SCR-584 Technical Description
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| The SCR-584, development of which began in 1941, could be operated in either a search or track mode. In the search mode the antenna was rotated through 360 degrees at 6 RPM. On each revolution the antenna elevation is raised so that it reaches a maximum elevation of 20 degrees in one minute. The result is a complete helical search of the space surrounding the radar. | The SCR-584, development of which began in 1941, could be operated in either a search or track mode. In the search mode the antenna was rotated through 360 degrees at 6 RPM. On each revolution the antenna elevation is raised so that it reaches a maximum elevation of 20 degrees in one minute. The result is a complete helical search of the space surrounding the radar. | ||
| - | The collected information was displayed on a Plan Position Indicator [PPI] controlled by a mechanical computer. It allows the operator to see all the radar returns on a map-like screen with the radar at its centre. On the console there were also two J-displays, a coarse-range display and fine-range display. Having designated the target on the PPI the operator could cause the antenna to carry out a spiral scan around the selected elevation and azimuth, and could thus locate a target. | + | There were three different scan patterns available on the antenna: |
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| [[Image:Helical scan.jpg|right|thumbnail|180px|Helical scan mechanism:<BR>''Image – ‘Electronics’; Fig 2, Dec ’45, p.104'']] | [[Image:Helical scan.jpg|right|thumbnail|180px|Helical scan mechanism:<BR>''Image – ‘Electronics’; Fig 2, Dec ’45, p.104'']] | ||
| [[Image:Conical beam.jpg|left|thumbnail|250px|A conical scan beam:<BR> ''Image – ‘Electronics’; Fig 1, Nov ’45, p.104'']] | [[Image:Conical beam.jpg|left|thumbnail|250px|A conical scan beam:<BR> ''Image – ‘Electronics’; Fig 1, Nov ’45, p.104'']] | ||
| - | There were three different scan patterns available on the antenna: | ||
| - | |||
| '''(a)''' a '''helical scan''' (see diagram to the right) in which the antenna scans the sky around the radar; | '''(a)''' a '''helical scan''' (see diagram to the right) in which the antenna scans the sky around the radar; | ||
| - | '''(b)''' a '''spiral scan''' in which the antenna is caused to spiral outwards from a designated azimuth and elevation and then back to the designated position until a particular target is located. This would be limited in extent, probably only 1 or 2 degrees maximum; and | + | '''(b)''' a '''spiral scan''' in which the antenna beam spirals outwards from a designated azimuth and elevation and then back to the designated position until a particular target is located. This would be limited in extent, probably only 1 or 2 degrees maximum; and |
| - | '''(c)''' the rotation of the beam around the bore sight line of the antenna so as to provide a '''conical beam pattern''' (see diagram above left) which allows the system to automatically determine the position of, and automatically track, the target. | + | '''(c)''' the rotation of the beam around the antenna's bore sight line provides a '''conical beam pattern''' (see diagram above left) which allows the system to determine the position of the target, and then automatically track it. |
| ''Where there was more uncertainty about the target path, a '''nutating''' mode was used (see diagram below left) where the slightly offset dipole feed was rotated rapidly to produce off-axis radiation increasing the effective beam width from 2.5° to about 5.5° . Nutation was switched off when the target was acquired.'' | ''Where there was more uncertainty about the target path, a '''nutating''' mode was used (see diagram below left) where the slightly offset dipole feed was rotated rapidly to produce off-axis radiation increasing the effective beam width from 2.5° to about 5.5° . Nutation was switched off when the target was acquired.'' | ||
| [[Image:offset dipole.jpg|left|thumbnail|290px|Nutating antenna dipole feed:<BR>''Image – ‘Electronics’; Fig 5, Dec ’45, p.107'']] | [[Image:offset dipole.jpg|left|thumbnail|290px|Nutating antenna dipole feed:<BR>''Image – ‘Electronics’; Fig 5, Dec ’45, p.107'']] | ||
| + | |||
| + | The angle scans, both the helical and the spiral, were generated by motor driven cams in the angle control panel. The caption on the photograph of the interior of this panel at http://www.hamhud.net/darts/scr584.html <BR> refers to the angle control panel as a mechanical computer in the PPI unit. The analogue computer associated with the SCR584 was the M-9, a separate device. | ||
| + | |||
| + | The collected information was displayed on a Plan Position Indicator [PPI]. It allows the operator to see all the radar returns on a map-like screen with the radar at its centre. On the console there were also two J-displays, a coarse-range display and fine-range display. Having designated the target on the PPI the operator could cause the antenna to carry out a spiral scan around the selected elevation and azimuth, and could thus locate a target. | ||
