Fiber Tractography

Fiber tractography is the neurological procedure to study neuron axons tracts in a human brain using magnetic resonance imaging techniques and computer-based image analysis. A fiber tractography test can be shown in either two dimensional or three dimensional images. In the cerebrum the myelinated neuron axons of the cerebral cortex cluster together to form fibers, and these get together to form thick bundles or tracts called fasciculus which connect one lobe or region of the cortex with another. Thus, there is a complicated three-dimensional network formed by short connections among different cortical and subcortical regions.


The existence of these bundles has been revealed by histochemistry and biological techniques on post-mortem specimens. Brain tracts are not identifiable by direct exam, CT, or MRI scans. This difficulty explains the paucity of their description in neuroanatomy atlases and the poor understanding of their functions. The magnetic resonance imaging (MRI) sequences used look at the symmetry of brain water diffusion. Bundles of fiber tracts make the water diffuse asymmetrically in a tensor, the major axis parallel to the direction of the fibers. The asymmetry here is called anisotropy. There is a direct relationship between the number of fibers and the degree of anisotropy.

Inferior Longitudinal fasciculus

The inferior longitudinal fasciculus is a bundle of myelinated axons which connects the occipital lobe with the temporal lobe in each hemisphere of the cerebrum. It runs parallel to the lateral walls of the inferior and posterior cornua of the lateral ventricle. Some anatomists call this bundle of fibers "occipitotemporal projection system." The function of the inferior longitudinal fasciculus is highly involved in visual memory as a 47-year-old woman with visual memory disturbance, demonstrated by the Wechsler Memory Scale-Revised, suffered from brain tumor in the right temporal lobe that disrupted the fibers bundle of the ILF. Disruption of white matter integrity in the inferior longitudinal fasciculus in teenagers with schizophrenia was also revealed by fiber tractography.

Superior Longitudinal Fasciculus

The superior longitudinal fasciculus is a thick and long bundle of myelinated axons which links the frontal lobe to the occipital, and part of the parietal and temporal lobes of each cerebral hemisphere. The association fibers that constitute the superior longitudinal fasciculus are bi-directional, which means that some axons originate in cortical neurons of the frontal lobe, while others in neurons located in the occipital and back regions of the temporal and parietal lobes, integrating motor and decision-making centers with visual and sensory ones. The superior longitudinal fasciculus sweeps along the superior margin of the claustrum in a great arc.

The superior longitudinal fasciculus consists of three distinct components: 1) SLF I is the dorsal component and originates in the superior and medial parietal cortex, passes around the cingulate sulcus and terminates in the dorsal and medial cortex of the frontal lobe and in the supplementary motor cortex; 2) SLF II is the major component of SLF and originates in the caudal-inferior parietal cortex and occipital lobe, ending in the dorsolateral prefrontal cortex (Brodmann 6, 8 and 46); 3) SLF III is the ventral component which begins in the supramarginal gyrus (rostral portion of the inferior parietal lobe) and ends in the ventral premotor and prefrontal cortex (Brodmann 6, 44, and 46).

Occipitofrontal Fasciculus

The occipitofrontal fasciculus is a bundle of association fibers which connects the frontal lobe with the occipital lobe of each brain hemisphere. The myelanated fibers that make up the occipitofrontal fasciculus radiate in a fan-like manner, extending into occipital and temporal lobes, lateral to the posterior and inferior cornua.

Uncinate Fasciculus

The uncinate fasciculus is a band of cortical neuron myelinated axons in the human brain that connects the inferior part of the frontal lobe with the anterior temporal lobe and parts of the limbic system, such as the hippocampus and amygdala that are located in this lobe. It is the last fasciculus to mature in the brain (beyond the age of 30). The average length of the uncinate fasciculus is 45 mm. It has three parts: a frontal extension, an intermediary segment, and a temporal segment. The uncinate fasciculus is a hook-shaped tract of fibers which go from the inferior frontal gyrus and the lower surfaces of the frontal lobe to the forward portions of the temporal lobe.

Uncinate Fasciculus and Schizophrenia

Evidence suggests that a disruption in connectivity between different brain regions, especially between the frontal and temporal lobes, linked up by the uncinate fasciculus, may partly explain some of the primary symptoms of schizophrenia. This idea, first proposed by Wernicke in 1906, posits a disturbance in functional connectivity between the frontal and temporal cortices in schizophrenia that might have as its basis a disruption in the white matter tracts connecting them. Abnormalities within the fiber bundles of the uncinate fasciculus associate with social anxiety, Alzheimer's disease, bipolar disorder, and depression in the elderly that had first had it in adolescence or early adulthood. Such abnormalities also link to schizophrenia.

Arcuate Fasciculus

The arcuate fasciculus is the thick bundle of myelinated axons which links the Broca's area to the Wernicke's area, which are the two language centers of the brain. Thus, the arcuate fasciculus fibers go from the inferior frontal gyrus of the frontal lobe to the back area of the superior temporal gyrus and a small area in the parietal lobe and vice versa. The function of this bundle of nerve fibers is to articulate or coordinate the motor verbal function of the Broca's area and the semantic and syntactic comprehension of the Wernicke's area. Damage to the arcuate fasciculus can cause a form of aphasia known as conduction aphasia, where auditory comprehension and speech articulation are preserved, but people find it difficult to repeat heard speech.

