Apparatus and method for modulating and digitally predistorting a signal in a multiple modulation schemes
US7362820B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | May 18, 2005 |
| Grant date | Apr 22, 2008 |
| Priority date | — |
| Expiry date | Nov 4, 2025 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04W28/18
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A programmable modulator (100) is programmable to operate in either of a GMSK or 8PSK mode. When operating in a GMSK mode, a signal modulating circuit 105 receives (210) a bit stream (110), maps the bit stream (110) to a phase value in complex I, Q form and applies a progressive rotation to the phase value according to GMSK specifications. The output (140) is filtered by a filter circuit (135), preferably using a complex Finite Impulse Response (FIR) filter using the standard coefficients for an 8PSK modulation to create (215) an approximate GMSK output (165). A GMSK correction circuit (150) determines a correction term that is added to the filter circuit output (165) so as to correct amplitude variations to allow the output to conform to GSM/EDGE standards. The same modulator (100) may be programmed to operate in an 8PSK mode with linear predistortion.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.