With my PicoScope, laptop and new test lead in hand I went out the car park to test my parking sensors. With health and safety in mind, I was joined by a colleague who controlled the vehicle. He sat with the engine running in reverse, with the handbrake on and a foot on the brake. This way I could safely capture a waveform of the reverse parking sensor. When I had captured the waveform my colleague put the vehicle in park and turned the engine off, leaving the hand brake on.
I used the following settings:
You can see the captured waveform below:
So what did this waveform tell me? Well on this occasion we can see two signals from the operating parking sensor.
Waveform zoomed in:
The image above highlights the parking sensor activity with finer detail thanks to the zoom function in PicoScope.
By using the signal rulers, the peak to peak value of the obtained signal can be measured to determine the signal strength.
Typical values range from 50 mV to 200 mV depending on location and distance in relation to the sensor. The frequency of the measured signal can also be established with the time rulers, in the example above the parking sensors are transmitting a frequency of approximately 46 kHz.