The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 09, 2003
Filed:
Nov. 30, 1999
Dan Raphaeli, Kfar Saba, IL;
Avner Matmor, Omer, IL;
Itran Communications Ltd., Beersheva, IL;
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 can be placed in the FIR frequency response to filter out specific frequencies such as those corresponding to the amateur radio band. A method of constructing a notch filter having one or more notches in its frequency response is also presented.