08-03-2011, 12:32 PM
PRESENTED BY :
VINUPRASAD O M
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ADD-ON MULTIPLEXER IN WIRE COMMUNICATION SYSTEM AND A COMPARITIVE STUDY WITH OLD TECHNIQUE
AN OVER-VIEW……..
Conventional wire communication.
What’s an ADD-ON multiplexer.
Basic difference between Conventional and add-on multiplexer using wire communication.
A comparative study.
Basic principle and working.
Positive results.
Further improvements…..
• Conventional Wire-Communication :
Our Point of Interest
Communicates between powered terminals via a main unit by changing the voltage signal between positive and negative.
Uses On-Off control mechanism.
Mainly used for lightning and air –conditioning purpose.
• Problems in Conventional Technique
Speed is very low.
Adding supplement wire to existing system is difficult.
Impedance problem.
With the Range of transmission increases, signal strength will vary.
Reflection of signal in different units.
For Normal Reception :-
For Long-distance and Reflection :-
Add on Multiplexer.. [/b]
Transmitter
Receiver
Waveform Correction
Impedance Matching
• Conventional and add-on multiplexer using wire communication : Basic difference
Conventional :-
Wire communication using Multiplexer :-
• An Example
• Basic Principle & Working
Block Diagram Representation of multiplexer module
Main parts are :
Transmitter, Receiver, Waveform correction circuit, Constant current Circuit, CPU, Diode Bridge, Power Supply, RS485
Transceiver, Equipment, Main Unit Voltage Signal Receiver.
Signal Inputting at RS485 Equipment.
Receiver communicate by receiving Voltage Drop Signal.
In Constant Current Circuit, the current that accompanies the voltage signal from Transmitter is supplied from Main Unit.
Waveform Correction Circuit is used to Prevent the signal from Distortion due to Long distance Transmission and Reflection.
Transmission Circuit :-
• Const. I Circuit- Amp+Trans.
• Volt. Drop- I from main unit & Impedance of line.
Transmission Waveforms :-
Reception Circuit :-
Reception Waveform :-
• Receive Volt. Drop as signal.
• Trigger at Rising edge.
• UART(Universal Asynch. Rxr.Txr.)
Waveform Correction :-
• Multiplexer send 40 bit data with a T=1ms, divide data as shown :
• To start communication as UART start bit “0” and stop bit “1”.
• 34 different possibilities of data conversion.
• Communication speed of UART is 156.25 kbps.
• For 1bit, 6.4μs.
• For 100 bit, it’s 640μs. (40 bit become 100bit)
Data Conversion Table :-
• 32 kinds of data are used as Data Codes.
• Remaining two kinds are :
1) Packet Start (Start Code)
2) Packet End (End Code)
• Each packet having 10 bit Length.
Positive Results
Speed can be improved to several kbps, in on-off switching communication network.
There is no additional wire connection, conventional wire connections are only required.
Impedance problems can be avoided.
Reflection of signal can be minimized by using this technique.
The signal strength variation is reduced by using add-on multiplexer.
From Analysis and measuring :
• communication distance = 1000m
• Switch and relay on opposite ends of communication line.
• Moving Multiplex module (Reception) and note the signal amplitude at each point.
Graphical Representation :
• High amplitude at 0 point. This is because the impedance of communication line is high.
• At 500m amplitude will be small, since impedance of communication line is small.
• Speed of communication can be improved.
• Long distant transmission and Reflection problem can be reduced by this method.
• Within the power lines this communication can be possible. No need for external wire connection.
Further Improvements….
Using repeater modules in this system.
It can be modified by taking two or more terminals.
In addition, an extra degree of flexibility can be obtained by using emerging technologies.
Conclusion..
Here proposed a new signal multiplex technique that connects a multiplex module to an existing system and enables the multiplex module to communicate with the existing system. In the transmission state, a voltage drop is caused by the supply current from the main unit and the impedance of the communication line. The reception terminal receives the voltage drop as a signal. The communication signal waveform is distorted by the reflection of the signal. Therefore, the multiplex module has a waveform correction circuit that uses a one-shot timer. Moreover, here measured and analyzed signal amplitude. The resulting measurement data and analysis data corresponded well.