Industrial Visit at BSNL Aligarh

An industrial visit to BSNL was scheduled for students of the Electrical & Electronics Engineering Department on 30th April 2022. Sub Divisional Engineer Mr. Vikas Kumar demonstrated the students about different modules namely switching, transmission and MDF (Main Distribution Function). In the switching modules, students learnt about practical aspects of call making and receiving. How to create the calling number and how to check the dial tone. In the transmission module, students were briefed about OFC communication and it’s uses, advantages, and applications. The students were shown the real cables and their working procedure. In the MDF module, students learnt about the requirement of the main distribution function. They were briefed about the line side and exchange side of MDF. The students were shown the functioning parts of the distribution unit.

A telephone exchange consists of 4 functional blocks:


a) It consists of digital electronic switches which guides the user to the destination by identifying a physical communication path.

b) This identification is done with the help of logical or directory numbers.

c) How the switches work in real time, with an operating terminal.

  • MDF (Main Distribution Frames)

a) All subscriber lines are terminated at the end of MDF.

b) It consists of front (line) end and a back (switch) end which are interconnected with the help of a jumper.

c) A safety point is created in MDF to avoid any damages caused due to faults at the customer end.


a) The main function of transmission rooms is the interconnection of 2 exchanges within or outside the town. It involves optical fibre communication.

b) Voice signals are first identified. 30 voice channels are combined with the help of first order European multiplexers which can handle a speed of 2.048Mbps


Pulse Code Modulation of voice signals are carried out along with digitization. Voice signals of frequency 0-4 KHz are converted to 64Kbps.

During the visit, students got the idea about the following concepts:

  • Local Telephone Exchange
  • Broadband – DSLAM, PCM/OFC / DWDM
  • BTS – GSM System, MDF
  • Battery Power Plant, NIB cloud unit (Aligarh Zone)

Students were happy by gaining practical knowledge from the BSNL employees.The visit was conducted with the efforts of faculty of Electrical & Electronics Department . 

Leave a Reply

Your email address will not be published. Required fields are marked *