File:Spark gap transmitter bandwidth - 2.png

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DescriptionSpark gap transmitter bandwidth - 2.png	English: "Characteristic of preoperly adjusted transmitter showing single wave." A graph showing the broad band of frequencies radiated by a spark gap transmitter, the type of radio transmitter used until about 1920. The vertical axis is the energy of the received signal at the test receiver, and the horizontal axis is frequency. Since they generated radio waves using an impulsive spark, spark transmitters did not transmit on a single frequency but a band of frequencies, and tended to interfere with other transmitters on neighboring frequencies. From the graph, this transmitter's center wavelength was near 900 meters (a frequency of 330 kHz) but the emissions extend from 850 - 975 meters (350 - 307 kHz) with its signal. This graph was submitted by the US Bureau of Standards (the predecessor of the National Institute of Standards and Technology) to the radiotelegraph committee of US Congress 1912 when this book was published, to illustrate the noise problem of spark transmitters, to support legislation to restrict their use. Spark transmitters were superseded by vacuum tube transmitters around 1920, and remaining legacy sets on ships were banned in 1934.
Date	1912
Source	(1912) Hearings Before the Committee on the Merchant Marine and Fisheries, Washington, DC: US Government Printing Office, pp. 64–70 H.R. 15357
Author	Frederick A. Kolster

	This work is in the public domain in the United States because it is a work prepared by an officer or employee of the United States Government as part of that person’s official duties under the terms of Title 17, Chapter 1, Section 105 of the US Code. Note: This only applies to original works of the Federal Government and not to the work of any individual U.S. state, territory, commonwealth, county, municipality, or any other subdivision. This template also does not apply to postage stamp designs published by the United States Postal Service since 1978. (See § 313.6(C)(1) of Compendium of U.S. Copyright Office Practices). It also does not apply to certain US coins; see The US Mint Terms of Use.
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	Date/Time	Thumbnail	Dimensions	User	Comment
current	00:34, 13 October 2023		460 × 545 (46 KB)	Mu301	Uploaded a work by Frederick A. Kolster, from Kolster, Frederick A. (18 January 1912). "Statement of Mr. F.A. Kolster". Radio Communication. Hearings Before the Committee on the Merchant Marine and Fisheries. US House of Representatives. Washington: US Government Printing Office. pp. 64–70. H.R. 15357. Retrieved 10 October 2023. with UploadWizard

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