{"id":885,"date":"2020-07-14T21:13:46","date_gmt":"2020-07-15T03:13:46","guid":{"rendered":"http:\/\/www.malos-ojos.com\/?p=885"},"modified":"2020-07-14T21:18:26","modified_gmt":"2020-07-15T03:18:26","slug":"what-i-learned-about-software-defined-radios-in-a-few-days","status":"publish","type":"post","link":"http:\/\/www.malos-ojos.com\/?p=885","title":{"rendered":"What I learned about Software Defined Radios in a few days\u2026"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\">As usual, it has been quite a while since I\u2019ve posted anything to the site, but I figured since I spent some time learning about Software Defined Radios (now that I finally got a bit of down time from work) that I\u2019d share what I learned.&nbsp; One caveat, I did have a purpose in learning more about SDRs and that was to be able to listen to and record all the Chicago Police and Fire dispatch radio traffic on the old analog radio system.&nbsp; After a bit of trial and error and testing a few of the hardware and software options  I settled on a working configuration that I&#8217;ll share in the video series below.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong><span style=\"text-decoration: underline;\">Background<\/span><\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">SDRs are hardware devices, controlled by software and the configuration of that software, that allow us to use the radio hardware to tune to and receive radio transmissions, and in some case transmit radio as well, within the spectrum covered by the hardware device.&nbsp; These devices range from $25 on the low end to $1,000\u2019s on the upper end, and in this post I\u2019ll mainly focus on the lower end devices (RTL-SDR and Nooelec SMART NESDRs).&nbsp; The links to the hardware, software, and other sites mentioned in the video series are posted below for reference.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong><span style=\"text-decoration: underline;\">Objectives<\/span><\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The objective, as mentioned above, was to be able to receive and record radio transmissions.&nbsp; These transmissions happen to be in the 460 MHz range (from 460.025 to 460.525 MHz) as Chicago is still using an old analog radio system for dispatch (yes, SWAT and other have moved to a digital encrypted system already).&nbsp; The issue I ran into was there is a lot of information on how to setup and configure a digital, or digitally trunked system, but not a lot on how to setup the hardware and software for older analog radio systems.&nbsp; Turns out, it is not that difficult\u2026<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong><span style=\"text-decoration: underline;\">The Videos<\/span><\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">I figured this post was better suited for a series of videos that cover the basics of the radio spectrum through the installation and configuration of hardware and software to meet my objectives.&nbsp; Starting with the basics, Video 1 below covers:<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li>The basics of the <strong>radio spectrum<\/strong> in the US<\/li><li>An overview of <strong>my use case<\/strong> and objectives<\/li><li>Sites that can be used to lookup radio frequencies<\/li><li>Hardware options (handheld scanners) and <strong>types of radio systems<\/strong> (analog, digital, and trunked)<\/li><\/ul>\n\n\n\n<p class=\"wp-block-paragraph\"><iframe loading=\"lazy\" src=\"https:\/\/player.vimeo.com\/video\/438408107\" width=\"500\" height=\"281\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">In Video 2, I\u2019ll cover:<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li>SDR <strong>Hardware <\/strong>options (limiting to $350 and under)<\/li><li><strong>Software <\/strong>options<\/li><li>The hardware and software I chose for my use case<\/li><li>Where can I stream these transmissions? <strong>OpenMhz<\/strong>!<\/li><\/ul>\n\n\n\n<p class=\"wp-block-paragraph\"><iframe loading=\"lazy\" src=\"https:\/\/player.vimeo.com\/video\/438407975\" width=\"500\" height=\"281\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\">&amp;amp;lt;\/p><\/iframe><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Video 3 gets us started on the build, and covers:<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li>Connecting our SDRs to Windows and Linux<\/li><li>Using <strong>SDR#<\/strong><\/li><li>Installing <strong>rtl_eeprom<\/strong>, <strong>docker<\/strong>, and getting <strong>trunk-recorder<\/strong> to a working state<\/li><\/ul>\n\n\n\n<p class=\"wp-block-paragraph\"><iframe loading=\"lazy\" src=\"https:\/\/player.vimeo.com\/video\/438407904\" width=\"500\" height=\"281\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\">&lt;\/p><\/iframe><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Finally, in Video 4, we work on:<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li>Determining your error correction or PPM using <strong>GQRX<\/strong><\/li><li>Configuring <strong>trunk-recorder<\/strong> (config.json and talkgroup files)<\/li><li>Determining a center frequency for our use case (analog 460 Mhz transmissions)<\/li><li>Pushing our recordings to <strong>OpenMHz<\/strong> and listening locally<\/li><\/ul>\n\n\n\n<p class=\"wp-block-paragraph\"><iframe loading=\"lazy\" src=\"https:\/\/player.vimeo.com\/video\/438407815\" width=\"500\" height=\"281\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\">&amp;lt;\/p><\/iframe><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">And one final bonus video that shows the quick and dirty way to get trunk-recorder working using a pull from Docker Hub of the latest <strong>robotastic\/trunk-recorder<\/strong> docker.