TACAN: Tactical Air Navigation System Basics

The TACAN (Tactical Air Navigation) avionic system is a short-range navigational aid used primarily for military purposes. It provides aircraft with bearing and distance information relative to a ground station.

The bearing component of TACAN is similar to VOR (VHF Omnidirectional Range), but tailored for military operations. The distance measurement capability is achieved through an integrated DME (Distance Measuring Equipment) system within the TACAN ground station.

On the ground, TACAN or VORTAC (VOR with TACAN) systems are used for transmitting and receiving signals. These systems operate in the UHF (Ultra High Frequency) band, specifically from 960 to 1215 MHz, supporting 252 channels. Aircraft utilize TACAN systems for both transmitting and receiving in the UHF band. The range of operation extends to approximately 200 miles.

Figure depicts TACAN Ground station system.

Advantages of TACAN

• Rejection of Bounced Signals: TACAN is designed to minimize interference from reflected signals, ensuring accuracy.
• Low Power Consumption: It requires relatively little power to operate.
• Resistant to Environmental Factors: It withstands shock, vibration, and electromagnetic interference (EMI).
• Robustness in Harsh Environments: It functions reliably in severe conditions like snow, humidity, rain, fungus, sand, and dust.
• No Moving Parts: The antennas require minimal maintenance due to the absence of moving components.
• Combined Bearing and Distance: It offers both bearing and distance measurement capabilities in a single system.
• DME Backup: If the bearing transmitter fails, the station remains operational as a DME ground station.

Disadvantages of TACAN

• Bearing Error: The bearing accuracy is subject to an error of approximately +/- 3.5 degrees.
• Slant Range Error: Distance measurements can be affected by slant range error, especially at high altitudes.
• Line-of-Sight Limitation: Due to its UHF operation, TACAN is limited to line-of-sight propagation.
• Though GPS is more accurate TACAN will remain: Despite the availability of more precise systems like GPS, TACAN is a dependable military navigational aid that will continue to be used for the foreseeable future.

Differences Between Various Systems

• Difference between DME and TACAN
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• Difference between FDM and OFDM
• Difference between SC-FDMA and OFDM
• Difference between SISO and MIMO
• Difference between TDD and FDD
• Difference between 802.11 standards viz.11-a,11-b,11-g and 11-n
• OFDM vs OFDMA
• CDMA vs GSM
• Bluetooth vs zigbee
• Fixed wimax vs mobile wibro vs mobile wimax
• Microcontroller vs microprocessor
• FDM vs TDM
• wimax vs lte