Hypoglossal Nerve (CN XII)

Also known as CN XII, the hypoglossal nerve is the twelfth of twelve paired cranial nerves. The CN XII innervates the muscles of the tongue. It is a somatomotor nerve whose fibers originate in the hypoglossal nucleus neurons situated in the dorsal medulla oblongata of the brainstem. The hypoglossal nucleus nerve cells send axons that exit as rootlets that emerge in the ventrolateral sulcus of the medulla between the olive and pyramid. Then, the rootlets come together to make up the hypoglossal nerve, exiting the cranium through the hypoglossal canal.

As the CN XII comes out of the hypoglossal canal, it gives off a small meningeal branch, picking up a branch from the anterior ramus of C1. Then, it spirals behind the vagus nerve and passes between the internal carotid artery and internal jugular vein lying on the carotid sheath. After passing deep to the posterior belly of the digastric muscle, the hypoglossal nerve passes to the submandibular region to enter the tongue.

Accessory Nerve (CN XI)

The accessory nerve is the eleventh of the twelve paired cranial nerves. It is also known as cranial nerve XI (CN XI). It is called accessory since it receives an accessory root from the upper part of the spinal cord as it emerges from the skull. The spinal fibers of the accessory nerve provides motor innervation from the central nervous system to two muscles of the neck: the sternocleidomastoid muscle and the trapezius muscle. The cranial part rapidly joins the vagus nerve and serves the same function as other vagal nerve fibers.

Although it originates in the central nervous system, the spinal accessory nerve begins outside the skull rather than inside, with its axonal fibers arising from neurons located in the upper spinal cord, near the medulla oblongata. These fibers coalesce to form the spinal accessory nerve, which enters the skull through the foramen magnum, the large opening at the base of the skull. Then the nerve runs along the inner wall of the skull towards the jugular foramen, through which it exits the skull together with the glossopharyngeal (CN IX) and vagus nerves (CN X). Thus, the accessory nerve is notable for being the only cranial nerve to both enter and exit the skull.

Vagus Nerve (CN X)

Also known as cranial nerve X (CN X), the vagus nerve is one of the twelve paired cranial nerves. Consisting of both motor and sensory fibers, the vagus nerve emerges from the medulla oblongata in the groove between the olive and the inferior peduncle. Then, it projects through the jugular foramen, passing into the carotid sheath between the internal carotid artery and the internal jugular vein down below the head, to the neck, chest and abdomen, where it contributes to the innervation of the viscera. Besides output to the various organs in the body the vagus nerve conveys sensory information about the state of the body's organs to the central nervous system. Between 80 and 90% of the fibers that make up the vagus nerve are sensory nerves communicating the state of the viscera to the brain.

The vagus nerve also supplies motor parasympathetic fibers to all the organs except the suprarenal glands, from the neck down to the second segment of the transverse colon. This means that the vagus nerve is responsible for such varied tasks as heart rate, gastrointestinal peristalsis, sweating, and quite a few muscle movements in the mouth, including speech (via the recurrent laryngeal nerve) and keeping the larynx open for breathing, via action of the posterior cricoarytenoid muscle, the only abductor of the vocal folds. It also has some afferent fibers that innervate the inner (canal) portion of the outer ear, via the Auricular branch, which also known as Alderman's nerve, and part of the meninges. This explains why a person may cough when tickled on their ear (such as when trying to remove ear wax with a cotton swab).

Glossopharyngeal Nerve (CN IX)

The Glossopharyngeal nerve is the ninth cranial nerve (CN IX). It consists of both motor and sensory fibers and emerges from the brain stem as the most rostral of a series of nerve rootlets that protrude between the olive and inferior cerebellar peduncle. The CN IX supplies the tongue, throat, and one of the salivary glands (the parotid gland). Problems with the glossopharyngeal nerve result in trouble taste and swallowing. Compared with other lower cranial nerves, the glossopharyngeal nerve (GPhN) is well hidden within the jugular foramen, at the infratemporal fossa, and in the deep layers of the neck. "Glosso-" comes from the Greek "glossa", the tongue and "pharynx" is the Greek for throat. So the glossopharyngeal nerve is the nerve that serves the tongue and throat.

Glossopharyngeal Nerve Overview.
 

The glossopharyngeal nerve consists of five components with distinct functions: Brancial motor (special visceral efferent) - supplies the stylopharyngeus muscle. Visceral motor (general visceral efferent) provides parasympathetic innervation of the smooth muscle and glands of the pharynx, larynx, and viscera of the thorax and abdomen. Visceral sensory (general visceral afferent) carries visceral sensory information from the carotid sinus and body. General sensory (general somatic afferent) provides general sensory information from the skin of the external ear, internal surface of the tympanic membrane, upper pharynx, and the posterior one-third of the tongue. Special sensory (special afferent) provides taste sensation from the posterior one-third of the tongue.

Glossopharyngeal Nerve (Video)

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Vestibulocochlear Nerve (CN VIII)

The vestibulocochlear nerve, also known as cranial nerve VIII (CN VIII), is composed of sensory fibers which carry two types of sensory information to the brain: balance and hearing. It is the 8th of the twelve cranial nerves. The vestibulocochlear nerve is made up of bipolar neuron axons and splits into two branches: 1) the vestibular nerve, which carryies sensory information about balance; 2) the cochlear nerve, carrying information about hearing. The CN VIII enters the brain stem at the junction of the pons and medulla, lateral to the facial nerve. The auditory component of the eighth nerve terminates in a sensory nucleus called the cochlear nucleus, which is located at the junction of the pons and medulla. The vestibular part of the CN VIII ends in the vestibular nuclear complex located in the floor of the fourth ventricle.

