Amplitude Modulation by Means of Two-Dimensional Semirecursive Digital Filters

Modulation can be mathematically interpreted as a special case of two-dimensional convolution. Hence, it is possible to use two-dimensional sampled-data filter techniques for the realization of modulators in modern communication systems. The modulator structures consist of active elements and resistors only, and for that reason they are well adapted to large-scale integration (LSI) circuit design. It is shown that amplitude modulation (AM, OM, SSB, VSB) can be produced by nonrecursive, semirecursive or recursive twodimensional digital filters (also phase modulation for digital modulating signals). From the viewpoint of realization, the semirecursive modulator structures are of predominant interest. Some details are given of a simulated single-sideband data transmitter equipped with such a modulator structure.