![]() ![]() The superhet solved this problem for all time by using frequency conversion that was controlled by a local oscillator. Prior attempts at amplifying radio signals included the regenerative and super-regenerative receivers (both invented by Armstrong, but stolen by greedy RCA), which at least offered some gain to boost far-away signals, but were prone to drift. ![]() Prior to the superhet receiver, radio listeners had to constantly play with a set of knobs on a radio to keep locked on to radio programs of the day. Order "Man of Fidelity: Edwin Howard Armstrong" by Lawrence Lessing on our book page to corroborate that fact. Although Fessenden was able to receive signals by mixing them, there is no evidence that he used a detector to sort out the baseband therefore Fessenden only managed to put together just one of the five pieces of Armstrong's superhet receiver (RF amp, mixer, local oscillator, detector and audio amp). Heterodyning is the same as mixing, we offer a little history on the topic here. The word "heterodyne" was coined by Reginald Aubrey Fessenden, also in our Hall of Fame. Don't ever think your services are as valuable as the work of more deserving corporate lawyers! But we digress. As an engineer you'd best remember your place at the bottom of the corporate food-chain or you'll be living in a cardboard house behind the Circle K pretty soon. From this perspective, nothing's changed, big companies ruin many engineers' lives today, especially in arguments over inventions. Unfortunately, he had a bad habit of inventing stuff independently of the corporate anti-Christ of the time, which was RCA (Radio Corporation of America) RCA and others pretty much ruined Armstrong's life. Edwin Armstrong (see him in our Hall of Fame) was truly one of the great minds of the twentieth century. The superheterodyne receiver is still the most popular microwave receiver, and it was invented during and directly after the Great War and patented in 1918. Selected topics on superhet receivers History of the superheterodyne receiver Here's a clickable index to our super material on superhet! A common contraction of the word is simply "superhet". The word "superheterodyne" is often hyphenated to "super-heterodyne". In most microwave receivers, the upper sideband is ignored. The sum frequency is the upper sideband, and the difference frequency is the difference sideband. These are referred to as the two sidebands. Actually, two signals are always created, the sum frequency and the difference frequency. To heterodyne means to mix two signals of different frequencies together, resulting in a "beat" frequency. Click here to go to our main page on microwave receiversĬlick here to go to our main page on mixersĬlick here to go to our page on noise figureĬlick here to go to our page on low noise amplifiersĪ superheterodyne receiver contains a combination of amplification with frequency mixing, and is by far the most popular architecture for a microwave receiver.
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