{"id":2204,"date":"2012-05-22T09:07:00","date_gmt":"2012-05-22T13:07:00","guid":{"rendered":"http:\/\/w4kaz.com\/qth\/?p=2204"},"modified":"2012-06-13T23:06:46","modified_gmt":"2012-06-14T03:06:46","slug":"skimming-cw-at-w4kaz","status":"publish","type":"post","link":"http:\/\/w4kaz.com\/qth\/?p=2204","title":{"rendered":"Skimming CW at W4KAZ"},"content":{"rendered":"<p><em>Note&#8230;.Post dated this material to original date written&#8230;superseded by new reality&#8230;..<\/em><\/p>\n<p>&#8220;All is proceeding as I have foreseen it&#8230;&#8230;&#8230;&#8230;..&#8221;<\/p>\n<p>Been just about four years since the <a title=\"cw skimmer\" href=\"http:\/\/www.dxatlas.com\/CwSkimmer\/\" target=\"_blank\">CW skimmer<\/a> stuff really hit the contest rotary impeller. A bit of review&#8230;..<\/p>\n<ul>\n<li><a title=\"CW Skimmer \u00e2\u20ac\u201c Barking At The Moon\" href=\"http:\/\/w4kaz.com\/qth\/?p=140\" target=\"_blank\">First impressions in May 2008<\/a>.<\/li>\n<li><a title=\"CW Skimmer \u00e2\u20ac\u201c Genie Out of the Bottle?\" href=\"http:\/\/w4kaz.com\/qth\/?p=167\" target=\"_blank\">More observations June 2008<\/a>.<\/li>\n<li><a title=\"CW Skimmer \u00e2\u20ac\u201c Top Ten Reasons Skimmer is the Same As Packet\" href=\"http:\/\/w4kaz.com\/qth\/?p=193\" target=\"_blank\">And I sure wish I had plagiarized W4PA completely in July 2008, his original post was clear, concise, and 100% accurate<\/a>.\u00c2\u00a0 But lost in the internet rabbit hole&#8230;.<\/li>\n<\/ul>\n<p>So in hindsight &#8211; I&#8217;m glad contest sponsors read my blog.\u00c2\u00a0 \ud83d\ude09<\/p>\n<p>Since the rule-parsing panned out to my immense satisfaction, it is easier to concentrate on the toy itself.\u00c2\u00a0 Since then, skimmer stations sprouted, and <a title=\"link to the reverse beacon network\" href=\"http:\/\/www.reversebeacon.net\/\" target=\"_blank\">the Reverse Beacon Network was born<\/a>.\u00c2\u00a0 That is a really interesting project.\u00c2\u00a0 Its a great tool for checking propagation, comparing station signals, and getting impartial signal reports.\u00c2\u00a0 Outstanding resource.<\/p>\n<p>Unfortunately there is not a local skimmer station that is feeding the RBN.\u00c2\u00a0 Spots from MD are not always useful in Central NC.<\/p>\n<p>So it with the moon in phase and the planets approaching the grand alignment, it seemed like time to look into the subject of skimming.<\/p>\n<h5><span style=\"color: #008000;\">Options<\/span><\/h5>\n<p>The Skimmer software comes with a component that is designed to work with <a title=\"link to QS1R web site\" href=\"http:\/\/www.srl-llc.com\/\">the QS1R SDR<\/a>.\u00c2\u00a0 That combination is likely the ideal solution.\u00c2\u00a0 So all I need is a fast Pentium i7 Quad core, and a thousand <a title=\"definition, samolies\" href=\"http:\/\/www.google.com\/url?sa=t&amp;rct=j&amp;q=samolies&amp;source=web&amp;cd=1&amp;ved=0CFQQFjAA&amp;url=http%3A%2F%2Fwww.urbandictionary.com%2Fdefine.php%3Fterm%3Dsamolies&amp;ei=AU-8T4qfLIOu8QSxuuxM&amp;usg=AFQjCNFK-vncdVQiZX2vp8SFrfalR9zmrA&amp;cad=rja\" target=\"_blank\">samolies<\/a>&#8230;&#8230;\u00c2\u00a0 Great idea, just not possible.<\/p>\n<p>Much more possible&#8230;.