|All our interactive displays work in the same way. The speed to be displayed is measured by one of our Speedar radars, which may be hand-held, mounted externally on the display or built internally into the display.
The Speedar may be either the standard version or a Speedlog version. The speed measured by the Speedar or Speedlog is sent via an RS232 serial link to the display controller. Since Speedar is a direction sensing radar, as well as measuring speed, it knows whether a vehicle is approaching or receding.
This direction information is also sent to the display, so that the controller can discard the speeds of vehicles which are travelling away from the display and would not therefore be able to see it.
The controller then drives the appropriate segments in the electromagnetic display or the pixel groups in the LED display.
In the electromechanical displays the minimum speed to be shown is settable via thumbwheel switches on the back of the unit. The display may also be programmed to blank above set speeds to stop drivers trying to see how fast they can go.
In the LED displays several inbuilt messages can be shown at settable speed thresholds, along with a minimum and maximum speed to be shown. These are programmable via a serial link from a pc or laptop.
Any of the following combinations may be chosen, show all speeds, show messages at different threshold speeds, blank speed at message threshold, show messages only.