Wireless Communications and Mobile Technology

Wireless LAN technology is gaining broad acceptance and being adopted world-wide in organizations that clamor for competitive advantage of an increasingly mobile and highly productive workforce. The WAP 2000 series access point, which sets the enterprise standard for secure, manageable and reliable wireless LANs while also providing a smooth migration path to future high-speed wireless LAN technologies. This innovative, state-of-the art wireless infrastructure platform features dual-band functionality that simultaneously supports current and emerging wireless standards.One of the most innovative aspects of the WAP 2000 series access point is that it is both software and hardware upgrade their software to take advantage of new features that DAX will develop in the future, but they also will be able to upgrade the radios in the field to take advantage of new high-speed wireless standards.

WIMAX (world-wide interoperability for microwave access) is the IEEE 802.16 standards based wireless technology that provides MAN (metropolitan area network) broad band connectivity. WIMAX can offer a solution to what is normally called the“last-ile”problem by connecting individual homes and business offices Communications. It is to be less expensive than their wired counterparts,such as digital subscriber lines (DSL). This will now be able to enjoy high-speed internet access since distance up to 30miles (50km) are supported.

“No wires, No rules”. Zooming down the highway, you will be able to use a laptop or PDA to check the weather or traffic a few miles ahead. From physical issues up to applications aspects, Mobile Ad hoc networking in Wi-Fi (wireless-fidelity) comprehensively covers all areas of the technology including protocols and models with an emphasis on the most current research and development. To understand wireless technology trends and to see why non infrastructure-based Mobile Ad hoc networks are poised to play an important role in the evolution of future wireless networks. It helps in the evolution path of different technology generations.

Device control using Telephone Electronics

Controlling devices using switches are common. From a few decades controlling devices using remote control switches like infrared remote control switch, wireless remote control switches, light activated switches re becoming popular. But these technologies have their own limitations. Laser beams are harmful to mankind. Some technologies like IR remote control are used for short distance applications. In such case if we have system which does not require any radiations or which is not harmful, long remote control switch!! Yes here is the solution. Here I am introducing such a system which does not require any radiations, any laser beam which has no limitation of range, I mean it can be used from any distance from meters to thousand kilometers using a simple telephone line or mobile phone.

Here I am using a telephone as a media, which serves main part of this system. By using home phone as a local phone and another phone – either landline or mobile phone as a remote phone we are controlling devices.

Features:-

1. You can control up to 10 devices. It may be any electric or electronic appliances or devices with simple to heavy appliances. Each device is given a unique code.
2. It makes accurate switching, any false switching of device are not done.
3. There is no risk for false switching.
4. Your local phone (i.e., home phone or office phone) can be used for normal use by using a DPDT switch. So you need not use a separate telephone line for this device controlling.
5. To perform any operations through remote phone line, the user needs to dial to the local telephone (to which the interfacing circuit is connected) then the respective code of the device is dialed.
6. This circuit does not require any complex IC, so any one with little knowledge of electronics can construct this circuit, because it does not need any programmable IC’s or programming.
7. This system detects the ringing signal from your exchange with the help of ring detector and automatically switches ON.
8. This device saves your money. This circuit switches OFF after a time of 60 seconds (you can change this switch ON-Time which is discussed in detail in coming section).
9. Before changing the state of the device we can confirm the present status of the device.
10. This circuit gives an acknowledgement tone after switching ON the devices to confirm the status of the device.
11. You can control devices from local telephone. It can also be controlled by PCO.

Taking a tour of the project:

This system uses Dual Tone Multi Frequency (DTMF) technology of our telephone set. Every telephone set will have this facility. We have two type of dialing facilities in our telephone system (i) Pulse dialing mode (ii) Tone dialing mode. Here this system works on tone dialing mode. The DTMF mode is shortly called as tone dialing mode. (Check for availability of tone dialing mode in your telephone set).

This system is divided into two sections

1: Remote Section:

It is nothing but remote telephone set which is present in the remote place. This may be your workspace (office / school) phone or mobile phone or a phone in PCO. Signals are sent through this telephone.

