Specific radar designs and specifications
This is a list of different types of
radar
.
Detection and search radars
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Search radars scan great volumes of space with pulses of short radio waves. They typically scan the volume two to four times a minute. The waves are usually less than a meter long. Ships and planes are metal, and reflect radio waves. The radar measures the distance to the reflector by measuring the time of the roundtrip from emission of a pulse to reception, dividing this by two, and then multiplying by the
speed of light
. To be accepted, the received pulse has to lie within a period of time called the
range gate
. The radar determines the direction because the short radio waves behave like a search light when emitted from the reflector of the radar set's antenna.
Search
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Targeting radars
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Targeting radars utilize the same principle but scan smaller volumes of space far more often, usually several times a second or more, while a search radar will scan a larger volume less frequently.
Missile lock-on
describes the scenario where a targeting radar has acquired a target, and the fire control can calculate a path for the missile to the target; in
semi-active radar homing
systems, this implies that the missile can "see" the target that the targeting radar is "illuminating". Some targeting radars have a range gate that can track a target, to eliminate clutter and
electronic countermeasures
.
Missile guidance systems
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Others
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- Target Tracking (TT) Systems
- Multi-Function Systems
Battlefield and reconnaissance radar
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- Battlefield Surveillance Systems
- Countermortar/Counterbattery Systems
- Air Mapping Systems
- Ground Surveillance Radar
[1]
- Man portable radar
Instrumentation radars
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Instrumentation radars are used to test aircraft, missiles, rockets, and munitions on government and private test ranges. They provide Time, Space, Position, Information (TSPI) data both for real time and post processing analysis.
[2]
Repurposed NASA and military radars
Commercial off-the-shelf (COTS)
Custom
- AN/MPS-39 Multi-Object Tracking Radar (MOTR)
- TAMTS
- BAE Rule
- ROTR
- ROSA
- ROSA II
- COSIP
- Dynetics MRS
Fuzes and triggers
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Radar
proximity fuzes
are attached to
anti-aircraft artillery
shells or other
explosive
devices, and detonate the device when it approaches a large object. They use a small rapidly pulsing omnidirectional radar, usually with a powerful battery that has a long storage life, and a very short operational life. The fuzes used in anti-aircraft artillery have to be mechanically designed to accept fifty thousand
g
, yet still be cheap enough to throw away.
[
citation needed
]
Weather-sensing radar systems
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Weather radars
can resemble search radars. This radar uses radio waves along with horizontal, dual (horizontal and vertical), or circular polarization. The frequency selection of weather radar is a performance compromise between precipitation reflectivity and attenuation due to atmospheric water vapor. Some
weather radars
uses
doppler shift
to measure wind speeds and dual-polarization for identification of types of precipitations.
[3]
[4]
-
Storm front
reflectivities
on a weather radar screen (NOAA)
-
Wind profiling radar
Navigational radars
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Navigational radars resemble search radar, but use very short waves that reflect from earth and stone. They are common on commercial ships and long-distance commercial aircraft.
Marine radars are used by ships for collision avoidance and navigation purposes. The frequency band of
radar
used on most ships is
X band
(9 GHz/3 cm), but
S band
(3 GHz/10 cm) radar is also installed on most oceangoing ships to provide better detection of ships in rough sea and heavy rain condition.
Vessel traffic services
also use marine radars (X or S band) for tracking
ARPA
and provides collision avoidance or traffic regulation of ships in the surveillance area.
General purpose radars are increasingly being substituted for pure navigational radars. These generally use navigational radar frequencies, but modulate the pulse so the receiver can determine the type of surface of the reflector. The best general-purpose radars distinguish the rain of heavy storms, as well as land and vehicles. Some can superimpose sonar and map data from
GPS
position.
Air Traffic Control and navigation
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Air traffic control
uses primary and secondary radars. Primary radars are a "classical" radar which reflects all kind of echoes, including
aircraft
and clouds. Secondary radar emits pulses and listens for special answer of digital data emitted by an Aircraft
Transponder
as an answer. Transponders emit different kind of data like a 4 octal ID (mode A), the onboard calculated altitude (mode C) or the Callsign (not the
flight number
) (mode S). Military use transponders to establish the nationality and intention of an aircraft, so that air defenses can identify possibly hostile radar returns. This military system is called IFF (
Identification Friend or Foe
).
Space and range instrumentation radar systems
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Mapping radars
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Mapping radars are used to scan a large region for
remote sensing
and
geography
applications. They generally use
synthetic aperture radar
, which limits them to relatively static targets, normally terrain.
Specific radar systems can sense a human behind walls. This is possible since the reflective characteristics of humans are generally more diverse than those of the materials typically used in construction. However, since humans reflect far less radar energy than metal does, these systems require sophisticated technology to isolate human targets and moreover to process any sort of detailed image. Through-the-wall radars can be made with
Ultra Wideband
impulse radar, micro-
Doppler radar
, and synthetic aperture radar (SAR).
[5]
Speed radar
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- Radar gun
, for traffic policing and as used in some sports
Radars for biological research
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Radar range and wavelength can be adapted for different surveys of bird and
insect
migration and daily habits. They can have other uses too in the biological field.
See also
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Notes
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