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79-583: From 1957 to 1965, Bear Island was a radar site on the Mid-Canada Line and also housed a petroleum depot and small airfield. After being abandoned, it lay derelict. In 1996 it was identified for remediation, and this work was completed during the summer of 2010 at a cost of $ 5.5 million. This Qikiqtaaluk Region , Nunavut location article is a stub . You can help Misplaced Pages by expanding it . This article related to an island or group of islands in Canada

158-823: A bullet . In mathematical notation the inverse square law can be expressed as an intensity (I) varying as a function of distance (d) from some centre. The intensity is proportional (see ∝ ) to the reciprocal of the square of the distance thus: intensity   ∝   1 distance 2 {\displaystyle {\text{intensity}}\ \propto \ {\frac {1}{{\text{distance}}^{2}}}\,} It can also be mathematically expressed as : intensity 1 intensity 2 = distance 2 2 distance 1 2 {\displaystyle {\frac {{\text{intensity}}_{1}}{{\text{intensity}}_{2}}}={\frac {{\text{distance}}_{2}^{2}}{{\text{distance}}_{1}^{2}}}} or as

237-428: A point source (energy per unit of area perpendicular to the source) is inversely proportional to the square of the distance from the source, so an object (of the same size) twice as far away receives only one-quarter the energy (in the same time period). More generally, the irradiance, i.e., the intensity (or power per unit area in the direction of propagation ), of a spherical wavefront varies inversely with

316-404: A degree, the proposal was to build two interlinked fences, so that each pair of stations was perhaps 30 kilometres (19 mi) apart, a short enough distance that the radar on an interceptor aircraft would be able to find the target within that area. Using two overlapping sets also allowed one pair to cover the dead zone directly above the towers of the other. Lewis' initial concept was to place

395-430: A great deal about the spectral ‘signatures’ of aircraft crossing the line at different points, and demonstrated the capability to detect all sizes of aircraft from 100 ft to over 40,000 ft in altitude. During this time Dr. Ross Warren of RCA Victor and Dr. Whitehead jointly developed the theoretical background for the work in a major report to DRB. The Spider Web trials were followed in 1954 by intensive tests on

474-568: A letter to Isaac Newton : my supposition is that the attraction always is in duplicate proportion to the distance from the center reciprocall . Hooke remained bitter about Newton claiming the invention of this principle, even though Newton's 1686 Principia acknowledged that Hooke, along with Wren and Halley, had separately appreciated the inverse square law in the solar system, as well as giving some credit to Bullialdus. The force of attraction or repulsion between two electrically charged particles, in addition to being directly proportional to

553-467: A point source can be calculated using the inverse-square law. Since emissions from a point source have radial directions, they intercept at a perpendicular incidence. The area of such a shell is 4π r where r is the radial distance from the center. The law is particularly important in diagnostic radiography and radiotherapy treatment planning, though this proportionality does not hold in practical situations unless source dimensions are much smaller than

632-463: A point source obeys an inverse square law: Sicut se habent spharicae superificies, quibus origo lucis pro centro est, amplior ad angustiorem: ita se habet fortitudo seu densitas lucis radiorum in angustiori, ad illamin in laxiori sphaerica, hoc est, conversim. Nam per 6. 7. tantundem lucis est in angustiori sphaerica superficie, quantum in fusiore, tanto ergo illie stipatior & densior quam hic. Just as [the ratio of] spherical surfaces, for which

711-547: A second moving west from Flin Flon, Manitoba , while a third crewed by the Army left Lake Nipigon near Thunder Bay , Ontario for Lansdowne House about 200 kilometres (120 mi) further north. The missions proved that it was possible to build the new line, but only during the winter when the muskeg was frozen solid. These missions also inspired the U.S. Army to invest in purpose-built overland trains which they experimented with in

790-608: A single 30 miles (48 km) wide link, built in the Eastern Townships by Bell Canada , who had by this time been given the go-ahead for the implementation of the Mid-Canada Line. When Whitehead inquired why RCA had not been given the contract, a colleague replied "Who do you think runs Canada?" The trials on this prototype link were also conducted by Whitehead and a small team in collaboration with Air Defence Command, St. Hubert, this time on behalf of Bell. The trials involved

