Radiomodtager

En radiomodtager beregnet til FM-radio og AM-radio (mellembølgebåndet).
En gammel radiomodtager beregnet til AM-radio via mellembølgebåndet og en del af kortbølgebåndet.

En radiomodtager, radiofonimodtager eller kort radio er et apparat, som kan modtage radiofoni og omsætte signalets modulation til en brugbar form. En radiomodtager kan fx forstærke signalet og sende lydsignal ud i en højttaler, hovedtelefoner - eller data ud i en visningsenhed.

Radiomodtagere kan inddeles efter flere egenskaber. De nævnte inddelingers emner er de mest kendte - der er flere emner:

Teknisk

En radiomodtager har altid en radioforsats - og kan fx have en forforstærker og en effektforstærker.

I radioantennen omdannes radiobølgerne til elektricitet. Den ledes nu via et antennekabel til forsatsen, som udvælger og forstærker den ønskede kanal i et bestemt frekvensinterval. Forsatsen foretager demodulering af det modulerede signal. I en gammeldags retmodtager detekteres signalet direkte på bærebølgens frekvens. Indførelsen af superheterodynmodtagere gav en bedre og mere stabil modtager: En stor del af radiomodtagere arbejder efter dette princip nu.

Se også

Referencer

  1. ^ worldradiohistory.com: Broadcast listening in the pioneer days of radio on the short waves, 1923 1945 Jerome S. Berg Citat: "...Three basic types of superhet receivers with shortwave capability soon emerged: all wave home radios with shortwave bands, communications receivers, and high fidelity shortwave sets.7...In a different category from the consumer radios were the communications receivers. The full story of the communications receiver is beyond the scope of this book.14 Suffice it to say that they were intended to offer a level of sensitivity, selectivity, and signal handling that would get the most out of whatever signal was reaching the antenna, without regard to operational simplicity or decor. The term communications receiver was not entirely self-defining, for there were communications receivers that were "little more than broadcast receivers repackaged in metal communications-type cabinets, "15 modest radios like the Hallicrafters Sky Champion and Super Defiant, and high-performance sets like some of the Hallicrafters Sky Riders and many of the Hammarlund and National models...", backup

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Truetone-Radio.jpg
Forfatter/Opretter: Raul654, Licens: CC BY-SA 3.0
Uploader's description: Picture of a Truetone brand old-fashioned radio. Taken by Raul654 on March 25, 2004. Released under the GFDL
Comment: Truetone (aka Western Auto Supply Co. of Kansas City MO) built many similarly styled console radios since mid-1930s; the closest (probably exact) match is the 1947 model D1845 [1]. This was the last iteration of large consoles by Truetone, built until around 1950.
Radio01.jpg
Forfatter/Opretter: unknown, Licens: CC BY-SA 3.0