I want to extend the cable of the Weatherproof Ultrasonic Sensor with Separate Probe and was wondering if this would have any adverse effects on the operation of this device? (ie Is there a limit on the length of cable between the probe and the sensor circuitry, after which the termination impedance would need to be adjusted?)
Are these sensors a good choice for detecting movement of people or vehicles?
You can work out the resistance of the cable If you are running at 30mA I would try to keep the drop less than .1 volt so a line resistance of 3.3Ohms. There can be other problems such as noise and time delay with really long cables and noise so ideally, you keep the cable as short as is possible.
This shoudl work for that though the detection range is 4.5meters so it would depend on your application.