Keyless entry
 

http://www.wsdmag.com/Article/Articl...453/13453.html

Hehe, we where actually bored enough to try this, we tried a number of combinations of phone, An 02 3 Series and an 03 Honda Accord, not surprisingly we couldn't get it to work.

Discuss

Re: Keyless entry
 

Remeber that TV show years ago, "It'll Never Work"... this should be there.

Please. Mobile phones haven't got the range to pickup the radio frequency let alone play it back again.

Junk mail sent to confuse the masses & amuse the few.

*awaits counter arguments before refining*

Re: Keyless entry
 

Hmm wheres the BBcode for [counterargument]BLAH BLAH BLAH[/counterargument] ?

Hehe

No-one is playing yet :(

You're rubbish!

HTH

:wink:

Variation on an old spam. I remember reading (and laughing at) claims that Vestax's (then new) PDX2000 turntable would sometimes accidentally stop/start or change pitch when certain mobile phones were near it! It was of course, utter tosh. :D

Mine did. Was when my mate had his old style erricossssson neaar it

Certain central locking keyfobs set off my cheap Asda doorbell playing the ring tones no-one in their right mind would ever set it to... :?

So far it's whistled dixie, twinkled a little star and barked at me...

:lol:

Technology's great! :lol:

Not quite true in this case, not far from the truth, but not quite there.

OK, since no-one wants to play, a little explaination of what's happening.

Your mobile phone picks up voice frequency (VF), translates this into electrical impulses, then translates this further to radio signals, and the whole shebang is reversed at the other end.

What is the range of VF? Approx 300Hz to 3400Hz. If you include guard bands, plus overheads, it's actually sampledat around the 4kHz band. A household phone, since it relies heavily on DTMF, samples at 8kHz. Because a house phone does twice the sampling, this is why sometimes you can have a dodgy signal whilst in a call, the person on the house phone has no problems, the person on the mobile does.

OK, so now we know the theory of how phones work, what about the car transmitters? The article linked to says the transmitter uses 315Mhz. This is 315,000,000Hz. WAY WAY WAY beyond the VF range.

So, why does this work in some cases, and not in others? The reason is the pickup used in the phones to translate audio back to electrical impulses. The speaker can happily emit 315Mhz, you'll never hear it anyway, so why do the manufacturers care? If the pickup is good enough, it will pick up sounds in the frequency beyond that of human hearing. This does take a GOOD pickup though.

Tricky, in your case, the pickup simply wasn't up to scratch.

(Yes, I have used this same principal, with a very VERY good dictaphone to scare friends witless on numerous occasions - eg, they lock their car, I unlock it, leave the door open, and wait for them to realise - always in a relatively safe area)

Ping, in your case, that happens because the reciever is setup to allow multiple frequencies. A different frequency triggers a different ring tone. Just so happens that the doorbell was designed for use in countries where car keyfobs don't operate on the same frequency (I'd guess at China/Japan).

Viney, most old phones actually violated the Trade Descriptions Act, because they interfered with other devices, nothing new. :D

Well, that just took all the fun out of it... Cheers dude...

:lol: