A wireless signal jammer is a device which blocks transmission by creating interference. This wireless signal jammer can be categorized into the Radio Frequency (RF) jammer and GSM jammer.
A Radio Frequency jammer is a device used to disrupt or prevent communication via a broadcasted RF signal. It is an RF and GSM frequency disrupter commonly known as wideband radio frequency (RF) and GSM cell phone jammer. Simultaneously, they can blocks all commercial FM broadcast band (87.5 MHz to 108 MHz) and GSM signal transmissions within the jammer’s transmission range. The device can possibly block these frequencies by transmitting a dirty signal (like noise) on the same frequency at which the GSM and radio system operates.
A Radio Frequency jammer is a device that transmits a radio frequency signal on the same frequency at which the radio system operates and the jamming succeeds when the radio sets in the area where the jammer is located are disabled.
A GSM jammer is a device that transmits a signal on the same frequency at which the GSM operates. The jamming succeeds when the mobile phones in the area where the jammer is located are disabled.
In recent times, where bombs are being planted and detonated by GSM or Radio Frequency signals, this device can be at an advantage by jamming the signals required for the detonation of the bomb.
Presently, the mobile jammer devices are becoming civilian products rather than electronic warfare devices, since with the increasing number of the mobile phone users the need to disable mobile phones in specific places where the ringing of cell phone would be disruptive has increased. These places include worship places, university lecture rooms, libraries, concert halls, meeting rooms, and other places where silence is appreciated.
The solution to these annoying and disrupting noises is to install a device which can block the signal transmission from mobile phones and radio sets and thus, disrupt the triggering of bombs by these wireless signals.
1.2 Project Background
The technology being used by this device is very simple. The mobile phone transmission is being blocked and interfered by RF which creates high noise. The frequency being generated by the jamming device jams the signal being generated by the cell tower (as illustrated in figure 1.1 below). When the signal has been blocked, the mobile phone will show “NO NETWORK” on the network bar, and radio devices will not be able to tune into any signal. Thus, all phones and radio devices in the 200m radius of the jammer will be having the same situation.
Radio Frequency (RF) and Mobile signal jammer is an illegal device in many countries. It is because the device is blocking the signal which has been approved by government agency as a legal communication transmission system. According to the National Communications Commission (NCC) in Nigeria, “The manufacture, importation, sale, or offer for sale, of devices designed to block or jam wireless transmission is prohibited”. 
The reason I am developing this device is for educational purpose only. This device was developed and tested in this report just for Final Year Project presentation. There is no intention of manufacturing or selling such device in Nigeria or elsewhere
In the construction of this wireless signal jammer, the device will be able to jam GSM and Radio Frequency (RF) signals and this can be done alternatively through a switch.
As shown in Fig. 1.1 below, the wireless signal jammer is divided into two major branches: the GSM signal jammer, and the radio receiver jammer. The radio receiver jammer is also sub-divided into the Amplitude Modulated (AM) signal jammer and the Frequency Modulated (FM) Signal jammer. The Cell phones and Radio receivers cannot be blocked simultaneously as they operate at separate frequencies. The frequency can then be varied using a frequency tuner mounted on the jammer.