The blog of a dedicated radio amateur and electronics enthusiast

"Having fun on the air and in the workshop - communicating and creating"

04 February 2018

Software Defined Radio - RTL SDR


RTL.SDR hardware - connections for usb and antennas
SDR# software - tuned to VHF FM broadcast station on 105.6MHz

For several years usb 'dongles' for DVB-T reception have been available. The dongle consists of a tuner and down-converter. The frequency coverage of the tuner depends on the dongle variant, and typically from VHF to SHF. A common chip set is R820T tuner, RTL2832 down-converter and ADC ( analogue to digital converter, 8bit ). In-phase and Quadrature ( I - Q ) digital samples of the signal are sent at speeds up to 3.2MSamples/S over a USB2 connection for digital signal processing by a computer running appropriate software.
Using  a similar architecture, although a little different from the dongles in size and appearance, is the RTL SDR ( Software Defined Radio ), sometimes called RTL Downconverter. I recently bought one of this type online for GBP27 (  + free shipping + 10 week wait ) which has the new R820T2 tuner. This particularly interested me as the tuning range is continuous ( no gaps ) from 100KHz to 1.7GHz, ( LF-SHF ); so includes the amateur LF ( 136KHz ) and MF ( 475KHz ) bands. I plan to use the RTL SDR as a spectrum analyser to check some of the equipment I've built for these bands. I downloaded SDRSharp ( SDR# ) software, selected source RTL-SDR ( USB ), connected the supplied antenna and casually tuned and listened. The dynamic range seems to be about 60-65dB; not an impressive figure but should be enough for my purposes.
Further information is available from RTL-SDR.com and I downloaded SDR# from www.sdrsharp.com
There are also many video tutorials at www.youtube.com , e.g., Getting started with SDR# and an RTL SDR tuner - YouTube
An alternative software package which I haven't tried yet is 'SDR Console'.

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