Facial Nerve (CN VII)

The facial nerve is the seventh cranial nerve (CN VII). It is a paired nerve with both motor and sensory functions, providing motor innervation to the muscles of facial expression and sensory information of taste sensations from the anterior two-thirds of the tongue and oral cavity. It also supplies preganglionic parasympathetic fibers to several head and neck ganglia. The CN VII originates in the facial nerve nucleus in the pons while the sensory part of it arises from the nervus intermedius. It emerges from the brainstem between the pons and the medulla.

The motor fibers of the facial nerve innervate all the facial musculature; the principal muscles are the frontalis, orbicularis oculi, buccinator, orbicularis oris, platysma, the posterior belly of the digastric, and the stapedius muscle. The sensory fibers has the following components: 1) taste to the anterior two-thirds of the tongue; 2) secretory and vasomotor fibers to the lacrimal gland, the mucous membranes of the nose and mouth, and the submandibular and sublingual salivary glands; 3) cutaneous sensory impulses from the external auditory meatus and region back of the ear.

Abducens Nerve (CN VI)

The abducens nerve, also known as cranial nerve VI (CN VI), is one of the twelve paired cranial nerves. It is made up of motor axons and innervate the lateral rectus muscle of the eyeball. The CN VI originates in the abducens nucleus which is located in the pons, on the floor of the fourth ventricle. Motor axons leaving the abducens nucleus run ventrally and caudally through the pons, passing lateral to the corticospinal tract, which runs longitudinally through the pons at this level. Then, the abducens nerve leaves the brainstem at the junction of the pons and the medulla, medial to the facial nerve. In order to reach the eye, it runs upward, superiorly, and then bends forward, anteriorly.

Trigeminal Nerve (CN V)

The trigeminal nerve, also known as cranial nerve V (CN V), is both a sensory and motor nerve which emerges from the side of the pons, near its upper border, by a large sensory and a small motor root. The sensory fibers of CN V carries sensory information of the head and face, and its motor fibers innervate (contract) the mastication muscles (biting and chewing). The cranial nerve V originates in the trigeminal nuclei located in the brainstem (pons, midbrain, medulla).

The name "trigeminal" means "three-branched", deriving from the fact that this paired nerve, one on each side of the pons, has three major branches: the ophthalmic nerve (CN V1), the maxillary nerve (CN V2), and the mandibular nerve (CN V3). The ophthalmic and maxillary nerves are purely sensory. The mandibular nerve has both sensory and motor functions. The three branches converge on the trigeminal ganglion, that is located within Meckel's cave, and contains the cell bodies of incoming sensory nerve fibers.

Trochlear Nerve (CN IV)

The trochlear nerve, which is also called cranial nerve IV (CN IV), is the motor nerve which innervates the superior oblique muscle of the eyeball. The trochlear nerve is composed of axons of neurons situated in the trochlear nucleus, in the ventral part of the brainstem.

In terms of the number of axons that make it up, the cranial nerve IV is the smallest nerve of the twelve cranial nerves, but has the greatest intracranial length. Along with the optic nerve, it is the only cranial nerve that decussates (crosses to the other side) before innervating the superior oblique muscle. Trochlear nerve is also the only cranial nerve that exits from the dorsal aspect of the brainstem.

Oculomotor Nerve (CN III)

The oculomotor nerve, or cranial nerve III, is the third of twelve paired cranial nerves. It is responsible of eyelid and eyeball movement. The cranial nerve III (CN III) originates in the oculomotor nucleus situated in the superior colliculus of the midbrain.

When the oculomotor nerve emerges from the brain, it is invested with a sheath of pia mater, and enclosed in a prolongation from the arachnoid. It passes between the superior cerebellar (below) and posterior cerebral arteries (above), and then pierces the dura mater anterior and lateral to the posterior clinoid process, passing between the free and attached borders of the tentorium cerebelli.

The muscles that the CN III controls are the striated muscle in levator palpebrae superioris of the eyelid and all extraocular muscles of the eyeball, except for the superior oblique muscle and the lateral rectus muscle.

Olfactory Nerve (CN I)

The olfactory nerve is one of the twelve cranial nerves that emerge directly from the base of the brain. Also called cranial nerve I (CN I), it is the first and shortest of the twelve. The olfactory nerve is formed by axons from specialized olfactory receptor neurons which are situated in the olfactory mucosa of the upper parts of the nasal cavity. These same nerve cells also projects axons that extend from the olfactory epithelium to the olfactory bulb, passing through the many openings of the cribriform plate of the ethmoid bone.

The nerve cells in the nasal cavity are chemosensitive and respond to chemical signals which are converted to electrical impulses that are carried up through the cranial nerve I to the olfactory bulb. The axons that make up the olfactory nerve continually regenerate throughout life as they project towards the olfactory bulb.

CAPTOR Radar

The Euroradar CAPTOR, also known as ECR-90, is a multi-mode pulse-doppler radar used in the Eurofighter Typhoon aircraft. The radar was developed from the BAE Systems Blue Vixen, which had been designed for the BAE Sea Harrier, by Euroradar. The ECR-90 was renamed CAPTOR as the project passed the production contract milestone. The CAPTOR detects, identifies, prioritizes and engages targets beyond the effective range of the enemy weapon systems while remaining resistant to severe electronic jamming. It features active electronic beam steering with nearly instantaneously repositioning of radar beam which enables faster detection and increased tracking ranges. The CAPTOR enables the Eurofighter to operates in complex scenarios with high agile airborne and ground-based threats in combination with assimetric warfare.

