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http://kc.flex-radio.com/KnowledgebaseArticle50363.aspx -Tim -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Blume, Ron Sent: Thursday, October 15, 2009 9:27 PM To: [email protected] Subject: [Flexradio] HIgh IMD on PSK31 Help! I have been receiving high IMD reports when using PSK31 and cannot seem to solve the problem. The infrastructure I am using is as follows: - FLEX 5000, PowerSDR 1.18.2 - FLEX Driver 3.4.2.6300, Sample Rate 192kHz, Buffer Size 1024 - PowerSDR Setup; PowerSDR Setup: Buffer 1024, Sample Rate 192kHz, - Windows Vista 64 Bit Quad (No Drop Outs) - VAC Configured as illustrated in FLEX 5000 Owner's Manual (MS per int = 7, BPS Range 8-16, Max Instances = 20, MC Range 1..2, Stream fmt limit = Cable Format, Volume ctl = Disabled) - Eltima Virtual Serial Port Ver 6.9, (Using Ports 6 and 16) - Ham Radio Deluxe (HRD), DM 780, : Version 5 Beta, Build 2356 (has been very stable) Using HRD on PSK31, the high IMD reports appear to be the result of a significant spike in the sideband on the signal; 1800-1900 cycles above or below (depending upon which sideband) the primary signal at approximately 1/2 to 1/3 the peak value of the primary signal (as shown on the PowerSDR screen). Thinking I may be overdriving PowerSDR from then audio output of HRD through the virtual line, when I insert 2.5 db attenuation (provided through an optional soundcard setting on HRD) in the transmit audio output the sideband signal somewhat disappears but the average signal increases to 1/2 to 1/3 the maximum value of the primary signal across the entire 3000 cycles width of the signal! It looks very weird. Lastly, thinking it may be an HRD problem, I switched to Fldigi on PSK31 and experienced the same results as first described about without the attenuation. Does anyone have any ideas on what I have missed? Ron K9WWX _______________________________________________ FlexRadio Systems Mailing List [email protected] http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flex-radio.com/ Homepage: http://www.flex-radio.com/ Message delivered to [email protected] _______________________________________________ FlexRadio Systems Mailing List [email protected] http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flex-radio.com/ Homepage: http://www.flex-radio.com/ Message delivered to [email protected]
