Directional detector for power level control

Abstract

Disclosed is power level adjusting apparatus for a data transmission system of the type having a power amplifier means for providing a modulated output signal. A detecting circuit for providing a voltage proportional to the power amplifier means output signal level includes a coupling circuit connected to the output of the power amplifier means for coupling the modulated voltage signal therefrom to provide a detected voltage proportional to the power level of the power amplifier means modulated output voltage signal. A source of bias signal is included for selectively providing a bias signal embodied in one of two bias level states, and a switchable active device circuit is connected to the output of the power amplifier means, to the coupling means and to the source of bias signal, the switchable active device which may be a PIN diode or a GaAs FET is being responsive to the bias signal in a first one of the two bias level states for switching to a non-conducting condition and thereby providing a low signal coupling mode for the coupling means, and the switchable active device circuit is responsive to the bias signal in a second one of the two bias level states for switching to a conducting condition and thereby providing a high signal coupling mode for the coupling means.