ABSTRACT:
The problem of providing reliable and accurate position location of mobile units in wireless communication systems has attracted a lot of attention in recent years. There exist many incentives for wireless service providers to have such a system in place. Knowing a user’s location enables many new applications, often times called location-based services. They can use reliable position location as a means to optimize the performance and design of the wireless networks and can also additional features to the subscribers.

The main objective of the project is to design and set up a system to track a radio frequency transmitter. The system consists basically of mobile stations and base stations. The Time Difference of Arrival (TDOA) technique is one of the most promising position location techniques for cellular-type wireless communication systems. In this technique the mobile unit which is to be tracked consist of the transmitter, the base stations consist of receiver. TDOA is concerned with tracking based on time difference of arrival of a signal emitted from the object to three or more receivers. The exact location of the radio frequency transmitter can be obtained by using four receivers. In fact the most striking fact about TDOA is that the change in magnitude of transmitting signal will not affect the accuracy of the system considerably, which makes it ideal for the future use.

The ‘Security and Surveillance’ system consist of two levels of security checks that include biometric scanning and RFID based authentication. Biometric identification can provide extremely accurate, secured access to information; fingerprints, retinal and iris scans produce absolutely unique data sets when done properly. Automated biometric identification can be done very rapidly and uniformly, with a minimum of training. RFID technology plays a critical role in identifying articles and serving the growing need to combat counterfeiting and fraud. The ‘Tracking and Positioning’ allows for the monitoring of a person who has been authorized to access the secured area.
INTRODUCTION:
The project ‘Tracking and positioning’ is a part of a ‘Security and Surveillance’ system which requires monitoring the positions of security personal within the secured area. The word "security" in general usage is synonymous with "safety," but as a technical term "security" means that something not only is secure but that it has been secured.
The ‘Security and Surveillance’ system looks to provide all-round security to a restricted area (like a research lab) and also monitor the area round the clock so as to prevent a possible security breach. In this regard the ‘Tracking and Positioning’ system is of utmost importance as it allows a security official to monitor the position of the other security staff in the secured area and direct them appropriately as and when required.

PROJECT DISCUSSION:

LITERATURE SURVEY

METHODS USED FOR TRACKING and POSITIONING
The use of RF signals has become an integral part of modern day tracking and positioning systems. Various signal parameters like signal strength, timing delay between the arrival of the signal at multiple receiver stations etc. Some of these technologies are as follows:

METHOD 1: USING SIGNAL POWER

In this method of tracking, the change in signal strength received at each of the stations is mapped to the transmitter coordinates. The locations can be estimated based on received signal strength indicator (RSSI) values from multiple access points. Signal power based positioning works indoor as well as outdoors thus overcoming the defect of GPS system.

Path Loss Model
The basic path loss model tells us that a drop in signal power or signal strength is correlated to distance. For example, if we disregard obstructions, multipath delay spread, scattering, refraction and diffractions effects, and assume all stations to be Stationary (i.e. no Doppler effect), we can model the signal loss by

, where
Pr = Power measured at Receiver in Watts (W)
Pt = Power measured at the transmitter in Watts (W)
λ = Wavelength in Meters (m)
r = Receiver to transmitter distance in Meters (m)
Solving the above equation for r, we can easily determine the distance between receiver and transmitter based on the wavelength and the measured power at receiver and transmitter. Knowing the distance between multiple receivers and a transmitter, one can determine the location of the transmitter by triangulation.

The described model clearly makes assumptions (e.g. no obstructions, no multipath delay spread) that clearly do not hold in the real world. Wireless LANs are mostly deployed indoors where there are many obstacles such as walls or furniture. One can augment the above propagation model by taking different types of materials or multiple building floors into account. However, propagation models quickly become overly complex if one aims at high level of accuracy.

• TOOLS REQUIRED
  
  1. Digital trainer kit
  2. PC with required soft wares.
  3. Digital Storage Oscilloscope(350 MHz)
  
  PROGRAMMER HARDWARE
  
  1. Microcontroller
  2. Programmer of microcontroller.
  
  SOFTWARES REQUIRED
  
  Matlab
  PSpice
  MPLab ASM
  Embedded C

SUMMARY AND CONCLUSION:

The proposed ‘Tracking and Positioning’ system forms an integral part of the high end ‘Security and Surveillance System’. The Security and Surveillance System provides high level security to a restricted area which includes biometric identification, RFID Authentication, Tracking and ONpositioning of personnel and secured wireless communication link between security officials. Tracking and Positioning System helps in monitoring any authorized personnel entering the restricted area and to direct them as and when required. There are mainly two different methods for tracking, one being signal power positioning, which works on the principle that a change in signal strength is correlated to the distance between two stations and we can estimate locations based on received signal strength indicator (RSSI) values from multiple access points. The other one being TDOA which deals with locating an object accurately by the time difference of arrival of a signal emitted from the object to three or more receivers. A mathematical approach to TDOA has been briefed, which high-lightens the precision of the system. The accuracy of TDOA is a function of several variables, which includes the geometry of the receiver(s) and transmitter(s), the timing accuracy of the receiver system, bandwidth of the emitted pulse, etc. The efficiency of the system being a function of the time difference of the transmitted signal, TDOA holds advantage over other existing systems as the accuracy of the system is not appreciably affected by drop in signal strength. The ‘Tracking and Positioning’ system can be used to monitor the position of the tagged personal from a central control room.