US 2003/0142659 A1 · Automatic gain control for communication receivers

Abstract

A communication receiver amplifies a pulse-amplitude-modulated (PAM) signal representing an integer-valued sequence of first data elements (D1) with an adjustable first gain (G1) and digitizes the amplified signal to produce a sequence of second data elements (D2) representing successive magnitudes of the PAM signal. A first automatic gain control (AGC) circuit determines the rate at which magnitudes of the second data sequence elements fall within a first range and adjusts G1 to maintain that rate within a second range. Digital signal processing circuits within the receiver process the second data to produce a sequence of third data elements (D3), each having a real number value substantially equal to a product of a second gain G2 and a corresponding one of the first data elements D1. A slicer rounds the real number represented by each third data sequence element to produce a corresponding integer-valued element of a fourth data sequence (D4). A second AGC circuit adjusts the second gain based on a combination of a sign of each fourth sequence element and a sign of a difference between corresponding third and fourth data sequence elements to keep each third data element as close as possible in value to its corresponding first data element.

Claims37

Dependent claims

An apparatus for processing a differential first pulse amplitude modulated (PAM) signal (P1) having a time varying magnitude representing a sequence of integer-valued first data elements (D1), the apparatus comprising:

amplifying means (70) for amplifying the first PAM signal with an adjustable first gain (G1) to produce a second PAM signal (P2);
digitizing means (72) for processing the second PAM signal to generate a sequence of second data elements (D2) having values representing magnitudes of the second PAM signal at a succession of times;
and
first automatic gain control (AGC) means (66) for determining a number of second data elements generated per unit of time having values within a first range and for adjusting the first gain when the determined number falls outside a second range.

1 more element

amplifying means (70) for amplifying the first PAM signal with an adjustable first gain (G1) to produce a second PAM signal (P2);
digitizing means (72) for processing the second PAM signal to generate a sequence of second data elements (D2) having values representing magnitudes of the second PAM signal at a succession of times;
first means (90, 92, 94) for generating seventh data (D7) of value representing a number of second data elements within a succession of N data elements having values falling within a first range, where N is an integer greater than 1, and
second means (95, 96, 97) for adjusting the first gain when the value of the seventh data falls outside a second range;
digital signal processing (DSP) means (74) for processing the second data elements to produce a sequence of third data elements (D3), each having a real number value that is substantially proportional to a product of the integer value of a corresponding one of the first data elements and a second gain (G2);
slicer means (78) for processing the third data elements to produce a sequence of fourth data elements (D4), wherein each fourth data element has an integer value approximating a value of a corresponding one of the third data elements;
and
second AGC means (68) for controlling the second gain in response to a comparison of values of corresponding third and fourth data elements.

5 more elements

A method for processing a differential first pulse amplitude modulated (PAM) signal (P1) having a time varying magnitude representing a sequence of integer-valued first data elements (D1), the method comprising the steps of:

a. amplifying the first PAM signal with an adjustable first gain (G1) to produce a second PAM signal (P2);
b. digitizing the second PAM signal to generate a sequence of second data elements (D2) having values representing magnitudes of the second PAM signal at a succession of times;
and
c. processing the second data elements to determine a number of second date elements generated per unit time falling within a first range and adjusting the first gain when the determined number falls outside a second range.

1 more element

a. amplifying the first PAM signal with an adjustable first gain (G1) to produce a second PAM signal (P2);
b. digitizing the second PAM signal to produce a sequence of second data elements (D2) representing magnitudes of the second PAM signal at a succession of times;
c. generating seventh data (D7) of value representing a count of a number of second data elements within a succession of N data elements having values falling within the first range, where N is an integer greater than 1;
d. adjusting the first gain when the value of the seventh data falls outside the second range;
e. processing the second data elements to produce a sequence of third data elements (D3), each having a real number value that is substantially proportional to a product of the integer value of a corresponding one of the first data elements and a second gain (G2);
f. processing the third data elements to produce a sequence of fourth data elements (D4), wherein each fourth data element has an integer value approximating a value of a corresponding one of the third data elements;
and
g. controlling the second gain in response to a comparison of values of corresponding third and fourth data elements.

5 more elements

Dependencies are inferred from the claim text.

Automatic gain control for communication receivers

Life of this patent

Automatic gain control for communication receivers

Life of this patent

Abstract

Claims37