05-03-2013, 11:10 AM
MILITARY RADARS
[attachment=52601]
INTRODUCTION
Military radar should be an early warning, altering along with weapon control functions. It is specially designed to be highly mobile and should be such that it can be deployed within minutes.
Military radar minimizes mutual interference of tasks of both air defenders and friendly air space users. This will result in an increased effectiveness of the combined combat
operations. The command and control capabilities of the radar in combination with an effective ground based air defence provide maximum operational effectiveness with a safe, efficient and flexible use of the air space. The increased operational effectiveness is obtained by combining the advantages of centralized air defence management with decentralized air defence control.
THE SYSTEM CONFIGURATION
A typical military radar system can be split up into three parts:
1) Radargroup
The radargroup consists of antenna, mast unit, remote control, high tension unit, LO/AFC (Local Oscillator/Automatic Frequency Control) unit, radar transmitter, radar receiver, video processor, waveguide drier and IFF interrogator.
The transmitter and receiver forms the active part of the system. The integrated radar/IFF antenna is fitted on the collapsible mast, mounted on the container. The container is connected by cable to the operator/control shelter.
2) Shelter
Shelter contains display unit, processor unit, TV monitor, colour PPI (Plan Position indicator), IFF control unit, air conditioner, battery charger with battery, Radio set with antenna for data link, radio set with antenna for voice transmission i.e. communication, filter box for radios.
SETS OF TERMINAL EQUIPMENT
These are the sets of lightweight man portable units, which can be easily be stacked together and consists of: -
1) TDR (Target Data Receiver)
The TDR is either connected to a VHF-FM radio receiver or to a LCA to receive transmitted target data. The TDR itself is intelligent, it performs parallax correction, threat evaluation and it displays the result in a threat sequence, enabling the weapon commander to make the correct decision.
2) Radio Receiver or LCA (Line Connection Adapter)
A radio receiver or LCA (with standard 2 wire telephone line) can be used to receive target data. In principle any VHF-FM radio receiver can be used as a part of the terminal equipment set. In case line connection is applied, no radio receiver is required. An LCA connects the 2-wire telephone line to the TDR cable.
OPERATING THE RADAR
The operator’s main task is to watch the PPI (Plan Position Indicator) display, which presents only moving targets in the normal mode (MTI-MODE). Detected target can be assigned with the joystick controlled order marker to initiate target tracking. Target tracking is started and a track marker appears over the target echo. A label is displayed near the track marker. The system computer in the processor unit processes data on this tracked target. When an aircraft does not respond to the IFF interrogation it is considered to be unknown.
FUNCTIONAL DESCRIPTION OF RADAR SUBSYSTEM
The detection of air targets is accomplished by the search radar, the video processor and the colour PPI unit. The colour PPI unit provides the presentation of all moving targets down to very low radial speeds on a PPI screen
The search radar is pulse Doppler radar (also called MTI radar) i.e. it is capable of distinguishing between the echo from a fixed target and that of a moving target. The echoes from fixed target are eliminated, so that the echoes from the moving targets are presented on the screen.
The great advantage of this is that it is possible to distinguish a moving target among a large number of fixed targets, even when the echoes from these fixed targets are much stronger. To achieve this the search radar makes use of the Doppler effect, if the target having a certain radial speed with respect to the search antenna is hit by a series of transmitter pulses from the search radar antenna, the change in range between this target and antenna is expressed by successive echo pulses in phase shifts with respect to the phase of the transmitter pulses.
For moving targets the phase difference from echo pulse to echo pulse is continually subject to change, whereas for fixed targets this is a constant. The distinction between the echo signals from a fixed target and moving target is obtained by detecting the above
phase differences.
CONCLUSION
Military radars are one of the most important requirements during the wartime, which can be used for early detection of ballistic missile and also for accurate target detection and firing. Radar system discussed here has a built in threat evaluation program which automatically puts the target in a threat sequence, and advises the weapon crew which target can be engaged first. Most essential, the target data is available to the weapon crew in time, so the can prepare themselves to engage the ‘best’ target for their specific weapon location.