AN/SPS-73(V)12

The AN/SPS-73(V)12 is a two-dimensional, surface-search/navigation radar. It provides contact range, bearing information, and improved signal processing and automatic target detection capability. The radar has its own display indicator, which is capable of displaying radar contacts from the AN/SPS-73 radar or other shipboard radars. The AN/SPS-73's surface-search function provides short-range detection and surveillance of surface units and low-flying air units, while the AN/SPS-73's navigation function enables quick and accurate determination of ownship position relative to nearby vessels and navigational hazards. The AN/SPS-73 radar video is displayed on the ship control console in the Pilot House to provide an alternate source of navigation data to the Officer of the Deck. Radar triggers and antenna bearings are used to properly display the Furuno radar video data on the ship control console.

AN/SPS-10B

The AN/SPS-10B was a medium range, C-band, surface warning radar with a limited air capability. In the Canadian Forces, this type was used in pre-DELEX steamers and training facilities. The AN/SPS-10B was used for the detection, ranging and tracking of surface contacts and to a limited extent, air contacts as well. Range and bearing information was passed to a PPI type display. This radar type had the potential to be used with IFF/SIF equipment so the SPS-10 was originally fitted with a built in beacon. The RCN never used this feature, so it was disabled.

Specifications for the AN/SPS-10B

Type: C-band warning radar
Frequency: 5450 Mcs variable to 5825 Mcs
Wavelength: 5 cm
Peak power output: short pulse = 190 kw; long pulse = 280 kw
Pulse Width: short range pulse - .25 microsecond; long range pulse - 1.3 microsecond PRR  625; variable to 650
Receiver IF: 30 Mcs
Antenna rotation: 15 rpm fixed
Beamwidth: vertical, 12 to 16 degrees; horizontal 1.5 degrees
Resolution: on short range, 50 yds; on long range, 275 yds
For Bearing: less than 1 degree of error

AN/SPA-4 Range-Azimuth Indicator

The AN/SPA-4 was a self-contained range-azimuth indicator which was designed for operation with any naval search radar system having a pulse repetition frequency between 140 and 3,000 pps. This indicator was capable of receiving radar information from one of eight different radar systems as selected by a front panel control. This feature was not used in HMCS HAIDA but ships of succeeding classes did use it. That switch controlled a radar switchboard called the SB-440. Position 1 selected the SPS-10, 2 for SPS-12 and 3 for Sperry Mk2. On HAIDA there was an externally mounted selector switch that was used to select the radar input source. The AN/SPA-4 utilized a remote PPI type indicator using a 10 inch, flat CRT.

The AN/SPA-4 determined the azimuth by means of a mechanical cursor coupled to an electronic cursor; jointly they were accurate to within one degree. Azimuth information was also indicated by a mechanical counter when the cursor was moved. The SPA-4 had also the capability of transmitting electrically, the bearing and range information to other systems such as fire control or directly to a projector on the plot table. That would cut down on verbal communication.

Specifications for the AN/SPA-4 Indicator

Type: range-azimuth radar indicator
Vintage: September 1954
Range selection: 1.5 to 300 miles continuous using a centered PPI and limited by the pulse rate of radar set that it was connected to.
Weight: 378 pounds
Dimensions: 38" H x 19" W x 21" D
Power requirements: 120 VAC, 60 Hz at 10 amps
Contractor: RCA Victor Company, Montreal P.Q.
Contract number: FE 113375, A/T 2-P-1-1877

Sperry 127E

Sperry 127E was a solid state navigation radar which utilized integrated circuit (IC) technology and was first fitted aboard DDH 280 class. It was fitted with a 12 inch CRT and was designed on the precepts of the Radio Law, Safety Agreement of Life at Sea (SOLAS), the American FCC standards and the British DTI standards.

Specifications for the Sperry 127E

Type: naval navigation radar
Peak power: 25 kilowatts
Operating frequency: 9410 Mhz +\- 30 MHz
Range: 120 miles
Pulse length: 0.05 to 1.2 microseconds depending on range
Pulse repetition rate: 500 to 4000 pulses per second depending on range
Scanner rotation: 30 rpm for 1/4 to 6 mile scales; 15 rpm for 12 to 120 mile scales
Dimensions and weights: indicator, 27"D x 20"W x 51"H , 350 lbs; scanner, 20"L x 50"W x 49.5"H, 300 lbs; Xcvr, 26.5"D x 22"W x 17"H, 190 lbs; M-G Set, 36"L x 15"W x 12"D, 330 lbs; Antenna, 7 foot end fed, slotted array, waveguide type
Power requirements: 115 VAC 60 Hz, 600 VA
Circa: 1975- 76

Sperry Marine Radar MK 2

The Sperry Marine Radar MK 2 was a medium range, surface search radar which was designated High Definition Warning Surface (HDWS) set. From the early 1950's, until well into the 1970's, almost every ship in the Royal Canadian Navy was fitted with the Sperry Mk 2. Although its primary use was to locate other ships, helicopters, navigation aids and shorelines, it was very effective in detecting submarine periscopes. The Sperry MK 2 was fitted aboard HAIDA. After life expiry, the Mk 2 was replaced by the Sperry Mk 127E solid state radar.

