by Girish Linganna

The Defence Acquisition Council (DAC), led by Defence Minister Rajnath Singh, recently approved the acceptance of necessity (AoN) -- the initial step in the procurement process -- for acquiring Advanced Land Navigation Systems (ALNS) for the Indian Army's Armoured Fighting Vehicles (AFVs).

According to a statement from the Defence Ministry, the ALNS Mk-II is compatible with the Indian Regional Navigation Satellite System (IRNSS, NavIC) in addition to the Global Positioning System (GPS) -- a satellite-based navigation system from the USA -- and the Global Navigation Satellite System (GloNaSS) -- a satellite-based navigation system from Russia.

What Is Advanced Land Navigation System?

The system is highly secure with advanced encryption to prevent spoofing, a deceptive practice where false data is sent to a system to make it believe it is receiving genuine information.

In navigation systems, spoofing involves sending fake GPS signals to mislead the receiver about its actual location, potentially causing significant navigational errors.

The ALNS MK-II system operates faultlessly with defence series maps, with exceptionally high accuracy results for AFV navigational applications.

Bharat Electronics Limited (BEL), Chennai, will supply this equipment under the Buy (Indian-Indigenously Designed Developed and Manufactured, IDDM) category of the buying process.

How Does Advanced Land Navigation System Work?

The ALNS is a device installed in ‘A’ vehicle to help navigate through areas without distinct landmarks. ‘A’ vehicle refers to any mode of transportation, such as cars, trucks, or military vehicles, which can move people or goods from one place to another. BEL has created this equipment that helps navigate routes based on the coordinates of a military map.

The ALNS helps both the commander and the driver by constantly updating the vehicle’s current location and direction to the chosen destination. The main sensor used in the system is known as an Inertial Measurement Unit. The ALNS can function in three distinct modes based on the requirements. These modes are:

Inertial Mode: The system relies entirely on data from inertial sensors. Inertial sensors are devices that measure specific force, angular rate and, sometimes, the magnetic field surrounding the sensor. These measurements allow the system to track its position, orientation and velocity without external references, using such instruments as accelerometers and gyroscopes.

Hybrid Mode: In this mode, the system uses data from both an inertial sensor and a GPS receiver, choosing the most precise information to calculate navigational parameters. A GPS receiver is a device that determines one’s exact location on Earth by receiving signals from satellites.

GPS Mode: In this mode, the system works on its own without using data from the inertial sensor. It relies solely on GPS signals to function.

Advanced Land Navigation System MK-II

The ALNS MK-II is a navigation system that uses a Hemispherical Resonating Gyro (HRG)—a type of gyroscope—a device that helps measure and maintain orientation and angular velocity—used for precise navigation. It works by detecting changes in orientation using the vibrations of a small, hemispherical resonator.

The system helps navigate routes defined by the coordinates on a military map in Digital Surface Model (DSM) format, which is a type of digital representation that captures Earth’s surface, including all natural and man-made features, such as trees and buildings.

This data is often used in mapping and navigation to provide detailed terrain information.

The system offers navigation data using Inertial, GPS, GLONASS, Indian Regional Navigation Satellite System (IRNSS) and Hybrid, which combines data from multiple sources to provide the most accurate navigation information—methods to meet various navigation needs.

The author of this article is a Defence, Aerospace & Political Analyst based in Bangalore