Implementation of complex-arithmetic heterodyne filter

Abstract

Heterodyne filters provide both tunable and adaptive filters with applications in narrow-band interference attenuation for spread-spectrum and other broad-hand communications systems. A new complex-arithmetic version of the tunable heterodyne filter offers significant hardware savings over previous versions and can more easily he implemented in adaptive filter applications.

Residue Number System Implementations of Complex Heterodyne Tunable Filters

“…In modulus 17, the integer 2 is the 8 th root of one because 2 raised to the power 8 is 256, and 256 modulus 17 is one. These properties of RNS are covered in detail in most books on Number Theory [26] Figure 1 shows the basic structure for the complex heterodyne filter [25]. The input x(n) is multiplied by the first complex heterodyne signal generating the output r(n).…”

“…Finally, the output w(n) is multiplied by the complex heterodyne signal generating the final output y(n). The detailed operation of these complex heterodyne filters can be found in the earlier paper [25]. Our goal in this paper is to implement the whole system in MRNS using the integer representations of the M th root of one as a convenient method for implementing the complex heterodyne signal.…”

“…Here we will concentrate on the implementation of the complex heterodyne signal that is required to make the FIR filter tunable [25]. We shall first illustrate the process using a simple MRNS.…”

“…Recently the authors have introduced the concept of tunable heterodyne filters [15][16][17][18][19][20][21][22][23][24][25]. The most recent of these papers discuss the implementation of heterodyne filters that make use of a complex heterodyne signal to convert complicated fixed coefficient digital filters into tunable digital filters tunable by a single heterodyne frequency [25].…”

“…The most recent of these papers discuss the implementation of heterodyne filters that make use of a complex heterodyne signal to convert complicated fixed coefficient digital filters into tunable digital filters tunable by a single heterodyne frequency [25]. This approach allows for both FIR and IIR filters to serve as the prototype fixed-coefficient filter that will be made tunable.…”