Digital automatic level control system
First Claim
1. A digital automatic level control (DALC) system comprising:
- a level detector module including;
a first digital delay element having an input for receiving a sequence of inputted digital time samples of a signal to be leveled and an output for sequentially outputting a first sequence of outputted time samples after a pre-selected delay;
a first accumulator for receiving said sequence of inputted time samples and adding each of said inputted samples to a first running sum, and for receiving said sequence of outputted time samples on said output of said delay element and subtracting each of said outputted time samples from said first running sum, whereby said first running sum is representative of the average value of all time samples presently contained in said first delay element;
a second digital delay element having an input for receiving said sequence of outputted digital time samples from said output of said first digital delay element and an output for sequentially outputting a second sequence of outputted time samples after a predetermined delay; and
a second accumulator for receiving said first sequence of outputted time samples and adding each of said first sequence of outputted time samples to a second running sum, and for receiving said second sequence of outputted time samples on said output of said second delay element and subtracting each of said outputted time samples in said second sequence from said second running sum, whereby said second running sum is representative of the average value of all time samples presently contained in said second delay element; and
a level adjustment module for employing the greater of said first and second running sums to form a level adjusted output sequence of digital time samples.
4 Assignments
0 Petitions
Accused Products
Abstract
A digital automatic level control system employs delay elements, which enable information about a signal parameter from the past, present and future to be processed to provide an optimal gain that can be used to level rapidly varying signals, such as bursty signals. As digital time samples of a signal are passed through first and second buffers, first and second accumulators maintain running sums that are related to the sum of the samples presently in the first and second buffers, respectively. The sums in the first and second accumulators represent information about the signal parameter for the future and the past, respectively. By choosing the maximum of these two values, the system can anticipate the beginning of a signal burst, and still have enough delay to compensate the end of a signal burst. In one embodiment of the invention, multiple channel signals can be leveled, either individually or in groups.
14 Citations
20 Claims
-
1. A digital automatic level control (DALC) system comprising:
-
a level detector module including; a first digital delay element having an input for receiving a sequence of inputted digital time samples of a signal to be leveled and an output for sequentially outputting a first sequence of outputted time samples after a pre-selected delay; a first accumulator for receiving said sequence of inputted time samples and adding each of said inputted samples to a first running sum, and for receiving said sequence of outputted time samples on said output of said delay element and subtracting each of said outputted time samples from said first running sum, whereby said first running sum is representative of the average value of all time samples presently contained in said first delay element; a second digital delay element having an input for receiving said sequence of outputted digital time samples from said output of said first digital delay element and an output for sequentially outputting a second sequence of outputted time samples after a predetermined delay; and a second accumulator for receiving said first sequence of outputted time samples and adding each of said first sequence of outputted time samples to a second running sum, and for receiving said second sequence of outputted time samples on said output of said second delay element and subtracting each of said outputted time samples in said second sequence from said second running sum, whereby said second running sum is representative of the average value of all time samples presently contained in said second delay element; and a level adjustment module for employing the greater of said first and second running sums to form a level adjusted output sequence of digital time samples. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
-
-
13. A method for automatically controlling the level of one or more digital signals comprising the steps of:
-
providing an input sequence of digital time samples of at least one signal to be leveled; adding each of said time samples in said sequence to a first running sum; passing said input sequence of digital time samples through a first digital delay element, thereby forming a first outputted sequence of digital time samples; subtracting each of said time samples in said first outputted sequence from said first running sum as they are outputted from said first digital delay element, whereby said first running sum is representative of the average value of all time samples presently contained in said first delay element; adding each of said time samples in said first outputted sequence to a second running sum as they are outputted from said first digital delay element; passing said first outputted sequence of digital time samples through a second first digital delay element, thereby forming a second outputted sequence of digital time samples; subtracting each of said time samples in said second outputted sequence from said second running sum as they are outputted from said second digital delay element, whereby said second running sum is representative of the average value of all time samples presently contained in said second delay element; and employing the greater of said first and second running sums to form a level adjusted output sequence of digital time samples. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
-
Specification