# Keys Locked In Vehicle, Far From Home?



## SINC (Feb 16, 2001)

We've all done it at one time or another. We're miles from home and inadvertently locked the keys in the car at the mall. There is an extra set at home and now you have to use your cell to call home for someone to somehow get that extra set of keys to you.

No more, if you own a vehicle with remote entry. Simply use the cell to call home, ask someone on the other end to get the spare key fob for the vehicle. Then have them hold the fob to the phone and depress the button to open the door. Meanwhile, you hold your cell about a foot from the door lock, and presto, the vehicles door unlocks.

Call it a low tech version of "On Star", but it apparently does work. Not a bad thing to know if you or someone else has this happen to them.

Cheers


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## SkyHook (Jan 23, 2001)

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## SINC (Feb 16, 2001)

Like I said, the idea "apparently" works.

This was sent to me by a regular reader who has given me dozens of tips over the years that were always reliable. He claims to have tested this and says it works. Here is what he wrote to me:

"This is absoulutely fantastic.  We have all done this, especially on a cold winter day/night. Locked the keys in our car?   Now there is an easy solution. There are 2 conditions. 1- your keys must be the newer " key fob" type--and 2- you must have a cell phone.

When locked out, you simply phone home ( or wherever your spare set of key fob's are located) using a cell phone. This person then "buzz's" the key fob into the phone receiver..You hold your cell phone about a foot from the locked out door---and presto---the door will un-lock.  I know this works, because I have tried it myself.  Please share this with your readers---as my Christmas gift to all."

Think of the signal a fax machine puts out to connect with another fax. It is much the same type of thing, so I don't see why it would not work.

I will try to test this in the next few days unless someone happens to have an opportunity today. Just remember to be sure and be far enough away from the vehicle that the fob is out of range for normal door opening.

Cheers


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## MacDoc (Nov 3, 2001)

Works like a charm  
We just did it with both Windstars - one on the 900 mHz phone the other on the cell.

Handsfree on both ends for us worked best.
18" from the driver door - point the speaker at the door lock.  

Very cool.


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## SINC (Feb 16, 2001)

Thanks for the test MacDoc. I saw no reason to doubt the reader!

Cheers


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## SkyHook (Jan 23, 2001)

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## SINC (Feb 16, 2001)

> Anybody know what frequency the door locks work at?


Can't be any specific frequency or your fob would open anyone's vehicle.

More likely works within a certain range of frequencies, a la garage door openers, or even auto car starters.

Years ago it was quite common for your garage door opener to open other garage doors, say a few blocks from your home. (We used to experiment with this by pushing it willy nilly as we drove along!) 

Today, with the number of vehicles using some type of auto opener or start, the frequency range must be vast to avoid duplication.

Cheers


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## Greenman (Feb 22, 2003)

Hmmm...

Why am I thinking "Kryptonite bike lock fiasco" ...part 2


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## MaxPower (Jan 30, 2003)

Thanks SINC.

Where were you last weekend when my wife lost her keys.

I got the phone call that she lost them, packed my son up and as soon as we were pulling out of the driveway, she found them  

That little trick might have helped me there. Oh well. It got me out of the house anyway. My boy and I went to get a feed of Bacon & Eggs at the local greasy spoon.


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## MacDoc (Nov 3, 2001)

SkyHook - it's bugging me too - piggy back on the RF is the best I can come up with.

There has to be a carrier signal and the fob must modulate that. I suspect the antennae NOT the speaker is opening the door.

Cell phone to cell phone makes sense but would it over a long distance?? No.








Maybe you have to be on the same cell tower???

Bears some experimenting tomorrow - too damn cold right now.

It should NOT work. It did at a distance the fob would not normally function at. Must be amplifying the fob signal in some way.

Hummph









Now my fob usually works from about 30-40' away.
Update
I stand in the kitchen at the back of the house with the garage and several walls in the way to the car which is at the curb about 90' away.
Damn thing works from within the house.....ergo the false positive....but why so far away.

Soooooooo.......*urban legend for the cell phone trick* BUT something is amplifying the fob. Maybe the 900 mHz phone in my pocket while I was doing this. It works as far as the curb as well.

