Railway Signal Engineering

Government expenditure is divided into two parts- 1. Voted - made from consolidated fund of India  2. Charged - Charged from consolidated fund of India.  Article 113(1) - Charged Expenditure is not subjected to vote of parliament. Article 113(2) of Constitution -  Voted expenditure Abstract Estimate - For obtaining Administrative Approval  Detailed Estimate - For obtaining Technical Sanction of competent authority.Cost should not exceed Abstract Estimate.Prepared in sufficient Detailed.Detailed Estimate is not required for work less than 5 Lakh. Supplentary Estimate - An item of work, which is found later,should be considered as being a part of an estimate already prepared and sanctioned. Revised Estimate -  1. If the expenditure on a work likely to exceed the sanctioned cost. 2. Prepared and submitted for sanction of the competent Authority. 3. Prepared based on earnings/ expenditure trends of first five months and projections for the balance period. For open ...

  SM fibre ( Single mode fibre)- It is a type of fibre optics cable that has smaller core diameter compared to multimode fibre. This means only a single mode of light can travel through it,resulting less signal loss and higher bandwidth. It transmits a single ray of light,which has higher bandwidth capabilities and preferred in longer distance applications. Multi mode Fibre Optic Cable- Large diameter core that allows multiple modes of light to propogate. As the core increases,more data passes through a given time. Quality of signal reduced over long distances. Typically used for short distances,data and audio/video applications in LANs. Windows of OFC - 1 st window - 850 nm - Short wavelength region 2 nd window - 1310 nm - O band 3rd window - 1550 nm - C band Attenuation is minimum at 3 rd window. 2nd and 3rd window are used in Single Mode Fibre.