{"id":146,"date":"2020-11-26T22:34:20","date_gmt":"2020-11-26T21:34:20","guid":{"rendered":"https:\/\/lipkowski.com\/?page_id=146"},"modified":"2020-11-26T23:00:42","modified_gmt":"2020-11-26T22:00:42","slug":"etherify3","status":"publish","type":"page","link":"https:\/\/lipkowski.com\/pl\/etherify3\/","title":{"rendered":"Etherify 3 &#8211; the PI 4&#8217;s dirty little secret"},"content":{"rendered":"<p>Recently i&#8217;ve published <a href=\"https:\/\/lipkowski.com\/etherify\/\">Etherify &#8211; bringing the ether back to ethernet<\/a>, please read this article first, before reading this one.<\/p>\n<p>Script source is on: https:\/\/github.com\/sq5bpf\/etherify , see etherify3.sh<\/p>\n<p>That article uses primarily raspberry PI 4 for transmission, which give an exceptionally strong signal, and fast link-up time.<\/p>\n<p>So i wanted to investigate if maybe there is something unique to this device. And when i accidentally disconnected the ethernet cable it turned out there is \ud83d\ude42<\/p>\n<p>The Raspberry PI 4 ethernet hardware can send a very strong signal even when it is unconnected. To test i&#8217;ve connected it to a powerbank (so there is less wires to act as an antenna). The result is here (sorry for the upside-down video):<\/p>\n<p><iframe loading=\"lazy\" title=\"Etherify 3 demo\" width=\"525\" height=\"295\" src=\"https:\/\/www.youtube.com\/embed\/pKqaqh7EFH8?feature=oembed\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen><\/iframe><\/p>\n<p>So i&#8217;ve set up an elaborate transmit position at 5m height using a balcony and 3 strategically placed chairs:<\/p>\n<p><iframe loading=\"lazy\" title=\"Etherify 3 transmit position for tests at 12m and 50m\" width=\"525\" height=\"295\" src=\"https:\/\/www.youtube.com\/embed\/AON7Wrbo0nk?feature=oembed\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen><\/iframe><\/p>\n<p>This was tested at various harmonics of 125MHz using and rtl-sdr and a simple dual-band 145\/435MHz antenna mounted on a car. This antenna is not tuned to these frequencies, but is much easier to use outside.\u00a0 The mistuning probably isn&#8217;t a problem, because the signal\/noise is affected by interference from local ethernet networks, not by the receiver noise factor.<\/p>\n<p>Tests at various harmonics at 12m:<\/p>\n<p><iframe loading=\"lazy\" title=\"Etherify 3 distance 12m at different harmonics of 125MHz\" width=\"525\" height=\"295\" src=\"https:\/\/www.youtube.com\/embed\/mUTRbnl8W7c?feature=oembed\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen><\/iframe><\/p>\n<p>And a test at 50m:<\/p>\n<p><iframe loading=\"lazy\" title=\"Etherify 3 on 375MHz distance 50m\" width=\"525\" height=\"295\" src=\"https:\/\/www.youtube.com\/embed\/iZyNICOiN4Y?feature=oembed\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen><\/iframe><\/p>\n<p>The test at 50m is incredible, because the device doesn&#8217;t have any big conductors to radiate it. A 1\/4 wave monopole is 19.2cm long at 375MHz, there are no conductors comparable in size on the Raspberry PI 4. Probably a similar result could be achieved with <a href=\"https:\/\/github.com\/F5OEO\/rpitx\">rpitx<\/a> without an antenna at higher frequencies.<\/p>\n<p>The board says: Raspberry PI 4 Model B, FCC ID: 2ABCB-RPI4B, IC: 20953-RPI4B.<\/p>\n<p>I will test other Raspberry pi 4s in the future, because maybe i have a bad specimen. If this is true, then the 100m reception results shown in the <a href=\"https:\/\/lipkowski.com\/etherify\/\">Etherify article<\/a> are not that spectacular. Actually i hope i have a bad specimen. Maybe others could test their hardware and send me a note?<\/p>\n<p>But don&#8217;t fear, Etherify 4 will soon be published, with no RPIs, just good old laptops \ud83d\ude42<\/p>\n<p>If you cite this, please include the webpage address and attribute Jacek Lipkowski (SQ5BPF). Email can be sent to my_callsign @ this_domain.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Recently i&#8217;ve published Etherify &#8211; bringing the ether back to ethernet, please read this article first, before reading this one. Script source is on: https:\/\/github.com\/sq5bpf\/etherify , see etherify3.sh That article uses primarily raspberry PI 4 for transmission, which give an exceptionally strong signal, and fast link-up time. So i wanted to investigate if maybe there &hellip; <\/p>\n<p class=\"link-more\"><a href=\"https:\/\/lipkowski.com\/pl\/etherify3\/\" class=\"more-link\">Continue reading<span class=\"screen-reader-text\"> &#8220;Etherify 3 &#8211; the PI 4&#8217;s dirty little secret&#8221;<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-146","page","type-page","status-publish","hentry"],"translation":{"provider":"WPGlobus","version":"3.0.1","language":"pl","enabled_languages":["en","pl"],"languages":{"en":{"title":true,"content":true,"excerpt":false},"pl":{"title":false,"content":false,"excerpt":false}}},"_links":{"self":[{"href":"https:\/\/lipkowski.com\/pl\/wp-json\/wp\/v2\/pages\/146","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/lipkowski.com\/pl\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/lipkowski.com\/pl\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/lipkowski.com\/pl\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/lipkowski.com\/pl\/wp-json\/wp\/v2\/comments?post=146"}],"version-history":[{"count":6,"href":"https:\/\/lipkowski.com\/pl\/wp-json\/wp\/v2\/pages\/146\/revisions"}],"predecessor-version":[{"id":148,"href":"https:\/\/lipkowski.com\/pl\/wp-json\/wp\/v2\/pages\/146\/revisions\/148"}],"wp:attachment":[{"href":"https:\/\/lipkowski.com\/pl\/wp-json\/wp\/v2\/media?parent=146"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}