Method and apparatus for improved auto-correlation and range correlation in pseudo-random noise coded systems
US5497160A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 17, 1993 |
| Grant date | Mar 5, 1996 |
| Priority date | — |
| Expiry date | Sep 17, 2013 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01S13/536
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method and apparatus is disclosed for improved out-of-range rejection in pseudo-random noise (PN) coded systems by adjusting the relative phase difference between the two phase states of a bi-phase modulation. The energy in the spectral lines of the bi-phase modulated RF signal to generate a signal to be fedback to a voltage-controlled bi-phase modulator to adjust the relative phase difference between the two phase states. Sampled signals are mixed down to baseband using single sideband suppressed carrier modulation of the center frequency of the transmitted signal and the offset frequency. The offset frequency is chosen to be less than the PN code repetition frequency. The baseband signal is filtered and envelop detected producing a DC voltage proportional to the amplitude of the center line of the PN spectrum which is compared to either a fixed reference or to the amplitude of one or more of the remaining lines in the spectrum. The comparison provides an error signal adjusting the phase of the bi-phase modulator providing improved out-of-range rejection.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.