Digital modulator and demodulator

Claim 2

Apparatus for generating an output signal commensurate with information contained in an input signal comprising: means for generating a pulsating reference signal; means responsive to said reference signal and the informationbearing input signal for generating a pulse width modulated gating control signal characterized by pulses having widths commensurate with the information; gate means responsive to said gating signal and to said pulsating reference signal for selectively passing said reference signal; up-down counter means connected to the output of gate means; means responsive to said reference signal for generating counter control signals having a preselected phase and frequency relationship to said pulse width modulated signals whereby the direction of counting of reference signal pulses passed by said gate means may be varied during each cycle of said pulse width modulated signal; and means applying said counter control signals to said counter means whereby the totalized count will be commensurate with the information.

Claim 3

The apparatus of claim 1 wherein said counter control signals are in the form of pulses 90* out-of-phase with said pulse width modulated signals whereby the middle of each pulse of the pulse width modulated gating signal is synchronized with the middle of one of said counter control signals.

Claim 4

The apparatus of claim 2 wherein said pulse width modulated signal generating means comprises: scanning signal generator means responsive to said reference signal for providing a linear sweep voltage; and pulse width modulator means responsive to the output of said scanning signal generator and to said input signals.

Claim 5

The apparatus of claim 3 wherein said scanning signal generator comprises a triangular wave form generator.

Claim 6

The apparatus of claim 3 further comprising: frequency divider means connected between said reference signal generating means and said scanning signal generator whereby the pulse width modulated signal is at a first frequency lower than the frequency of said reference signal.

Claim 7

The apparatus of claim 5 wherein said scanning signal generator comprises a triangular waveform generator.

Claim 8

The apparatus of claim 6 wherein said counter control signal generating means comprises: second frequency divider means connected between said reference signal generating means and said means for applying counter control signals to said counter, said frequency divider means providing a pair of output signals at twice said first frequency.

Claim 9

A digital demodulator comprising: clock means for generating a pulsating reference signal; means connected to said clock means and responsive to said reference signal for generating control signals at a first frequency less than the frequency of said reference signal, first and second of said control signals respectively leading and lagging a third control signal by 90*; scanning voltage generating means connected to said control signal generating means and responsive to said third control signal for generating a linear swEep voltage synchronized with said third control signal, said sweep voltage being at a second frequency which is one-half said first frequency; modulator means connected to said scanning voltage generating means and responsive to said sweep voltage and information bearing input signals for providing a gating signal having pulses which vary in width with the information contained in said input signals; gate means connected to said clock means and to said modulator means, said gate means passing reference signal pulses when enabled by said gating signals; and bidirectional counter means responsive to reference signal pulses passed by said gate means, said counter means being connected to said control signal generating means and counting in the direction commanded by said first and second control signals.

Claim 10

A digital demodulator comprising: clock means for generating a pulsating reference signal; means connected to said clock means and responsive to said reference signal for generating control signals at a first frequency less than the frequency of said reference signal, first and second of said control signals respectively leading and lagging a third control signal by 90*; scanning voltage generating means connected to said control signal generating means and responsive to said third control signal for generating a linear swEep voltage synchronized with said third control signal, said sweep voltage being at a second frequency which is one-half said first frequency; modulator means connected to said scanning voltage generating means and responsive to said sweep voltage and information bearing input signals for providing a gating signal having pulses which vary in width with the information contained in said input signals; gate means connected to said clock means and to said modulator means, said gate means passing reference signal pulses when enabled by said gating signals; and bidirectional counter means responsive to reference signal pulses passed by said gate means, said counter means being connected to said control signal generating means and counting in the direction commanded by said first and second control signals.

Claim 11

The apparatus of claim 8 wherein said scanning voltage generating means comprises: first frequency divider means for providing a signal at one-half the frequency of said third control signal; and sweep voltage generator means responsive to the output provided by said first frequency generator means.

Claim 12

The apparatus of claim 9 wherein said control signal generating means comprises: second frequency divider means.