2: Local Control Section:

This is a control system through which you can control your appliances. This contains one telephone line and a control unit. The appliances to be controlled must be connected to telephone line through control unit .Control unit is kept with a sufficient backup.

What is DTMF?

When you press a button in the telephone set keypad, a connection is made that generates a resultant signal of two tones at the same time. These two tones are taken from a row frequency and a column frequency. The resultant frequency signal is called “Dual Tone Multiple Frequency”. These tones are identical and unique.

A DTMF signal is the algebraic sum of two different audio frequencies, and can be expressed as follows:

f(t) = A0sin(2*П*fa*t) + B0sin(2*П*fb*t) + ……….. ——->(1)

Where fa and fb are two different audio frequencies with A and B as their peak amplitudes and f as the resultant DTMF signal. fa belongs to the low frequency group and fb belongs to the high frequency group.

Each of the low and high frequency groups comprise four frequencies from the various keys present on the telephone keypad; two different frequencies, one from the high frequency group and another from the low frequency group are used to produce a DTMF signal to represent the pressed key.

The amplitudes of the two sine waves should be such that

(0.7 < (A/B) <>(2)

The frequencies are chosen such that they are not the harmonics of each other. The frequencies associated with various keys on the keypad are shown in figure (A).

When you send these DTMF signals to the telephone exchange through cables, the servers in the telephone exchange identifies these signals and makes the connection to the person you are calling.

Wireless Data Transmission between Computers using Sequence Detector.

Here for the purpose, we have made four distinct stages for the effective implementation .The stages are described in brief as follows. In the first stage, we are constructing the transmitter circuit that transmits data and sequence bits at infrared frequency. Now the second part is to develop receiver circuit that receives infrared signals coming out from transmitter and convert them into bits. The next stage is to compare the incoming sequence with that of receiver computer. If sequence is matched only then it will be able to catch the data sent by transmitting computer. The fourth and final stage is the make software program that gets the data and displays on computer.

INTRODUCTION

Wireless data transmission between computers is a flexible data communication system implemented as an extension to, or as an alternative for, a wired LAN within a building. It can further be extended to wireless LAN with secure data transmission. For the purpose of secure data transmission a unique code is sent before actual data bits. This unique code is known to receiver. In this project sequence detector at receiver side has been used which is set for a particular code. This sequence detector detects binary bit stream coming out from transmitter and if code of incoming bit stream is matched with the code of sequence detector than rest of bits are received in form of data at the receiving computer’s side. To further enhance the concept of security we are using Infrared waves as a channel between transmitter and receiver because security of infrared systems against eavesdropping is better than that of radio systems. The block diagram of whole system is shown below.

Vehicle Monitoring and Security System

In this modern, fast moving and insecure world, it is become a basic necessity to be aware of one’s safety. Maximum risks occur in situations wherein an employee travels for money transactions. Also the Company to which he belongs should be aware if there is some problem. What if the person traveling can be tracked and also secured in the case of an emergency?! Fantastic, isn’t it? Of course it is and here’s a system that functions as a tracking and a security system. It’s the VMSS. This system can deal with both pace and security.

The VMSS (Vehicle Monitoring and Security System) is a GPS based vehicle tracking system that is used for security applications as well. The project uses two main underlying concepts. These are GPS (Global Positioning System) and GSM (Global System for Mobile Communication). The main application of this system in this context is tracking the vehicle to which the GPS is connected, giving the information about its position whenever required and for the security of each person travelling by the vehicle. This is done with the help of the GPS satellite and the GPS module attached to the vehicle which needs to be tracked. The GPS antenna present in the GPS module receives the information from the GPS satellite in NMEA (National Marine Electronics Association) format and thus it reveals the position information. This information got from the GPS antenna has to be sent to the Base station wherein it is decoded. For this we use GSM module which has an antenna too. Thus we have at the Base station; the complete data about the vehicle.

