Radar apparatus and method of determining sign of velocity
US9817121B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 23, 2014 |
| Grant date | Nov 14, 2017 |
| Priority date | — |
| Expiry date | Feb 3, 2036 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01S17/58
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A radar apparatus which can simply determine the sign of velocity of an object is provided. Laser light reflected by the object undergoes quadrature optical heterodyne detection performed by mixers, optical detectors, and a π/2 phase shifter, whereby I and Q component signals are output. A frequency analyzer performs FFT on a complex signal composed of the I component signal (real part) and the Q component signal (imaginary part) to thereby obtain its frequency spectrum. Since the frequency spectrum is calculated without being folded back even in a region where the frequency is negative, the sign of the Doppler frequency fd can be determined. When the Doppler frequency fd is positive, the sign of the velocity of the object is a direction toward the radar apparatus. When the Doppler frequency fd is negative, the sign of the velocity of the object is a direction away from the radar apparatus.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.