Multi-stage automatic gain control for spread-spectrum receivers

An automatic gain control apparatus (400) for a spread-spectrum receiver, the apparatus comprising:

• a received signal strength indicator;
• an analog amplifier in signal communication with the received signal strength indicator;
• an analog-to-digital converter in signal communication with the analog amplifier;
• a digital automatic gain control loop in signal communication with the analog-to-digital converter, the digital automatic gain control loop including a fast digital automatic gain control unit and a slow analog automatic gain control unit;
• and
• a digital-to-analog converter in signal communication with the digital automatic gain control loop for providing a signal indicative of a digital gain to the analog amplifier.

A program storage device readable by machine, tangibly embodying a program of instructions executable by the machine to perform method steps for controlling the gain of a spread-spectrum receiver, the method steps comprising:

• receiving an analog signal;
• measuring the strength of the received analog signal;
• deriving a first analog gain in correspondence with the measured strength;
• applying the derived first analog gain to an analog amplifier;
• deriving a second analog gain from a pilot channel signal within an automatic gain control loop;
• deriving a digital gain from the pilot channel signal within the automatic gain control loop;
• and
• applying an automatic gain control signal indicative of the second analog gain and the digital gain to the analog amplifier.

A system for controlling the gain of a spread-spectrum receiver, the system comprising:

• receiver means for receiving an analog signal;
• measurement means for measuring the strength of the received analog signal;
• first analog derivation means for deriving a first analog gain in correspondence with the measured strength;
• first analog application means for applying the derived first analog gain to an analog amplifier;
• second analog derivation means for deriving a second analog gain from a pilot channel signal within an automatic gain control loop;
• digital derivation means for deriving a digital gain from the pilot channel signal within the automatic gain control loop;
• and
• automatic gain control application means for applying an automatic gain control signal indicative of the second analog gain and the digital gain to the analog amplifier.