Narrow Results

This paper presents the design of tunable heterodyne filter that can be used very effectively in the elimination of narrowband interference in wide-band communications. The filter makes use of the heterodyne process to create a tunable notch filter from a fixed coefficient high-pass filter. It has been shown that it is possible to generate a signal that can be used to set the heterodyne frequency to match the tunable heterodyne notch filter to the center of the detected interference through the use of a simple second order IIR band-pass filter to detect the narrowband interference. Moreover various options have been illustrated for the implementation of heterodyne filters using Xilinx Virtex field programable gate arrays (FPGAs).

This paper presents analysis and behavior of ferrite beads with reference to the impedance, frequency, and spread spectrum modulation.

The first section of this paper will address the basic principles of EMI, ferrite chips, and will explain the characteristics of ferrites associated with EMI at low and higher frequencies. While the section two discusses reducing EMI with spread spectrum modulations.