Modulator having encoder for fault-adaptive pulse step modulation

Abstract

An improved pulse step modulator (PSM) is presented herein for use in an AM transmitter. The modulator includes a plurality of unit step modules connected together in series with each module including a DC voltage source together with an associated actuatable switch for, when actuated, turning on the associated module to provide a unit step voltage. An output circuit is connected to the series connected modules for providing an output voltage to a load wherein the magnitude of the output voltage is equal to the sum of all of the voltage sources of the modules that are turned on. A plurality of module turn on signals are provided with each turn on signal serving to actuate one of the switches in one of the modules with the number of turn on signals being provided being dependent upon the magnitude of the input signal. The turn on signals are provided by circuitry including an addressable memory and addressing means. The memory has a plurality of addressable storage locations each including a number of turn on signals. The addressing means addresses one of the storage means in the memory dependent upon the magnitude of the input signal to obtain from the address storage means the stored pattern of turn on signals.