Method and apparatus for determining an operating point of a non-linear amplifier of a communication channel

Apparatus for determining an operating point of a non-linear amplifier of a communication channel through which a payload signal is transmitted at a predetermined level, comprising:

• first pseudo noise signal generating means for generating a pseudo noise signal PN(t);
• first modulating means for modulating a clean carrier signal f(t) with said first pseudo noise signal PN(t) to generate a PN modulated clean carrier signal s(t);
• transmitting means for transmitting said PN modulated clean carrier signal s(t) simultaneously with said payload signal through said communication channel at a level below the level of said payload signal;
• receiving means for receiving a receive signal s′(t) corresponding to said PN modulated clean carrier signal s(t) after having traveled through said communication channel;
• first correlating means for correlating said receive signal s′(t) with said pseudo noise signal PN(t) to generate a recovered carrier signal f′(t);
• and
• first delaying means for delaying said first pseudo noise signal PN(t).

Method for determining an operating point of a non-linear amplifier of a communication channel through which a payload signal is transmitted at a predetermined level, comprising:

• generating a first pseudo noise signal PN(t);
• modulating a clean carrier signal f(t) with said first pseudo noise signal PN(t) to generate a PN modulated clean carrier signal s(t);
• transmitting said PN modulated clean carrier signal s(t) simultaneously with said payload signal through said communication channel at a level below the level of said payload signal;
• receiving a receive signal s′(t) corresponding to said PN modulated clean carrier signal s(t) after having traveled through said communication channel;
• correlating said receive signal s′(t) with said first pseudo noise signal PN(t) to generate a recovered carrier signal f′(t);
• and
• determining the operating point of said non-linear amplifier of the communication channel on the basis of said clean carrier signal f(t) and said recovered carrier signal f′(t);
• wherein a gain variation of said clean carrier signal f(t) and said recovered carrier signal f′(t) is determined in response to a small variation of the input power of said payload signal to determine the absolute input power of said payload signal.

Apparatus for determining an operating point of a non-linear amplifier of a communication channel through which a payload signal is transmitted at a predetermined level, comprising:

• first pseudo noise signal generating means for generating a pseudo noise signal PN(t);
• first modulating means for modulating a clean carrier signal f(t) with said first pseudo noise signal PN(t) to generate a PN modulated clean carrier signal s(t);
• transmitting means for transmitting said PN modulated clean carrier signal s(t) simultaneously with said payload signal through said communication channel at a level below the level of said payload signal;
• receiving means for receiving a receive signal s′(t) corresponding to said PN modulated clean carrier signal s(t) after having traveled through said communication channel;
• first correlating means for correlating said receive signal s′(t) with said pseudo noise signal PN(t) to generate a recovered carrier signal f′(t);
• and
• means for determining a gain variation of said clean carrier signal f(t) and said recovered carrier signal f′(t) in response to a small variation of the input power of said payload signal to determine the absolute input power of said payload signal.