Week 4: Learning how to make a signal jammier and How it's work

Last Tuesday me and Jason we have discussed how we are going to make the signal jammier for our project "text-walking accident avoiding system on traffic lights". That is the first thing we are going to start up with. We have done some researches and found how a signal jammier works. We are trying to make it work on radius of less than five meters. Because we can't disturb other drivers or other people around that area.

Basic operation of a signal jammier

Cell phones works by communicating with it's service network through a signal tower or a base station. So, when you move one place to another signal is handed from tower to tower. And cell phone are using radio frequencies to communicate with towers.

Fig 1: How cell phone signal works (howstuffworks.com) 

 What jamming device do is transmitting on the same radio frequency as the cell phone and disturb the communication between cell phone and the base station in the tower. they call it denial-of-service attack. Jamming device transmitting a signal on same frequency and at high enough power so the two signals collide and cancel each other out.

Fig 2: how jamming device works (howstuffworkes.com)

So now we know how a signal jammier works. But we need to find out whats the frequency cell phones are using for the communicate. As I found out they use two separate frequencies, one for talking and one for listening. When you block one frequency cell phone are trick to think there is no signal when its get only one frequency. So, its effective to block only one signal.
To jam signal we need to make a device that transmit same radio frequency as cell phone. Most of the cell phones are using radio frequency between 0.9GHz to 1.9GHz. And depends on the continental you are in, its changing.

What we need to make a signal jammier

Basically as I found out we need the antenna, circuitry and power supply to make a signal jammier. Below are the main electric components we need to have in our circuit.

1. Voltage controlled oscillator- this creates the radio signal 
2. Tuning circuit- this controls frequency at which the jammier broadcast its signal by sending particular voltage to the oscillator. 
3. Noise generator- this is to creates random electronic output in a specified frequency to jam the cell phone network signal. 
4. RF amplification- this thing boost the power of the radio frequency out put to high enough level to jam signal.

This is what we found on signal jammier and Jason found a circuit diagram on signal jammier. We are planing to use it as our guide to make the jammier. Hope we can make a strong enough jammier to disrupt the cell phone signal around traffic lights.

Fig 3: Circuit diagram Jason found (Reference unknown)

 And that's all for the week. hope this information's here are enough to understand how a signal jammier works. Feel free to leave a comment below if I wasn't cover anything.

See you until next time,

Derick