Channelization is one of the most important operations in building digital electronic warfare (EW) receivers. The equivalent analog operation is the filter bank. Therefore, digital channelization can be considered a digital filter bank. It can also be considered as an N-port network with one input and N-1 outputs. An input signal will appear at a certain output according to its frequency. By measuring the outputs from the filter bank, the frequency of the input signal can be determined. The design of a specific digital filter bank will be presented. This specific example is used to illustrate the design procedure while avoiding the unnecessary mathematical complexity of a general design. In this example the concepts of polyphase filter and multirate operation will be introduced. In order to understand these concepts, decimation and interpolation are discussed first.

Chapter Contents:

• 11.1 Introduction
• 11.2 Filter Banks
• 11.3 FFT and Convolution Operations
• 11.4 Overlapping Input Data in the FFT Operations
• 11.5 Output Data Rate from FFT Operation
• 11.6 Decimation and Interpolation
• 11.7 Decimation and Interpolation Effects on the Discrete Fourier Transform
• 11.8 Filter Bank Design Methodology
• 11.9 Decimation in the Frequency Domain
• 11.10 Output Filter Shape from a Decimated FFT
• 11.11 Using Weighting Function to Widen the Output Filter
• 11.12 Changing Output Sampling Rate
• 11.13 Channelization through Polyphase Filter
• 11.14 Operation of the Polyphase Filter
• 11.15 Filter Design
• References

Inspec keywords: digital filters; electronic warfare; channel bank filters

Other keywords: decimation; digital electronic warfare receivers; interpolation; frequency channelization; digital filter bank; digital channelization; multirate operation; polyphase filter

Subjects: Electronic warfare; Digital filters