[attachment=52601]
INTRODUCTION
Military radar should be an early warning, altering along with weapon control functions. It is specially designed to be highly mobile and should be such that it can be deployed within minutes.
Military radar minimizes mutual interference of tasks of both air defenders and friendly air space users. This will result in an increased effectiveness of the combined combat
operations. The command and control capabilities of the radar in combination with an effective ground based air defence provide maximum operational effectiveness with a safe, efficient and flexible use of the air space. The increased operational effectiveness is obtained by combining the advantages of centralized air defence management with decentralized air defence control.
THE SYSTEM CONFIGURATION
A typical military radar system can be split up into three parts:
1) Radargroup
The radargroup consists of antenna, mast unit, remote control, high tension unit, LO/AFC (Local Oscillator/Automatic Frequency Control) unit, radar transmitter, radar receiver, video processor, waveguide drier and IFF interrogator.
The transmitter and receiver forms the active part of the system. The integrated radar/IFF antenna is fitted on the collapsible mast, mounted on the container. The container is connected by cable to the operator/control shelter.
2) Shelter
Shelter contains display unit, processor unit, TV monitor, colour PPI (Plan Position indicator), IFF control unit, air conditioner, battery charger with battery, Radio set with antenna for data link, radio set with antenna for voice transmission i.e. communication, filter box for radios.
SETS OF TERMINAL EQUIPMENT
These are the sets of lightweight man portable units, which can be easily be stacked together and consists of: -
1) TDR (Target Data Receiver)
The TDR is either connected to a VHF-FM radio receiver or to a LCA to receive transmitted target data. The TDR itself is intelligent, it performs parallax correction, threat evaluation and it displays the result in a threat sequence, enabling the weapon commander to make the correct decision.
2) Radio Receiver or LCA (Line Connection Adapter)
A radio receiver or LCA (with standard 2 wire telephone line) can be used to receive target data. In principle any VHF-FM radio receiver can be used as a part of the terminal equipment set. In case line connection is applied, no radio receiver is required. An LCA connects the 2-wire telephone line to the TDR cable.
OPERATING THE RADAR
The operator’s main task is to watch the PPI (Plan Position Indicator) display, which presents only moving targets in the normal mode (MTI-MODE). Detected target can be assigned with the joystick controlled order marker to initiate target tracking. Target tracking is started and a track marker appears over the target echo. A label is displayed near the track marker. The system computer in the processor unit processes data on this tracked target. When an aircraft does not respond to the IFF interrogation it is considered to be unknown.
FUNCTIONAL DESCRIPTION OF RADAR SUBSYSTEM
The detection of air targets is accomplished by the search radar, the video processor and the colour PPI unit. The colour PPI unit provides the presentation of all moving targets down to very low radial speeds on a PPI screen
The search radar is pulse Doppler radar (also called MTI radar) i.e. it is capable of distinguishing between the echo from a fixed target and that of a moving target. The echoes from fixed target are eliminated, so that the echoes from the moving targets are presented on the screen.
The great advantage of this is that it is possible to distinguish a moving target among a large number of fixed targets, even when the echoes from these fixed targets are much stronger. To achieve this the search radar makes use of the Doppler effect, if the target having a certain radial speed with respect to the search antenna is hit by a series of transmitter pulses from the search radar antenna, the change in range between this target and antenna is expressed by successive echo pulses in phase shifts with respect to the phase of the transmitter pulses.
For moving targets the phase difference from echo pulse to echo pulse is continually subject to change, whereas for fixed targets this is a constant. The distinction between the echo signals from a fixed target and moving target is obtained by detecting the above
phase differences.
CONCLUSION
Military radars are one of the most important requirements during the wartime, which can be used for early detection of ballistic missile and also for accurate target detection and firing. Radar system discussed here has a built in threat evaluation program which automatically puts the target in a threat sequence, and advises the weapon crew which target can be engaged first. Most essential, the target data is available to the weapon crew in time, so the can prepare themselves to engage the ‘best’ target for their specific weapon location.