Noise cancellation method and apparatus
US5940025A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 15, 1997 |
| Grant date | Aug 17, 1999 |
| Priority date | — |
| Expiry date | Sep 15, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01S7/4008
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A radar transmitter for producing a radar signal in response to a radar trigger signal fed thereto. The transmitter includes a radio frequency oscillator for producing a signal having a radio frequency carrier to be used in each transmitted radar signal. The signal produced by the oscillator is amplified by a radio frequency amplifier. In response to the system trigger signal, the transmitter is configured in a normal operating mode to operate with three noise cancellation loops; i.e., an automatic level control loop (ALC); an amplitude modulation noise cancellation loop (AM noise cancellation loop); and a phase modulation noise (PM noise cancellation loop). In response to the system trigger signal, the normal operating mode is preceded with two calibration modes: an AM noise calibration mode used to determine a nominal operating point for the AM noise calibration mode; and a subsequent phase modulation (PM) noise calibration mode used to establish a nominal operating point for the PM noise calibration mode. During the AM noise calibration mode, a nominal operating level is determined which places the TWT amplifier slightly below saturation.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.