3 Techniques of Direction Finder Systems

A radio direction finder is also known as an antenna system or radio receiver that is designed to determine the direction of the radio signal source. Mostly, a ship or aircraft is using this DF as its navigational aid. Users are going to measure the direction of two transmitters with specific locations.

Each transmitter’s measured directions will then be plotted on the map. When it is done, the intersection of those two plotted lines is going to provide the location of the ship or aircraft carrying the DF. This unique technique that involves the directions of two transmitters is known as the triangulation technique.

Other Techniques in Identifying the DF Carrier

The triangulation technique isn’t the only technique to spot the DF carrier. Some other techniques can be used to identify the signal’s origin. Among many techniques, the most common ones are correlative interferometry, Watson-watt, and Doppler.

1. Doppler-based DF system

What is this Doppler direction-finding system? The system is using the Doppler effect’s fundamentals. It is using the frequency change that is perceived by the receiver when both the source and receiver are in motion relative.

The system is going to produce direction by measuring the Doppler shift. The signal is going to receive the Doppler shift before measuring it. To measure the shift, the signal will sample around the circular array’s elements.

In the past, the Doppler DF used an antenna that is going to be physically rotated. But the more modern one has a multi-antenna circular array.

2. Watson-Watt direction finder

This is an amplitude-based technique that has been developed since the end of World War I. The Watson-Watt system is using two pairs of Adcock antennae that will compare the incoming signal’s amplitude.

One pair of Adcock antennae is a pair of a dipole or monopole antennas. The antennas are going to measure the received signal’s vector difference at every single antenna.

Two of them are co-located but oriented perpendicularly to East-West (E-W) and North-South (N-S). And then the system is going to pass the signals to the receiver.

3. Correlative interferometry direction finder

The third technique is a phase-based DF system that will calculate the direction based on the phase difference. The antenna system is going to get the phase difference by using the configuration at the known wave angle.

This technique has antennas in odd numbers and in circular patterns. The antenna size for the DF technique varies depending on the signal frequency. The higher wavelength or lower frequency signals need bigger antennas that are ground-based.

Those frequencies are crucial in marine navigation because the lower frequency is going to result in better noise immunity.

Applications of Direction-Finding System

This system is used in many applications. At first, this system was used as the navigation aid of aviation. But after the end of the World Wars, the system is still useful. Today, the DF has enough functions in the modern world. Below are some examples of DF system applications.

1. Emergency aid

The first modern use of the direction finder system is as an emergency aid. Many radio transmitter forms are designed so that they can transmit as a beacon if there is an emergency situation. This DF emergency aid is widely used on civil aircraft.

Modern emergency beacons will transmit a unique identification signal which is going to help in finding the transmitter’s exact location.

2. Avalanche rescue

The transceivers of avalanches operate on the standard 457 kHz. Those transceivers are designed to help locate equipment and people buried by the avalanches.

The beacon’s power is so low so that it affects the radio signal’s directionality. Small-scale field effects can dominate the radio signal directionality.

3. Wildlife tracking

Another best application of this DF system is for tracking wildlife. The location of animals that have been tagged by the triangulation help those in the wildlife sector to conduct research technique and study the animals’ movement. The technique has been used since the 1960s.

When they started using the technology in radio transmitters and batteries, the system became small enough so that they can attach the system to wild animals. Now, many wildlife studies are using the same system.

Those who need more details about this direction finder system can get more information and product recommendations from SMS Broadcaster. Visit the official website to get all details you need.