Radio

radio communicationradio communicationswireless
Weather radar – A Doppler radar which maps weather systems and measures wind speeds by reflection of microwaves from raindrops. Phased-array radar – a radar set that uses a phased array, a computer-controlled antenna that can steer the radar beam quickly to point in different directions without moving the antenna. Phased-array radars were developed by the military to track fast-moving missiles and aircraft. They are widely used in military equipment and are now spreading to civilian applications. Synthetic aperture radar(SAR) – a specialized airborne radar set that produces a high-resolution map of ground terrain.

Rockwell B-1 Lancer

B-1 LancerB-1B LancerB-1B
The Lancer's offensive avionics include the Westinghouse (now Northrop Grumman) AN/APQ-164 forward-looking offensive passive electronically scanned array radar set with electronic beam steering (and a fixed antenna pointed downward for reduced radar observability), synthetic aperture radar, ground moving target indication (GMTI), and terrain-following radar modes, Doppler navigation, radar altimeter, and an inertial navigation suite. The B-1B Block D upgrade added a Global Positioning System (GPS) receiver beginning in 1995.

List of radars

Chinese radarsType 1007AN/APS-20
AN/APY-8 synthetic aperture radar by Sandia National Laboratories for General Atomics MQ-9 Reaper nicknamed as lynx. AN/APY-9 ultra high frequency surveillance radar under development by Lockheed Martin for E-2D. AN/APY-10 A much-modernized evolutionary development of the Raytheon APS-149 maritime surveillance radar by Raytheon for P-8 Poseidon. AN/APY-11 US designation for Elta EL/M-2022 maritime, littoral and surveillance radar jointly produced by ITT Exelis to support the United States Coast Guard’s Long Range Surveillance HC-130J aircraft. AN/APY-12 Phoenix Eye synthetic aperture radar surveillance radar developed by Lockheed Martin. AN/AWG-3 for the F8U-2. AN/AWG-4 for the F8U-2N.

Raytheon Sentinel

Sentinel R1ASTORRaytheon Sentinel R.1
The main radar is a Raytheon dual-mode synthetic aperture radar / moving target indication (SAR/MTI) radar known as Sentinel Dual Mode Radar Sensor (DMRS). It uses AESA active electronically scanned array technology. Raytheon claim it could be modified to match the maritime surveillance capability of the cancelled Nimrod MRA4, and the ground stations could be adapted to receive data from Watchkeeper, MQ-9 Reaper and the future Scavenger programme.

Titan (moon)

TitanSaturn's moon Titanatmosphere
The Cassini spacecraft used infrared instruments, radar altimetry and synthetic aperture radar (SAR) imaging to map portions of Titan during its close fly-bys. The first images revealed a diverse geology, with both rough and smooth areas. There are features that may be volcanic in origin, disgorging water mixed with ammonia onto the surface. There is also evidence that Titan's ice shell may be substantially rigid, which would suggest little geologic activity. There are also streaky features, some of them hundreds of kilometers in length, that appear to be caused by windblown particles.

Signal processing

signal analysissignalsignal processor
Analog signal processing is for signals that have not been digitized, as in legacy radio, telephone, radar, and television systems. This involves linear electronic circuits as well as non-linear ones. The former are, for instance, passive filters, active filters, additive mixers, integrators and delay lines. Non-linear circuits include compandors, multiplicators (frequency mixers and voltage-controlled amplifiers), voltage-controlled filters, voltage-controlled oscillators and phase-locked loops. Continuous-time signal processing is for signals that vary with the change of continuous domain (without considering some individual interrupted points).

Antenna aperture

apertureaperture efficiencyeffective area
In electromagnetics and antenna theory, antenna aperture, effective area, or receiving cross section, is a measure of how effective an antenna is at receiving the power of electromagnetic radiation (such as radio waves). The aperture is defined as the area, oriented perpendicular to the direction of an incoming electromagnetic wave, which would intercept the same amount of power from that wave as is produced by the antenna receiving it. At any point \mathbf{x}, a beam of electromagnetic radiation has an irradiance or power flux density which is the amount of power passing through a unit area of one square meter.

Signal-to-noise ratio

signal to noise ratioSNRsignal-to-noise
Signal-to-noise ratio (abbreviated SNR or S/N) is a measure used in science and engineering that compares the level of a desired signal to the level of background noise. SNR is defined as the ratio of signal power to the noise power, often expressed in decibels. A ratio higher than 1:1 (greater than 0 dB) indicates more signal than noise.

