Range extender

I got an email from a coworker the other day about some useful things that you can do with your cell phone. It was a forward so I didn’t pay too much attention to it but nonetheless I read it. There was one section of the email that informed you how to use your cell phone to unlock your car. I didn’t have a keyless entry system in my car so I had no way of test it out.

Does your car have remote keyless entry? This may come in handy someday. Good reason to own a cell phone: If you lock your keys in the car and the spare keys are at home, call someone at home on their cell phone from your cell phone. Hold your cell phone about a foot from your car door and have the person at your home press the unlock button, holding it near the mobile phone on their end. Your car will unlock. It’ll save someone from having to drive your keys to you. Distance is no object. You could be hundreds of miles away, and if you can reach someone who has the other “remote” for your car, you can unlock the doors (or the trunk).

Usually, every Friday, my coworkers and I would go out for lunch. When we got out of the car, my coworker wanted to test out this theory. The driver walked down the street to the restaurant while my coworker stayed behind. Then my coworker called the driver and asked her to press the unlock button. Nothing happened so we were a little disappointed. We thought nothing of it and went to lunch.

The other day, my friends and I were hanging out around Pier 1. It started to get dark so we started heading to the parking lot. One of my friends had a keyless remote for his car so he unlocked it from away. That’s when it occurred to me to try out the trick again. I told him about it and I wanted to test it out to see if maybe it’ll work. He had a really good system since he want about 100m away from the car and it still worked. Then I had an idea of taking his remote to the top of the hill and trying it from there.


The green X is the location of my friend’s car. The blue X is where he’s located when he tried to unlock the car. From that location, he was able to unlock his doors. The red X is where I was standing when I tested it. It didn’t work at first but when I called my friend on the cell phone and tested it, it worked.

It worked over the phone from that far of a distance so we decided to test out how far we could go before it stopped working. My friend and I drove to my house while the other car drove half way across town. My friend called me on the cell phone and we started the test. After a few click, nothing happened. Another friend thought that it might work if we somehow amplified the signal. He told me to call him and start a we way call with him and my other friend in hopes of amplifying the signal. At first there was a lot of feedback because both of them were on speaker phone with me so the sound was being looped back but after that part was quiet down, I tried the keyless remote again. Unfortunately, nothing happened. I guess there’s a bit of a range to this thing.

There might be a range issue when it comes to transmitting and receiving radio signals. I think there’s something wrong with their speaker phones or something and it wasn’t outputting the sound correctly. The signal that is being transmitted from the keyless remote is just a radio signal. As long as the receiver is able to detect that signal, the car door should unlock. I’m guessing that as the radio signal is being transmitting, it’s losing its momentum so when it gets outputted, it’s not strong enough for the receiver to detect. I’ll have to look into that to see if that’s the case or not. Either way, this is a cool like trick to try out.

2 replies on “Range extender”

  1. I was wondering. Since it’s a radio signal, you can track the signal and if you have the right program you can probably convert the signal to something that humans can read.. well maybe. Lets just say there is a program that can convert radio signal to a format humans can read. If you do this trick with a keyless remote. Someone or the cellphone network company can get hold of the radio signal information and then duplicate those signal and make a new keyless remote. What would you do then if you were to own a very rare super car and do this trick? Haha.. suckers..

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