Railway Signal Engineering

  Size of Cable - The various size of conductors used in Cable are - 0.4 mm,0.51 mm,0.63 mm,0.9 mm and 1.2 mm. Twisting is done to avoid crosstalk. Distortionless condition- If there is no phase Distortion, the velocity of propogation must be same for different Frequency components and should be independent of Frequency. GL=RC is distortionless condition  Loading of Underground cable - When diameter of conductor increases,  value of R decreases . This is not possible due to its increased cost. If the value of G increases, transmission loss will increase which is also not acceptable. Therefore there is only one way to increase the value of GL by increasing L.This is achieved by using the coils of suitable inductance value wound on dust cores are placed in series with line on suitable intervals. This is called coil loading or lump loading.Value of each coil connected in each limb of a quad cable is 59 mh. V.F.balancing of underground cable - V. F balancing of underground ca...

Connectors- Two most common connectors used for professional audio are 3 pin XLR and 1/4 phone connectors. RCA Connectors- A round,press on connector used for audio and video connections. F connectors- used for television and antenna applications. N connectors- used by  cable TV industry.N means Navy. C connectors- Similar to N connector. However they are Bayonet locking. BNC Connector-( Bayonet Neil Conelment connector) RF connector used for terminating coaxial cable. Used in video and RF applications to 2 GHz. TNC connector- Threaded version of BNC connector  Used in cellular telephone RF antenna connections. Waveguide Tees - Waveguide Tees are Waveguide junctions. 1. E type T junction  2. H type T junction.  Attenuator - Used to Control the amount of power transferred between the  points on a transmission line by absorbing or reflecting some of Microwave power. Directional Coupler- It is four port component in which two transmission lines are employed in suc...

  PPTC - Power and Telecommunication Co-ordination Committe. Central standing committee for co-ordination of Power and Telecommunication system. Local Telephone Equipment ( LTE) LTE is used to provide 20 local telephones at HQ. Types of cables  A)   Quad Cable 0.9 mm or 1.4 mm dia. 1.4 dia Quad used for Block Section more than  12 kms. Suitable for underground laying. Used for control Circuits and block interfaces. IRS Specifications IRS: TC 30/05 B)  PIJF cable -  Multi pair ( from 10 pairs to 200) Multi dia ( 0.5 mm/0.63 mm/0.9 mm) Suitable for underground laying. Used for exchange subscriber lines or branch cables branching off from main quad cable. C) Twisted Pair Switch Board Cable ( 0.5 mm/0.6 mm) Not designed for underground laying. Used for indoor applications such as distribution to various telephone subscribers in a building. Jointing Kit - For quad cable jointing- RTSF ( Reinforced Thermo Shrink Jelly Filled kit) type jointing kit to be used...

Frequency alloted by WPC to Indian Railway is 146.2 - 167.95 Mhz VHF - Line of sight,Reflection, Scattering. Type of operation : Half Duplex ( for present Railway operations) Equipment- Walkie-talkie set,Base radio Antenna- Whip, Ground Plane  Feeder cable- 50 Ohms Unbalanced Coaxial cable  Mobile Station   The Mobile station represents the terminal equipment used by cellular subscriber by GSM system. Mobile system has two entities. Mobile Equipment (ME) Subscriber Identify Module ( SIM) Functions of SIM card- User authentication  Storage of subscriber related information.  Base Station Subsystem ( BSS) BSS has two entities. 1. Base Transceiver Station( BTS) 2. Base Station Controller ( BSC) BTS - It facilitates wireless communication between User equipment( mobile)  and network. Antenna is also part of BTS. It serves as Accesss point for Mobile devices to connect to network. Transmit and receive radio signals to and from mobile devices. Each BTS has a de...