Code shift keying transmitter for use in a spread spectrum communications system
US6616254B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 30, 1999 |
| Grant date | Sep 9, 2003 |
| Priority date | — |
| Expiry date | Nov 30, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B2203/5416
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A transmitter apparatus and method for use in a spread spectrum data communications system that utilizes the Differential Code Shift Keying (DCSK) or non-differential Code Shift Keying (CSK) modulation technique. The transmitter transmits data in the form of packets to the receiver. Each packet is consists of a header, one or more data symbols followed by a CRC checksum. The preamble comprises a sequence of one or more zero rotated symbols and one or more predetermined non-zero rotated symbols. In one embodiment, a shift index is calculated based on the input data. The shift index is used to form the address in a PN sample ROM. The PN sequence is read out using a counter of length modulo the PN sequence length. Samples of the PN sequence are read out and input to a Manchester encoder whose output is amplified and filtered to obtain a particular spectrum shape. In a second embodiment, the shift index is loaded into a counter and used as a starting address to address the PN sample ROM. The counter is cycled for a symbol period causing the entire PN sequence to be read out rotated in accordance with the input data. A FIR filter is used to filter the sample stream. Optionally, notches …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.