ASR-11

Last updated
ASR-11
Country of origin United States
Introduced1998 (1998)
Type Airport surveillance radar [1]
Frequency2.7–2.9 Ghz [1] [2] (S band)
PRF 4 CPIs (~1000 Hz avg.) [2]
Beamwidth 1.4° (horizontal), 5° (vertical) [2]
Pulsewidth1.0 μs, 80 μs [2]
RPM12.5 RPM [2]
Range60 NM (110 km; 69 mi) [1]
Power2.1kW avg 25kW pk [1]

ASR-11 is a Digital Airport Surveillance Radar (DASR,) an advanced radar system utilized by the United States as the next generation of terminal air traffic control. [1] The ASR-11 is an upgraded, advanced version of the previous ASR-9 radar. This next generation radar system has been developed through a joint effort by the Federal Aviation Administration, the Department of Defense and the United States Air Force, who took most of the lead development tasks. [3]

Contents

Operation

Much like the previous ASR-9, the ASR-11 has been deployed around airport terminals across the United States to meet the requirements of a digital, automated air traffic monitoring system. The main purpose of the ASR-11 is to replace aging radar systems at airfields that did not receive the ASR-9, as well as use across the world by the United States Military. Many of the advanced parameters such as weather monitoring and digital pinpoint monitoring found on the ASR-9 are also found on the ASR-11. This radar system consists of two separate electronic subsystems, the first being a primary radar and the other, a secondary surveillance radar often referred to as the beacon. Like the ASR-9, the ASR-11 uses a continuously rotating antenna that is mounted on a tower. Transmitted electromagnetic signals reflect off the surface of an aircraft that is within sixty nautical miles of the radar location. The signals are sent to the processing equipment which measures the echo delay, or the amount of time it takes for the electromagnetic signals to return, and the direction from which they came. [4] The information from the signal is sent to an Air Traffic Control tower, or a Radar Approach Control (RAPCON) with a digital tag that describes the location, heading, and speed at which the aircraft is moving. The overall operation of the ASR-11 is similar to that of the ASR-9, with relatively few differences between the two radar systems. There are only two main areas where the ASR-11 has an advantage over the ASR-9, with it also having some disadvantages due to its weather capability.

Advantages

The first advantage the ASR-11 offers is the use of a low peak-power, solid state transmitter with pulse compression technology, replacing the ASR-9's high peak-power, short pulse power system. This gives the radar the ability to provide the same amount of energy to a target at long range while making the radar less sensitive at shorter ranges. Any aircraft that comes closer than six nautical miles from the radar cannot be located with the long range pulse system built into the ASR-11. Installing additional radar equipment to the same antenna is required for close range location and weather detection. The second advantage of using an ASR-11 is the radar's ability to utilize a pulse sequence diversity. This gives the radar system the capability to limit processing dwells to a small number of pulses. This feature becomes most important when monitoring air traffic is the primary use of the radar. Reducing the number of pulses sent out by the radar system also has a direct effect on the Doppler resolution, resulting in a decreased ability to process live weather conditions. [2]

Disadvantages

The main disadvantage of using an ASR-11 radar system is the reduction of Doppler Radar Resolution. Like the ASR-9, the ASR-11 has an on-site, dedicated weather reflectivity processor, with six separate levels of precipitation reflectivity. The limited number of pulses sent out by the radar system has a direct effect on its ability to measure weather conditions. Unlike the ASR-9, the ASR-11 is less suited for wind shear detection, Doppler wind measurement, and precipitation reflectivity. The ASR-11 radar system will remain as is, with no further plans to upgrade the current detection system with a Weather Systems Processor (WSP.) [2]

ASR-11 during night operation ASR-11.jpg
ASR-11 during night operation

Related Research Articles

Radar Object detection system using radio waves

Radar is a detection system that uses radio waves to determine the distance (ranging), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. A radar system consists of a transmitter producing electromagnetic waves in the radio or microwaves domain, a transmitting antenna, a receiving antenna and a receiver and processor to determine properties of the objects. Radio waves from the transmitter reflect off the objects and return to the receiver, giving information about the objects' locations and speeds.