869-417: A total of 90 radar stations. Each of the radar stations consisted of a single tall mast with a number of small dishes in fixed positions on top (typically four, two pointed in either direction), with power and electronics located in a building beside the base of the mast. The sector control centres were linked using an advanced microwave communications system developed in part by CARDE , which scattered off

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948-410: Is in-phase with the instantaneous sound pressure p {\displaystyle p\,} : v   ∝ 1 r   {\displaystyle v\ \propto {\frac {1}{r}}\ \,} In the near field is a quadrature component of the particle velocity that is 90° out of phase with the sound pressure and does not contribute to the time-averaged energy or

1027-595: Is a stub . You can help Misplaced Pages by expanding it . Mid-Canada Line Download coordinates as: The Mid-Canada Line ( MCL ), also known as the McGill Fence , was a line of radar stations running east–west across the middle of Canada , used to provide early warning of a Soviet bomber attack on North America. It was built to supplement the Pinetree Line , which was located farther south. The majority of Mid-Canada Line stations were used only briefly from

1106-406: Is directly proportional to the product of their masses and inversely proportional to the square of their separation distance. The force is always attractive and acts along the line joining them. If the distribution of matter in each body is spherically symmetric, then the objects can be treated as point masses without approximation, as shown in the shell theorem . Otherwise, if we want to calculate

1185-434: Is evenly radiated outward from a point source in three-dimensional space . Since the surface area of a sphere (which is 4π r ) is proportional to the square of the radius, as the emitted radiation gets farther from the source, it is spread out over an area that is increasing in proportion to the square of the distance from the source. Hence, the intensity of radiation passing through any unit area (directly facing

1264-420: Is the resultant of radial inverse-square law fields with respect to one or more sources is proportional to the strength of the local sources, and hence zero outside sources. Newton's law of universal gravitation follows an inverse-square law, as do the effects of electric , light , sound , and radiation phenomena. The inverse-square law generally applies when some force, energy, or other conserved quantity

1343-472: Is the same as in the case of light, namely, the duplicate proportion, but inversely, of the distances [that is, 1/d²]. In England, the Anglican bishop Seth Ward (1617–1689) publicized the ideas of Bullialdus in his critique In Ismaelis Bullialdi astronomiae philolaicae fundamenta inquisitio brevis (1653) and publicized the planetary astronomy of Kepler in his book Astronomia geometrica (1656). In 1663–1664,

1422-597: The troposphere for long-distance communications. The southernmost site along the eastern portion of the line, at Cape Henrietta Maria on Hudson Bay , was used as the main communications point, with three additional repeater stations transferring data from the line southward to the NORAD command center in North Bay, Ontario . The easternmost station at Hopedale, Labrador was co-located with an existing Pinetree Line station in order to save construction costs. All aircraft transiting

1501-429: The 1960s but never put into production. While that was taking place, efforts were underway to start primary siting studies. It quickly became clear that the areas in question, at least in eastern Canada, were so remote that there was no really accurate topographical information. A huge effort to map the area in a 15-mile wide strip across the entire country was started by Transport Command almost immediately, and ended by

1580-518: The English scientist Robert Hooke was writing his book Micrographia (1666) in which he discussed, among other things, the relation between the height of the atmosphere and the barometric pressure at the surface. Since the atmosphere surrounds the Earth, which itself is a sphere, the volume of atmosphere bearing on any unit area of the Earth's surface is a truncated cone (which extends from the Earth's center to

1659-681: The French astronomer Ismaël Bullialdus (1605–1694) refuted Johannes Kepler's suggestion that "gravity" weakens as the inverse of the distance; instead, Bullialdus argued, "gravity" weakens as the inverse square of the distance: Virtus autem illa, qua Sol prehendit seu harpagat planetas, corporalis quae ipsi pro manibus est, lineis rectis in omnem mundi amplitudinem emissa quasi species solis cum illius corpore rotatur: cum ergo sit corporalis imminuitur, & extenuatur in maiori spatio & intervallo, ratio autem huius imminutionis eadem est, ac luminus, in ratione nempe dupla intervallorum, sed eversa. As for

