Conversations in the hallways and suites among delegates to the NAB convention at the Stevens Hotel in Chicago, April 6-8, 1964, were dominated by a single topic: a panel truck equipped with rotating antennas and electromagnetic scanning gear, which could detect and record all TV set usage within a 300-yard range as the truck cruised at speeds of 5 to 50 miles per hour. Most broadcast station owners, managers, and executives had much more confidence in electronic technology than in ratings produced by sample interviews. Consequently, the Tanner Engineering Co. display was quickly accepted at face value as the solution to the audience measurement problem.
The technique, called Tanner Electronic Survey Tabulation (TEST), had been developed by James L. Tanner, a young San Diego inventor with some broadcast experience. Tanner stressed that similar earlier proposals had depended on the TV sets' local oscillator radiation, whereas his system picked up, magnetically, the horizontal scanning signal radiating from sets in operation. Equipment in the truck compared radiated signals from sets with TV station signals (received via a separate loop antenna) to determine the channel tuned in. Up to 3500 sets could be counted per half hour. Data were recorded on tape and transmitted periodically to a computer center. Equipped trucks cost $15,000 to $20,000.
Tanner did not plan to set up a rating service; he merely offered his system and equipment on a lease basis to interested research companies. Unfortunately, mechanical problems with the truck prevented field demonstrations following the convention.
Researchers quickly pointed out that the system had no record of untuned sets, and therefore all that could be produced were "share of audience" figures. Moreover, there was little virtue in touring around to pick up average-minute figures for different times from block to block. It might be better to use fixed locations with known parameters. Engineers questioned the use of the system near apartment houses or for older, weaker sets. Then the cost seemed prohibitive; a national service would require a minimum of several hundred trucks, which would mean a multimillion-dollar investment for field equipment alone.
The number of research and economic questions surrounding the Tanner technique apparently were never seriously addressed. No research company ever acquired a Tanner truck, and as far as public record is concerned, no practical use was ever made of TEST.