ACCURACY OF ALIGNING THE MOVABLE RANGE MARKER WITH BLIPS ON THE PLAN POSITION INDICATOR.
SYSTEMS RESEARCH FIELD LAB JOHNS HOPKINS UNIV JAMESTOWN R I
Pagination or Media Count:
Four experiments were performed to determine the accuracy of aligning the movable range marker on the rotating sweep of the PPI with blips on a 20-mile sweep. The procedure consisted of mixing target simulator and range marker video and displaying the combined signals on the experimental PPIs and the VF precision indicators used for making the measurements. The task of the PPI operator was to align his marker as accurately as possible with the center of the blip. The VF operator then measured the degree and direction of the discrepancy between target and marker on the B-scope. These errors, expressed in yards, were the data used for describing alignment accuracy. In the first three experiments operator differences were significant. In the fourth experiment they were not. Since a number of the same operators served in all experiments this may have been due to practice. A constant error was found in the last three experiments. Operators tended to align the marker at a range about 10 yards short of the center of the target. These experiments set a value for the accuracy of the psychophysical performance which is the basis for the use of one kind of range strobe. The order of accuracy with which radarmen can adjust the movable range marker to a target suggests that PPI equipments furnished with stable, linear ranging circuits and more finely graduated counters could be read much more accurately than is now the case.
- Active and Passive Radar Detection and Equipment