Main Page | See live article | Alphabetical index The Tuned Radio Frequency Receiver was invented by Edwin Armstrong in 1918. The process of amplifying an input signal on a given frequency over several stages. The disadvantage to this process being that each stage must be tuned to the input carrier frequency individually. It was replaced by the Superheterodyne receiver also invented by Edwin Armstrong. This article is from Wikipedia. All text is available under the terms of the GNU Free Documentation License.