Li Report

TRANSMISSION

The medium that used in tranmit some signal;

1) Copper

2) Fiber optic

3) Air

There are some factors for analog system to change to the digital system;

1) Resistance

2) Inductance.

3) Capacitance.

4) Noise

5) Cross talk.

Analog system

- unit; Hz

- Have amplitude, fresuency and phase which not synchronous.

- Depends on pitch.

- Used a large cabel to transmit data.

- Used high power.

- Limited freqeuncy; 300 Hz- 3.4 kHz.

- Crosstalk can happen.

Digitl system

- unit; bit

- Have two condition; logic 1 and logic 0.

- Synchronous signal and no noise.

- Used binary code.

- Used multimed medium to transmit; fiber optic, satallite, copper.

- Different data can be transmits at a time.

- Used low power.

ANALOG SYSTEM TO DIGITAL SYSTEM.

The analog system from the telephone will convert to PAM signal (Pulse Amplitude Modulation) through the sampling process, PCM signal (Pulse Coded Modulation) through quantizing process and digital signal through encoding process

DIGITAL TRANSMISSION

A) PDH (Plesiochronous Digital Hierarchy)

- Transmission in a short distants with delay.

- Have primary order terminal or drop multiplex where the primary signal can be combine with others primary signals with the help of multiplexer and if there are losses before the de-multiplexer process, a repeater will be used to regenerate the signal.

- Multiplexer used TCM (Time Division Multiplexing) to combine the PCM signal to transmitt using digital signal.

- Voice/ analog/ phone signal will be encoding will be transmitt at 64 kb/s to share the same transmission system.

TDM (Time Digital Multiplexer) in PDH

PDH System in KTMB

PDH Interface card at KVDT

KTMB PDH Layout system at KVDT

PDH KTMB Digital-Analog Interface Card at KVDT

PDH NOKIA Transmission Rack at Station

B) SDH (Synchronous Digital Hierarchy)

SDH refers to a group of fiber-optic transmission rates that can ransport digital signals withdifferent capacities.

SDH has provided transmission networks with a vendor-independent and sophisticated signal structure that has a rich feature set. This has resulted in new network applications, the deployment of new equipment in new network topologies, and management by operations systems of much greater power than previously seen in transmission networks

- Ready a larger transmission data than PDH.

- A transmitted data will be sending in a container which each container have a data from PDH.

- The capacity of data at a time much larger.

- Used fiber optic as a medium.

Frame Structure of SDH

- Section overhead (SOH) = have a frame alignment, error checksum, auxiliary channel and can show when the data be transmitt.

- STM-1 Virtual Container = VC4 have synchronous data signal from PDH.

- The data being transmitted using STM-1 card (Synfonet Transport Module)

SDH Data System Speed

SDH NOKIA Transmission Rack at Station

Flow of Transmitted Data

AUTOMATIC TRAIN PROTECTION (ATP)

ATP is an abbrevation for Automatic Train Protection which is the name of the equipment used in conjunction with railway tracksidde equipment, such as speed boards and signalling system, used to maintain and increase the safety of trains and other ATP equipped vehicles used on a railway.

ATP will take over the control of the train by applying the brakes. The brake application xontinues until the driver manually acknowledges to the system that he is once more capable of controlling the train. ATP will continue to brake the train