E-rumours at their best. Too bad - nifty idea. Since a cell phone IS a rf transmitter someone could come up with a device to encode/decode but I guess it's a lot easier just to NOT lock your keys in.









Good laugh and bit of a puzzle.


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## iPetie (Nov 25, 2003)

The answer is:

Key fobs are frequency emitters, not RF transmitters. That is "THE ONLY" way this can work. The fob emits a frequency which can't be heard by the human ear but can be transmited over basically any interface. iChat, Skype, Cell, land line.

Or it's a hoax! You tell me!


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## MacDoc (Nov 3, 2001)

Hoax.
But FM ( frequency modulated ) IS RF.


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## Perfessor (Oct 10, 2004)

--------------------------------
Hoax.
But FM ( frequency modulated ) IS RF
--------------------------------

Not necessarily. The vibrato in a singer's voice is modulated frequency.


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## MacDoc (Nov 3, 2001)

Yes - FM modulated audio - this is not - unfortunately or it would work overr the phone.


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## SINC (Feb 16, 2001)

If vehicle manufacturers could be persuaded to use FM, are there any drawbacks?

Perhaps there is not enough room on the FM band to make enough different frequencies for fobs to satisfy today's vast numbers of vehicles? 

Still, it would be interesting if the concept worked. A competitor to GM's On Star program, which to my understanding is a paid subscription service, could offer what is perhaps the most used function of On Star as a free benefit using this method.

Cheers


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## MacDoc (Nov 3, 2001)

You mean a FM audio signal not radio which it s now.


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## gordguide (Jan 13, 2001)

Sounds like MacDoc is on the right track; ie the key fob is modulating the cellphone antennae.

The antennae shouldn't be thought of as separately receiving and transmitting; the two operations are one and the same.

Since an antennae is a form of signal amplifier, it will re-transmit everything, at a slightly better signal level. That may be just enough to work at close distances to the car's transceiver for door locks.

If it's a digital key (makes sense) then the specific frequency may be unimportant; the modulated pattern is what is recognized, probably via amplitude rather than frequency.

However, it could also be by frequency. All that would be necessary is that the car's frequency is either in the same band as the cellphone is using or mathematically related to that band (1/2; 1/4; 1/976th, 2x, 16x, a million times, whatever).

For the curious, modulation means one signal affects the other (could be in many ways). It's common, well understood, and forms the basic principle of how radio works at all.

Take one frequency and send/receive it. With the correct test equipment, you will be able to see only that frequency is involved. Add a second frequency and transmit it at the same time as the first, and you will detect both those frequencies, another that represents the difference between them (a "third" that you're not transmitting) and a whole bunch of others that happen to be mathematically related.

You could probably experiment to discover if it's by amplitude or frequency. Use a radio that doesn't work in the same band as the cellphone; perhaps an analog phone or one of those little 2-way radios like a Motorola TalkAbout. You would have to confirm the wavelengths are not fractions or multiples of the cellphone's. If they are not, and it still works, it's by amplitude.

" ... If vehicle manufacturers could be persuaded to use FM, are there any drawbacks? ..."

FM stands for Frequency Modulation; AM for Amplitude Modulation. Both are methods of radio transmission, not necessarily related to the actual radio frequency they use.

We routinely refer to certain bands as AM and FM, but they are just the frequencies assigned by regulators. You can use either method at any frequency, although FM works better at high frequencies and AM works best at lower ones.

Just like FM and AM radio, the auto manufacturers must use a frequency assigned to them for that particular use by Industry Canada; but the actual method is up to them.

[ December 12, 2004, 12:00 PM: Message edited by: gordguide ]


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## jrtech (Sep 24, 2002)

Off topic I know but I am curious is this the basic idea I read about some time back, where the people in Vancouver were caught with a box that would open the security doors on parking lots in Vancouver. I know there was quite a few eyebrows raised as they were or perhaps it was built at one of the local university electronics labs if I remember correctly.


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## gordguide (Jan 13, 2001)

jrtech, it's simple to do such things, if you want.

