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US 2015/0084808 A1Published application
Fmcw radar with refined measurment using fixed frequencies
AssigneeHoneywell International Inc.
InventorDavid C. Vacanti
Life of this patent
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Abstract
One embodiment is directed to a method for operating a radar altimeter. The method includes transmitting a radar signal at a first frequency, ramping the frequency of the radar signal from the first frequency to a second frequency, and transmitting the radar signal at the second frequency. The reflections can be processed by determining an approximate distance to a target based reflections of the frequency ramp and the approximate distance can be refined based on a phase difference between a reflection of the radar signal transmitted at the first frequency and a reflection of the radar signal transmitted at the second frequency.
Claims20
A method for operating a radar altimeter, the method comprising:
- transmitting a radar signal at a first frequency for a first length of time;
- ramping the frequency of the radar signal from the first frequency to a second frequency;
- transmitting the radar signal at the second frequency for a second length of time;
- receiving reflections of the radar signal;
- processing the reflections by:
- determining an approximate distance to a target from which the reflections are received based on an amount of time between transmission of the radar signal having the frequency ramp and reception of a reflection of the radar signal having the frequency ramp;
- determining a first phase of a reflection of the radar signal transmitted at the first frequency, wherein the first phase is the phase of the radar signal as received;
- determining a second phase of a reflection of the radar signal transmitted at the second frequency, wherein the second phase is the phase of the radar signal as received;
- calculating a phase difference between the first phase and the second phase;
- and
- refining the approximate distance to the target based on the phase difference between the first phase and the second phase.
8 more elements
A frequency modulated continuous wave (FMCW) radar comprising:
- a transmitter configured to:
- transmit a radar signal at a first frequency for a first length of time;
- ramp the frequency of the radar signal from the first frequency to a second frequency;
- transmit the radar signal at the second frequency for a second length of time;
- and
- a receiver configured to:
- receive reflections of the radar signal;
- and
- process the reflections by:
- determine an approximate distance to a target from which the reflections are received based on an amount of time between transmission of the radar signal having the frequency ramp and reception of a reflection of the radar signal having the frequency ramp;
- determine a first phase of a reflection of the radar signal transmitted at the first frequency, wherein the first phase is the phase of the radar signal as received;
- determine a second phase of a reflection of the radar signal transmitted at the second frequency, wherein the second phase is the phase of the radar signal as received;
- calculate a phase difference between the first phase and the second phase;
- and
- refine the approximate distance to the target based on the phase difference between the first phase and the second phase.
12 more elements
A method for operating a radar altimeter, the method comprising:
- ramping a frequency of a radar signal from a first frequency to a second frequency;
- receiving a reflection of the radar signal having the frequency ramp;
- determining an approximate distance to a target from which the reflections are received based on an amount of time between transmission of the radar signal having the frequency ramp and reception of a reflection of the radar signal having the frequency ramp;
- if the approximate distance is less than or equal to a distance corresponding to a center of a first FFT bin, then:
- transmitting the radar signal at a first frequency for a first length of time;
- transmitting the radar signal at the second frequency for a second length of time;
- receiving reflections of the radar signal transmitted at the first frequency and the second frequency;
- and
- processing the reflections by:
- determining a first phase of a reflection of the radar signal transmitted at the first frequency, wherein the first phase is the phase of the radar signal as received;
- determining a second phase of a reflection of the radar signal transmitted at the second frequency, wherein the second phase is the phase of the radar signal as received;
- calculating a phase difference between the first phase and the second phase;
- and
- refining the approximate distance to the target based on the phase difference between the first phase and the second phase.
11 more elements
Dependencies are inferred from the claim text.