Spread spectrum transmitter and communications system using multiple spreading codes
US5790591A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 1, 1995 |
| Grant date | Aug 4, 1998 |
| Priority date | — |
| Expiry date | May 1, 2015 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L7/042
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A spread spectrum transmitter for generating a plurality of spread spectrum codes comprises a shift register having a plurality of stages, with a plurality of tap sets connected to selected ones of said stages. Each tap set defines a different spread spectrum code, which may be maximal or non-maximal. Outputs from the tap sets are combined using exclusive-OR gates and fed back to through a table of logic gates to the input of the shift register. A serial data register is loaded from a data stream and clocked periodically into a parallel data register. The parallel data register corresponds to a data symbol and is connected to the table, whereby one of the spread spectrum codes at a time is selected. A code portion of the spread spectrum code up to a designated length is generated for each data symbol. More than one code portion may be simultaneously sent using offset quadrature phase shift keying. A receiver may detect the code portion or code portions sent by delaying the received signal and combining it with a plurality of delayed versions thereof, the delay period for each delayed version corresponding to the tap locations in the tap set of the transmitter shift register.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.