Phase representative digital signal modulating apparatus

Claim 2

Apparatus for providing an output signal which is modulated in accordance with another signal comprising, in combination: first and second digital number generators for each providing a repeating series of digital number waveform representative signals; and further means, including input means and output means connected to said first and second number generators for receiving signals therefrom, said further means providing predetermined output signals at said output means thereof for each possible combination of signals to said input means, said output signals being indicative of a first signal waveform being modulated by a second signal waveform.

Claim 3

Apparatus as claimed in claim 1 wherein: said further means further includes digital to analog conversion means for providing said output signals as an analog waveform.

Claim 4

Apparatus as claimed in claim 2 wherein: said further means also includes filter means for removing erroneous frequency components from the output signal of said further means whereby the output signal is more nearly representative of the waveform of the signal of said first number generator as modulated by the waveform of the signal from said second number generator.

Claim 5

Apparatus as claimed in claim 1 wherein the frequency of repetition of said first number generator is different from the frequency of repetition of said second number generator and where the outputs of said number generators and the further means is configured such that the output signal of said memory means basically comprises a sine wave signal modulated in accordance with a raised cosine signal.

Claim 6

Apparatus as claimed in claim 1 wherein said first number generator comprises a time multiplexed device for providing at least two repeating series of digital number representation signals in time division multiplexed format; and said further means includes a read-only memory divided into two portions one of which is used in conjunction with one of the time division multiplexed signals and the other portion of which is used in conjunction with the other of said time division multiplexed signals.

Claim 7

Apparatus for providing an output signal indicative of the amplitude modulation of one signal by another signal comprising, in combination: first signal generator means providing a repetitive series of output signals wherein each individual output signal is indicative in digital format of the phase of a carrier signal to be amplitude modulated; second digital number generator means for providing a second repetitive digital number representative signal indicative of the phase of an amplitude modulating signal; means, including input and output means, for providing an output signal representative of the product of two input signals wherein the input signals are phase representative and the output signal is indicative of the analog product of the signals represented by the digital phase information at the input; and means connecting said first and second digital number generator means to said last named means for providing input signals thereto.

Claim 8

Apparatus for providing an output signal indicative of the amplitude modulation of one signal by another signal comprising, in combination: first signal generator means providing a repetitive series of output signals wherein each individual output signal is indicative in digital format of the phase of a carrier signal to be amplitude modulated; second digital number generator means for providing a second repetitive digital number representative signal indicative of the phase of an amplitude modulating signal; means, including input and output means, for providing an output signal representative of the product of two input signals wherein the input signals are phase representative and the output signal is indicative of the analog product of the signals represented by the digital phase information at the input; and means connecting said first and second digital number generator means to said last named means for providing input signals thereto.

Claim 9

Apparatus as claimed in claim 6 wherein said means for providing the product includes digital to analog conversion means and low pass filter means.

Claim 12

The method of claim 8 comprising the additional steps of: converting each output product of said memory means to an analog value; and low pass filtering the analog values to reduce discontinuities in the composite output signal.