Dual antenna null elimination
US5923292A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 11, 1997 |
| Grant date | Jul 13, 1999 |
| Priority date | — |
| Expiry date | Jul 11, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01Q3/2611
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
RF signal nulling and loss of RF lock (i.e., loss of a communications or command link) is resolved by changing the phase of signals derived from first and second (+Z and -Z) antennas so that they add in phase instead of canceling. This is accomplished automatically by using a computer or processor to measure the RF signal level output by a receiver and change the phase of the incoming signal using a phase shifter to achieve the highest level. A squelch circuit in the receiver is used to determine the maximum obtainable RF signal level. The squelch level is compared in a computer to a threshold when the system looks for a higher squelch level. The phase of the phase shifter is changed using a computer to maximize the received signal level. A feedback loop from the receiver through the computer to the phase shifter provides a path to shift the phase of the incoming RF signal in one of the paths so the respective signals add instead of cancel, which eliminates the signal nulling problem.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.