Teardown of a consumer voice/location cellular spying device that fits in the tip of a USB cable

Originally published at: https://boingboing.net/2017/11/15/cottonmouth-for-the-rest-of-us.html


$25.00 for just the tip? And after market? Gross. No thanks.


it can also give a coarse approximation of its location (based on GSM towers, not GPS, and accurate to within about 1.57km).

That’s an oddly specific ‘approximate’ distance - works out to about 0.976 SAE miles. If they’d said “accurate to within about 1.61km” I’d know what their “approximation” with too many significant figures came from. But 1.57 km is a bit baffling.

The best I can come up with is it’s 1/4 of one of the common definitions of the medieval Dutch Mile - 20,000 Rhineland feet, 6,280 m. Which seems a bit… out of place when discussing cellular phone network triangulation…


Oh, that’s just “to improve the user experience”.
Nothing to worry about.

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Might have something to do with the radio frequency/frequencies used,
or the typical distances of cell towers to each other (in which frequencies probably play a part as well).

This device can tellguess the distance it is from a cell tower, but not the direction the tower’s signal comes from. So it would need at least signals from three towers to come up with a position.

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