Low-cost radio altimeter
First Claim
1. A radio altimeter comprising:
- a predetermined oscillator for generating an oscillation signal at a predetermined frequency;
means for modulating said oscillation signal with a predetermined modulation signal defining a modulated signal;
means for radiating said modulated signal defining a radiated modulated signal;
first means for coupling said modulated signal to said radiating means, said first coupling means including one or more radiating circuit microstrips;
means for amplifying said modulation signal, said amplifying means having a predetermined gain selected to eliminate the need to tune said one or more radiating circuit microstrips;
means for receiving a reflection of said radiated modulated signal defining reflection signals;
means for mixing said modulated signals with said reflection signals to generate an audio signal whose frequency is proportional to the altitude of the aircraft above ground;
second means for coupling said reflection signals to said mixing means, said second coupling means including one or more receiving circuit microstrips; and
means for amplifying said reflection signals, said amplifying means including a plurality of low-noise amplifiers, at least one of said low-noise amplifiers having a predetermined gain selected to eliminate the need to tune said one or more receiving circuit microstrips.
1 Assignment
0 Petitions
Accused Products
Abstract
A relatively low-cost FMCW radio altimeter includes a voltage-controlled oscillator based upon a GaAs FET. The oscillator produces, for example, a 4.3 GHz microwave signal that is modulated with a triangular wave having a pin-selectable modulation frequency. The modulated signal is amplified by a buffer amplifier, as well as a power amplifier, and connected to an RF output terminal by way of a plurality of microstrips. Reflected signals are received at an RF input and are coupled to a mixer by way of a low-noise amplifier. The modulation signal is also applied to the mixer by way of a microstrip coupling device to produce an audio output signal whose frequency is proportional to the altitude above ground. The gains of all of the amplifiers are selected to eliminate the need for hand-tuning of the microstrips and to enable the use of a glass/epoxy circuit board. The output of the radio altimeter is an audio signal whose frequency is proportional to the height above ground, which enables direct digital conversion by way of a frequency-to-binary converter.
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Citations
23 Claims
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1. A radio altimeter comprising:
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a predetermined oscillator for generating an oscillation signal at a predetermined frequency; means for modulating said oscillation signal with a predetermined modulation signal defining a modulated signal; means for radiating said modulated signal defining a radiated modulated signal; first means for coupling said modulated signal to said radiating means, said first coupling means including one or more radiating circuit microstrips; means for amplifying said modulation signal, said amplifying means having a predetermined gain selected to eliminate the need to tune said one or more radiating circuit microstrips; means for receiving a reflection of said radiated modulated signal defining reflection signals; means for mixing said modulated signals with said reflection signals to generate an audio signal whose frequency is proportional to the altitude of the aircraft above ground; second means for coupling said reflection signals to said mixing means, said second coupling means including one or more receiving circuit microstrips; and means for amplifying said reflection signals, said amplifying means including a plurality of low-noise amplifiers, at least one of said low-noise amplifiers having a predetermined gain selected to eliminate the need to tune said one or more receiving circuit microstrips. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A radio altimeter comprising:
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an oscillator for generating an oscillation signal at a predetermined frequency; a modulator for generating a modulation signal for modulating said oscillation signal, said modulation signal being a triangular wave at a predetermined modulation frequency, defining a modulated signal; a buffer amplifier having a predetermined gain for amplifying said modulated signal, said buffer amplifier being electrically coupled to said oscillator, said coupling including one or more microstrips; a power amplifier having a predetermined gain, electrically coupled to said power amplifier, said coupling including one or more microstrips; an RF output terminal electrically coupled to said power amplifier, said coupling including one or more microstrips; an RF input terminal for receiving reflected signals; a mixer for mixing said modulated signals with said reflected signals to generate a signal whose frequency is proportional to the altitude of the aircraft above ground; a local oscillator coupling device which includes one or more microstrips for coupling said modulated signal to said mixer; and a plurality of low-noise amplifiers, each of said amplifiers having a predetermined gain, said amplifiers electrically coupled to said RF input terminal and to said mixer by microstrips, wherein the gain of at least one of said amplifiers is selected to eliminate the need to tune said microstrips. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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21. A frequency modulated continuous wave radio altimeter comprising:
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(a) a transmit circuit for transmitting a first signal; (b) a receive circuit for receiving a reflection of said first signal and for producing a second signal indicative of a height above ground; and (c) at least one of said transmit circuit or said receive circuit including; (i) at least one microstrip circuit; and (ii) a plurality of amplifiers electrically coupled to said microstrip circuit, said amplifiers having a gain selected to eliminate the need to tune said microstrip circuit. - View Dependent Claims (22, 23)
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Specification