Specifications for the Sperry Marine Radar MK2

Type: naval surface search radar
Vintage: May 1953
Operating frequency: 9375 Mcs +\- 45 Mcs
Peak power: 30 kilowatts
Pulse length: 0.25 microseconds
Pulse repetition rate: 1000 pulses per second
Scanner rotation  15 rpm
Beam Width: horizontal, 2 degrees; vertical, 17 degrees
Range markers: fixed 0.5, 2, and 5 mile intervals +/- 1%; variable, 0.3 to 20 miles +/- 2%
Range scales: 1, 2, 6, 15 and 30 miles
Resolution: range, 80 yards; bearing, 2 degrees
Indicator CRT size: 12 inch diameter
Power requirements: 115 VAC 60 Hz, 1000 watts
Dimensions and Weights: indicator, 27"D x 20"W x 51"H , 350 lbs; scanner, 20"L x 50"W x 49.5"H, 300 lbs; Tx/Rx, 26.5"D x 22"W x 17"H, 190 lbs; M-G Set, 36"L x 15"W x 12"D , 330 lbs
Contractor: Sperry Gyroscope, Great Neck, N.Y

4356M Bottle Transmitter

The 4356M bottle transmitter (B.T.) did not emit any radio frequencies. This device was used to provide transmission to a group of repeater motors, such as those in a radar installation, or to step up the number of repeaters that can be controlled from a gyro-compass where it is inconvenient to use a multiple transmitter or transmitter panel. They were also used extensively where it was desired to use Admiralty type equipment controlled by some other type of gyro compass. Bottle transmitters fell into two groups: 1) pattern #5356 that transmitted to M-type repeater motors; 2) pattern #5355 that transmitted to Sperry-type repeater motors. The B.T. could operate a load equivalent to fifteen Mark 10 M-type repeater motors at its maximum. On HMCS HAIDA, the bottle transmitter was used to transmit azimuth information from the Admiralty Mk 5 Gyrocompass to remote indicators.

AN/SPG-34

The AN/SPG-34 was an X-band fire control radar for AA guns. The antenna was a 40 inch diameter dish that could produce a 2.4 degree beam. Designed for surface vessels of the Canadian Navy, AN/SPG-34 had a power output from 25 to 30 Kw and a range of 25,000 yards. The HAIDA was fitted with the AN/SPG-34 fire control radar.

AN/SPS-12

The AN/SPS-12 was an L-band, medium surveillance radar which was developed to detect aircraft and surface vessels. It was primarily an air search radar which was fitted on the original Canadian DDE class destroyers. Target range of the AN/SPS-12 was presented on an A-type indicator. Bearing data was also provided for presentation on PPI units. Provision was also made to connect IFF equipment to the radar set. The AN/SPS-12 had a maximum range of 200 miles and operated in the frequency range of 1250 to 1350 Mcs.

In 1960-61, the Flag Officer Atlantic Coast and the Vice Chief of the Naval Staff (Admirals Dyer and Brock) became very concerned about the problems being experienced with fighting equipment in the RESTIGOUCHE class. The culprits named were, in order of importance:  the 3-inch/70 gun, the SQS-503 sonar and the SPS-12 radar. The source for this was:  Minutes and papers, 11th Senior Officers' Conference, November 20-21, 1961, file NSS 1279-188, now in the National Archives.

An investigation revealed that the radar equipment, unlike the gun and the sonar, to be blameless. The difficulty was the poor quality of maintenance in the fleet at the time. During this period one must remember that the trade structure of the Navy had been turned upside down in 1960 and electrical officers had been removed from ships, as a result of the Tisdall report.  In the short run, shipboard maintenance  suffered badly. Later on, the addition of a parametric RF amplifier (the Dicke-Fix receiver, developed at the Defence Research Telecommunications Establishment in Ottawa) greatly improved the performance of the SPS-12, and made it much less sensitive to mistuning then so common in the fleet".

Specifications for the AN/SPS-12

Type: L-band air search radar
First delivered: September 1953
Frequency range: 1250 to 1350 Mcs
Range: 200 miles
Peak Power Output: 500 kilowatts
Wavelength: 22.2 to 24 Cm
Pulse Length: Long pulse - 4 microseconds; Short pulse - 1 microsecond
PRR: Long range - 300; Short range - 600 (Could be varied as an anti-jamming measure)
Receiver IF: 30 Mcs
Beamwidth: Vertical - 30 degrees; Horizontal - 3 degrees
Antenna rotation: Auto-clockwise; 2.5 to 15 rpm's; Emergency 10 rpm

AN/SPS-33

The AN/SPS-33 was a vertical, 3-dimensional target-tracking radar developed by the firm Hughes for the American Navy. It operated in combination with the AN/SPS-32 to form the SCANFAR system. The AN/SPS-33 was phased array and was frequency scanned in elevation and phase scanned in azimuth. The AN/SPS-33 had a maximum range of 250 nautical miles. It was unreliable and consumed a lot of power and it was built with vacuum tubes.

AN/SPS-32

The AN/SPS-32 was a long-range air search and target acquisition radar developed by Hughes for the US Navy. The AN/SPS-32 operated together with the AN/SPS-33, which was the square array used for 3D tracking, into one system known as SCANFAR. It  was installed on only two vessels, the cruiser USS Long Beach and the carrier USS Enterprise, placing a massive power drain on the ship’s electric system. The technology of the AN/SPS-32 was based on vacuum tubes and the system required constant repairs. The SPS-32 was a phased array radar which had a range of 400 nautical miles against large targets, and 200 nautical miles against small, fighter-size targets.

