Sunday, 8 April 2018

The rtlizer: low-cost spectrum analyzer using RTL2832U SDR

The Equalizer: 1985 TV Series
"Got a problem? Odds against you? Call the Equalizer. 212 555 4200." - The Equalizer

A spectrum analyzer is a serious piece of kit for an electronics engineer. You can easily spend over RM10,000 on one, although you can get generic ones online for RM4000. The RTL2832U DVB-T USB dongle SDR can be used to make a basic spectrum analyzer for RM39.

It is the great equalizer (after the 1985 TV Series), leveling the playing field for students, hobbyists and Third World engineers.

OZ9AEC has made an everyman's spectrum analyzer using a Raspberry Pi and the RTL2832U dongle. Happily, his design runs without modification on my Slackware 14.2 laptop.

rtlizer required rtl-sdr, which I had previously installed. Here we just need to tell rtlizer where to find it:

$export PKG_CONFIG_PATH=$PKG_CONFIG_PATH:/usr/local/lib/pkgconfig

And add '/usr/local/lib' to the file /etc/ If you had just installed rtl-sdr it helps to also do:


I downloaded rtlizer, and built it thus:


If necessary, unload (or even better, blacklist) the dongle's kernel drier:
$modprobe -vr dvb_usb_rtl28xxu
rmmod dvb_usb_rtl28xxu
rmmod dvb_usb_v2
rmmod rc_core

And it runs, right out of the box (with a complaint or two):

$./rtlizer 1024x720

(rtlizer:22436): Gtk-WARNING **: gtk_window_parse_geometry() called on a window w
ith no visible children; the window should be set up before gtk_window_parse_geom
etry() is called.
window size: 1024x720 pixels
SCALE: 7.20 / Y0: 216 / TXTMARG: 21
Found Fitipower FC0012 tuner

rtlizer responds to the the arrow keys. And wneh I centered rtlyzer on 330MHz, my autogate remote's frequency, I got the spike in the center, with the upper and lower sidebands when the button was pressed:

rtlizer centered on 330MHz
There you have it: an RM39 spectrum analyzer, courtesy of OZ9AEC. Happy Trails.

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