Discretionary access control equipment for differential subsystems

Discretionary access control (DAC) equipment (DAC-E – encoding, DAC-D – decoding) is designed for implementation of discretionary access to differential correction data (protection from unauthorized use) of GNSS (Global Navigational Satellite Systems) differential subsystems.

Correction data (CD) security is ensured by their encoding before being transferred to Control & Correction Station (CCS) of GNSS differential subsystem with further decoding upon their receipt by consumer navigation equipment (CNE).

The structural scheme of DAC equipment CCS & CNE installation is given below.

DAC-E encodes correction data transferred from Control & Correction Station in a form of binary sequence frames and transfers the encoded data to the transmitter through the modulator.

Consumer navigation equipment receives encoded correction signals and decodes them with the use of DAC-D.
Discretionary access mode is achieved through various code numbers (access levels) assigned to each DAC-D product.