Principle of the "Software Defined Radio" (SDR)
A "Software Defined Radio" handles the received signals mostly by software ("digital signal processing").
| An especially cost effective SDR can be built by converting the highfrequency radio signal to a lowfrequency
signal that can be fed directly to the audio input of a PC. The A/D-Converter in the PC digitizes the received signal. The SW transforms the signal in a frequency based representation (spectrum or waterfall), that contains the signals from many different stations. The desired station is now selected (with the receiving window or filter), reverse transformed into a time signal and converted again to an analog signal that goes to the speaker. |
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You can also receive amateur radio stations at home: www.websdr.org