<a title=\"link to softrock yahoo group\" href=\"http:\/\/groups.yahoo.com\/group\/softrock40\/\" target=\"_blank\">Combine a few Softrocks<\/a> with <a title=\"Dell Optiplex 745\" href=\"http:\/\/www.dell.com\/us\/dfb\/p\/optiplex-745\/pd\" target=\"_blank\">some cast off circa 2008 computers<\/a>.\u00c2\u00a0 Yup, that&#8217;s the ticket.\u00c2\u00a0 Rather than sit on my thumbs&#8230;.<em><strong><a title=\"Engineer The Possible\" href=\"http:\/\/w4kaz.com\/qth\/?p=481\" target=\"_blank\">Engineer the Possible<\/a>.<\/strong><\/em>\u00c2\u00a0 O&#8217;course, the possible is not always completely practical.\u00c2\u00a0 Everything is relative.\u00c2\u00a0 What tradeoffs are reasonable?\u00c2\u00a0 <em>Engineer the Possible<\/em>.<\/p>\n<p>It has been done before&#8230;<a title=\"AC0C  softrock skimmer document\" href=\"http:\/\/www.ac0c.com\/main\/page_antennas__homebrew_cwskimmer_array.html\" target=\"_blank\">AC0C has documented the challenges and his solutions<\/a>.\u00c2\u00a0 Despite the validity of his conclusions, it is now possible to cobble together a scaled down version using scrounged computer hardware.\u00c2\u00a0 Using softrocks, it is now very practical to put together a skimmer package for 160\/80\/40\/20 meter bands with obsolescent computer hardware. \u00c2\u00a0The price\/performance ratio of the softrock is a huge factor.\u00c2\u00a0 If they were a mass production commodity, they would probably cost under $10.<\/p>\n<p>15m and 10m may be more of a challenge, so that has been shelved for the moment.\u00c2\u00a0 So the softrock solution is not perfect.\u00c2\u00a0 But there are solutions to that too.\u00c2\u00a0 Future project&#8230;.<\/p>\n<h5><span style=\"color: #008000;\">The current project direction<\/span><\/h5>\n<p>So the game plan is to skim on 160m thru 20m using softrocks.\u00c2\u00a0 40m and 80m softrocks are done.\u00c2\u00a0 Its not going to be as professional a finished product as AC0C&#8217;s, but it should function.\u00c2\u00a0 Reclaimed from the off-lease refuse stream are an Dell Optiplex 745sff and a Dell optiplex 360 SDT.\u00c2\u00a0 Both of these boxes require low-form-factor cards.\u00c2\u00a0 The on-board sound of the 745 leaves something to be desired, but the 360 has an on-board sound card capable of 192khz bandwidth.\u00c2\u00a0 So small form factor add-in cards are needed to run skimmer on multiple bands.\u00c2\u00a0 Four bands on two computers.<\/p>\n<h5><span style=\"color: #008000;\">Other Naughty Tidbits&#8230;.<\/span><\/h5>\n<p>The Asus Xonar DG is a small form factor sound card that turned out to be a fabulous bargain. It allows only 96khz bandwidth, but has excellent dynamic range for its cost.\u00c2\u00a0 Sounds great with music too.\u00c2\u00a0 Also had an Asus Xonar DX, which is higher fidelity than the Xonar Dg, and offers 192khz bandwidth with a softrock.\u00c2\u00a0 The sound card issue is the real sticking point in this design, but the Xonar cards are able to coexist with the onboard SoundMax devices in the Dell boxes.<\/p>\n<p>Not so much luck with a Soundblaster Live 24.\u00c2\u00a0 Experiments installing and using the Soundblaster were problematic.\u00c2\u00a0 Compatibility issues with the other sound devices and SDR software crashes. The Asus cards are much higher quality, but attempts to pair either with the soundblaster caused problems.\u00c2\u00a0 Attempts to install both Xonar cards in the same system were also buggy.