Doppler radar Type of radar equipment

A Doppler radar is a specialized radar that uses the Doppler effect to produce velocity data about objects at a distance. It does this by bouncing a microwave signal off a desired target and analyzing how the object's motion has altered the frequency of the returned signal. This variation gives direct and highly accurate measurements of the radial component of a target's velocity relative to the radar.

Weather radar Radar used to locate and monitor meteorological conditions

Weather radar, also called weather surveillance radar (WSR) and Doppler weather radar, is a type of radar used to locate precipitation, calculate its motion, and estimate its type. Modern weather radars are mostly pulse-Doppler radars, capable of detecting the motion of rain droplets in addition to the intensity of the precipitation. Both types of data can be analyzed to determine the structure of storms and their potential to cause severe weather.

The pulse repetition frequency (PRF) is the number of pulses of a repeating signal in a specific time unit. The term is used within a number of technical disciplines, notably radar.

Imaging radar

Imaging radar is an application of radar which is used to create two-dimensional images, typically of landscapes. Imaging radar provides its light to illuminate an area on the ground and take a picture at radio wavelengths. It uses an antenna and digital computer storage to record its images. In a radar image, one can see only the energy that was reflected back towards the radar antenna. The radar moves along a flight path and the area illuminated by the radar, or footprint, is moved along the surface in a swath, building the image as it does so.

History of radar Aspect of history

The history of radar started with experiments by Heinrich Hertz in the late 19th century that showed that radio waves were reflected by metallic objects. This possibility was suggested in James Clerk Maxwell's seminal work on electromagnetism. However, it was not until the early 20th century that systems able to use these principles were becoming widely available, and it was German inventor Christian Hülsmeyer who first used them to build a simple ship detection device intended to help avoid collisions in fog. True radar, such as the British Chain Home early warning system provided directional information to objects over short ranges, were developed over the next two decades.

Pulse-Doppler radar Type of radar system

A pulse-Doppler radar is a radar system that determines the range to a target using pulse-timing techniques, and uses the Doppler effect of the returned signal to determine the target object's velocity. It combines the features of pulse radars and continuous-wave radars, which were formerly separate due to the complexity of the electronics.

Passive radar systems encompass a class of radar systems that detect and track objects by processing reflections from non-cooperative sources of illumination in the environment, such as commercial broadcast and communications signals. It is a specific case of bistatic radar, the latter also including the exploitation of cooperative and non-cooperative radar transmitters.

Secondary surveillance radar Radar system used in air traffic control

Secondary surveillance radar (SSR) is a radar system used in air traffic control (ATC), that unlike primary radar systems that measure the bearing and distance of targets using the detected reflections of radio signals, relies on targets equipped with a radar transponder, that reply to each interrogation signal by transmitting encoded data such as an identity code, the aircraft's altitude and further information depending on its chosen mode. SSR is based on the military identification friend or foe (IFF) technology originally developed during World War II, therefore the two systems are still compatible. Monopulse secondary surveillance radar (MSSR), Mode S, TCAS and ADS-B are similar modern methods of secondary surveillance.

The Air Route Surveillance Radar is used by the United States Air Force and the Federal Aviation Administration to control airspace within and around the borders of the United States.

Erieye Airborne Early Warning and Control System used on a variety of aircraft platforms

The Erieye radar system is an Airborne Early Warning and Control System (AEW&C) developed by Saab Electronic Defence Systems of Sweden. It uses active electronically scanned array (AESA) technology. The Erieye is used on a variety of aircraft platforms, such as the Saab 340 and Embraer R-99. It has recently been implemented on the Bombardier Global 6000 aircraft as the GlobalEye.

Airport surveillance radar Radar system

An airport surveillance radar (ASR) is a radar system used at airports to detect and display the presence and position of aircraft in the terminal area, the airspace around airports. It is the main air traffic control system for the airspace around airports. At large airports it typically controls traffic within a radius of 60 miles (96 km) of the airport below an elevation of 25,000 feet. The sophisticated systems at large airports consist of two different radar systems, the primary and secondary surveillance radar. The primary radar typically consists of a large rotating parabolic antenna dish that sweeps a vertical fan-shaped beam of microwaves around the airspace surrounding the airport. It detects the position and range of aircraft by microwaves reflected back to the antenna from the aircraft's surface. The secondary surveillance radar consists of a second rotating antenna, often mounted on the primary antenna, which interrogates the transponders of aircraft, which transmits a radio signal back containing the aircraft's identification, barometric altitude, and an emergency status code, which is displayed on the radar screen next to the return from the primary radar.

