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Freeze frame: this TV technology can handle serious tasks.


The advent of practical, efficient means of transmitting still video images over the dial-up telephone system has made possible a host of applications unimagined in the past.

Some of these uses of freeze-frame or slow-scan television have saved hundreds of thousands of dollars during a single use, saved lives, provided rapid transmission of scientific data, allowed remote education and environment monitoring, and enhanced corporate communications.

At least 20 vendors supply a variety of equipment, both black-and-white and color.

Here are 10 ways slow-scan has been used:

Banks have to verify signatures on checks and other notes.

Dedicated leased audio lines provide a means of low-cost cosmunication.

A bank in Denver that opened a drive-in branch three blocks from its main office originally planned to use conventional TV to access central signature files.

But to lease telco wideband video circuits would cost $300 per month.

By comparison, dedicated voice-grade audio channel costs were about $4 per month, a savings of nearly $3500 per year.

Also, the slow-scan system transmitted the entire signature in less than 2 seconds, while the memory at the receiving location could retain a picture as long as desired.

The core closed-circuit TV system used for signature verification throughout the main bank was tied up for only a short period.

The engineering department of the University of British Columbia (UBC) developed a device that could do three-dimensional machining from optical input data.

With the medical school of another Canadian university, UBC tested remote manufacturing of artificial limbs through transmission of slo-scan TV images over phone lines from one school to the other.

When an amputee was sufficiently recovered, any remaining limb was placed against a black background, viewed by a TV camera, and frozen in memory.

The image was then transmitted to UBC, where it was decoded and entered into computer memory.

The patient was slowly rotated and 60 pictures sent, to provide 3D information for computer analysis.

Once the automatic machining process was initiated, a "mirror image" of the remaining limb was created for proper symmetry.

During the recent restoration of the Statue of Liberty, trans-Atlantic video communications became important.

Original drawings and models were in an architect's office in Paris.

Slow-scan TV was used to coordinate activities on site at Ellis Island with Paris and with the supervising architect in New York.

In skiing mecca Vail, Colo., slow-scan lets the ski-lift operator at the top of the mountain monitor crowd lines at the bottom and adjust operating conditions.

Slow-scan TV has been used to observe ship movements in the English channel and the St. Lawrence Seaway.

In the latter, traffic control can be important, particularly as ships approach locks.

Normally, ship position is reported by radio and lock use priorities assigned on the basis of proximity, but some captains have been known to lie to speed their passage.

In Alaska the main approach to the Valdez airports is monitored in the control tower from a TV camera location some 20 miles distant, with radio communications from tower to airplane providing appropriate advice on flying conditions.

Another situation in Alaska involves maintenance of remotely located, unattended communications relay stations. In this instance helicopter crews can monitor visibility and other weather conditions at the relay site before taking off on a mission.

The FAA uses slow-scan TV for weather condition monitoring on the West Coast. At Stampede Pass near Seattle, a camera mounted on a rotating platform sequentially transmits views of four quadrants to a flight operations office at Boeing Field.

Aviators can walk in, look at the TV screen, and decide if they would like to take this particular flight path.

The use of radar to assess local and regional weather conditions is enhanced by slow-scan transmission of radar images via dedicated and dial-up telephone circuits.

That's how your local TV station can call the regional facility and have up-to-the-minute pictures on the 6 o'clock news.

Pictures came from the Voyager spacecraft through slow-scan technology. During the Neptune and Uranus encounters slow-s an TV was used to distribute pictures received at the Jet Propulsion Laboraty in California to audiences throughout the world.

Both amateur radio transmission and "dial-up" phone lines were used to relay images from the spacecraft.

The University of Hawaii brought a series of eminent "guest" lecturers from the mainland into the classroom with slow scan.

A compact system is shipped to the invited individual, and the presentation is made directly from his or her office or laboratory.

The system uses two-way video as well as audio, giving parity in communication, and only one or two hours is taken from a busy guest speaker's schedule, making a lecture even more convenient than a drive across town.

The university has also pioneered in ad hoc long-distance slow-scan TV, allowing students in Hawaii to electronically see and talk to their counterparts in Japan, Taiwan, Korea, and China.
COPYRIGHT 1990 Nelson Publishing
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Author:Southworth, Glen
Publication:Communications News
Date:Feb 1, 1990
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