Diffraction

diffraction patterndiffractdiffracted
Diffraction refers to various phenomena that occur when a wave encounters an obstacle or a slit. It is defined as the bending of waves around the corners of an obstacle or through an aperture into the region of geometrical shadow of the obstacle/aperture. The diffracting object or aperture effectively becomes a secondary source of the propagating wave. Italian scientist Francesco Maria Grimaldi coined the word "diffraction" and was the first to record accurate observations of the phenomenon in 1660. In classical physics, the diffraction phenomenon is described by the Huygens–Fresnel principle that treats each point in a propagating wave-front as a collection of individual spherical wavelets.

Super-resolution imaging

super-resolutionsuperresolutionOptical superresolution
In some radar and sonar imaging applications (e.g. magnetic resonance imaging (MRI), high-resolution computed tomography), subspace decomposition-based methods (e.g. MUSIC ) and compressed sensing-based algorithms (e.g., SAMV ) are employed to achieve SR over standard periodogram algorithm. Super-resolution imaging techniques are used in general image processing and in super-resolution microscopy.

Multistatic radar

multistaticmultistatic operation
A further subset of multistatic radar with roots in communications is that of MIMO radar. Since multistatic radar may contain both monostatic and bistatic components, the advantages and disadvantages of each radar arrangement will also apply to multistatic systems. A system with N transmitters and M receivers will contain NM of these component pairs, each of which may involve a differing bistatic angle and target radar cross section.

Chirp

chirp functionChirp modulationchirp signal
Continuous-wave radar. Dispersion (optics). Pulse compression. Radio propagation. Online Chirp Tone Generator (wav file output). CHIRP Sonar on FishFinder.

Cathode-ray tube

cathode ray tubeCRTcathode ray tubes
The images may represent electrical waveforms (oscilloscope), pictures (television, computer monitor), radar targets, or other phenomena. CRTs have also been used as memory devices, in which case the visible light emitted from the fluorescent material (if any) is not intended to have significant meaning to a visual observer (though the visible pattern on the tube face may cryptically represent the stored data). In television sets and computer monitors, the entire front area of the tube is scanned repetitively and systematically in a fixed pattern called a raster.

Beechcraft L-23 Seminole

U-8 SeminoleL-23 SeminoleBeechcraft U-8D Seminole
These aircraft featured belly-mounted radar, either AN/APS-85 in a large pod or AN/APQ-86 in a long narrow pod mounted on brackets with a modified nose as well. Also in 1958 Beechcraft began to develop a variant with a larger cabin at the request of the US Army. The L-23F that emerged had the same wings and tail but up to ten people could now fit in the longer, wider and higher cabin compared to only five in earlier L-23s. Beechcraft gave the type the in-house designation of Model 65 and developed it as a civilian aircraft as well, christening it the "Queen Air".

Lockheed Martin F-22 Raptor

F-22 RaptorF-22F-22A Raptor
Radar emissions can also be focused to overload enemy sensors as an electronic-attack capability. The radar changes frequencies more than 1,000 times per second to lower interception probability and has an estimated range of 125 - 150 mi against a 1 m2 target and 250 mi or more in narrow beams. F-22s from Lot 5 and on are equipped with the APG-77(V)1, which provides air-to-ground functionality through synthetic aperture radar mapping and various strike modes. Radar and Communication/Navigation/Identification (CNI) information are processed by two Hughes Common Integrated Processor (CIP)s, each capable of processing up to 10.5 billion instructions per second.

Interferometry

interferometerinterferometricoptical interferometry
Interferometric synthetic aperture radar (InSAR) is a radar technique used in geodesy and remote sensing. Satellite synthetic aperture radar images of a geographic feature are taken on separate days, and changes that have taken place between radar images taken on the separate days are recorded as fringes similar to those obtained in holographic interferometry. The technique can monitor centimeter- to millimeter-scale deformation resulting from earthquakes, volcanoes and landslides, and also has uses in structural engineering, in particular for the monitoring of subsidence and structural stability. Fig 20 shows Kilauea, an active volcano in Hawaii.

AN/APG-77

APG-77APG-77 radar
(Dead link[3]) More than 100 APG-77 AESA radars have been produced to date by Northrop Grumman, and much of the technology developed for the APG-77 is being used in the APG-81 radar for the F-35 Lightning II. The APG-77v1 was installed on F-22 Raptors from Lot 5 and on. This provided full air-to-ground functionality (high-resolution synthetic aperture radar mapping, ground moving target indication and track (GMTI/GMTT), automatic cueing and recognition, combat identification, and many other advanced features). * Phased array. Active electronically scanned array. AN/APG-77 radar technology explained. f22fighter.com: AN/APG-77.