Radar engineering details are technical details pertaining to the components of a radar and their ability to detect the return energy from moving scatterers — determining an object's position or obstruction in the environment. This includes field of view in terms of solid angle and maximum unambiguous range and velocity, as well as angular, range and velocity resolution. Radar sensors are classified by application, architecture, radar mode, platform, and propagation window.

Radar MASINT is a subdiscipline of measurement and signature intelligence (MASINT) and refers to intelligence gathering activities that bring together disparate elements that do not fit within the definitions of signals intelligence (SIGINT), imagery intelligence (IMINT), or human intelligence (HUMINT).

Moving target indication (MTI) is a mode of operation of a radar to discriminate a target against the clutter. It describes a variety of techniques used for finding moving objects, like an aircraft, and filter out unmoving ones, like hills or trees. It contrasts with the modern stationary target indication (STI) technique, which uses details of the signal to directly determine the mechanical properties of the reflecting objects and thereby find targets whether they are moving or not.

Automatic Dependent Surveillance–Broadcast Aircraft surveillance technology

Automatic Dependent Surveillance–Broadcast (ADS-B) is a surveillance technology in which an aircraft determines its position via satellite navigation or other sensors and periodically broadcasts it, enabling it to be tracked. The information can be received by air traffic control ground stations as a replacement for secondary surveillance radar, as no interrogation signal is needed from the ground. It can also be received by other aircraft to provide situational awareness and allow self-separation. ADS-B is "automatic" in that it requires no pilot or external input. It is "dependent" in that it depends on data from the aircraft's navigation system.

Terminal Doppler Weather Radar

Terminal Doppler Weather Radar (TDWR) is a Doppler weather radar system with a three-dimensional "pencil beam" used primarily for the detection of hazardous wind shear conditions, precipitation, and winds aloft on and near major airports situated in climates with great exposure to thunderstorms in the United States. As of 2011, all were in-service with 45 operational radars, some covering multiple airports in major metropolitan locations, across the United States & Puerto Rico. Several similar weather radars have also been sold to other countries such as China. Funded by the United States Federal Aviation Administration (FAA), TDWR technology was developed in the early 1990s at Lincoln Laboratory, part of the Massachusetts Institute of Technology, to assist air traffic controllers by providing real-time wind shear detection and high-resolution precipitation data.

Primary radar

A Primary radar is a conventional radar sensor that illuminates a large portion of space with an electromagnetic wave and receives back the reflected waves from targets within that space. The term thus refers to a radar system used to detect and localize potentially non-cooperative targets. It is specific to the field of air traffic control where it is opposed to the secondary radar which receives additional information from the target's transponder.

ASR-9

ASR-9 is an airport surveillance radar system admitted into the National Airspace System (NAS), to be utilized by the Federal Aviation Administration to monitor civilian and commercial air traffic within the United States. Developed by Westinghouse, ASR-9 was the first radar system to display air traffic, and weather conditions simultaneously. The ASR-9 is mainly intended to monitor and track aircraft below 25,000 ft and within forty to sixty nautical miles from the airport of operation. The ASR radar systems were widely used where an advanced radar system was needed, consisting of 135 different ASR-9 operating locations around the U.S. The FAA is currently working to upgrade the remaining ASR-9 radar sites to a modernized digital version known as the ASR-11.

References

  1. 1 2 3 4 5 "Airport Surveillance Radar (ASR-11)". Federal Aviation Administration. Retrieved 26 April 2017.
  2. 1 2 3 4 5 6 7 Weber, Mark E. (12 April 2000). "FAA SURVEILLANCE RADAR DATA" (PDF). Massachusetts Institute of Technology. Retrieved 27 April 2017.
  3. Airport Surveillance Radar Model 11. Department of Transportation/Federal Aviation Administration. February 1998. pp. 1–10.
  4. WOLFF, CHRISTIAN. "Register of historical and current radar sets – ASR-11 entry". radartutorial.eu. Retrieved 11 October 2017.