NCJ Number
241274
Date Published
2013
Length
32 pages
Annotation
The objective of this study is to develop a technology that can partially address the detection and location of cell phone use in correctional institutions and possibly other settings, such as texting in motor vehicles.
Abstract
The authors report the development of a high-performance system capable of locating CDMA2000 cell phones using time difference-of-arrival techniques. Using simulated CDMA2000 data, cell-phone location testing was favorable, even at low signal-to-noise ratios. Cell phone use was located within one or two prison cells in a prison setting. Preliminary testing was done with the receiving hardware built during the performance period. Tests have been performed with both a flip phone (LG VX5500) and with a cellular modem (MultiTech MTCBA-C1); both used the CDMA2000 cellular protocol over the Verizon network. The cellular modem has a SMA connector, which allows for direct wired hook-up to the hardware. This is useful for controlled testing and for calibrating differences in cable length. In preliminary tests, all inputs were terminated and data collected to measure the noise floor. Then, four 164-foot RG-400 cables were attached to the modem via a four-way splitter and 60 dB attenuator to verify that the signals were being received correctly and to calibrate small differences in cable length. Next, the modem was replaced with one antenna to test the reception of signals through air. Finally, antennas were connected to the ends of each of the four cables and extended 30-60 feet away, and data were collected to determine the sensitivity of the energy-detection algorithm. 45 figures and 5 tables