Radar configurations and types

search radarsearchTarget acquisition radar
Through-the-wall radars can be made with Ultra Wideband impulse radar, micro-Doppler radar, and synthetic aperture radar (SAR). * Radar gun, for traffic policing and as used in some sports 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. * Wearable radar and miniature radar systems are used as electric seeing aids for the visually impaired, as well as early warning collision detection and situational awareness. Bistatic radar. Continuous-wave radar. Doppler radar. Fm-cw radar. Monopulse radar. Passive radar. Planar array radar. Pulse-doppler. Synthetic aperture radar.

AN/APG-68

APG-6868
The AN/APG-68 radar is a long range (up to 296 km) Pulse-doppler radar designed by Westinghouse (now Northrop Grumman) to replace AN/APG-66 radar in the F-16 Fighting Falcon. The AN/APG-68(V)8 and earlier radar system consists of the following line-replaceable units: The AN/APG-68(V)9 radar system consists of the following line-replaceable units: The AN/APG-68(V)9 radar is the latest development. Besides the increase in scan range compared to the previous version, it has a Synthetic aperture radar (SAR) capability.

AN/ZPY-1

STARLite RadarAN/ZPY-1 STARLite Radar
The Northrop Grumman AN/ZPY-1 STARLite Small Tactical Radar - Lightweight is a small, lightweight synthetic aperture radar/GMTI radar used in tactical operations. The radar is under contract to the U.S. Army Communications and Electronics Command for its ERMP General Atomics MQ-1C Gray Eagle Unmanned Aerial System and is manufactured by Northrop Grumman. STARLite weighs 65 lb., occupies 1.2 cuft, and requires less than 750W of power. The Army began to take delivery of the system in 2010. Also in 2010 the system was ready for deployment to the battlefield. From the first orders in 2008 to October 2012, Northrop Grumman delivered half of the 174 radars ordered.

Microwave imaging

Microwave imagerymicrowave satellite imagerymicrowave examination
Synthetic aperture radar (SAR), ground-penetrating radar (GPR), and frequency-wave number migration algorithm are some of the most popular qualitative microwave imaging methods [1]. In general, a microwave imaging system is made up of hardware and software components. The hardware collects data from the sample under test. A transmitting antenna sends EM waves towards the sample under test (e.g., human body for medical imaging). If the sample is made of only homogeneous material and is of infinite size, theoretically no EM wave will be reflected.

Space-based radar

military orbital radarSatellite radarSpace Based Radar
German SAR-Lupe. Russian Kondor. Japanese Information Gathering Satellite. Indian RISAT. a synthetic aperture radar (SAR) for high-resolution imaging. a radar altimeter, to measure the ocean topography. a wind scatterometer to measure wind speed and direction. RISAT-1 (SAR,ISRO India, 2012). RORSAT (SAR, Soviet Union, 1967-1988). Seasat (SAR, altimeter, scatterometer, US, 1978). RADARSAT-1 (SAR, Canadian, 1995). RADARSAT-2 (SAR, Canadian, 2007). SAR Lupe 1-5 (SAR satellites of the German Air Force). TerraSAR-X (SAR Germany, 2007). TanDEM-X (SAR Germany, 2010). COSMO-SkyMed (SAR, Italy, 2007). SAOCOM (L band SAR constellation, Argentina). TecSAR (SAR, Israeli, 2008).

Aerial Common Sensor

Common SensorLockheed Martin Aerial Common Sensor
The aircraft would have been able to detect troop movements, intercept enemy communications and radar transmissions, and communicate with other aircraft. It would have had synthetic aperture radar, electro-optical and infrared detection instrumentation. The program was cancelled on January 12, 2006. The Army intended to acquire 34 units, with a further 19 going to the Navy. The initial contract, awarded on August 3, 2004, was valued at $79 million, but total contract value through 2010 would have been $879 million. Beyond that, the total program cost was to reach $7 billion, with only 20–30% going to the platform vendor.

Remote sensing (archaeology)

remote sensingArchaeological imageryArcheological imagery
Microwave Radar. Satellite Imaging. Laser altimeters or light detection and ranging (LIDAR). Synthetic Aperture Radar (SAR). INSAR - Interferometric SAR.

Mapping of Venus

The use of Interferometric synthetic aperture radar (InSAR) for mapping Venus has been proposed. Instead of surface mapping by SAR as done by previous missions, InSAR would measure the terrain motions during events such as earthquakes or tectonic movements. By performing the radar mapping at two separated times (before and after an event) over the same area, the terrain changes could be revealed. From the Magellan mission data, 3 types of images have been produced: (1) SAR images, (2) topographic images and (3) meter scale slope image. SAR images provide the highest resolution data set. Microwave are used to penetrate the thick atmosphere and map the surface of Venus.