an audible tone
11Motorola Minitor — Front view of the Minitor V pager. The Motorola Minitor is a portable, analog, receive only, voice pager typically carried by fire, rescue, and EMS personnel (both volunteer and paid) to alert of emergencies. The Minitor, slightly smaller than a… …
12telephone — telephoner, n. /tel euh fohn /, n., v., telephoned, telephoning. n. 1. an apparatus, system, or process for transmission of sound or speech to a distant point, esp. by an electric device. v.t. 2. to speak to or summon (a person) by telephone. 3.… …
13Selective calling — SECAL redirects here. For the French wine grape also known as Secal, see Jurançon (grape). In a conventional, analog two way radio system, a standard radio has noise squelch or carrier squelch which allows a radio to receive all transmissions.… …
14Variometer — The term Variometer also refers to a type of tunable electrical transformer A variometer (also known as a rate of climb indicator, a vertical speed indicator (VSI), or a vertical velocity indicator (VVI)) is an instrument in an aircraft used to… …
15Beat (acoustics) — In acoustics, a beat is an interference between two sounds of slightly different frequencies, perceived as periodic variations in volume whose rate is the difference between the two frequencies.When tuning instruments that can produce sustained… …
16Avalanche transceiver — Avalanche transceivers are a class of radio transceivers specialized to the purpose of finding people or equipment buried under snow. They are variously called ARVAs (Appareil de Recherche de Victimes en Avalanche, in French), avalanche beacons… …
17Continuous Automatic Warning System — For the gun, see Heckler Koch HK CAWS. For the wrestling video game creation mode, see Create a wrestler. The Continuous Automatic Warning System (CAWS) is a form of cab signalling and train protection system used in Ireland to help train drivers …
18Equal-loudness contour — An equal loudness contour is a measure of sound pressure (dB SPL), over the frequency spectrum, for which a listener perceives a constant loudness when presented with pure steady tones. The unit of measurement for loudness levels is the phon, and …
19Foghorn — For other meanings see Foghorn (disambiguation). A foghorn or fog signal or fog bell is a device that uses sound to warn vehicles of hazards or boats of the presence of other vehicles in foggy conditions. The term is most often used in relation… …
20Reginald Fessenden — Infobox Celebrity name = Reginald Fessenden caption = The Father of Radio Broadcasting birth date = birth date|1866|10|6|mf=y birth place = East Bolton, Quebec, Canada death date = death date and age|1932|7|22|1866|10|6|mf=y death place = Bermuda …