AN/APQ-180

The AN/APQ-180 is an all-weather, multi-mode radar which was developed by Raytheon from the APG-70 for the AC-130U Specter gunship aircraft. This X-band pulse-doppler radar is designed for both air-air and air-ground missions; they are able to look up at high-flying targets and down at low-flying targets without being confused by ground clutter. The APQ-180 radar has fixed target track, ground moving target indication and track, projectile impact point position, beacon track, and a weather mode. The AN/APQ-180 system uses a modified gimbaling scheme for the planar array, and an upgraded analog signal processor unit, and incorporates several enhanced (and new) air-to-ground modes.

Doppler Effect

The Doppler effect is the change in frequency of a wave for an observer moving relative to the source of the wave. It is commonly heard when a vehicle sounding a siren or horn approaches, passes, and recedes from an observer. The received frequency is higher (compared to the emitted frequency) during the approach, it is identical at the instant of passing by, and it is lower during the recession. Doppler effect phenomenon was named after Austrian physicist Christian Doppler who proposed it in 1842.

The relative increase in frequency can be explained as follows. When the source of the waves is moving toward the observer, each successive wave crest is emitted from a position closer to the observer than the previous wave. Therefore each wave takes slightly less time to reach the observer than the previous wave. Therefore the time between the arrival of successive wave crests is reduced, causing an increase in the frequency. While they are traveling, the distance between successive wavefronts is reduced; so the waves "bunch together". Conversely, if the source of waves is moving away from the observer, each wave is emitted from a position farther from the observer than the previous wave, so the arrival time between successive waves is increased, reducing the frequency.

In astronomy, the Doppler effect was originally studied in the visible part of the electromagnetic spectrum. Today, the Doppler shift, as it is also known, applies to electromagnetic waves in all portions of the spectrum. Also, because of the inverse relationship between frequency and wavelength, Doppler effect can be discribed in terms of wavelength. Radiation is redshifted when its wavelength increases, and is blueshifted when its wavelength decreases.

Astronomers use Doppler effects to calculate precisely how fast stars and other astronomical objects move toward or away from Earth. For example the spectral lines emitted by hydrogen gas in distant galaxies is often observed to be considerably redshifted. The spectral line emission, normally found at a wavelength of 21 centimeters on Earth, might be observed at 21.1 centimeters instead. This 0.1 centimeter redshift would indicate that the gas is moving away from Earth at over 1,400 kilometers per second (over 880 miles per second).

AN/TPS-58 MTLR

The AN/TPS-58 Moving-Target-Locating Radar (MTLR) is a coherent Doppler radar developed by Raytheon for the US Army. It is used for general surveillance and artillery burst detection. The AN/TPS-58 is a transportable (vehicle-mounted) radar which weighs 3,500 pounds and is equipped with a truncated parabolic reflector (65 × 52 cm) antenna. The AN/TPS-58 can locate moving personnel at ranges between 450 m and 12 km, and vehicles between 450 meters and 20 km to an accuracy of 50 meters. The AN/TPS-58B can automatically track moving targets and predict their future location. A well-trained crew can emplace or march-order the AN/TPS-58B within 15 minutes. The operations shelter can be remoted up to 48 meters from the antenna site.

The mission of the AN/TPS-58 MTLR is to detect, locate, and identify moving ground targets with sufficient accuracy for attack by friendly weapon systems. The radar also can vector friendly patrols to specified areas. The MTLRs are usually employed by division artillery in general support of the division and are therefore seldom directly controlled by cannon battalions. However, they may be attached to battalions for support only, such as security, survey, and Classes I and II.

AN/SPY-3

The AN/SPY-3 is an X-band, active phased array radar which has been developed by Raytheon for the US Navy to be used for both blue-water and littoral operations. It can combine the functions of up to five radars and ten antennas. AN/SPY-3 is the first US shipboard Active Electronically Scanned Array (AESA) system which operates in both the X-band and S-band of radar frequencies. The SPY-3 radar was designed for the Navy's newest amphibious warfare ships, the next generation aircraft carrier, CVN-77 and the DD(X) class of surface combatant ships. MFR was initially planned for introduction in CVN-77 and next-generation CVNX aircraft carriers and the now-refocused DDX surface warship programs.

While the AN/SPY-3 is capable of performing most functions in either frequency band, for functions such as horizon search (anti-sea skimmer) and precision track (for fire control), the band can be selected for current atmospheric, target characteristics, and other factors such as anomalous and multipath propagation. It has a single 6-faced antenna that can share the bands when, for example, the electronics in one band are controlling a maximum number of missiles. X-band functionality, in the 7 to 12.5 GHz frequency range, is optimal for low-altitude propagation effects, narrow beam width for best tracking accuracy, wide frequency bandwidth for effective target discrimination, and the target illumination for SM-2 and Evolved Sea Sparrow Missiles (ESSM). Using the S-band is advantageous for search, operation in all forms of weather, and a narrow beam width for target tracking and resolution.

RT-34/APS-13

The RT-34/APS-13 was a low power UHF tail warning radar transmitter/receiver which was used in Allied aircraft such as the P51 Mustang and also the P-38L, P-47D, P-61, P-63, P-82D in the later stages of the war. The APS-13 operated at 420 MHz with a receiver IF of 30 MHz and was powered by an internal rotary generator which was supplied from the aircraft 27V dc system. The electro-mechanical construction was all aluminium, and the equipment utilized all miniature glass valves except for the voltage stabilizer which was a VR105V (0C3). The PA was two 6J6s. The APS-13 equipment was manufactured by RCA, Camden, New Jersey, USA under a contract number 458-DAY-44 (1944).