Along with tracking the vehicle, the system is used for security applications as well. Each passenger/employee will have an ID of their own and will be using a remote containing key for Entry, Exit and Panic. The Panic button is used by the driver or the passenger so as to alert the concerned of emergency conditions. On pressing this button, an alarm will be activated which will help the passenger/employee in emergencies and keep them secure throughout the journey. The vehicle can also be immobilized remotely.

INTRODUCTION:

Of all the applications of GPS, Vehicle tracking and navigational systems have brought this technology to the day-to-day life of the common man. Today GPS fitted cars, ambulances, fleets and police vehicles are common sights on the roads of developed countries. Known by many names such as Automatic Vehicle Locating System (AVLS), Vehicle Tracking and Information System (VTIS), Mobile Asset Management System (MAMS), these systems offer an effective tool for improving the operational efficiency and utilization of the vehicles.

GPS is used in the vehicles for both tracking and navigation. Tracking systems enable a base station to keep track of the vehicles without the intervention of the driver whereas navigation system helps the driver to reach the destination. Whether navigation system or tracking system, the architecture is more or less similar. The navigation system will have convenient, usually a graphic display for the driver which is not needed for the tracking system. Vehicle tracking systems combine a number of well-developed technologies.

To design the VMSS system, we combined the GPS’s ability to pin-point location along with the ability of the Global System for Mobile Communications (GSM) to communicate with a control center in a wireless fashion. The system includes GPS-GSM modules and a base station called the control center.

Let us briefly explain how VMSS works. In order to monitor the vehicle, it is equipped with a GPS-GSM VMSS system. It receives GPS signals from satellites, computes the location information, and then sends it to the control center. With the vehicle location information, the control center displays all of the vehicle positions on an electronic map in order to easily monitor and control their routes. Besides tracking control, the control center can also maintain wireless communication with the GPS units to provide other services such as alarms, status control, and system updates.

The design takes into consideration important factors regarding both position and data communication. Thus, the project integrates location determination (GPS) and cellular (GSM) – two distinct and powerful technologies in a single system.

VMSS is based on a PIC microcontroller-based system equipped with a GPS receiver and a GSM Module operating in the 900 MHz band. We housed the parts in one small plastic unit, which was then mounted on the vehicle and connected to GPS and GSM antennas. The position, identity, heading, and speed are transmitted either automatically at user-defined time intervals or when a certain event occurs with an assigned message (e.g.; accident, alert, or leaving/entering an admissible geographical area).

The GPS Module outputs the vehicle location information such as longitude, latitude, direction, and Greenwich Time every five minutes. The GSM wireless communications function is based on a GSM network established in a valid region and with a valid service provider. Via the SMS provided by the GSM network, the location information and the status of the GPS-GSM VMSS are sent to the control center. Meanwhile, the VMSS receives the control information from the control center via the same SMS. Next, the GPS-GSM VMSS sends the information stored in the microcontroller via an RS-232 interface.

Water level indicator and controller

This indicates the water level in the water tank at four steps F, H, L, E, i.e., Full, Half, Low, Empty. When the tank is empty the unit automatically switches ON the water pump and switches OFF when the water level reaches to full.

Touch sensitive burglar alarm for internal security

This simple circuit when connected to a metal locker or cupboard generates an alarm when touched by an undesired entity.

Remote operated electrical equipments

This unit replaces the conventional switchboards. Fans, lights and other equipments can be operated and controlled using remote controlled unit.

Auto adjustable timer unit

This unit can be used to operate an electrical equipment for a fixed period of time. The circuit can be used for street lightning, billboard illumination and water supply to the garden where pump can be set to switch ON at one time and switch OFF at another tome.

Automatic gate light, call bell system

During day time, this unit generates a musical alarm, when anyone entering the compound of the house. During night time, at the entry of any person through the gate, the compound lights are switched ON together with musical bell.

Remote operated gate control

This unit is responsible for opening and closing the gates at the pressing of a button on remote transmitter.