blog/archive/2023/03/03.rss

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   4                 <title>Petter Reinholdtsen - Entries from March 2023</title>
   5                 <description>Entries from March 2023</description>
   6                 <link>https://people.skolelinux.org/pere/blog/</link>
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   8
   9         <item>
  10                 <title>rtlsdr-scanner, software defined radio frequency scanner for Linux  - nice free software</title>
  11                 <link>https://people.skolelinux.org/pere/blog/rtlsdr_scanner__software_defined_radio_frequency_scanner_for_Linux____nice_free_software.html</link>
  12                 <guid isPermaLink="true">https://people.skolelinux.org/pere/blog/rtlsdr_scanner__software_defined_radio_frequency_scanner_for_Linux____nice_free_software.html</guid>
  13                 <pubDate>Tue, 7 Mar 2023 23:10:00 +0100</pubDate>
  14                 <description>&lt;p&gt;Today I finally found time to track down a useful radio frequency
  15 scanner for my software defined radio.  Just for fun I tried to locate
  16 the radios used in the areas, and a good start would be to scan all
  17 the frequencies to see what is in use.  I&#39;ve tried to find a useful
  18 program earlier, but ran out of time before I managed to find a useful
  19 tool.  This time I was more successful, and after a few false leads I
  20 found a description of
  21 &lt;a href=&quot;https://www.kali.org/tools/rtlsdr-scanner/&quot;&gt;rtlsdr-scanner
  22 over at the Kali site&lt;/a&gt;, and was able to track down
  23 &lt;a href=&quot;https://gitlab.com/kalilinux/packages/rtlsdr-scanner.git&quot;&gt;the
  24 Kali package git repository&lt;/a&gt; to build a deb package for the
  25 scanner.  Sadly the package is missing from the Debian project itself,
  26 at least in Debian Bullseye.  Two runtime dependencies,
  27 &lt;a href=&quot;https://gitlab.com/kalilinux/packages/python-visvis.git&quot;&gt;python-visvis&lt;/a&gt;
  28 and
  29 &lt;a href=&quot;https://gitlab.com/kalilinux/packages/python-rtlsdr.git&quot;&gt;python-rtlsdr&lt;/a&gt;
  30 had to be built and installed separately.  Luckily &#39;&lt;tt&gt;gbp
  31 buildpackage&lt;/tt&gt;&#39; handled them just fine and no further packages had
  32 to be manually built.  The end result worked out of the box after
  33 installation.&lt;/p&gt;
  34
  35 &lt;p&gt;My initial scans for FM channels worked just fine, so I knew the
  36 scanner was functioning.  But when I tried to scan every frequency
  37 from 100 to 1000 MHz, the program stopped unexpectedly near the
  38 completion.  After some debugging I discovered USB software radio I
  39 used rejected frequencies above 948 MHz, triggering a unreported
  40 exception breaking the scan.  Changing the scan to end at 957 worked
  41 better.  I similarly found the lower limit to be around 15, and ended
  42 up with the following full scan:&lt;/p&gt;
  43
  44 &lt;p&gt;&lt;a href=&quot;https://people.skolelinux.org/pere/blog/images/2023-04-07-radio-freq-scanning.png&quot;&gt;&lt;img src=&quot;https://people.skolelinux.org/pere/blog/images/2023-04-07-radio-freq-scanning.png&quot; width=&quot;100%&quot;&gt;&lt;/a&gt;&lt;/p&gt;
  45
  46 &lt;p&gt;Saving the scan did not work, but exporting it as a CSV file worked
  47 just fine.  I ended up with around 477k CVS lines with dB level for
  48 the given frequency.&lt;/p&gt;
  49
  50 &lt;p&gt;The save failure seem to be a missing UTF-8 encoding issue in the
  51 python code.  Will see if I can find time to send a patch
  52 &lt;a href=&quot;https://github.com/CdeMills/RTLSDR-Scanner/&quot;&gt;upstream&lt;/a&gt;
  53 later to fix this exception:&lt;/p&gt;
  54
  55 &lt;pre&gt;
  56 Traceback (most recent call last):
  57   File &quot;/usr/lib/python3/dist-packages/rtlsdr_scanner/main_window.py&quot;, line 485, in __on_save
  58     save_plot(fullName, self.scanInfo, self.spectrum, self.locations)
  59   File &quot;/usr/lib/python3/dist-packages/rtlsdr_scanner/file.py&quot;, line 408, in save_plot
  60     handle.write(json.dumps(data, indent=4))
  61 TypeError: a bytes-like object is required, not &#39;str&#39;
  62 Traceback (most recent call last):
  63   File &quot;/usr/lib/python3/dist-packages/rtlsdr_scanner/main_window.py&quot;, line 485, in __on_save
  64     save_plot(fullName, self.scanInfo, self.spectrum, self.locations)
  65   File &quot;/usr/lib/python3/dist-packages/rtlsdr_scanner/file.py&quot;, line 408, in save_plot
  66     handle.write(json.dumps(data, indent=4))
  67 TypeError: a bytes-like object is required, not &#39;str&#39;
  68 &lt;/pre&gt;
  69
  70 &lt;p&gt;As usual, if you use Bitcoin and want to show your support of my
  71 activities, please send Bitcoin donations to my address
  72 &lt;b&gt;&lt;a href=&quot;bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b&quot;&gt;15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b&lt;/a&gt;&lt;/b&gt;.&lt;/p&gt;
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