Multi-line, multi-mode modulator using bandwidth reduction for digital fsk and dpsk modulation

Abstract From the Canadian patent

Abstract, A multi-line multi-mode modulator uses compatible digital modulation techniques for multifrequency (MF) frequency shift, keyed (FSK) and differential phase shift keyed (DPSK) modulation to achieve a multi-line multi-mode modulator which is capable of handling a plurality of lines requiring a dynamic mix of the three modulation techniques. The compatible modulation techniques utilize bandwidth reduction schemes which enable the use of simple RC filters on each output line for the sole purpose of removing the quantizing noise introduced by the digital modulation technique.