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1738-551: The MCL gave little information for vectoring interceptors to their targets, so these tasks still required the Pinetree radars much farther south. The extra time offered by the MCL was not considered worth the trouble of keeping the line operational. The USAF disagreed, but in spite of their objections, the western half of the line was shut down in January 1964, leaving the eastern half to help defend

1817-506: The MCL, and it lasted even a shorter time, shut down in 1963. From a December 1956 listing: Download coordinates as: Petroleums, Oils and Lubricants (POL) Supply Points were distribution centers for consumable petroleum materials used to fuel and maintain the Mid-Canada Line DDS sites. Co-located with Sector Control Stations when possible, petroleum products were received in bulk and shipped out by air from these locations. From

1896-556: The MSG recommended to both governments "that there be established at the earliest practicable date, an early warning line located generally along the 55th parallel between Alaska and Newfoundland", and outlined their minimum operational requirements. By the end of November 1953, the Mid-Canada Line had been approved in principle. Unlike the jointly-operated Pinetree line and future DEW line, the Mid-Canada line would be funded and operated entirely by

1975-463: The Pinetree Line. The major disadvantage of the system is that it did not indicate the aircraft's location within the beam, unlike a pulsed system where pulse timing can be used to determine range. This means the forward-scatter concept is useful for making a "radar fence" or "trip wire" that indicates that something is approaching, but not exactly where it is. To help address locating the target to

2054-504: The RCAF. The DRB estimated that the system would cost about $ 69,700,000, while an independent RCAF report placed it at $ 85,000,000, equivalent to $ 243,200,000 in 2023. In December an effort started to try to understand what sort of problems would be encountered during construction. Several "trains" consisting of tractor-pulled sleighs set out cross-country. One, manned by the RCAF, set out eastward from Fort Nelson, BC in order to link up with

2133-553: The UK Telecommunications Research Establishment (TRE) had proposed to the Defence Research Board (DRB) a system that avoided both of these problems. Known today as a forward scatter bistatic radar , it used two antennas, a transmitter and receiver, separated by some distance. The antennas were positioned and aimed so that the signal from the transmitter filled the space above the line between

2212-541: The attack reached Canadian or northern U.S. cities. Additionally, the Pinetree systems used pulsed radars that were fairly easy to jam and were unable to detect targets close to the ground due to "clutter." Although expensive in terms of fuel use, it would be possible for Soviet bombers to evade detection by flying lower and plotting a course between the stations. Bennett Lewis , head of the AECL Chalk River Laboratories and former Chief Superintendent of

2291-427: The attraction between massive bodies, we need to add all the point-point attraction forces vectorially and the net attraction might not be exact inverse square. However, if the separation between the massive bodies is much larger compared to their sizes, then to a good approximation, it is reasonable to treat the masses as a point mass located at the object's center of mass while calculating the gravitational force. As

2370-470: The behavior of force (F) and potential (Φ) within hyperbolic 3-space (H3). He explains that F and Φ obey the relationships F ∝ 1 / R² sinh²(r/R) and Φ ∝ coth(r/R), where R represents the curvature radius and r represents the distance from the focal point. The concept of spatial dimensionality, first proposed by Immanuel Kant, remains a topic of debate concerning the inverse-square law. Dimitria Electra Gatzia and Rex D. Ramsier, in their 2021 paper, contend that

2449-471: The construction of a cross-Canada microwave relay telephone system. Since many of the logistics problems were similar, the construction group, led by Bell Canada , was selected as a major contractor for the base construction. Detailed site selection started in 1955, with a major surveying effort running across Canada at the 55th parallel. The sites were so remote that the RCAF had to form up its first all-helicopter squadron in order to provide flight support for

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2528-409: The curvature of spacetime, leading particles to move along geodesics in this curved spacetime. John Dumbleton of the 14th-century Oxford Calculators , was one of the first to express functional relationships in graphical form. He gave a proof of the mean speed theorem stating that "the latitude of a uniformly difform movement corresponds to the degree of the midpoint" and used this method to study

2607-431: The distance r is doubled; if measured in dB would decrease by 6.02 dB per doubling of distance. When referring to measurements of power quantities, a ratio can be expressed as a level in decibels by evaluating ten times the base-10 logarithm of the ratio of the measured quantity to the reference value. In acoustics , the sound pressure of a spherical wavefront radiating from a point source decreases by 50% as

