HAM: Software Defined Radio (58.html)
SDR electronics.
The above photo shows a Raspberry Pi computer (rear) with an inexpensive RTL Blade
board (front)
SDR with a Dongle.
Above: SDR: Software Defined Radio (dongle) with an RTL2832U chipset
Today, a radio receiver can be purchased as an inexpensive USB dongle (shown above) that you plug into your computer. A simple antenna is plugged into the other end of the dongle. This dongle will receive high frequency radio stations (eg 24MHz-1786MHz). To receive lower frequency radio (such as low frequency amateur radio [ham] ) stations, the frequencies must be raised. This is done by the ham-it-up electronics board. The computer is used to select the frequency (and type of modulation . . . such as AM, FM, SSB,CW) of the desired radio station.
For more info: Visit Adafruit-1497 or Wikipedia: SDR
More information about SDR (Software Defined Radio) can be found in my articles 51 and 162.
Sources
Web Sources
Web Source S058:01: KiwiSDR Board 
from SEEED Studios
Web Source S058:02: KiwiSDR Board from SEEED Studios
WebMaster: David Cole ( VE3IAE )
Created: 2015 C Mar 12
Updated: 2021 D Apr 10
/58.html