Keyless Entry System -- how does it work


#1

Hi! My name is Lauren and I’m working on a physics project for school. It is
an inquiry project on “How Things Work” and I’m looking into how a Keyless
Entry System works, aka when I press the button on my keys, how does it
unlock my car. I was hoping anyone would have some insight or information that
could help me in my project and understanding of this system. Please respond
with any info you may think is helpful! Thanks so much.


#2

The fob broadcasts a short-range radio signal. An antenna in the car picks the signal up and feeds it to a computer which verifies that the key fob is sending the correct security codes. On confirmation, it unlocks the doors.

The physics of it is the same as any other radio signal transmission and reception.


#3

Anyone doing research in this day and age should take advantage of the web search engines.


#4

We are required to reach out to “experts in the field of inquiry”.


#5

The experts here all have screen names and very few will give out their personal information.


#6

Academic reality check: Asking a question on a web forum full of anonymous people for whom you do not have knowledge as to their qualifications is not proper academic research, nor is it “experts in the field of inquiry.”

If this is high school or above, I’d fail a student who just posted on an internet forum for their research.


#7

I appreciate your concern. I’m not looking for personal information rather, asking for understanding towards a topic from people more knowledgeable than I about cars. I have already looked into my topic on search engines and I am looking for any further information or insight. Thank you.


#8

Thank you but I have already talked to my teacher about this. She says that this suffices as a perfectly fine recourse. I’m only looking for some insight as to how keyless entry systems work from people knowledgeable about cars, not criticism for my academic inquiry. Thanks for your concern, but I am only looking for information, which is the purpose of the forum, not to critics people looking for help.


#9

This means your teacher is willing to accept completely false facts from an unknown person on the internet. That would make me suspect any subject she teaches.


#10

Again, thank you for your concern, but my academic research integrity is not the purpose of this forum. Either please provide some helpful information regarding my original inquiry or stop.


#11

Something you are going to learn as you gain more world experience is that when you post something in a public forum, others are free to say whatever they want in response. We understand what your objective was in coming here, but frankly we are not here solely to do your homework for you and are free to comment on the academic integrity of yours and your teachers’ methods. Telling us to stop is silly - this is our house and it is quite common here for advice to be given tangential to the question asked. You will not get away with this in college, and your teachers should be preparing you for post-secondary life.


#12

Yup, and it unlocks the doors by sending a 12 volt electrical current from the car’s battery to a little electric motor at each door that spins a gear attached to a rack (a rod with gear teeth) that tugs a rod that moves a pin out of the way of the door latch so it will open when the handle is pulled.

You lock it by spinning the motor the other way so the pin is inserted to block the latch from un-latching.


#13

The OP may be interested in knowing that Mercedes-Benz used to use infrared light, instead of radio signals.

Well, if the OP’s teacher decides to quit the field of education, she would now qualify as a candidate for POTUS, because tacitly accepting internet information (from questionable sources) as factual is now the norm in that position.


#14

Shame on you for picking on the Prevaricator Of The United States!


#15

@lmsabes18 May I suggest you read what @shadowfax posted above (twice), because he is 100% correct. I have to tell you as a very part-time adjunct professor at a local Community College, I too would fail you for using internet forum as their research.

May I suggest that you take what you learned via internet search and on this forum to a local mechanic or dealership mechanic to corroborate your information, and use their direct quotes in your project/paper? That is a far better source of information to quote from :slight_smile:


#16

I get much good information off forums and videos, I would qualify this as a good source for asking automotive questions, as did the teacher. As I am not familiar with keyless remote systems different manufacturers may have different approaches.


#17

Since we listen to the radio in the car while we drive, been doing that for years, that pretty much proves it is possible to transmit a radio signal from outside the car and receiving it inside. And after the reception of the radio signal, it’s also pretty clear that could electronically initiate the unlocking of the door. That’s how a garage door opener works. What isn’t quite so obvious is how it is possible to insure only the owner’s fob can unlock the door, and how to prevent someone with a radio receiver listening in from decoding the owner’s fob signal and then using that knowledge to open the door themselves. And steal all the owner’s Snickers bars.

OP might search on something like “one way encryption mapping”, “pseudo random sequences”, etc.


#18

Thank you!


#19

Thank you for your genuine advice and that was my exact intent. I’m just going on here as only one possible recourse and I will be fact checking everything that I read on here. I understand @shadowfax is trying to say and I appreciate the concern and understand the frustration thinking that I am using this to have other people “do my homework”. I also really appreciate your input as a professor and I have taken this up with my teacher and expressed to her the concerns brought up not only by me but the comments on the forum. We have at length talked about how she was the one to originally suggest this website and how it should only be used as one possible resource and then fact check and do deeper analysis.


#20

Thank you so much!