2686-488: The distance r is doubled; measured in dB , the decrease is still 6.02 dB, since dB represents an intensity ratio. The pressure ratio (as opposed to power ratio) is not inverse-square, but is inverse-proportional (inverse distance law): p   ∝   1 r {\displaystyle p\ \propto \ {\frac {1}{r}}\,} The same is true for the component of particle velocity v {\displaystyle v\,} that

2765-458: The distance. As stated in Fourier theory of heat “as the point source is magnification by distances, its radiation is dilute proportional to the sin of the angle, of the increasing circumference arc from the point of origin”. Let P   be the total power radiated from a point source (for example, an omnidirectional isotropic radiator ). At large distances from the source (compared to the size of

2844-406: The effective origin is located far behind the beam aperture. If you are close to the origin, you don't have to go far to double the radius, so the signal drops quickly. When you are far from the origin and still have a strong signal, like with a laser, you have to travel very far to double the radius and reduce the signal. This means you have a stronger signal or have antenna gain in the direction of

2923-570: The flyover of numbers of B-52 bombers by arrangement with Strategic Air Command and a local bombplot unit. They also had full-time use of an Avro Lancaster from CFB Greenwood for the important low-level tests. In February 1953 the Canada-U.S. Military Study Group (MSG) was asked "to study those aspects of the North American Air Defence System in general, and the early warning system in particular, which are of mutual concern to

3002-402: The formulation of a constant quantity: intensity 1 × distance 1 2 = intensity 2 × distance 2 2 {\displaystyle {\text{intensity}}_{1}\times {\text{distance}}_{1}^{2}={\text{intensity}}_{2}\times {\text{distance}}_{2}^{2}} The divergence of a vector field which

3081-519: The illumination increase the distance by a factor of 1.4 (the square root of 2 ), and to double illumination, reduce the distance to 0.7 (square root of 1/2). When the illuminant is not a point source, the inverse square rule is often still a useful approximation; when the size of the light source is less than one-fifth of the distance to the subject, the calculation error is less than 1%. The fractional reduction in electromagnetic fluence (Φ) for indirectly ionizing radiation with increasing distance from

3160-562: The industrial areas of Canada and the US. As the Soviet Union moved their offensive capability to ICBMs it became clear that both the MCL and Pinetree systems were of limited use, and the entire Mid-Canada line was shut down in April 1965. The operations site located at Cranberry Portage, Manitoba , for example, has been converted into a high school and residence since active operations at the site closed in

3239-606: The intensity of the sound. The sound intensity is the product of the RMS sound pressure and the in-phase component of the RMS particle velocity, both of which are inverse-proportional. Accordingly, the intensity follows an inverse-square behaviour: I   =   p v   ∝   1 r 2 . {\displaystyle I\ =\ pv\ \propto \ {\frac {1}{r^{2}}}.\,} For an irrotational vector field in three-dimensional space,

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3318-508: The inverse-square law corresponds to the property that the divergence is zero outside the source. This can be generalized to higher dimensions. Generally, for an irrotational vector field in n -dimensional Euclidean space , the intensity "I" of the vector field falls off with the distance "r" following the inverse ( n  − 1) power law I ∝ 1 r n − 1 , {\displaystyle I\propto {\frac {1}{r^{n-1}}},} given that

3397-421: The inverse-square law is more closely related to force distribution symmetry than to the dimensionality of space. In the context of non-Euclidean geometries and general relativity, deviations from the inverse-square law do not arise from the law itself but rather from the assumption that the force between two bodies is instantaneous, which contradicts special relativity . General relativity reinterprets gravity as

3476-417: The late 1950s to the mid-1960s, as the attack threat changed from bombers to ICBMs . As the MCL was closed down, the early warning role passed almost entirely to the newer and more capable DEW Line farther north. The MCL was based on the bistatic radar principle, using separated transmitters and receivers. An aircraft flying anywhere between the stations would reflect some of the transmitted signal towards