&nbsp; In this we will use <strong><em>docker -run<\/em><\/strong> and map some volumes and devices between our OS and the Docker container and get up and running quickly.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><iframe loading=\"lazy\" src=\"https:\/\/player.vimeo.com\/video\/438407758\" width=\"500\" height=\"281\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\">&amp;amp;lt;\/p><\/iframe><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Finally, here are the links:<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li><a onclick=\"javascript:pageTracker._trackPageview('\/outgoing\/www.rtl-sdr.com\/');\"  href=\"https:\/\/www.rtl-sdr.com\/\">https:\/\/www.rtl-sdr.com\/<\/a><\/li><li><a onclick=\"javascript:pageTracker._trackPageview('\/outgoing\/www.nooelec.com\/store\/');\"  href=\"https:\/\/www.nooelec.com\/store\/\">https:\/\/www.nooelec.com\/store\/<\/a><\/li><li><a onclick=\"javascript:pageTracker._trackPageview('\/outgoing\/airspy.com\/');\"  href=\"https:\/\/airspy.com\/\">https:\/\/airspy.com\/<\/a><\/li><li><a onclick=\"javascript:pageTracker._trackPageview('\/outgoing\/shop.hak5.org\/collections\/featured-makers\/products\/hackrf');\"  href=\"https:\/\/shop.hak5.org\/collections\/featured-makers\/products\/hackrf\">https:\/\/shop.hak5.org\/collections\/featured-makers\/products\/hackrf<\/a><\/li><li><a onclick=\"javascript:pageTracker._trackPageview('\/outgoing\/www.andrewmohawk.com\/2020\/06\/12\/trunked-radio-a-guide\/');\"  href=\"https:\/\/www.andrewmohawk.com\/2020\/06\/12\/trunked-radio-a-guide\/\">https:\/\/www.andrewmohawk.com\/2020\/06\/12\/trunked-radio-a-guide\/<\/a><\/li><li><a onclick=\"javascript:pageTracker._trackPageview('\/outgoing\/github.com\/robotastic\/trunk-recorder');\"  href=\"https:\/\/github.com\/robotastic\/trunk-recorder\">https:\/\/github.com\/robotastic\/trunk-recorder<\/a><\/li><li><a onclick=\"javascript:pageTracker._trackPageview('\/outgoing\/github.com\/AndrewMohawk\/trunkrecorder-helpers');\"  href=\"https:\/\/github.com\/AndrewMohawk\/trunkrecorder-helpers\">https:\/\/github.com\/AndrewMohawk\/trunkrecorder-helpers<\/a><\/li><li><a onclick=\"javascript:pageTracker._trackPageview('\/outgoing\/www.radioreference.com\/');\"  href=\"https:\/\/www.radioreference.com\/\">https:\/\/www.radioreference.com\/<\/a><\/li><li><a onclick=\"javascript:pageTracker._trackPageview('\/outgoing\/openmhz.com\/');\"  href=\"https:\/\/openmhz.com\/\">https:\/\/openmhz.com\/<\/a><\/li><\/ul>\n","protected":false},"excerpt":{"rendered":"<p>As usual, it has been quite a while since I\u2019ve posted anything to the site, but I figured since I spent some time learning about Software Defined Radios (now that I finally got a bit of down time from work) that I\u2019d share what I learned.&nbsp; One caveat, I did have a purpose in learning [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_feature_clip_id":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2},"jetpack_post_was_ever_published":false},"categories":[1],"tags":[],"class_list":["post-885","post","type-post","status-publish","format-standard","hentry","category-general"],"jetpack_publicize_connections":[],"jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/pme9o-eh","jetpack_featured_media_url":"","_links":{"self":[{"href":"http:\/\/www.malos-ojos.com\/index.php?rest_route=\/wp\/v2\/posts\/885","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/www.malos-ojos.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.malos-ojos.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.malos-ojos.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.malos-ojos.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=885"}],"version-history":[{"count":31,"href":"http:\/\/www.malos-ojos.com\/index.php?rest_route=\/wp\/v2\/posts\/885\/revisions"}],"predecessor-version":[{"id":916,"href":"http:\/\/www.malos-ojos.com\/index.php?rest_route=\/wp\/v2\/posts\/885\/revisions\/916"}],"wp:attachment":[{"href":"http:\/\/www.malos-ojos.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=885"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.malos-ojos.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=885"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.malos-ojos.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=885"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}