Communications system employing differential orthogonal modulation

US6519275B2 · kind B2 · utility

Assignee

• Motorola, Inc. · US

Inventors

• Edgar H. Callaway, Jr. · Boca Raton, US
• Neiyer S. Correal · Pembroke Pines, US
• Paul E. Gorday · Loxahatchee Groves, US
• Frederick L. Martin · Jasper, US
• Qicai Shi · Coral Springs, US

Key dates

• Filing date: Dec 18, 2001
• Grant date: Feb 11, 2003
• Expiry date: Dec 18, 2021

Classification

• Technology area (CPC H): Electricity
• CPC primary: H04B1/7075
• WIPO field: Telecommunications
• WIPO sector: Electrical engineering

Abstract

A system and method for orthogonal modulation of signals in communication systems. In the transmitter, differentially coded symbols are used to select time-shifted code sequences. The timing, or code position, of a code sequence is determined at the receiver by comparison to the previous code from the same channel, thus eliminating the need for dual-channel transmission and eliminating error due to differences in path propagation time. A fixed preamble code is also used to synchronize the receiver.