Sensor For Cellular Activity Supervised by : Yossi Hipsh Preformed by: Assaf Haim Ohad Fremder

Presentation’s Topics  Project’s Goal. –Introduction to the project’s main idea. –Motivation for the project.  Suggested Solution –Theoretical solution. –Justifications –Technical details. –Solution steps  Questions ?

Project’s Goal

Introduction to the project’s main idea  Detect existence of cellular activity  Pin-pointing a location of an existing cellular device in a confined location.

Motivation for the project  Prevent students inserting cellular devices into test rooms.  Alert for entering the operating room with a cellular device.  Detect cellular activity in an air-plane.  Find a man in distress inside a building.

Suggested Solution

Theoretical solution  We will use 2 different kinds of detectors – directional antennas and energy.  The energy detector will acknowledge cellular activity in the area.  We will place 3 antennas within the room.  Each antenna will give us the direction from the antenna to the cellular device.

Theoretical solution – Cont.  Each antenna actually gives us a direction (“plane”) in which the source can be found, and so with 3 crossing directions we will receive a single point.  We need each antenna to give us the direction with a 0.5mx0.5m precision.  To find the direction we decided to use an array of two elemental antennas in each antenna.

Theoretical solution – Cont. Antenna 1 BPF Gain Mixer BPF Gain Multiplier Out LO Antenna 2 BPF Gain Mixer BPF Gain LO

Justifications  The signal modulation does not effect the performance of the energy detector, for it samples the max amplitude of the signal.  The directional antennas will not be affected by the modulation. Due to the slow rate of modulation as against to the high speed of the Electro-Magnetic wave.

Justifications – Cont.  The chosen directional antennas will simply do the following: –Each elemental antenna will isolate the frequency and multiply it with the output of the other elemental antenna. –The result will be (We are considering a sinusoid signal) 2 elements, one will be DC and the other AC. –We will isolate the DC signal which will represent the phase difference between the two.

Justifications – Cont.  Mathematical solution:  Signal 1 : A(t)cos(w(t)t + b(t) + P1)  Signal 2 : A(t)cos(w(t)t + b(t) + P2)  When we remove the time dependencies and multiply the two elements: (A^2)/2{cos(P1-P2) + cos(2wt+2b +P1+P2)} AC Component DC component

Technical details  The cellular in Israel is working around two major frequencies : – Mhz – Mhz  The signal modulation according to the GSM protocol is phased modulation.  The cellular transmit Power is between 0.25W-0.6W

Solution steps  Finishing theory –Find the exact power and frequency transmitted by a cell phone. –Calculate the needed sizes and other properties of the antenna  Building one elemental antenna, testing.  Building one antenna, testing.  Setting up 3 antennas.  Testing. Schedule : -Finish by 5-10/2 - Finish by 2-9/3 - Finish by 2-9/4 - Finish by 2-9/5 - Finish by the end of the second semester

Questions ?