Method and circuit for extraction of Doppler information from a pseudo-noise modulated carrier
US4706286A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 30, 1986 |
| Grant date | Nov 10, 1987 |
| Priority date | — |
| Expiry date | May 30, 2006 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B1/707
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method and apparatus for detecting and identifying Doppler frequency and phase information contained within a signal of the direct sequence spread spectrum type. An incoming signal is split by a circuit and component parts mixed with first and second local oscillator signals, the frequency of the first local oscillator being less than that of the carrier and the second being greater than that of the carrier by the same amount, plus an amount equal to twice the maximum Doppler frequency shift. The heterodyned signals are then low pass filtered, mixed with each other to form a heterodyned output that is then low pass filtered. The resultant signal retains Doppler phase and frequency information and is independent of carrier frequency and modulating PN-code thereby providing an easily demodulated signal whose Doppler information may be readily identified.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.