{"id":2459,"date":"2012-09-09T12:44:17","date_gmt":"2012-09-09T16:44:17","guid":{"rendered":"http:\/\/w4kaz.com\/qth\/?p=2459"},"modified":"2012-09-09T12:44:17","modified_gmt":"2012-09-09T16:44:17","slug":"more-on-xonar-dx-experiments","status":"publish","type":"post","link":"http:\/\/w4kaz.com\/qth\/?p=2459","title":{"rendered":"More on Xonar DX Experiments"},"content":{"rendered":"

A thread over on the softrock user group list spurred the curiosity…..:\u00c2\u00a0http:\/\/groups.yahoo.com\/group\/softrock40\/message\/68324<\/a><\/p>\n

G4ZFQ has \u00c2\u00a0RightMark test data for a high end Xonar D2X card<\/a>, as well as several others<\/a>. \u00c2\u00a0An internet search found other RightMark tests of several other Xonar cards, all of whose test data show curve trends remarkably similar to those of the D2X, albeit with somewhat worse IMD, spurious, and noise figures.<\/p>\n

The curiosity is the test data shows a roll off on the frequencies above 50khz. \u00c2\u00a0The nature of the loopback test is an issue, but it also seems likely that using a sound card as the source may be having an effect on the test results at the higher edges of the sound card frequency response. \u00c2\u00a0But signal generators as input to the tests shows the same general trend. \u00c2\u00a0SDR at wider bandwidths pushes at these edges of a ‘sound’ card’s ability….So perhaps the SDR software is compensating for the expected performance drop-off at frequencies above audible levels?<\/p>\n

The Test- (Pertinent Excerpt from list post):<\/strong><\/p>\n

Having not yet thought of a better way to do a meaningful real-world\u00c2\u00a0test on the sound card with what is available in the KazShack, I fired up the\u00c2\u00a080m softrock on the xonar DX.<\/p>\n

Test condx:
\nTransmitting a cw signal(a string of dashes at about 18wpm) at 5w into a dummy\u00c2\u00a0load on separate radio, noting the SNR readings obtained by CW skimmer from the\u00c2\u00a0SoftRock center frequency(353395x) to its upper limit. With the xonar DX set to\u00c2\u00a0192khz scan rate, the actual upper limit on the readings was 3629.60. SoftRock\u00c2\u00a0connected to normal antenna system, a NE facing K9AY with W7IUV pre-amp. In\u00c2\u00a0summary, a sound card test using the SoftRock system as input source.<\/p>\n

fq….—-SNR(dB)
\n3534.5—-42<\/p>\n

3543-3593-42-40<\/p>\n

3603——37
\n3613——35
\n3623——32
\n3629.6—-36<\/p>\n

After CW skimmer collected a bit of data, the SNR readings above 3600 improved\u00c2\u00a0to 37-39.<\/p>\n

So the worst case for CW skimmer(as currently configured) using a Xonar DX is\u00c2\u00a0being 6db less sensitive at the upper edge of the 192khz bandwidth than it is at\u00c2\u00a0the center. That is actually a lot better than I expected for an audio device\u00c2\u00a0pressed into service outside normal audio ranges (and I already liked the Xonar\u00c2\u00a0DX).<\/p>\n

My curiosity is now nagging me to run the same tests on all of the other\u00c2\u00a0in-shack cards more methodically at their maximum scan rates(mostly 96khz), and\u00c2\u00a0to find a lower level outside signal source. I’ll try to recruit a fellow in\u00c2\u00a0the near field who will better be able to generate a low level test signal. \u00c2\u00a0It would be useful to see what happens at the band edges when the best copy close to the center of the SoftRock’s scan range starts out at 20dB, 10dB, or 6dB SNR.<\/p>\n

But with the WX here improving, all of that might not happen for several months.
\n\ud83d\ude09<\/p>\n

Engineer the Possible…<\/p>\n","protected":false},"excerpt":{"rendered":"

A thread over on the softrock user group list spurred the curiosity…..:\u00c2 http:\/\/groups.yahoo.com\/group\/softrock40\/message\/68324<\/p>\n

G4ZFQ has \u00c2 RightMark test data for a high end Xonar D2X card, as well as several others. \u00c2 An internet search found other RightMark tests of several other Xonar cards, all of whose test data show curve trends remarkably similar to those of the D2X, albeit with somewhat worse IMD, spurious, and noise figures.<\/p>\n

The curiosity is the test data shows a roll off on the frequencies above 50khz. \u00c2 The nature of the loopback test is an issue, but it also seems likely that using a sound card as the source may be having an effect on the test results at the higher edges of the sound card frequency response. \u00c2 But signal generators as input to the tests shows the same general trend. \u00c2 SDR at wider bandwidths pushes at these edges of a ‘sound’ card’s ability….So perhaps the SDR software is compensating for the expected performance drop-off at frequencies above audible levels?<\/p>\n

The Test- (Pertinent Excerpt from list post):<\/p>\n

Having not yet thought of a better way to do a meaningful real-world\u00c2 test on the sound card with what is available in the KazShack, I fired up the\u00c2 80m softrock on the xonar DX.<\/p>\n

Test condx: Transmitting a cw signal(a string of dashes at about 18wpm) at 5w into a dummy\u00c2 load on separate radio, noting the SNR readings obtained by CW skimmer from the\u00c2 SoftRock center frequency(353395x) to its upper limit. With […]<\/p>\n

Continue reading More on Xonar DX Experiments<\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":[],"categories":[13,12,10],"tags":[],"_links":{"self":[{"href":"http:\/\/w4kaz.com\/qth\/index.php?rest_route=\/wp\/v2\/posts\/2459"}],"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=2459"}],"version-history":[{"count":2,"href":"http:\/\/w4kaz.com\/qth\/index.php?rest_route=\/wp\/v2\/posts\/2459\/revisions"}],"predecessor-version":[{"id":2461,"href":"http:\/\/w4kaz.com\/qth\/index.php?rest_route=\/wp\/v2\/posts\/2459\/revisions\/2461"}],"wp:attachment":[{"href":"http:\/\/w4kaz.com\/qth\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=2459"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/w4kaz.com\/qth\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=2459"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/w4kaz.com\/qth\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=2459"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}