A communications satellite is an artificial satellite that relays and amplifies radio telecommunication signals via a transponder; it creates a communication channel between a source transmitter and a receiver at different locations on Earth. Communications satellites are used for television, telephone, radio, internet, and military applications. Many communications satellites are in geostationary orbit 22,236 miles (35,785 km) above the equator, so that the satellite appears stationary at the same point in the sky; therefore the satellite dish antennas of ground stations can be aimed permanently at that spot and do not have to move to track the satellite. Others form satellite constellations in low Earth orbit, where antennas on the ground have to follow the position of the satellites and switch between satellites frequently.
Co-channel interference or CCI is crosstalk from two different radio transmitters using the same channel. Co-channel interference can be caused by many factors from weather conditions to administrative and design issues. Co-channel interference may be controlled by various radio resource management schemes.
The S band is a designation by the Institute of Electrical and Electronics Engineers (IEEE) for a part of the microwave band of the electromagnetic spectrum covering frequencies from 2 to 4 gigahertz (GHz). Thus it crosses the conventional boundary between the UHF and SHF bands at 3.0 GHz. The S band is used by airport surveillance radar for air traffic control, weather radar, surface ship radar, and some communications satellites, particularly satellites used by NASA to communicate with the Space Shuttle and the International Space Station. The 10 cm radar short-band ranges roughly from 1.55 to 5.2 GHz. The S band also contains the 2.4–2.483 GHz ISM band, widely used for low power unlicensed microwave devices such as cordless phones, wireless headphones (Bluetooth), wireless networking (WiFi), garage door openers, keyless vehicle locks, baby monitors as well as for medical diathermy machines and microwave ovens. India's regional satellite navigation network (IRNSS) broadcasts on 2.483778 to 2.500278 GHz.
A cognitive radio (CR) is a radio that can be programmed and configured dynamically to use the best channels in its vicinity to avoid user interference and congestion. Such a radio automatically detects available channels, then accordingly changes its transmission or reception parameters to allow more concurrent wireless communications in a given band at one location. This process is a form of dynamic spectrum management.
Spectrum management is the process of regulating the use of radio frequencies to promote efficient use and gain a net social benefit. The term radio spectrum typically refers to the full frequency range from 1 Hz to 3000 GHz that may be used for wireless communication. Increasing demand for services such as mobile telephones and many others has required changes in the philosophy of spectrum management. Demand for wireless broadband has soared due to technological innovation, such as 3G and 4G mobile services, and the rapid expansion of wireless internet services.
The Department of Telecommunications, abbreviated to DoT, is a department of the Ministry of Communications of the executive branch of the Government of India.
Radio resource management (RRM) is the system level management of co-channel interference, radio resources, and other radio transmission characteristics in wireless communication systems, for example cellular networks, wireless local area networks, wireless sensor systems, and radio broadcasting networks. RRM involves strategies and algorithms for controlling parameters such as transmit power, user allocation, beamforming, data rates, handover criteria, modulation scheme, error coding scheme, etc. The objective is to utilize the limited radio-frequency spectrum resources and radio network infrastructure as efficiently as possible.
The Mumbai Amateur Radio Society or MARS is an amateur radio club based in Mumbai, India. The club was founded on 7 August 2000 by a group of 25 active hams. Since then it has grown to over two hundred members and is the largest such club in the metropolis. MARS is a registered 80G tax-deductible non-profit organization.
The Wireless Planning & Coordination Wing (WPC) is a Wing of Department of Telecommunications coming under the Ministry of Communications of the Government of India. The department is responsible for issuing amateur radio licenses, allotting the frequency spectrum and monitoring the frequency spectrum. The WPC is headquartered in New Delhi and has regional branches in Mumbai, Chennai, Kolkata and Guwahati.
Call signs in India are unique identifiers for telecommunications and broadcasting in India. The Ministry of Communications and Information Technology regulates call signs nationally, and the International Telecommunication Union regulates call signs internationally.
Amateur radio or ham radio is practised by more than 22,000 licensed users in India. The first amateur radio operator was licensed in 1921, and by the mid-1930s, there were around 20 amateur radio operators in India. Amateur radio operators played an important part in the Indian independence movement with the establishment of illegal pro-independence radio stations in the 1940s. The three decades after India's independence saw only slow growth in the number of operators until the then Prime Minister of India and amateur radio operator, Rajiv Gandhi (VU2RG), waived the import duty on wireless equipment in 1984. Since then, numbers have picked up, and as of 2007, there were more than 16,000 operators in the country. Amateur radio operators have played a vital role during disasters and national emergencies such as earthquakes, tsunamis, cyclones, floods, and bomb blasts, by providing voluntary emergency communications in the affected areas.
Radio is the technology of communicating using radio waves. Radio waves are electromagnetic waves of frequency between 3 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transmitter connected to an antenna which radiates oscillating electrical energy, often characterized as a wave. They can be received by other antennas connected to a radio receiver, this is the fundamental principle of radio communication. In addition to communication, radio is used for radar, radio navigation, remote control, remote sensing, and other applications.
The Indian Telegraph Act, 1885 was the enabling legislation in India which governed the use of wired and wireless telegraphy, telephones, teletype, radio communications and digital data communications. It gives the Government of India exclusive jurisdiction and privileges for establishing, maintaining, operating, licensing and oversight of all forms of wired and wireless communications within Indian territory. It also authorizes government law enforcement agencies to monitor/intercept communications and tap phone lines under conditions defined within the Indian Constitution. The act came into force on 1 October 1885. Since that time, numerous amendments have been passed to update the act to respond to changes in technology.
The 1978 regulations established five categories of Amateur radio licence in India. The regulations were revised in 2009 and now only two categories are issued.
Radio frequency sweep or frequency sweep or RF sweep apply to scanning a radio frequency band for detecting signals being transmitted there. A radio receiver with an adjustable receiving frequency is used to do this. A display shows the strength of the signals received at each frequency as the receiver's frequency is modified to sweep (scan) the desired frequency band.
The Spectrum Policy Task Force was established in June 2002 to assist the Federal Communications Commission in identifying and evaluating changes in spectrum policy that will increase the public benefits derived from the use of the radio spectrum.
The Indian Radio Regulatory Service (IRRS) is one of the cadre of central government recruit-engineers of the Wireless Planning & Coordination Wing (WPC) and Wireless Monitoring Organisation (WMO), composed of a cadre of central government recruit engineers Group 'A' officers and Group 'B' officers (Jr. Wireless Officer) of the WPC and WMO. There are a total of 22 Wireless Monitoring Stations, 5 International Monitoring Stations and 1 International Satellite Monitoring Earth Station in India, The functions of the service are the allocation of spectrum licenses, ensuring an interference free spectrum to wireless users, conducting GMDSS and RTR (Aero) examination, SACFA clearances to Telecom service Providers, ensuring adherence to international standards and cooperation with the International Telecommunication Union (ITU). The Government of India established the service by a gazette notification on 16 July 2013. The Wireless Adviser to the Government of India is the highest officer in the service's hierarchy and reports to the Member (Technology) of Telecom Commission of India under the Department of Telecommunications.
One way of outlining the subject of radio science is listing the topics associated with it by authoritative bodies.