3555-519: The law of gravitation, this law was suggested in 1645 by Ismaël Bullialdus . But Bullialdus did not accept Kepler's second and third laws , nor did he appreciate Christiaan Huygens 's solution for circular motion (motion in a straight line pulled aside by the central force). Indeed, Bullialdus maintained the sun's force was attractive at aphelion and repulsive at perihelion. Robert Hooke and Giovanni Alfonso Borelli both expounded gravitation in 1666 as an attractive force. Hooke's lecture "On gravity"

3634-492: The line HQ, which was set up in the equipment hut of one of the seven stations, located in Deep River . Flight Lieutenant Andrew Matthews of the 104 Communications Flight at RCAF St. Hubert arranged for a series of different aircraft to fly through the network, including an Auster light aircraft, a T-33 Shooting Star , an Avro Lancaster bomber and even a recently acquired de Havilland Comet jet transport. The tests revealed

3713-519: The line would have to file a flight plan through the Mid Identification Zone , or MIDIZ , centred on the fence. The plans also called for the construction of several airbases known as Line Clearance Aerodromes just to the north of the line, where interceptor aircraft could operate in times of heightened alert. At about this time another huge civil engineering project was underway in Canada,

3792-526: The line-breaking capabilities of the MCL, and located much farther north to dramatically improve the detection and response times. Emerging as the Distant Early Warning Line , or DEW, construction started before the MCL had become operational. When the DEW line became operational in 1957, the value of the MCL was eroded, and the RCAF started pressing for it to be dismantled. Although technically capable,

3871-408: The mid-1960s. The DEW line stations were sited to provide the best possible view of the horizon, but there remained a minimum detection angle below which aircraft could sneak by without being seen. During early planning, a system like the MCL's towers was considered as gap-fillers between the stations to prevent these sorts of intrusions. As the MCL came online and the problem with birds became clear,

3950-426: The narrow beam relative to a wide beam in all directions of an isotropic antenna . In photography and stage lighting , the inverse-square law is used to determine the “fall off” or the difference in illumination on a subject as it moves closer to or further from the light source. For quick approximations, it is enough to remember that doubling the distance reduces illumination to one quarter; or similarly, to halve

4029-603: The need for 1,000 such radars, but it is also likely that the desired to locate the line further north than the heavily settled areas in southern Canada was likely significant as well. In any event, the simplicity of the concept helped bring it to the attention of air planners. The DRB decided to pursue Lewis’ idea in 1950–51 by directing a research contract to the Eaton Electronics Research Laboratories of McGill University , headed by Professor Garfield Woonton. Lewis suggested to DRB and Woonton that he put

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4108-554: The number of stations required. Nevertheless, the price rose, now estimated at about $ 120,000,000. Although their final report was not yet ready, the SEG put in an interim report in June and it was approved by cabinet by the end of the month. In their report they outlined the system that would be built almost exactly. It called for eight major Sector Control Centres , numbered from 200 to 900, each of which control up to thirty unmanned radar sites for

4187-432: The original forward-scatter concept was replaced by one using Doppler filtering to ignore anything flying below 125 miles per hour (201 km/h). These AN/FPS-23 "Fluttar" systems did indeed filter out birds, but failed to filter out the general aviation aircraft flying in the area, including those flying base-to-base for servicing and crew rotations. As a result, the false-alarm rate rendered it just as ineffective as

4266-401: The point source) is inversely proportional to the square of the distance from the point source. Gauss's law for gravity is similarly applicable, and can be used with any physical quantity that acts in accordance with the inverse-square relationship. Gravitation is the attraction between objects that have mass. Newton's law states: The gravitational attraction force between two point masses

4345-449: The power by which the Sun seizes or holds the planets, and which, being corporeal, functions in the manner of hands, it is emitted in straight lines throughout the whole extent of the world, and like the species of the Sun, it turns with the body of the Sun; now, seeing that it is corporeal, it becomes weaker and attenuated at a greater distance or interval, and the ratio of its decrease in strength

4424-492: The precise location of the target, only its presence. Throughout its history, the MCL suffered from a problem that was never solved; because of the way bistatic radar works, any object relatively close to either station produces a large signal, in contrast to conventional monostatic (single site) radars where this effect is limited to the area immediately around the site. In the case of the MCL, this caused problems when flocks of birds would fly anywhere near either station and swamp

