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View Full Version : How does the ALP determine distance (parking sensor mode)?



awj223
06-20-2014, 09:34 PM
LIDAR guns determine distance by the formula t=2d/c, where d is the distance and c is the speed of light. How does the ALP do it? I was behind a truck today, and the ALP sensors started giving a parking alert. I was at least 10 FEET away from the truck's bumper.

I've noticed that shiny things (like chrome) tend to set the thing off, much farther away than they should. How exactly are the ALP sensors determining distance?

tmcmenam
06-20-2014, 09:37 PM
Its got to be IR light intensity, since colors/chrome seem to change the range of the parking feature a lot.

awj223
06-20-2014, 09:39 PM
I wonder if it's actually sending out IR pulses, and if it is, whether disabling the parking sensor mode would prolong the life of the sensors (as well as avoid polluting the area around the car with 905nm light, which can cause falses on other people's jammers and detectors).

BestRadarDetectors
06-20-2014, 09:46 PM
I wonder if it's actually sending out IR pulses, and if it is, whether disabling the parking sensor mode would prolong the life of the sensors (as well as avoid polluting the area around the car with 905nm light, which can cause falses on other people's jammers and detectors).

AL Sensors by design always send out pulses to check distance to the vehicles in front of you. They have been doing this for many years with no issues. If you actually turned off the parking mode it would only turn off the alerts but the heads would still send out the random pulses. Its part of the design... After all they are advanced parking sensors and are sold that way. In most cases with my setting set at Level 3 I get parking alerts at 2-3FT but if there is heavy chrome in front of you it will alert at greater distance. I was behind a Classic car with chrome bumpers and I was getting around 8FT alerts because of all the reflection from the chrome.

Tman
06-20-2014, 09:55 PM
I wonder if it's actually sending out IR pulses, and if it is, whether disabling the parking sensor mode would prolong the life of the sensors (as well as avoid polluting the area around the car with 905nm light, which can cause falses on other people's jammers and detectors).

It sends out IR pulses at very low intensity , the parking pulses are always on , if you cancel the parking you only cancel
the bipps.

As far as i know , a laser diode is good for 50,000 hours when run within the specifications ,
ur good for 2083.3333 years if run 24\24 :friendly_wink:

awj223
06-20-2014, 10:09 PM
Why don't they change it to measure distance by round trip time instead of IR intensity, to eliminate falses from shiny surfaces?

RedRocket
06-21-2014, 07:35 AM
Why don't they change it to measure distance by round trip time instead of IR intensity, to eliminate falses from shiny surfaces?Apply some logic here,it's b/c at the speed of light a couple of feet separation distance is an infinitesimally small amount of time duration to calculate & display w/o using a Cray computer processing power inside your AL-P CPU. :nevreness:

awj223
06-21-2014, 09:59 AM
Apply some logic here,it's b/c at the speed of light a couple of feet separation distance is an infinitesimally small amount of time duration to calculate & display w/o using a Cray computer processing power inside your AL-P CPU. :nevreness:

The CPU inside those ALPs is probably more powerful than those inside the Cray-1 were. In any case, a LIDAR gun MUST be able to measure distance accurately or it would never be certified to measure speed. The range accuracy quoted on most guns is +/-6", which is enough to use this method for the parking sensors too.

BestRadarDetectors
06-21-2014, 10:04 AM
The CPU inside those ALPs is probably more powerful than those inside the Cray-1 were. In any case, a LIDAR gun MUST be able to measure distance accurately or it would never be certified to measure speed. The range accuracy quoted on most guns is +/-6", which is enough to use this method for the parking sensors too.

Do you want to waste resources on the ALP worrying about how many inches or feet you are away from the vehicle in front of you or do you think the resources are better spent monitoring in defense mode for interference from other sources? Parking sensors operate just fine the way they work and defense works exceptionally well at the same time.

oddpedestrian
06-21-2014, 12:57 PM
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