Editing History of radio (section)

===Broadcasting===
{{See also|Old-time radio|History of broadcasting|Radio broadcasting#History|AM broadcasting#History|FM broadcasting#History}}

The Dutch company ''Nederlandsche Radio-Industrie'' and its owner-engineer, [[Hanso Idzerda]], made its first regular entertainment radio broadcast over station [[PCGG]] from its workshop in [[The Hague]] on 6 November 1919. The company manufactured both transmitters and receivers. Its popular program was broadcast four nights per week using narrow-band FM transmissions on 670 metres (448&nbsp;kHz),<ref>[[:File:Soireé-Musicale.jpg|"Radio Soireé-Musicale"]] ''Nieuwe Rotterdamsche Courant'', 05 November 1919, p. 16</ref> until 1924 when the company ran into financial trouble.

Regular entertainment broadcasts began in [[Argentina]], pioneered by [[Enrique Telémaco Susini]] and his associates. At 9 pm on August 27, 1920, Sociedad Radio Argentina aired a live performance of Richard Wagner's opera ''Parsifal'' from the Coliseo Theater in downtown [[Buenos Aires]]. Only about twenty homes in the city had receivers to tune in this program.

On 31 August 1920 the ''[[Detroit News]]''  began publicized daily news and entertainment "Detroit News Radiophone" broadcasts, originally as licensed amateur station 8MK, then later as WBL and [[WWJ (AM)|WWJ]] in [[Detroit|Detroit, Michigan]].

Union College in Schenectady, [[New York (state)|New York]] began broadcasting on October 14, 1920, over [[WRUC|2ADD]], an amateur station licensed to Wendell King, an [[African-American]] student at the school.<ref name="Radio Broadcasting">{{cite web|url=http://w2uc.union.edu/RADIO_web.htm |title=Radio Broadcasting at Union College|publisher=W2UC.union.edu |author=Rowan Wakefield|date=February 1959|access-date=2009-07-22 |url-status=dead |archive-url=https://web.archive.org/web/20080515103959/http://w2uc.union.edu/RADIO_web.htm |archive-date=May 15, 2008}}</ref> Broadcasts included a series of Thursday night concerts initially heard within a {{convert|100|mi|adj=on}} radius and later for a {{convert|1000|mi|adj=on}} radius.<ref name="Radio Broadcasting"/><ref>{{cite web|title=From a Shed to the World Wide Web|publisher=Union College Magazine|access-date=2018-02-03 |url=https://muse.union.edu/newsarchives/1995/11/01/from-a-shed-to-the-world-wide-web/|date=1 November 1995}}</ref>

In 1922 regular audio broadcasts for entertainment began in the UK from the [[Guglielmo Marconi|Marconi]] Research Centre [[2MT]] at [[Writtle]] near [[Chelmsford, England]].

==== Wavelength and frequency  ====
In early radio, and to a limited extent much later, the transmission signal of the radio station was specified in meters, referring to the [[wavelength]], the length of the radio wave. This is the origin of the terms [[long wave]], [[medium wave]], and [[short wave]] radio.<ref>{{Cite web|title=Radio Waves and the Electromagnetic Spectrum|url=https://radiojove.gsfc.nasa.gov/education/lesson_plans/lesson4.pdf|website=radiojove}}</ref> Portions of the radio spectrum reserved for specific purposes were often referred to by wavelength: the [[40-meter band]], used for [[History of amateur radio|amateur radio]], for example. The relation between wavelength and frequency is reciprocal: the higher the frequency, the shorter the wave, and vice versa.

As equipment progressed, precise frequency control became possible; early stations often did not have a precise frequency, as it was affected by the temperature of the equipment, among other factors. Identifying a radio signal by its frequency rather than its length proved much more practical and useful, and starting in the 1920s this became the usual method of identifying a signal, especially in the United States. Frequencies specified in number of cycles per second (kilocycles, megacycles) were replaced by the more specific designation of [[hertz]] (cycles per second) about 1965.