Digital signal/noise ratio amplifier apparatus for a communication system
First Claim
1. In a communication system including a transmitter, a receiver and a communication channel, a signal modifier apparatus associated with said transmitter comprising:
- sampler means responsive to an input signal to be transmitted through said communication channel for deriving a series of samples representative of a segment of said input signal;
analog-to-digital converter means for converting each sample to a digital sample value;
first means responsive to said digital sample values for subtracting a first predetermined digital value M1 thereof to derive digital values representative of deviations of said input signal from said first predetermined value M1 ;
second means for determining with said digital values representative of deviations a common factor K with K>
I;
third means for multiplying each of said representative digital values by said common factor K to derive corresponding amplified digital values;
fourth means for adding a second predetermined digital value M2 to each of said amplified digital values to derive corresponding augmented digital values;
digital-to-analog converter means for converting said augmented digital values into an intermediary analog signal;
said transmitter transmitting said intermediary analog signal through said communication channel.
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Abstract
The signal-to-noise ratio of a signal to be transmitted through a communication channel having an upper and lower limit in magnitude is sampled digitally and a common corrective factor for the deviations about the mean value of the signal is determined for amplifying the low portions of the signal without exceeding the limits. By a reverse process at the receiving end of the communication channel, the signal is returned to its original amplitude, thus reducing any noise superposed in the transmission.
The invention is applicable to a video channel where the sampled signal is an audio signal. In such case, the deviations of the samples about the mean of the digital information of the audio signal are matched with the mean of the video channel between the black level and the maximum white level.
151 Citations
5 Claims
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1. In a communication system including a transmitter, a receiver and a communication channel, a signal modifier apparatus associated with said transmitter comprising:
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sampler means responsive to an input signal to be transmitted through said communication channel for deriving a series of samples representative of a segment of said input signal; analog-to-digital converter means for converting each sample to a digital sample value; first means responsive to said digital sample values for subtracting a first predetermined digital value M1 thereof to derive digital values representative of deviations of said input signal from said first predetermined value M1 ; second means for determining with said digital values representative of deviations a common factor K with K>
I;third means for multiplying each of said representative digital values by said common factor K to derive corresponding amplified digital values; fourth means for adding a second predetermined digital value M2 to each of said amplified digital values to derive corresponding augmented digital values; digital-to-analog converter means for converting said augmented digital values into an intermediary analog signal; said transmitter transmitting said intermediary analog signal through said communication channel. - View Dependent Claims (2, 3, 4, 5)
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Specification