Our local TV station, TV3 recently did a piece on the urban myth of notebook detectors, basically a device that's able to detect if you have a notebook in your car or not. A transcript of the segment is here, but it's in Bahasa Malaysia so if you're not from around here I guess it's gibberish to you. I'll just provide a summary

Basically it says that CHEAP notebook detectors are easily available in the open market, and are being sold for RM49. It has a detection range of 1.5~3 KILOMETERS.

Not only is it able to detect notebooks but with the use of a transmission range of 50Mhz to 6Ghz the device is able to CRACK PASSWORDS!

Users of Bluetooth headsets should also be aware because the device is able to listen in on the transmissions as well.

But there are ways to stop them from detecting your notebook, basically if you cover your notebook with a pot cover (I'm gonna think they mean the cover for the WOK) the metal will disperse the waves causing the culprits to not know WHAT is in your car even though they have a response on their reader.

Car parks can be equipped with devices that can jam these readers, but all sorts of other equipment like handphones, etc. etc. will also be jammed as well.

What a load of bullshit! I still can't believe TV3 actually broadcast this piece. I wonder if anyone actually recorded it. Let's start with the first questionable point.. an effective range of 1.5~3 KM, wow.. you have a cheap off the shelf equipment which is able to scan for a range of 1.5~3KM... That's so unbelieveable, considering the power that would be required to be able to transmit at such a range.

The next one would be the statement that because the device uses the transmission range of 50Mhz to 6Ghz it is able to CRACK PASSWORDS!!! What the heck? You mean this device is actually about to access my notebook which is turned off at a range of up to 3KM away AND access my HDD as well??? Shit... I need to get my aluminum foil hat now!

I can't comment on the Bluetooth statement, but as far as I know BT is supposed to be secure unless there's a man in the middle attack during the pairing process. Of course there have been papers and other research documents written about it. But like I said to me.. since I have no idea about this. I won't comment about it.

Then for the precautionary method where they say you should cover your notebook under a wok cover so the thieves will find it harder to get a lock on your device. That's... TRUE!! Metal absorbs most radio transmissions, so it's always a problem when you're designing radio equipment, look.. even the iPhone needed a plastic cap to allow the antennae to get better reception.

So... metal absorbs the signals and thus it's best to keep your notebook under a metal wok cover in the trunk of your car.... which of course consists of mostly metal as well....

I just don't believe in all these stories about notebook detectors, I really don't see how a device that is able to detect the ambient energy emissions from a powered off notebook placed inside a car. For my day job I work with passive RFID tags, something which is MEANT to be detected by a transmitter, and we celebrate if we can even hit a detection range of 15CM on our handheld readers. So how is it that a device that is small enough to be carried around (I'm assuming it has to be portable to be used as a tool in crime!) is able to detect something that isn't meant to be identifiable wirelessly (the notebook's battery, clock crystal, etc. etc.) over a range of 3KM AND through metal! Let's face it people... you just got seen when you put your bag into the trunk!

I'll only change my stand if someone actually shows me a detection device in action!

ps. Here's a nice explanation of the EE involved, hit the link and scroll to the post which lj0000 made.