AN/TPQ-36 Firefinder radar

The AN/TPQ-36 Firefinder is a light weight, weapon locating, I-band radar developed by Northrop Grumman for the US Army. The radar was designed to detect and track artillery projectiles to find out the exact point from which they have been fired. With a coverage of 360º, the AN/TPQ-36 is capable of simultaneously locating up to 10 different firing plataforms or weapons situated in different positions. It has a maximum range of 18 miles (25km) and can locate mortars, artillery, and rocket launchers. The AN/TPQ-36 is an electronically-steered radar, which means that the radar antenna does not actually move while in operation; nevertheless it can be moved manually if required. This radar system is made up of an operational control group and an antenna transceiver group. The AN/TPQ-36 is currently manufactured by Hughes and is in service at brigade and higher levels in the US Army, US Marine Corps, Spanish Army, and Australian Army. The radar is mounted on trailer and towed by a High Mobility Multipurpose Wheeled Vehicle. The AN/TPQ-36 Firefinder (V)8 version can extend system performance, improves operator survivability and lowers life cycle cost. Greater processing power and the addition of a low noise amplifier to the radar antenna improves detection range (by up to 50%) and performance accuracy against certain threats.

Specifications for the AN/TPQ-36

Maximum range: 25 km
Effective range: artillery, 12 miles (18km); rockets, 18 miles (25km)
Azimuth sector: 90°
Frequency: I-band, 32 frequencies
Prime power: 115/200 VAC, 400 Hz, 3-phase, 8 kW
Peak transmitted power: 23 kW, min.

AN/SPY-1

The AN/SPY-1 is a ship-based, passive phased array radar developed by Lockheed Martin for the US Navy. Using four complementary antennas in order to provide full 360 degree coverage, the AN/SPY-1 is an important component of the Aegis Combat System, which is computer controlled. This 3-dimensional, S-band radar has a range of 100+ nautical miles, and an azimuth of 360º. Up until the introduction of the AN/SPY-1, an ordinary mechanically rotating radar could detect a target when a radar beam struck that target once during each 360º rotation of the antenna; a separate tracking was then used to engage each approaching target. Now, the computer-controlled AN/SPY-1 is capable of bringing these functions into one system. The four fixed arrays of "SPY" send out beams of electromagnetic energy in all directions simultaneously, continuously providing a search and tracking capability for hundreds of target at the same time.

Although the AN/SPY-1 was fist installed on the the USS Norton Sound 1973, it became fully operational in 1983 on USS Ticonderoga as the SPY-1A. The SPY-1D was first installed on Arleigh Burke in 1991. The SPY-1F is a smaller version of the 1D designed to fit frigates. It is not used by the US Navy but has been exported to Norway.

AN/MPQ-64 Sentinel

Using an X-band range-gated, pulse-doppler system, the AN/MPQ-64 Sentinel is an acquisition and tracking surveillance three-dimensional radar which is used to alert and queue Short Range Air Defense (SHORAD) weapons to the locations of hostile targets approaching their front line forces. The AN/MPQ is deployed with forward area air defense units of the US Army and USMC. The Sentinel automatically detects, tracks, identifies, classifies, and reports airborne threats in a range of 75 kilometers. This surveillance radar provides early warning to ground crews by supporting engagement of threats including helicopters, high-speed attack aircraft, cruise missiles, and unmanned aerial vehicles. Over 200 systems have been ordered world-wide, with more than 100 delivered or in production.

The new upgraded versions of the AN/MPQ-64 is fitted with new, modern COTS based electronics which ensures greater performance while implementing a low risk technology insertion. This improved Sentinel radar provides a significant range extension improvement, which means improved target detection at extended ranges and improved target detection for rotary wing and fixed wing aircraft. The AN/MPQ-64 was developed by Raytheon at its Fullerton, California facility.

AN/MPN-14

The AN/MPN-14 was a Mobile Ground Approach System which could be configured as a complete Radar Approach Control (RAPCON) or Ground Controlled Approach (GCA) facility. The AN/MPN-14 radar was used by air traffic controllers to identify, sequence, and separate participating aircraft, provide final approach guidance through air defense corridors and zones, and coordinate ID and intent with local air defense units at assigned airports and air bases. These services could be provided in all types of weather.

The AN/MPN-14 was capable of identifying aircraft using secondary radar up to a 200-nautical-mile (370 km) radius and primary radar coverage to 60 nautical miles (110 km). It provided both azimuth and elevation information from 15-nautical-mile (28 km) to touchdown. The unit had three ASR display indicators and one PAR indicator located in the operations shelter, and one each ASR and PAR indicator located in the maintenance shelter. Complete operations were conducted from the operations trailer. The system was limited to a single runway but had the capability of providing opposite direction runway operations with the aid of a transportable turntable.

AN/MPQ-14

The AN/MPQ-14 was a height and direction-finding radar which was used for Ground Directed Bombing (GDB), during the Korean and Vietnam War. The AN/MPQ-14 was employed to guide attack aircraft at night or during adverse weather conditions. It was the first guiding radar system used to direct bombing missions conducted by the US Marine Corps, introducing the ability to deliver ordnance in close air support missions in poor visibility conditions. The AN/MPQ-14 operated in the frequency range of 2,740 to 2,960 MHz and had an azimuth of 360º.