| Having located the target in angles the fine range display would then be used to differentiate between, for example a friendly fighter and enemy bomber and then allow the operator initiate automatic tracking of that target. | Having located the target in angles the fine range display would then be used to differentiate between, for example a friendly fighter and enemy bomber and then allow the operator initiate automatic tracking of that target. | ||
| In the track mode the operator was required to adjust the rate of range change by operating a hand-wheel on the console. The Azimuth, Elevation, and Range analogue signals were fed to the external M-9 Gun Predictor. The M-9 was an analogue computer which solved the targeting problem and pointed the associated 90mm anti-aircraft guns so that the shell and the target arrived at the same spot simultaneously. | In the track mode the operator was required to adjust the rate of range change by operating a hand-wheel on the console. The Azimuth, Elevation, and Range analogue signals were fed to the external M-9 Gun Predictor. The M-9 was an analogue computer which solved the targeting problem and pointed the associated 90mm anti-aircraft guns so that the shell and the target arrived at the same spot simultaneously. | ||
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| - | The angle scans, both the helical and the spiral, were generated by motor driven cams in the angle control panel. The caption on the photograph of the interior of this panel at http://www.hamhud.net/darts/scr584.html refers to the angle control panel as a mechanical computer in the PPI unit. The analogue computer associated with the SCR584 was the M-9, a separate device. | ||
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Revision as of 23:59, 29 February 2008
Back to Verlort Radar
These notes have been prepared by Ken Anderson, one time AN-FPQ6 radar supervisor at the Carnarvon Tracking Station supplemented (in italics) by Paul Dench.
The SCR-584, development of which began in 1941, could be operated in either a search or track mode. In the search mode the antenna was rotated through 360 degrees at 6 RPM. On each revolution the antenna elevation is raised so that it reaches a maximum elevation of 20 degrees in one minute. The result is a complete helical search of the space surrounding the radar.
There were three different scan patterns available on the antenna:
Image – ‘Electronics’; Fig 2, Dec ’45, p.104
Image – ‘Electronics’; Fig 1, Nov ’45, p.104
(a) a helical scan (see diagram to the right) in which the antenna scans the sky around the radar;
(b) a spiral scan in which the antenna beam spirals outwards from a designated azimuth and elevation and then back to the designated position until a particular target is located. This would be limited in extent, probably only 1 or 2 degrees maximum; and
(c) the rotation of the beam around the antenna's bore sight line provides a conical beam pattern (see diagram above left) which allows the system to determine the position of the target, and then automatically track it.
Where there was more uncertainty about the target path, a nutating mode was used (see diagram below left) where the slightly offset dipole feed was rotated rapidly to produce off-axis radiation increasing the effective beam width from 2.5° to about 5.5° . Nutation was switched off when the target was acquired.
Image – ‘Electronics’; Fig 5, Dec ’45, p.107
The angle scans, both the helical and the spiral, were generated by motor driven cams in the angle control panel. The caption on the photograph of the interior of this panel at http://www.hamhud.net/darts/scr584.html
refers to the angle control panel as a mechanical computer in the PPI unit. The analogue computer associated with the SCR584 was the M-9, a separate device.
The collected information was displayed on a Plan Position Indicator [PPI]. It allows the operator to see all the radar returns on a map-like screen with the radar at its centre. On the console there were also two J-displays, a coarse-range display and fine-range display. Having designated the target on the PPI the operator could cause the antenna to carry out a spiral scan around the selected elevation and azimuth, and could thus locate a target.
Having located the target in angles the fine range display would then be used to differentiate between, for example a friendly fighter and enemy bomber and then allow the operator initiate automatic tracking of that target.
In the track mode the operator was required to adjust the rate of range change by operating a hand-wheel on the console. The Azimuth, Elevation, and Range analogue signals were fed to the external M-9 Gun Predictor. The M-9 was an analogue computer which solved the targeting problem and pointed the associated 90mm anti-aircraft guns so that the shell and the target arrived at the same spot simultaneously.
See: http://www.infoage.org/sigcww2-test-p265-scr584.html for The Test; a history of the SCR-584's use by the US Signal Corps.
See: http://www.fas.org/man/dod-101/navy/docs/es310/trksys/trksys.htm for an explanation of the principles of Tracking Systems.
