<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html><head> <meta content="text/html; charset=UTF-16" http-equiv="content-type"><title>remote SDR</title></head><body style="background-image: url(index_soubory/kos.jpg); direction: ltr;"> <table style="text-align: left; width: 803px; height: 800px; font-family: Arial;" border="0" cellpadding="0" cellspacing="2"> <tbody> <tr> <td style="vertical-align: top; text-align: left; background-color: rgb(218, 218, 218);"><big><big><span style="font-weight: bold;"><br> </span></big></big> <table style="width: 801px; height: 44px; text-align: left; margin-left: auto; margin-right: auto; color: rgb(255, 255, 255);" border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td style="height: 33px; text-align: center; background-color: rgb(153, 0, 0);"><big style="font-weight: bold;"><big>My remote RX story</big></big></td> </tr> </tbody> </table> <a href="../../pics/ES2405_1.bmp"><small><span style="font-weight: bold; color: rgb(255, 0, 0);"></span></small></a><small><span style="font-weight: bold; color: rgb(255, 0, 0);"><br> </span><span style="color: rgb(255, 0, 0);"><span style="color: rgb(0, 0, 0);"><br> </span></span></small><small><span style="font-weight: bold; color: rgb(255, 0, 0);"> </span></small><small><span style="color: rgb(255, 0, 0);"><span style="color: rgb(0, 0, 0);"><br></span></span></small><br> <span style="font-weight: bold; color: red;">Why remote RX?</span><br> Central Europe, industrial city in the middle of the continent, very far from ocean - that all parameters play against efficient receiving on low bands. <br> <br> You can add possibilities of housing in a city for ordinary people, It all results in a very small chance for good work on low bands. <br> <br> Add a fact that ordinary working people cannot afford buying large properties and build big antenna systems. It is only for the chosen. At least in the Czech Republic. <br> <br> As many other city hams my receiving capabilities have been very limited by man made noise. Computers, switching supplies, mobile telephone chargers, plasmatic TV and many others produce noice usualy in levels of S9 and more.<br> Low band DX-ing becomes a horrible story and turns to impossibility of hearing any DX signal. <br> It is a big difference in comparison of receiving capabilities of stations in absolute silence on an ocean beach with S0 on S-meter with RF gain on maximum. <br> <br> This all was the main reason why I had started thinking about placing RX to quiet enviroment. Our familly has a small garden at the outskirts of the city (about 4 km from my QTH). It is quite far from city noise sources. Not everything is ideal, but first tests showed that noise level is much lower than in my fixed QTH - just S2 to S3 (about -110 to -115 dBm).&nbsp; <br> Very quiet rural eviroment gives even lower noise, but I do not have better place on one hand and on the other hand there was a possibbility in connection to the Internet in a reasonable way.<br> <br> <br> <span style="font-weight: bold; color: red;">Building remote.</span><br> After first listening tests had been done I asked a friend of mine - Marek OK2VVD about the Internet connection (he is known as a local Internet provider). We made it as a wireless link on 5 GHz. Next step was to obtain any good quality SDR receiver. Marek had one simple SDR RX - Fifi made by german magazine Funkamater unemployed&nbsp; and I borrowed this receiver for tests.<br> This RX (<a href="http://o28.sischa.net/fifisdr/trac">http://o28.sischa.net/fifisdr/trac)</a> is build in a small metallic box together with reasonable band filtering and covers frequencies 200 kHz to 30 MHz. All detail are on their website.<br> <br> <img src="pics/sdr/BX-222_1.png" alt="" style="width: 295px; height: 223px;"><img style="width: 310px; height: 223px;" alt="" src="pics/sdr/BX-222_2.png"><br> <br> <br> <span style="font-weight: bold; color: red;">How antenna ?</span><br> First test have been done since November 2013 using very simple magnetic loop tuned to 160m. Bandwidth was not ideal - about 40 kHz. Loop had diameter of 2 metres and was fixed on laminate telescope 4 metres above the ground.