Jamming Demonstration by Denial-Of- Mobile Service (DOS) using Extrinsic Noise for Audience Improvement in University’s Environment

Abstract

This paper reports the result of a research carried out in Osun State University, Osogbo, Nigeria to improve audience in lecture rooms and other environments using a locally constructed mobile phone jammer. The jammer suspended communication activities by denial-of- mobile service (DOMS) using extrinsic noise for audience improvement in university’s environment. It (the jammer)was constructed employing extrinsic (man-made) noise. This jammer transmits an interference signal on the downlink of the popular GSM 900 MHz and DCS 1800 MHz frequency bands. It comprises of an intermediate frequency (IF) circuit, a radio frequency transmitter (RFT), an antenna and a power source. The IF circuit generates a ramp signal using a 555timer, this ramp signal is mixed with two noise sources, the extrinsic noise sensed by a high sensitivity microphone and a zener diode noise source; the resulting IF signal is fed to the RFT. At the RFT, the ramp signal tunes the voltage controlled crystal oscillator to desired frequency range. This produces an interference radio frequency (RF) signal on the same frequency as the downlink of the GSM and DCS cellular system. The resulting interference RF signal is amplified to cover a radius of 10 meters which implies an area of 628m2. Finally, a test was carried out to investigate the effect of the mobile phone jammer in eliminating phone activity at various locations on campus. This took place over a period of one semester (4 months). Expectedly, out of 343 cases whereby mobile phone activity was prevalent in form of circuit and packet switching (phone calls, text messages, and data connection) without the use of a jammer, this figure diminished greatly to 8 cases upon the activation of the jammer; at same locations and periods. It is therefore obvious that the commandeering of the mobile communication system in educational institutions can be efficiently achieved by the use of a mobile phone jammer.
DOI: 10.17762/ijritcc2321-8169.150518