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Old 19th October 2005, 19:55   #16
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Quote:
Originally Posted by RX135
Didn't get this last part which you said is impossible. If let's say, the frequency is 5KHz, can't we sample at 10KHz and pass it on?
Public phone systems all around the world sample only at 8KHz, this is not something you can change on one side.
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Old 19th October 2005, 20:38   #17
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Quote:
Originally Posted by Samurai
Public phone systems all around the world sample only at 8KHz, this is not something you can change on one side.
Why does sound come into picture to open car doors? when we press the button on the remote; remote does not make the sound the system in the car makes the sound; now how is that got to do anything with MIC etc...
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Old 19th October 2005, 20:48   #18
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Quote:
Originally Posted by bruce
Why does sound come into picture to open car doors? when we press the button on the remote; remote does not make the sound the system in the car makes the sound; now how is that got to do anything with MIC etc...
Well, you are one who dragged in the phone. And the phone sends and receives sound, and has a mic etc...

Sound is just a wave like any other waves. If it is moving in your direction and it is in human audible frequency range, you hear it. If it is in higher frequencies, you don't hear it.

Remote sends a wave that is way beyond the human audible frequency, hence you don't hear it. Besides, it sends an encrypted signal probably packaged in a carrier frequency. Ok, now we are getting too technical here, not something I intended.
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Old 19th October 2005, 20:54   #19
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Default EMI Hormonics

Samurai makes me put in my thoughts too!
I have to agree with Samurai, technically it does not work.
If it works, how does it work?

My 2 cents..
I think the answer lies in two phenomenon. EMI(Electro magnetic interference) and Hormonics!
The remote transmitter is an intentional antenna. It also has signal which may be audio frequency (I am guessing) and a carrier, Radio Frequency.
And the telephone may be a unintentional antenna, which is capable of recieving the interference and letting in the audio signal or its hormonics into the system.
These signals may get carried along even wothout a notice.
And at the car end, both cel phone and autocop reciever are intentional antennea which interfere with each other whose frequencies or their hormonic frequencies match somewhere which make them probably work.

Remember, Hormonics do not have the same signal stengths as original signals. So airfoil's experiments might have woked sometimes and sometimes not!
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Old 19th October 2005, 20:56   #20
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Pordon me if I am getting too technical the non-car way!
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Old 19th October 2005, 21:30   #21
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Quote:
Originally Posted by airfoil
I've tried this and it works!

A little bit of trial & error is involved - it worked for me when I put the cell phone on speaker. I use the Autocop system.
Thats really hard to belive.
I had read this article a whlie back and i think its total BS.
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Old 19th October 2005, 21:43   #22
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Quote:
Originally Posted by DRC
These signals may get carried along even wothout a notice.
But here is the flaw in the logic... All cellphone transmissions are done after A2D conversion which will eliminate any possibility of stray harmonics beyond 4KHz frequency. Therefore they can't get a free ride.
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Old 19th October 2005, 22:15   #23
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I guess it'll only work if its radio waves.... if its infrared.....like in my car... no way its going to work...
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Old 19th October 2005, 23:15   #24
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Quote:
Originally Posted by Samurai
Now, the human voice falls within 2KHz-4KHz frequency. .
while your theory looks right the range of human voice is aout 300hz to 4khz.

also i think DRC may be right; the freq being used is the modulating freq not the modulated freq.

Last edited by navin : 19th October 2005 at 23:19.
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Old 19th October 2005, 23:37   #25
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Quote:
Originally Posted by navin
while your theory looks right the range of human voice is aout 300hz to 4khz..
You are right. Somehow that 2K stuck in mind. Anyway, the phone will catch anything between 0 to 4KHz.

Quote:
Originally Posted by navin
also i think DRC may be right; the freq being used is the modulating freq not the modulated freq.
But the phone transmissions are not single stage operations. Phone to exchange, exchange to other exchange, exchange to phone, there will be multiple stages. If some variation was introduced into carrier frequency (Kinda FM effect), the carrier will be discarded after the first stage. The second stage is usually through TDM via fiber, no carrier wave will be involved, that will be pure digital transmission.
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Old 19th October 2005, 23:48   #26
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I barely see any chance that this may ever work.

The reason is all good quality remote control systems use code-hopping technology to provide security that only the intended pair of Tx(Transmitter=Remote here) and the Rx (Receiver=base Unit here) matches and the matched pair only unlocks the system.

The Code-hopping by the very nature of it works much out of the upper audio frequency ceiling capable on a cell phone or a wireline tel system(4 Khz). Even after this, the hopping code is modulated by a high frequency carrier and sent by the transmitter.

So even the harmonics of it working out a correct code can be ruled out completely.

I'm 101% confident that this is just a hoax...

Last edited by Digital Vampire : 19th October 2005 at 23:49.
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Old 20th October 2005, 00:14   #27
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Myself has landed up in this mess of keeping the key inside and getting the car doors accidentally autolocked. And the most wierd part is it happened to me during my honeymoon trip at a remote hill station in Kerala.

After having spend nearly 20 minutes in the bitter cold exhausing all the known tricks (even the safety pin tricks seen in movies...lol)waiting for some help in the deserted hillside road, I decided to finally break open the glass. Just then one tourist taxi came and the driver happened to know how to "lift" cars.

In 2 minutes flat, he opened the door with simplest of the tricks which even defeated my 12K worth security system.

For people who are curious to know the trick: Just lift the glass beading and slide a thin tree stem or even a plastic ruler to release the latch inside... it is as simple as that.


It was a revelation to me and a lesson well learnt.

Never enable the autolock feature and never leave anything too valuable inside the car. There is every possible chance that it can be lifted very easily.

Use Engine Immobilizer to safeguard the car itself from being lifted this way. But again i heard that even the engine immobilizer can be fooled easily.

After this incident, i've tried this on my second car and my friends car and it all worked the same...You can simply open the car door with a Plastic Ruler!!!! Thought i took a little more than 5 minutes than the "expeienced" Taxi Driver. many thanks to him anyway...

Take care.. It is your hard earned money...and companies dont care a damn about security. I wonder whether this is kept as a feature rather than a design flaw to get inside in such emergency situations. But unfortunately the crooks know this and now you all too ;-)

Last edited by Digital Vampire : 20th October 2005 at 00:21.
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Old 20th October 2005, 00:18   #28
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Hmm, didn't think this topic would get so technical. One of the links posted states that obviously the frequencies of the waves emitted froim the remote are different from the ones emitted by the phone. In addition, most high-end car security systems change their frequencies regularly.
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Old 20th October 2005, 13:25   #29
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Yes I guess nobody read the links I posted.. The remotes work on high RFs
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Old 20th October 2005, 13:28   #30
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Hmm!!
Well I have not tried this either..! I am not proposing a theory here but, just thinking aloud!

I guess (only guess) the signal may still be in audio spectrum. Remember, in the whole experiment we dont care to hear in the phone.

Have you ever heard of a crazy noise on the speaker either in the music system or an other phone when a cell phone is nearby and you recieve a call on cell phone? I think this means, cell phone is capable of producing broad spectrum noise in all possible hormonics of carrier and otherwise.

Bottom line, this phenomenon may work, just because it is not a perfect world!
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