising;
a phased-lock loop circuit for generating the radar signal;
a direct digital synthesizer for generating a reference signal based on a pre-defined clock signal and a control signal;
an oscillator and multiplier component for generating a clock signal; and
a mixer for offsetting the reference signal by combining the reference signal with the clock signal,wherein the phased-lock loop circuit generates the radar signal based on the offset reference signal, wherein the offset reference signal is greater than at least 30 MHz.
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Accused Products
Abstract
The present invention provides a radar altimeter system with a closed loop modulation for generating more accurate radar altimeter values. The system includes an antenna, a circulator, a receiver, and a transmitter. The circulator receives or sends a radar signal from/to the antenna. The receiver receives the received radar signal via the circulator. The transmitter generates a radar signal and includes a phase-locked loop circuit for generating the radar signal based on a pre-defined phase signal. The transmitter includes a direct digital synthesizer that generates the phase signal based on a pre-defined clock signal and a control signal. The system includes a digital signal processor and a tail strike warning processor that determine position of a tail of the aircraft relative to ground and present an alert if a warning condition exists based on the determined position of the tail of the aircraft and a predefined threshold.
57 Citations
20 Claims
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1. A radar system on an aircraft, the system comprising:
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an antenna for outputting and receiving a radar signal; a circulator in signal communication with the antenna; a receiver for receiving the radar signal via the circulator; and a transmitter for generating a radar signal, the transmitter comprising; a phased-lock loop circuit for generating the radar signal; a direct digital synthesizer for generating a reference signal based on a pre-defined clock signal and a control signal; an oscillator and multiplier component for generating a clock signal; and a mixer for offsetting the reference signal by combining the reference signal with the clock signal, wherein the phased-lock loop circuit generates the radar signal based on the offset reference signal, wherein the offset reference signal is greater than at least 30 MHz. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method performed by a radar altimeter system on an aircraft, the method comprising:
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generating a clock signal; generating a reference signal using a direct digital synthesizer; offsetting the reference signal by combining the reference signal with the clock signal; generating a radar signal using a transmitter having a closed loop circuit that receives the offset reference signal; outputting the generated radar signal via an antenna; and receiving a radar signal at a receiver via the antenna, wherein the offset reference signal is greater than at least 30 MHz. - View Dependent Claims (15, 16, 17, 18, 19, 20)
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Specification