Principle of Operation
The direct-conversion receiver feeds the radio frequency signal into a frequency mixer, just as in a superheterodyne receiver. However unlike the superheterodyne, the frequency of the local oscillator is not offset from but right at the received signal's frequency. The result is a demodulated output just as you would obtain from a superheterodyne receiver using synchronous detection (a product detector) following an intermediate frequency (IF) stage. In other words, the conversion to baseband is done in a single frequency conversion. This avoids the complexity of the superheterodyne's two (or more) frequency conversions, IF stage(s), and image rejection issues.
Read more about this topic: Direct-conversion Receiver
Famous quotes containing the words principle of, principle and/or operation:
“What is an atheist, but one who does not, or will not, see in the universe a ruling principle of love; and what a misanthrope, but one who does not, or will not, see in man a ruling principle of kindness?”
—Herman Melville (1819–1891)
“Now, what I want is, Facts. Teach these boys and girls nothing but Facts. Facts alone are wanted in life. Plant nothing else, and root out everything else. You can only form the minds of reasoning animals upon Facts: nothing else will ever be of any service to them. This is the principle on which I bring up my own children, and this is the principle on which I bring up these children. Stick to Facts, sir!”
—Charles Dickens (1812–1870)
“Waiting for the race to become official, he began to feel as if he had as much effect on the final outcome of the operation as a single piece of a jumbo jigsaw puzzle has to its predetermined final design. Only the addition of the missing fragments of the puzzle would reveal if the picture was as he guessed it would be.”
—Stanley Kubrick (b. 1928)