Stereo Tool

Point is that, for example, when you drive car and at some point when you notice and recognize multipath.. then you stops there and try DSB vs SSB.

Yes, I know this very well.

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Urban Junglist

A good laptop handles both, line and mic levels.
You can connect "line level" to your mike input, and in soundcard settings switch to "line in"

A separate soundcard can also be an option. (usb)

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That video was highly suspect.They should have done an AB comparison at the same time.It could have EASILY been done.You have to remember the effect it has on most receivers is not the same. Like i say the jury is still out on this black magic.

I'm not a broadcaster, but I am in Information Technology, thus I'm familiar with testing methodologies. That said, I completely agree that the test should have been on the same day so that the weather conditions were the same.

From what I can tell by looking at Weather Underground's history for Boston on the days in question, there were some differences in humidity and solar radiation levels between the two days. On the day the reception was better, it also rained.

Based on those observations, my own personal belief is that there was an atmospheric inversion layer in place on one of the two days that was not there on the other day. Inversion layers have impacts on wave propagation and reception.

Conclusion: There may be a little benefit from the technology, but the dramatic difference seen on November 15-16, 2011, has a more plausible explanation of weather-related wave propagation.

I did next real test with multipath distortion and DSB is better than SSB. I have conneted mpx tool to reciver demodulator output composite now and with SSB is more spikes over 100% than DSB but with signal good no spikes in both.

http://speedy.sh/MHxCA/multipath-test2.flac
long distance separation test SSB first and change about half to DSB
http://speedy.sh/FpwBe/multipath-test.flac
strong multipath distorsion test DSB first and about half change to SSB

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Urban Junglist

Interesting. Which SSB mode did you use? Based on what I read about the solutions in the Omnia hardware boxes, Hilbert mode might have issues. And I would really want to hear some audio though to hear what actually happens to it - that's more important than just looking at measurements. Although they might very well be a good indicator.

Performance update: I've been working on a new clipper implementation that needs less processing power. I have not compared the audio yet (!!!) and I'm not finished yet, but I see a very strictly clipped signal with Strictness set to 10 instead of 20!

I will finish this, and when I'm done I'll post it, listen to it and wait for feedback. If there's no reduction in audio quality, I can use the same new trick also in the traditional clipper, which would also decrease the CPU load (or actually: required strictness level) there.


Edit: O I see you added flac files! Will check them

SSB mode hilbert transform was used to record test.

http://speedy.sh/BrHwx/good-signal-test.flac
very good signal test first DSB/half SSB (but distance a few kilometers)

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Urban Junglist

Ok. I read that several receivers have big issues with this strict SSB mode. I would really be interested in the 3rd SSB mode, that's the one where I expect the best result. (Only tones that cause *really* big issues in DSB mode are transmittted in SSB mode).

http://www.nxtbook.com/nxtbooks/newbay/ ... 130417/#/6


Jeff from Vorsis on multipath..good read