4503-486: The product of the electric charges, is inversely proportional to the square of the distance between them; this is known as Coulomb's law . The deviation of the exponent from 2 is less than one part in 10 . F = k e q 1 q 2 r 2 {\displaystyle F=k_{\text{e}}{\frac {q_{1}q_{2}}{r^{2}}}} The intensity (or illuminance or irradiance ) of light or other linear waves radiating from

4582-611: The project in the hands of associate professor, J. Rennie Whitehead as project leader, a former colleague of his from the TRE days in the UK who had recently taken a position at the Lab. Some preliminary tests were made in 1952 with breadboard hardware built by a graduate student, Hugh Hamilton, in order to confirm the validity of the idea. In the meantime RCA Victor had been brought in by the DRB to design and produce

4661-476: The quantitative decrease in intensity of illumination in his Summa logicæ et philosophiæ naturalis (ca. 1349), stating that it was not linearly proportional to the distance, but was unable to expose the Inverse-square law. In proposition 9 of Book 1 in his book Ad Vitellionem paralipomena, quibus astronomiae pars optica traditur (1604), the astronomer Johannes Kepler argued that the spreading of light from

4740-399: The receiver, where it would mix with the signal travelling directly from the transmitter. The mixing of the two signals produces a pattern that is very easy to detect using simple electronics. As the transmitter is not pulsed, it does not require high voltages and is very simple as well. This leads to a very low-cost system that can cover huge areas, at the cost of providing no information about

4819-559: The receivers, transmitters and antennas for tests on a substantial scale. The testing was performed in the summer of 1953, when Whitehead and his team of RCA Victor and RCAF personnel installed and operated a string of seven stations stretching from Ottawa to Mattawa along the Ottawa River valley. Known under the code name of "Spider Web" at the suggestion of Hamilton, the tests were made with aircraft from CFB St. Hubert , near Montreal. All observations were transmitted to and made in

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4898-411: The resulting radar equation contains a fourth-power dependence. In contrast, a forward-scatter radar signal always travels about the same total distance, from the transmitter to the receiver, modified only by the altitude of the target. This means it is dependent on the square root of range and not the fourth root, and thus delivers considerably more energy onto the receiver than a conventional radar over

4977-483: The same December 1956 listing. Inverse square law In science , an inverse-square law is any scientific law stating that the observed "intensity" of a specified physical quantity is inversely proportional to the square of the distance from the source of that physical quantity. The fundamental cause for this can be understood as geometric dilution corresponding to point-source radiation into three-dimensional space. Radar energy expands during both

5056-503: The same range. Also, unlike a conventional "monostatic" radar, the transmitter did not have to turn off to allow the receiver to listen for the signal. Since the total amount of energy received at the receiver is a function of both the peak power and the length of the pulse, using a continual signal means the same total energy will be deposited using much lower peak transmitter power. As a result, Lewis' system would require smaller sites and much less power than conventional radars like those of

5135-546: The signal of a more distant aircraft. Solving this problem using the Doppler effect was a major design criterion for the AN/FPS-23 "Fluttar" that filled a similar role in the DEW line. Construction of the Pinetree Line had only just started when air planners started to have concerns about its capabilities and siting. By the time it detected a potential attack by jet -powered aircraft, there would be little time to do anything before

5214-450: The signal transmission and the reflected return, so the inverse square for both paths means that the radar will receive energy according to the inverse fourth power of the range. To prevent dilution of energy while propagating a signal, certain methods can be used such as a waveguide , which acts like a canal does for water, or how a gun barrel restricts hot gas expansion to one dimension in order to prevent loss of energy transfer to

5293-447: The source of light is the center, [is] from the wider to the narrower, so the density or fortitude of the rays of light in the narrower [space], towards the more spacious spherical surfaces, that is, inversely. For according to [propositions] 6 & 7, there is as much light in the narrower spherical surface, as in the wider, thus it is as much more compressed and dense here than there. In 1645, in his book Astronomia Philolaica ...,