AN/SPN-46

The AN/SPN-46 is a precision aproach and landing radar system developed by Textron Systems for the US Navy aircraft carriers. The AN/SPN-46 utilizes an X-band coherent transmitter and receiver using monopulse tracking and doppler processing on received signals for clutter rejection and rain attenuation at an operating range of 8 nmi. During day and night operations and in adverse weather conditions, the AN/SPN-46 provides safe and reliable final approach and landing guidance for Marine Corps helicopters and AV-8B Harrier VSTOL attack aircraft. Since this radar system is equipped with two dual-band radar antennas/transmitters, the AN/SPN-46 can control up to two aircraft simultaneously in a "leapfrog" pattern. The AN/SPN-46 is also capable of providing for a manually controlled approach (MODE III landing) in which the AN/SPN-46 air traffic controller relays to the pilot continuous updates on his position and direction. The AN/SPN-46 also uses low-probability-of-intercept (LPI) technology to decrease the probability of passive detection by hostile forces.

AN/SPG-53

The AN/SPG-53 was a ship-based fire control radar developed in the 1960s by Western Electric for the US Navy and manufactured by AT&T. It was designed for controlling the Mark 42 5"/54 caliber gun on the Belknap class cruisers, Mitscher class destroyers, and the Knox class frigates. The AN/SPG-53 operates in the frequency range between 8.5 and 10 GHz with a constant performance of 35 kW and is used in combination with the Mark 68 gun fire-control system. The AN/SPG-53F variant can track targets, sending this data to the Gun Computer System which calculates the firing solution for the Mk 42 Mod 10 Gunmounts.

AN/MPN-1

The AN/MPN-1 was a mobile ground-controlled approach radar first used during the Second World War. This radar was employed to assist the process of directing aircraft over a predetermined glide path for safe approach to an airdrome runway under conditions approaching zero visibility. The AN/MPN-1 provided range and azimuth information on aircraft within a radius of 30 miles (48 km) with an operational ceiling of 4,000 feet (1,200 m). Communications were provided by the SCR-274 transmitter, and BC-342 receivers. A V-8 truck contained the system's two PE-127 power units (rated output of each 7.5-KW), one air conditioner unit, and equipment spare parts. The V-2 trailer contained the system's radar and communications sets.

AN/SPS-49

The AN/SPS-49 was a ship-based, L-band, air search radar developed by Raytheon for the US Navy. The first SPS-49 prototype was installed on board the destroyer USS Gyatt in 1965 for a test period, effectively entering service with the Navy in 1976 on board the USS Dale. Up until 1992, more than 200 units in several variants had been produced and installed in different ships. The AN/SPS-49 utilized a line-of-sight, horizon-stabilized antenna to provide acquisition of low-altitude targets in all sea states.

The AN/SPS-49 was a long-range, narrow-beam, 2-dimensional radar which operated in the frequency between 850 and 942 MHz with a range of 250 nmi (460 km). Used for early target detection, the SPS-49 was capable of performing accurate centroiding of target range, azimuth, ECM level background, amplitude, and radial velocity with an associated confidence factor to produce contact data for command and control systems. The orange-peel parabolic shape of the antenna creates a narrow 3.3°-beam to reduce the probability of detection or jamming. It can rotate at 6 rpm for long-range mode or 12 rpm in short-range mode.

Variants: AN/SPS-49(V)1, which was the first basic version; AN/SPS-49(V)2; AN/SPS-49(V)3, which was fitted with the radar video processor (RVP) interface (FC-1) (USS Long Beach); AN/SPS-49(V)4, with the RVP interface; AN/SPS-49(V)5, which was fitted out with automatic target detection (ATD) (New Threat Upgrade (NTU) ships); AN/SPS-49(V)6, equipped with double shielded cables and a modified cooling system (USS Ticonderoga (CG-47); AN/SPS-49(V)7, based on the (V)5 system, but fitted with a (V)6 cooling system (Aegis combat system); AN/SPS-49(V)8, which included the AEGIS Tracker modification kit; AN/SPS-49(V)9, with medium PRF upgrade (MPU).

AN/SPS-48

The AN/SPS-48 was a long-range, 3-dimensional, air search radar which operated in the E band and F band (2 to 4 GHz) frequencies. Manufactured by ITT Corporation, the AN/SPS-48 entered service with the US Navy in 1965, installed in the USS Worden. This ship-based radar was mounted on a base that allowed for 360 degrees of rotation. The target could be located at a given azimuth. The range of the target was also identified due to the time it took the beam to go out and back to the receiver. The AN/SPS-48 was capable of detecting the height of the target above the surface of the water. Thus, the radar's central processor had the ability to place the target in an X,Y,Z, 3 dimensional space.

This radar system had a range exceeding 200 nmi (370 km) and could track targets up to 69 degrees in elevation. The AN/SPS-48E was capable of providing target range, bearing and altitude information using a frequency-scanning antenna using a range of different frequencies in E band and F band with three power modes: high, medium and low. The AN/SPS-48's antenna could rotate at 7.5 or 15 rpm. Although it was mechanically rotated to scan azimuth, beams were electronically steered to cover elevation. It could stack multiple beams in a train of pulses at different frequencies. The beams scanned different elevation areas, allowing the stack to cover up to 69 degrees of elevation. The SPS-48 was a key component of the New Threat Upgrade (NTU) and was the predecessor of the AEGIS system currently in use on Arleigh Burke-class destroyers and Ticonderoga-class cruisers.