Microprocessor controlled AGC

DETAILED DESCRIPTION It is an object of this invention to provide an MLS receiver with a microprocessor controlled automatic gain control.
The apparatus according to the invention is for receiving a first scanning signal followed by a second scanning signal.
The apparatus includes an antenna for receiving the first and second scanning signals.
Means are provided for converting each of the first and second scanning signals received by the antenna into a corresponding intermediate frequency signal.
A linear amplifier having a variable gain first amplifies the corresponding intermediate frequency signals.
A logarithmic amplifier then amplifies the linearly amplified signal.
Means are provided for detecting the logarithmically amplified signal.
An analog-to-digital converter converts the detected signal into corresponding digital information.
A digital peak detector detects a peak magnitude of the corresponding digital information.
First means are provided for developing a first average peak magnitude signal corresponding to the average of the magnitude of the detected peaks of the information corresponding to the first scanning signal.
Second means are provided for developing a second average peak magnitude signal corresponding to the average of the magnitudes of the detected peaks of the information corresponding to the second scanning signal.
Means, such as a digital microprocessor, provides a digital gain signal in response to the first and second average peak magnitude signals.
The digital gain signal corresponding to the first average peak magnitude signal is provided during periods when the antenna is expected to be receiving the first scanning signal.
The digital gain signal corresponding to the second average peak magnitude signal is provided during periods when the antenna is expected to be receiving the second scanning signal.
A digital-to-analog converter converts the digital gain signal into a corresponding analog gain signal which is applied to the gain control input of the linear amplifier