From Sandia Lab News, July 26, 1991:
Cameras, Radar Keep Eyes on Test
“Prime Time” at Tonopah Test Range (TTR) has nothing to do with television. The phrase refers to the best time for optical tracking of test subjects, a half hour after sunrise and a half hour before sunset.
“This can mean being out in some frigid Nevada pre-dawns”, says Ron Taylor of Optical Measurement DIV. 7514. “We prime time for testing to avoid the worms”, he says, explaining that the “worms” are the heat shimmers that undulate over the flat desert floor during other parts of the day. “you can completely lose an object in that shimmer”, says Ron.
Ron operates one of TTR’s nine Contraves cinetheodolites. A cinetheodolite records elevation angle, azimuth angle and time on each frame of film exposed as an object is being tracked. Operating it is something like being in a Word War II bomber turret, exposing film instead of firing guns. The film from two or more cinetheodolites can be combined to determine the trajectory of a test object to within about a meter.
Although the cinetheodolites are mobile, they are placed at accurately surveyed locations to provide necessary precision in calculating trajectories.
Linkup of Radars, Cameras
One thing the cinetheodolite operator doesn’t have to worry about is finding the target and focusing on it. The optical trackers – both the cinetheodolites and several telescopes that are used for documenting the events of a test, but not position – are combined into a system that also includes radar and a computer at the command post (CP). The radars can determine a range as well as azimuth and elevation. This information, from as many as five radars, goes to the CP by microwave and fiberoptic links, along with a time signal for synchronization. From the CP the data goes out to all the tracking stations, each which has a computer. Each station’s computer uses the data from radars that may be miles away to calculate the direction to point the camera and the correct distance for focusing.
That information is handy, explains Ron, both for picking up the target when it first comes over the horizon and for keeping it in focus. What he doesn’t say, but what is apparent from films of TTR tests, is that the camera operators are truly indispensable links in the system. They have to keep the cinetheodolites and telescopes steady on the test object even when the unexpected happens, if a test is to yield useful data.
“There is no script for any of this”, comments 7514 Supervisor Carl Smith, while showing tape footage where the unexpected did happen, such as a bomb’s parachute failing to open or a cargo-delivery parachute ripping into useless pieces. “It takes an awful lot of experience for a guy driving a heavy camera mount to react to a failure and get something useful for the engineers”, says Carl.
The same applies to radar operators. Though the radars can automatically track an object such as an aircraft, the aircraft is no longer the object of interest after it drops, for example, a bomb. So at each radar site, one operator handles a control that keeps the radar pointed at the correct object. This manual override is particularly necessary for complex tests, such as the one conducted last February involving a B-1B bomber, two F-16s and small rockets (see “TTR Delivered the Goods for Desert Storm“).
“The radars are also important for range safety”, says Gary West, TTR safety officer and Supervisor of Range Operations Div. 7513. “They confirm that the airspace is clear for the test and that the approaching aircraft is on course. To run a range like this”, says Gary, “definitely takes a combination of radar and optics.”
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