Transversal Filters

Transversal filters, the electrical analogue to the grating spectroscope, offer close approximation to any desired amplitude response without any phase distortion. They consist of a series of matched delay cable sections to which energy is fed at one end to be dissipated in the termination resistance at the other end. Signals are derived as the sums or differences of voltages tapped off at equidistant points along the cable. Electronic devices are described which are suitable for the summation of such voltages without interaction and without causing reflections in the cable, as well as "condensed cables" which provide, without appreciable dispersion, the necessary delays for a wide range of frequencies.