5372-508: The source), this power is distributed over larger and larger spherical surfaces as the distance from the source increases. Since the surface area of a sphere of radius r is A  = 4 πr , the intensity I (power per unit area) of radiation at distance r is I = P A = P 4 π r 2 . {\displaystyle I={\frac {P}{A}}={\frac {P}{4\pi r^{2}}}.\,} The energy or intensity decreases (divided by 4) as

5451-479: The space outside the source is divergence free. The inverse-square law, fundamental in Euclidean spaces, also applies to non-Euclidean geometries , including hyperbolic space . The curvature present in these spaces alters physical laws, influencing a variety of fields such as cosmology , general relativity , and string theory . John D. Barrow , in his 2020 paper "Non-Euclidean Newtonian Cosmology," expands on

5530-474: The spring and fall, which created signals so powerful that it rendered the radars useless. Testing on the Spider Web and Eastern Townships systems had both been carried out during the summer, so this had not been noticed. Even before the line became operational, in a repeat of earlier history, a new and more capable line was already under study that would combine the plotting capability of the Pinetree system with

5609-539: The spring of 1954. With this information in hand a construction division was set up, the Systems Engineering Group (SEG), in February 1954, tasked with producing a final report on the system to be submitted on June 1. As the experiments continued it became clear that by using taller masts, 350 feet (110 m) tall, the radar stations could be located further apart, up to 90 kilometres (56 mi). This reduced

5688-567: The square of the distance from the source (assuming there are no losses caused by absorption or scattering ). For example, the intensity of radiation from the Sun is 9126 watts per square meter at the distance of Mercury (0.387 AU ); but only 1367 watts per square meter at the distance of Earth (1 AU)—an approximate threefold increase in distance results in an approximate ninefold decrease in intensity of radiation. For non- isotropic radiators such as parabolic antennas , headlights, and lasers ,

5767-429: The survey teams. Construction started in 1956 and proceeded quickly. By April 1957 the eastern half was operational, and the line was declared fully operational on January 1, 1958. Operations were shortly integrated into the newly formed NORAD . Even the SEG's revised estimates turned out to be too low, and the fence's final cost is estimated at $ 224,566,830, equivalent to $ 2,321,000,000 in 2023. Almost as soon as

5846-484: The transmitters and receivers on telephone poles and electric power transmission towers, which provided both a convenient location as well as the small amount of power needed to run the electronics. In the case of the telephone poles, the lines would also be used to send the data back to the tracking stations. This concept generated a considerable amount of interest, although it was abandoned for reasons that are not entirely clear. Willis and Griffiths speculate it might be

5925-488: The two countries." The MSG then asked the air defence commanders of Canada and the United States to prepare independent briefs on the subject. By July 1953, RCAF Air Defense Command had completed its brief, followed shortly thereafter by its USAF counterpart. Both reports suggested building a Doppler fence farther north, along the 55th parallel , roughly at the entrance of James Bay into Hudson Bay . In October 1953

6004-414: The two stations. An aircraft flying into this region would reflect some signal back towards the receiver, allowing detection at altitudes as great as 65,000 ft. A major advantage of the system is that it requires much less power to operate effectively. In a conventional radar, the radio signal has to travel to the target and back again. As each leg of the journey is subject to the inverse square law ,

6083-445: The units went into operation, a serious problem was seen. Due to the large radar cross sections seen in forward-scattering radars, even small targets produced detectable signals. This was multiplied if the targets were roughly the same size as the wavelength of the radar, or in this case, tended to be spread out in patterns that were multiples of that wavelength. This problem was triggered by the large flocks of migrating waterfowl during

6162-401: The vacuum of space; obviously only the section of the cone from the Earth's surface to space bears on the Earth's surface). Although the volume of a cone is proportional to the cube of its height, Hooke argued that the air's pressure at the Earth's surface is instead proportional to the height of the atmosphere because gravity diminishes with altitude. Although Hooke did not explicitly state so,

6241-599: Was at the Royal Society, in London, on 21 March. Borelli's "Theory of the Planets" was published later in 1666. Hooke's 1670 Gresham lecture explained that gravitation applied to "all celestiall bodys" and added the principles that the gravitating power decreases with distance and that in the absence of any such power bodies move in straight lines. By 1679, Hooke thought gravitation had inverse square dependence and communicated this in

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