\u00c2\u00a0 So the Soundblaster is sidelined for later rainy day experimentation,\u00c2\u00a0 the ASUS cards are each on a different host system, and it is fortunate that the onboard sound cards are useable.<\/p>\n<p>The final compromise chosen was to install the 192khz Xonar DX in the Optiplex 745 that has 48khz onboard SoundMax.\u00c2\u00a0 The Xonar DG is installed in the Optiplex 360 that has 192khz SoundMax onboard sound.\u00c2\u00a0 In testing the Xonar cards work very well with all of the SDR software tested.\u00c2\u00a0 The SoundMax cards are noticeably less capable, but not terrible.<\/p>\n<h5><span style=\"color: #008000;\">Mix and Match<\/span><\/h5>\n<p>The skimmer sessions sound card pairings in daily usage are likely to be:<\/p>\n<ul>\n<li>160m&#8230;48khz on Optiplex 745 onboard sound<\/li>\n<li>&#8230;&#8230;&#8230;&#8230;&#8230;..Center@????????,Covers ?<\/li>\n<li>80m&#8230;..96khz on Optiplex 360 Asus Xonar DG<\/li>\n<li>&#8230;&#8230;&#8230;&#8230;&#8230;.Center@3533950, covers ~3485 thru 3581<\/li>\n<li>40m&#8230;..192 or 96khz on Optiplex 745\u00c2\u00a0 Asus Xonar DX<\/li>\n<li>&#8230;&#8230;&#8230;&#8230;&#8230;.Center@7055015, covers ~6959 thru 7151@192Khz, 7007 thru 7103@96Khz<\/li>\n<li>20m&#8230;..192 or 96 Khz on Optiplex 360 onboard sound<\/li>\n<li>&#8230;&#8230;&#8230;&#8230;&#8230;..Center@????????,Covers ?<\/li>\n<\/ul>\n<p>Those pairings should spread the CPU load somewhat.\u00c2\u00a0 A live test on 40m and 80m during CQ WPX should give me a benchmark for CPU loading.\u00c2\u00a0 CW Skimmer allows the definition of the maximum number of active decoders, and I expect to get some insight on setting those values to help moderate the load.\u00c2\u00a0 Currently, allowing 500-600 decoders seems workable.<\/p>\n<p>During 160m contests, the 160m skimmer will likely switch to a wider bandwidth card, at least 96Khz.\u00c2\u00a0 The fall contest season will allow more testing to determine if the 192khz skimmers will need to be narrowed during contests or throttled by limiting the max number of decoders &#8211; maybe both.\u00c2\u00a0 Also, the nature of any given contest may also make temporary changes to the line-up appropriate.\u00c2\u00a0 But that&#8217;s the basic setup.<\/p>\n<h5><span style=\"color: #008000;\">Using the spots<\/span><\/h5>\n<p>The Reverse Beacon Network Blog has <a title=\"RBN telnet server\" href=\"http:\/\/reversebeacon.blogspot.com\/search?q=rbn+spots\" target=\"_blank\">info on connecting to the RBN telnet server<\/a>.\u00c2\u00a0 Highly recommend taking their advice on filtering! \u00c2\u00a0The RBN server <a title=\"DXSpider Wiki\" href=\"http:\/\/wiki.dxcluster.org\/index.php\/DXSpider_Command_Reference\" target=\"_blank\">uses DXSpider documented on DXSpider Wiki<\/a>.<\/p>\n<p><a href=\"http:\/\/w4kaz.com\/qth\/wp-content\/uploads\/2012\/05\/skimmer_visit.gif\"><img decoding=\"async\" loading=\"lazy\" class=\"aligncenter size-medium wp-image-2249\" title=\"skimmer_visit\" src=\"http:\/\/w4kaz.com\/qth\/wp-content\/uploads\/2012\/05\/skimmer_visit-300x38.gif\" alt=\"\" width=\"300\" height=\"38\" srcset=\"http:\/\/w4kaz.com\/qth\/wp-content\/uploads\/2012\/05\/skimmer_visit-300x38.gif 300w, http:\/\/w4kaz.com\/qth\/wp-content\/uploads\/2012\/05\/skimmer_visit-150x19.gif 150w, http:\/\/w4kaz.com\/qth\/wp-content\/uploads\/2012\/05\/skimmer_visit-400x51.gif 400w, http:\/\/w4kaz.com\/qth\/wp-content\/uploads\/2012\/05\/skimmer_visit.gif 462w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Note&#8230;.Post dated this material to original date written&#8230;superseded by new reality&#8230;..