Morse code is a telecommunications method which encodes text characters as standardized sequences of two different signal durations, called dots and dashes, or dits and dahs. Morse code is named after Samuel Morse, one of the early developers of the system adopted for electrical telegraphy.
Wireless telegraphy or radiotelegraphy is the transmission of text messages by radio waves, analogous to electrical telegraphy using cables. Before about 1910, the term wireless telegraphy was also used for other experimental technologies for transmitting telegraph signals without wires. In radiotelegraphy, information is transmitted by pulses of radio waves of two different lengths called "dots" and "dashes", which spell out text messages, usually in Morse code. In a manual system, the sending operator taps on a switch called a telegraph key which turns the transmitter on and off, producing the pulses of radio waves. At the receiver the pulses are audible in the receiver's speaker as beeps, which are translated back to text by an operator who knows Morse code.
A continuous wave or continuous waveform (CW) is an electromagnetic wave of constant amplitude and frequency, typically a sine wave, that for mathematical analysis is considered to be of infinite duration. It may refer to e.g. a laser or particle accelerator having a continuous output, as opposed to a pulsed output.
A walkie-talkie, more formally known as a handheld transceiver (HT) or handheld radio, is a hand-held, portable, two-way radio transceiver. Its development during the Second World War has been variously credited to Donald Hings, radio engineer Alfred J. Gross, Henryk Magnuski and engineering teams at Motorola. First used for infantry, similar designs were created for field artillery and tank units, and after the war, walkie-talkies spread to public safety and eventually commercial and jobsite work.
PMR446 is a licence-exempt service in the UHF radio frequency band and is available for business and personal use in most countries throughout the European Union.
CQ is a station code used by wireless operators derived from long established telegraphic practice on undersea cables and landlines, particularly used by those communicating in Morse code,, but also by voice operators, to make a general call. Transmitting the letters CQ on a particular radio frequency means that the transmission is a broadcast or "General Call" to anyone listening, and when the operator sends "K" or says "Go Ahead" it is an invitation for any licensed radio station listening on that frequency to respond. Its use on radio matched the existing use on Morse landline telegraphy and dates from the earliest wireless stations. It was widely used in point-to-point diplomatic and press services, maritime, aviation, and police services until those services eliminated Morse radiotelegraphy. It is still widely used in amateur radio which still has active use of Morse radiotelegraphy.
Amateur radio frequency allocation is done by national telecommunication authorities. Globally, the International Telecommunication Union (ITU) oversees how much radio spectrum is set aside for amateur radio transmissions. Individual amateur stations are free to use any frequency within authorized frequency ranges; authorized bands may vary by the class of the station license.
An amateur radio repeater is an electronic device that receives a weak or low-level amateur radio signal and retransmits it at a higher level or higher power, so that the signal can cover longer distances without degradation. Many repeaters are located on hilltops or on tall buildings as the higher location increases their coverage area, sometimes referred to as the radio horizon, or "footprint". Amateur radio repeaters are similar in concept to those used by public safety entities, businesses, government, military, and more. Amateur radio repeaters may even use commercially packaged repeater systems that have been adjusted to operate within amateur radio frequency bands, but more often amateur repeaters are assembled from receivers, transmitters, controllers, power supplies, antennas, and other components, from various sources.
The history of amateur radio, dates from the dawn of radio communications, with published instructions for building simple wireless sets appearing at the beginning of the twentieth century. Throughout its history, amateur radio enthusiasts have made significant contributions to science, engineering, industry, and social services. Research by amateur radio operators has founded new industries, built economies, empowered nations, and saved lives in times of emergency.
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.
KPH is a coast radio station on the Pacific Coast of the United States. For most of the 20th century, it provided ship to shore communications including telegrams and marine telex service. The station discontinued commercial operation in 1998, but is operated occasionally as a historic service – its signal can be received over a large portion of the western hemisphere.
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.
Citizens band radio is a system of short-distance radio communications between individuals on a selection of channels within the 27-MHz band. In India, this frequency band extends from 26.957 MHz to 27.283 MHz. There are several different channel plans in use. Citizens band is distinct from the Family Radio Service, GMRS, Multi-Use Radio Service and amateur radio (Ham). In many countries CB operation does not require a license, and it may be used for business or personal communications. Like many other two-way radio services, any citizens band channel is shared by many users. Only one station may transmit in a channel at a time; other stations must listen and wait for the shared channel to be available. Also, the system works in half-duplex mode, which means we may transmit and receive information, but not both at the same time.
Amateur radio, also known as ham radio, is the use of the radio frequency spectrum for purposes of non-commercial exchange of messages, wireless experimentation, self-training, private recreation, radiosport, contesting, and emergency communications. The term "amateur" is used to specify "a duly authorized person interested in radioelectric practice with a purely personal aim and without pecuniary interest" ; and to differentiate it from commercial broadcasting, public safety, or professional two-way radio services.
The Wireless Monitoring Organisation (WMO), set up in 1952, is responsible for monitoring all wireless transmissions on behalf of the Wireless Planning & Coordination Wing (WPC) in the Ministry of Communications of the Government of India. Its primary task is to monitor the entire radio frequency spectrum with a view to provide the requisite technical data logistic support to the WPC Wing in the enforcement of the National and International Radio Regulatory and statutory provisions for efficient management of Radio Frequency Spectrum and Geo-Stationary Orbit. This is in the interest of vital national service which, though not revenue bearing, yields considerable indirect benefits through promoting the efficient utilisation of the radio frequency spectrum and the geostationary orbit.
