I have heard others mention the harmonics as they have seen in PowerSDR as well when using DM780. I have been plagued by this from the beginning when I used HRD over a year ago. My "solution" was to tighten up the TX filters in PowerSDR so that harmonics wouldn't be transmitted. A Band-aid approach, but it worked to keep me clean on the air. HRD tech support pointed at Flex Radio and Vice-Verse. Well, as it turns out, it is neither of those party's fault. Nor is it VAC's fault. I have now discovered why it occurs, at least in my particular case. I knew it had something to do with the data not being converted correctly, but I didn't know why it occurred.
I had looked at all the settings in PowerSDR and DM780. I had tried every possible driver and sample rate. Nothing seemed to work. So I contacted Eugene Muzychenko (writer of VAC) and asked him. He explained how VAC worked at a basic level and had me look at some things, using the manual to VAC. The problem kept pointing me back to the chain BETWEEN PowerSDR & DM780. Through Eugene's manual, I discovered there is an advanced settings in the audio of windows that can affect sample rates, regardless of what you do elsewhere. I found that there are some settings in windows that are defaulted to 44100 (CD Redbook settings) under advance audio settings for the line 1 & line 2 (VAC lines in my case) in control panel. It had both record and playback limited to 44100 in VAC! I finally had found the "magic switch". Once I set both the playback and record to 48000 in these tabs (Windows DVD sample rate settings), I went back to DM780 and looked at PowerSDR in TX mode. It is now clean, clean, clean! (Funny thing is that now I do see a single spike in the TX of FLDigi that wasn't there before, but that is another subject.) So for those that might have been experiencing this same thing, I thought I would share this little "fix". I hope it helps someone. 73, Scott AC8DE _______________________________________________ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz 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/
