[Spacebug]

Originally Posted by claykin

In your original post you mentioned only about the sensors beeping. Do you recall if the graphic showed an obstruction (the post) but the obstruction just didn't audibly announce itself before it bashed in your bumper?

As far as i recall i did not hear or see anything. My wife was in the car with me and she didn't see anything either. I was flipping between looking in all three mirrors when reversing so can not be 100% certain that the graphic was not showing the obstruction.

I have been testing the sensors and the graphic does look to be a little out of sync with the sensors. I have a video of the graphic showing the first hint of red but no beeping for a brief period whilst reversing. Basically i can be reversing up to a wall at a 'very' slow speed and i can get the graphic jumping backwards and forwards along with audible warnings that come and go.

The key thing, however, is that there is some kind of warning whereas when i hit that post there was none. I suspect that the post was just too low to be seen by the sensors.

All of the above is academic anyway as in my mind the sensors are still substandard compared to the outgoing E90/91 models. I aim to do a crude latency test over the weekend. I'll stand clear of the sensors and flick something in front of the sensor whilst recording the sounds from inside the car. The only thing i need to figure out is how i tie together the trigger points of dropping something in front of the sensors whilst recording the audio in the car.

What i need is somekind of remote switch to a flash light/LED. I could then set a camera/iphone up recording the graphic, LED and audio.

OK i'm thinking out loud here.. at the danger of this becoming silly, it could get a little more technical/accurate. I have access to digital scope and a photdiode (with a 3uS response time). I could mount the photodiode near the sensor with a light source shinning on it. When i trigger the sensor (by dropping something in front of it) it would interrupt the light source on the photodiode. What i would then need to do is hook a probe up to the speaker (Left or Right depending on which sensor) and look for the beep. I could then correlate the tow signals and determine the latency.

The one thing i can not do is carry out the same test on an E90/91 (as i don't know anyone who owns one).

The question is, what is an acceptable latency? Also, does it matter what type of material is used? I would have thought that material would play a factor in detection range, which would not be affected by this test since i would be dropping something in close up to the sensor.

For acceptable latency i guess once i know what the latency is this could be converted to speed vs the operating range of the sensors. i.e if the speed that you reverse means that you will travel more than the operating range of the sensors within the latency period of the sensors then the sensors will not respond before you hit something...

I'm getting carried away now...