Brian,

Again this is of course based on the assumption current technology cannot effectively monitor all 79 channels constantly for the duration of the call. However it also makes the assumption the data packets can be reconstructed into audio.

Are you familiar with SDRs software defined radios? These are capable of monitoring a chunk of radio spectrum continuously. They're becoming very popular in amateur radio because they can monitor a band and visually indicate where the signals exist. I have one on my desk that works over 200kHz on frequencies up to 30MHz. The Bluetooth band is much higher in frequency and occupies 80MHz of spectrum. There's at least one SDR out there that can handle a 20MHz chunk of spectrum so, in theory, it could continuously monitor 1/4 of the Bluetooth band. Four radios (each a few thousand dollars) and some PCs and you might be able to monitor the whole band. You'd have to put the packets back together. I expect the difficulty of that depends on how noisy or quiet the Bluetooth spectrum is where the device is being used. If there isn't much traffic, it might be easy to match the packets together. Presumably the hopping works so that a transmission begins on one channel immediately after one ends on another. That might be enough to match them. You could also use the power level to help narrow down transmissions that might match each other. I have no idea if this would work in practice. Realtime would be more difficult than delayed processing. It's a potential method anyway. In reality it might be that the 2.4GHz band, which is also full of WiFi and other low power unlicensed radio stuff, is too noisy to do this easily. Even if you did get all the packets, you're still let with the encryption of the data. My point is, using SDRs it's possible to monitor a chuck of spectrum - not just one channel - continuously. Martyn -- Martyn Williams 2012 John S. Knight Journalism Fellow Stanford University Cell: 650-391-4868 @martyn_williams _______________________________________________ liberationtech mailing list liberationtech@lists.stanford.edu Should you need to change your subscription options, please go to: https://mailman.stanford.edu/mailman/listinfo/liberationtech If you would like to receive a daily digest, click "yes" (once you click above) next to "would you like to receive list mail batched in a daily digest?" You will need the user name and password you receive from the list moderator in monthly reminders. Should you need immediate assistance, please contact the list moderator. Please don't forget to follow us on http://twitter.com/#!/Liberationtech ----- End forwarded message ----- -- Eugen* Leitl <a href="http://leitl.org">leitl</a> http://leitl.org ______________________________________________________________ ICBM: 48.07100, 11.36820 http://www.ativel.com http://postbiota.org 8B29F6BE: 099D 78BA 2FD3 B014 B08A 7779 75B0 2443 8B29 F6BE