Rick wrote: > I have seen some multipath, especially when I have tested PSK31 on > VHF, but much of that was from aircraft. I am not sure how I can > discern multipath when on HF. Is there any clue in the waterfall or > do you go by the sound?
On HF I have noticed one of the consequences of multipath, selective fading, only on rather wide signals, like pactor 3 or DRM. I have not noticed it so far in narrower signals, which doesn't mean it isn't there too. It shows up as a fast darker banding on the waterfall, that sweeps across the signal bandwidth. I have noticed it using Spectran. I have noticed something that may be multipath on some distinct double clock tics on WWV that do not correspond with the leap seconds info. For me, it is rare, random, not long lasting, and hard to discern in other signals. Also used Spectran at almost maximum speed during an offset frequency WWV recording on 10 MHz. It might be some momentarily intensified long delayed signals from WWVH, I cannot tell for sure. In any case, the delay is a few milliseconds, trailing not far behind the second tics. If the ticks are 5 cycles of a 1 kHz sinewave, the delay between the double ticks beginning, the moments when they showed up, may have been some 8 to 10 milliseconds. Something peculiar in the waterfall is that both 500 and 600 Hz tones were present, which are switched alternately in WWV and WWVH emissions. I was certainly not looking for those double ticks. 73, Jose, CO2JA Announce your digital presence via our Interactive Sked Page at http://www.obriensweb.com/sked Check our other Yahoo Groups.... http://groups.yahoo.com/group/dxlist/ http://groups.yahoo.com/group/contesting http://groups.yahoo.com/group/themixwgroup Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) <*> To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
