Near Intersection of I-35 & I-90 Southern Mn. | Finding the signal wire and splitting it to go to two devices is usually fine. Generally I would split the other wire also (signal ground) also and run them both to each device. That may or may not be necessary. I ran a Raven 440 with a single wire for speed for several years.
Radar signals like most other flow meter signals etc. work on a "shorting" concept. When the device (flow meter or radar gun) senses movement it "shorts" the signal line temporarily to ground. The flow meter or radar gun then "releases" the signal wire from ground and it returns to a higher voltage due to a pull up resistor. Each monitor is watching for this change from HIGH to LOW and counts them. Each device then uses its own calibration number to convert these Pulses into useful measurements such as gallons, feet, etc. It can then display those values or use them in other calculations.
The flow meter or radar gun has the ability to "sink" a certain amount of current so typically they can supply several devices. There would be a limit but generally this is not a problem with a couple of monitors. When radar first became popular, some companies made splitters and amplifiers that could be used when more than one monitor was being used at the same time. As the electronics improved, the need for these amplifiers disappeared. Some of them included "slow down" circuitry so that a radar gun could be used with the older monitors that were expecting to be connected to wheel magnetic sensors. The need for the "slow down" kits has disappeared also. |
Speed source