<\/p>\n<p>&#8220;All is proceeding as I have foreseen it&#8230;&#8230;&#8230;&#8230;..&#8221;<\/p>\n<p>Been just about four years since the CW skimmer stuff really hit the contest rotary impeller. A bit of review&#8230;..<\/p>\n<p> First impressions in May 2008. More observations June 2008. And I sure wish I had plagiarized W4PA completely in July 2008, his original post was clear, concise, and 100% accurate.\u00c2 But lost in the internet rabbit hole&#8230;. <\/p>\n<p>So in hindsight &#8211; I&#8217;m glad contest sponsors read my blog.\u00c2 \ud83d\ude09<\/p>\n<p>Since the rule-parsing panned out to my immense satisfaction, it is easier to concentrate on the toy itself.\u00c2 Since then, skimmer stations sprouted, and the Reverse Beacon Network was born.\u00c2 That is a really interesting project.\u00c2 Its a great tool for checking propagation, comparing station signals, and getting impartial signal reports.\u00c2 Outstanding resource.<\/p>\n<p>Unfortunately there is not a local skimmer station that is feeding the RBN.\u00c2 Spots from MD are not always useful in Central NC.<\/p>\n<p>So it with the moon in phase and the planets approaching the grand alignment, it seemed like time to look into the subject of skimming.<\/p>\n<p> Options <\/p>\n<p>The Skimmer software comes with a component that is designed to work with the QS1R SDR.\u00c2 That combination is likely the ideal solution.\u00c2 So all I need is a fast Pentium i7 Quad core, and a thousand samolies&#8230;&#8230;\u00c2 Great idea, just not possible.<\/p>\n<p>Much more possible&#8230;.Combine a few Softrocks with some cast off circa 2008 computers.\u00c2 Yup, that&#8217;s the ticket.\u00c2 [&#8230;]<\/p>\n<p>Continue reading <a href=\"http:\/\/w4kaz.com\/qth\/?p=2204\">Skimming CW at W4KAZ<\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":[],"categories":[12,14,10],"tags":[],"_links":{"self":[{"href":"http:\/\/w4kaz.com\/qth\/index.php?rest_route=\/wp\/v2\/posts\/2204"}],"collection":[{"href":"http:\/\/w4kaz.com\/qth\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/w4kaz.com\/qth\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/w4kaz.com\/qth\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"http:\/\/w4kaz.com\/qth\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=2204"}],"version-history":[{"count":20,"href":"http:\/\/w4kaz.com\/qth\/index.php?rest_route=\/wp\/v2\/posts\/2204\/revisions"}],"predecessor-version":[{"id":2250,"href":"http:\/\/w4kaz.com\/qth\/index.php?rest_route=\/wp\/v2\/posts\/2204\/revisions\/2250"}],"wp:attachment":[{"href":"http:\/\/w4kaz.com\/qth\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=2204"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/w4kaz.com\/qth\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=2204"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/w4kaz.com\/qth\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=2204"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}