Electromagnetic waves - Indian Laws - General

Electromagnetic waves Electromagnetic waves have been described in Telecommunications Law : David Gilles Roger Marshal: Butterworths :- 1.14. Electromagnetic waves travel through free space from one point to another but can be channeled through waveguides which may be metallic cables, optical fibres or even simple tubes. All electromagnetic waves are susceptible to interference from one another and unrelated electrical energy can distort or destroy the information they carry. To reduce these problems they have been organized within the spectrum into bands of frequencies or wavelengths for the transmission of particular types of services and information. The process of sending a signal is as follows :- Data is superimposed on a carrier current or wave by means of a process called modulation. Signal modulation can be done in either of two main ways: analog and digital . In recent years, digital modulation has been getting more common, while analog modulation methods have been used less and less. There are still plenty of analog signals around, however, and they will probably never become totally extinct. Except for DC signals such as telegraph and baseband, all signal carriers have a definable frequency or frequencies. Signals also have a property called wavelength, which is inversely proportional to the frequency . (Encyclopedia of Technology Terms of Techmedia) BHARAT SANCHAR NIGAM LTD. (BSNL) VERSUS UOI - 2006 (3) TMI 1 - SUPREME COURT