Method and apparatus for signal classification using I/Q quadrant histogram
US5687163A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 7, 1995 |
| Grant date | Nov 11, 1997 |
| Priority date | — |
| Expiry date | Jun 7, 2015 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L27/0012
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
An efficient method and apparatus for determining, recording, and analyzing the phase history of a Line-in signal. The Line-in signal is coupled to a conventional demodulator. I and Q components are output by the conventional demodulator and coupled to an IQ quantizer. The IQ quantizer determines a quadrant on an I/Q plot from the amplitude of each component. A histogram is generated which indicates in which quadrant the Line-in signal was for a first sample, and in which quadrant the Line-in signal was for a second sample, the second sample having been taken immediately after the first sample. From this histogram, the number of times the Line-in signal transitions from one quadrant to another over a predetermined period of time is known. If the number of times the input signal crosses one of the axis of the I/Q plot in a first direction is greater than the number of times the input signal crosses that axis in the opposite direction, then the frequency of the Line-in signal differs from the frequency of the In-phase reference signal and the Quadrature reference signal. The frequency of the Line-in signal is directly related to the difference between the number of times the signal c…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.