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General discussion

Bluetooth Device Hunt...... How?

Dec 20, 2005 7:13AM PST

Does anyone know what is needed to locate the source of a Bluetooth signal? I have a device that confirms the presence of the Bluetooth signal, but offers nothing in regards to signal strength or direction. I need to determine what/where is the source of the indicated Bluetooth signal. I'm not aware of any Bluetooth enabled devices in the office, as I've eliminated any cellphones or PDA's of employees. Thanks! - Lars

Discussion is locked

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A big problem is...
Dec 20, 2005 7:53AM PST
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Question & Thank you Bob!
Dec 21, 2005 5:37AM PST

The device I have has the capability to detect Wi-Fi and indicates signal strength (one to five "bars") which is useful for location/sniffing, however the Bluetooth functionality is simply an indicator if Bluetooth is present/detected. Am I to understand that it is possible for this device to interpret an unusually high Wi-Fi signal as being bluetooth? If this were the case, would the signal indication eventually be detected as Wi-Fi as you distanced yourself from the source?

Currently I get no indication of anything until just outside of the location's building (approx. 50 feet), and then it detects bluetooth. There is occassionally a weak (1 to 3 bar) wi-fi signal detected near the parking structure next door.

Thanks.

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I forgot to mention another BT source.
Dec 21, 2005 5:47AM PST

Cars. Some cars have bluetooth inside them. Some of my prior work was in the CCTV arena so I can imagine you want to find the RF source. If I had only your device I might build a parabolic dish to place it into so I could get some direction of the source. Then you can roughly triangulate (read http://en.wikipedia.org/wiki/Triangulation ) to narrow down where it is.

Given how close BT and WIFI is intertwined I would not bet on any device's accuracy of telling which is which.

Bob

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Update.
Dec 22, 2005 6:52AM PST

Ok, here is what I've established. The device indicates only Bluetooth and the detection begins about 30 feet from the facility door. There is no BT or Wi-Fi detected outside of this distance, however as I mentioned, farther away near parking, I receive Wi-Fi detection. So, there is detection of nothing until almost inside front door, then it is BT being detected and everywhere inside, consistently throughout.

I have to find the source and am struggling. I like the parabolic dish idea. Would you suggest fabricating one or purchasing? Does it need to be fabricated from a conductive material like a Faraday cage would be or so something similar?

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Wok.
Dec 22, 2005 9:26AM PST

A trip to the kitchen can have you a dish in under a hour. I have no end of fun building dishes at houses that needed them with a trip the kitchen.

It's loads of fun as puzzlement turns into a group project.

Here's a web link about such -> www.freeantennas.com

Sorry, but the forum filter will eat the words if I put the http on that.

Bob

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Thanks Bob. I'll give 'er a whirl.
Dec 27, 2005 8:31AM PST

Maybe I will make a family project out of it and include the 7 year old buttercup (girl) and 10 year-old bobo monkey (buttercup's big brother).

Oh yeah... Does this sound right.... On Wi-Fi, device has signal strength detection, but only on/off for BT. Device will sometimes indicate BT on the fringe/edge/weak area of Wi-Fi. Is this because it can't tell the difference between very weak Wi-Fi and BT?

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Anotehr source of "BT"
Dec 29, 2005 4:23PM PST

Bluetooth is a radio frequency that operates in the 2.4 GHz band, just like wi-fi (excepting 802.11a) so weak wi-fi signals could be mis-interpreted as bluetooth signals, also, the building may use a RFID card lock system to regulate entrance to authorized employeese, it is possible that this too could cause a "false-positive" It has been documented that UHF RFID tags can cause interfernce with other radio devices with their return signal.