<br> <br> This antenna has never been properly matched. But it worked! My next step was to build a better antenna.<br> <br> My choice for better antenna for a such limited space was K9AY.<br> (<a href="http://www.k9ay.com/TechData/K9AYLoopArrays.pdf">http://www.k9ay.com/TechData/K9AYLoopArrays.pdf</a>). It just fit to our garden dimensions. <br> All components of K9AY antenna are home made. Switching box includes preamplifier W7IUV with bandpass filtering all except 160 and 80m bands.&nbsp; <br> <br> This box is connected by two cables (coax and switching FTP cable) to a control cabinet. This is located in a small garden hut together with a simple PC, SDR radio, switching circuits allowing local or remote service and power supllies.<br> <br> PC is "Windbox" by MSI, running software SDR-Radio by Simon Brown HB9DRV. To the ethernet port is connected latvian Mikrotik link towards Internet provider. <br> <br> <a href="pics/sdr/dc100_06.jpg"><img style="border: 0px solid ; width: 500px; height: 285px;" alt="" src="pics/sdr/dc100_06.jpg"></a><br> <br> To the USB port is connected modul K8055N (kit) or VM110 (assemled and tested) made by Velleman, that allows remote switching of K9AY loops and toggle preamplifier with band filtering.<br> <br> <img style="width: 500px; height: 375px;" alt="" src="pics/sdr/k8055.jpg"><br> <br> Details are available at: <a href="http://www.vellemanusa.com/products/view/?country=us&amp;lang=enu&amp;id=522053">http://www.vellemanusa.com/products/view/?country=us&amp;lang=enu&amp;id=522053 <br> </a><br> <br> <span style="font-weight: bold; color: red;">How it works:</span><br> First tests brought plenty of new findings. Firts tests showed that for european signals there are not big difference between my home transmitting antenna (dipol at 25 metres) and this remote RX. However for DX stations I don't have undoubted result. There are situations when DX station was much better readable on remote RX (HS0ZKX). On the other hand some of US stations were better on my home dipol, other on remote RX. More tests still not been done.<br> <br> It is late spring now and almost all winter DX season is over. I have some time prepare rest of things for next winter.<br> <br> I am pretty used to listening about deaf stations. Some top equipped station owners turn up their nose at us - ordinary hams, because we cannot hear all signals around the world even in daylight. <br> We must still wait for better conds and be very patient. It is really hard work from places plagued by noise.&nbsp;&nbsp;&nbsp;&nbsp; <br> <br> All we can do is keeping a spirit of hamradio and know that our hobby is just a hobby. And there are more important things on the world. <br> <br> <br> Ostrava, April 2014<br> <br> <a href="../../pics/ES2405_1.bmp"><small><span style="font-weight: bold; color: rgb(255, 0, 0);"></span></small></a><br> <br> <small><span style="color: rgb(255, 0, 0);"><span style="color: rgb(0, 0, 0);"></span></span></small><big><big><small><small><small><br> <br> </small></small> <table style="text-align: left; background-color: rgb(0, 0, 153); width: 800px; height: 15px;" border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td style="width: 200px; text-align: center; height: 20px;"><span style="font-weight: bold; color: rgb(255, 255, 204);"></span><big><small><a style="color: rgb(255, 255, 204); font-weight: bold;" href="index_gb.html">Home</a></small></big><span style="color: rgb(255, 255, 204);"></span></td> <td style="text-align: center; color: rgb(255, 255, 204); width: 200px; height: 31px;"><small><a style="color: rgb(255, 255, 204); font-weight: bold;" href="../../clenove.html"><br> </a></small></td> <td style="height: 31px; width: 200px; text-align: center;"><small><a style="color: rgb(255, 255, 204); font-weight: bold;" href="../../../cz.html"><br> </a></small></td> <td style="height: 31px; width: 200px;"><br> </td> </tr> </tbody> </table> </small></big></big></td> </tr> </tbody> </table><span style="font-family: Arial;"> &nbsp;</span><br style="font-family: Arial;"> <div style="font-family: Arial;" align="center"><br> </div> <br style="font-family: Arial;"> </body></html>