Low-cost radio altimeter
US5719581A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 12, 1996 |
| Grant date | Feb 17, 1998 |
| Priority date | — |
| Expiry date | Feb 12, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01S13/882
- WIPO fieldMeasurement
- WIPO sectorInstruments
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.