A novel approach to Filtering the main lobe of a baseband Spread Spectrum Signal

FPGA: XC4005 PC84

VHDL FILE: pnfilt.vhd

SYNTHESIS TOOL: XILINX/ALDEC Foundation Software

XILINX RBT FILE: pnfilt.rbt

XILINX PROM FILE: pnvfilt.mcs (not needed but available)

C Code Real Time Control File: pnfilter.cpp/pnfilter.ide

C Development Platform: Borland C++ 5.0

MATLAB File: pnfilt.mat

EXAMPLE DESCRIPTION:

This example builds on the PN/LRS Generator example mentioned above and shows a novel approach to filtering PN sequences in FPGAs. The FCC has specific band limitations on Spread Spectrum transmissions, which often require that the lobes outside the main lobe be severely attenuated. This can of course be done at the output filter, or can be done at the PN Code by causing the phase shifts to be more gradual. In this example, a novel approach for doing this without Analog to Digital converters or Digital to Analog converters.

Spread Spectrum Note: A good tutorial on Linear Recursive sequences is available on our homepage under spread spectrum products. It was the main article in the August 1994 RF Design Directory Issue. Further APS sells a PN SIM package which allows generation, viewing and correlation analysis of two sequences (LRS/PN). Also SIGTEK (http://www.sigtek.com/sigtek) offers some great spread spectrum products and design and engineering services. You can call the President of SIGTEK anytime to talk about any proposals or Spread Spectrum projects. I highly reccomend them for both cost and expertise. Call Jim Shea at 410-290-3918 and talk to him for five minutes and you'll see what I mean. Also a great web page for Spread Spectrum information in general is the Spread Spectrum Scene which can be found at http://sss-mag.com/index.html .

[INFORMATION REQUEST]