| | Overview of the Global System for Mobile Communications (Site not responding. Last check: 2007-11-05) |
 | | The length of a 26-frame multiframe is 120 ms, which is how the length of a burst period is defined (120 ms divided by 26 frames divided by 8 burst periods per frame). |
 | | This ciphering key, together with the TDMA frame number, use the A5 algorithm to create a 114 bit sequence that is XORed with the 114 bits of a burst (the two 57 bit blocks). |
 | | Enciphering is an option for the fairly paranoid, since the signal is already coded, interleaved, and transmitted in a TDMA manner, thus providing protection from all but the most persistent and dedicated eavesdroppers. |
| ccnga.uwaterloo.ca /~jscouria/GSM/gsmreport.html (6509 words) |