Remember, all radio is constantly vibrating every molecule on Earth at a whole host of frequencies simultaneously. Your teeth are receiving every radio broadcast in your area; it's just that your teeth don't know how to amplify and decode it.

Get a good multiband receiver, listen for the transmission when someone uses it (which will give you the exact frequency used), and make a transmitter for that frequency. You might need to hack the method or code; and it's this area where any and all security exists. The radio part is trivially easy. Done.


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## iPetie (Nov 25, 2003)

Poor explanation by me. 
Remember the early answering machines that you had to carry a little fob around with you to check messages remotely. You would dial your home number and when the machine picked up, you would hold the fob to the mouth piece of the phone. And presto, like magic, it would rewind and play back your messages. Those fobs where called Emitters(I think) and would transmit an analog frequency over the phone line.


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## MacDoc (Nov 3, 2001)

You mean audio signal. If that were true the fobs might work at a distance.


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## ErnstNL (Apr 12, 2003)

This is really neat. Just a month ago my wife locked her keys in the car at Wal Mart. 
I walked in the rain for 20 mins to get to the car. Next time I'm trying this.
Thanks to you and your contributor, Sinc.


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## Rob (Sep 14, 2002)

I have a simpler solution. Keep a spare key in your wallet or purse, something that you always keep on your person.

This goes for house keys too.

So far, this method hasn't failed me. It's far more reliable than this cell phone method.


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## SINC (Feb 16, 2001)

ErnstNL, please read the entire thread. It does not work, so please do not rely on it.

I prefer Rob's solution. Like Rob, I too have carried an extra door lock key in my wallet for 30 years. (Sorry Rob, I didn't mean to infer you were old!) but you get my point.

It's a wise bit of insurance to carry.

Cheers


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## SkyHook (Jan 23, 2001)

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## SkyHook (Jan 23, 2001)

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## hayesk (Mar 5, 2000)

"Can't be any specific frequency or your fob would open anyone's vehicle."

Uhm... yes they can. If they are digitally encoded. My 2.4GHz cordless phone works for several hundred metres, but I can't listen to the neighbours cordless phones.

Anyway, I would call this a hoax. There are several reasons this won't work:
- most phones are designed to pick up and play human voice - they can't even reproduce highs and lows in music, let alone a signal outside of a human's audible range.
- the digital encoding used by telephone switches to encode your voice to transmit calls over fibre optic lines throw out highs and lows outside of human voice. It's a 64kbps algorithm that is far more primitive than MP3 (it was developed in the 80s). Ever wonder why it's hard to distinguish "S" and "F" sounds over the phone? This is why.
- key fobs use radio transmission not audio - it wouldn't even be picked up by the microphone in your phone
- and finally, you said to place the phone near the lock. Why? Your car doesn't have a separate receiver for each lock, trunk, and panic alarm. There's no RF receiver by the lock. There's only one receiver and it's usually in the centre of the dash board. The only mechanism near the lock is the motor to lock/unlock it, not to pick up the signal.


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## MacDaddy (Jul 16, 2001)

Two things:

1.You claim it a Hoax, yet MacDoc stated that he has done it? How can it be a hoax if somebody here has done it (Especially sombody as esteemed at MacDoc

2. Who makes this product and what is it called!!!! I see lots of what it does, but I did not see anywhere who makes it!


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## MacDoc (Nov 3, 2001)

You did not read the whole thread.
It worked but in an odd circumstance where the fob signal went further than normal most likely due to amplification of the signal by the remote phone system in the house.

It just worked much further than would be normal - read the post.

What we really need is a receiver that can pick up a wide spectrum to be at the other end of the test to see if anything from the fob is being transmitted.

It's slightly possible the fob is modulating the cell phone carrier and then being broadcast at the other end to the lock by the antennae not the speaker but I think it's unlikely.


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## MacDaddy (Jul 16, 2001)

OK, so I missed something when I was reading, but it has worked, even if it was only once!


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## MacDoc (Nov 3, 2001)

But not "as advertised".


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## SkyHook (Jan 23, 2001)

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