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PostPosted: Sat Apr 27, 2013 4:39 am 
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Location: Buenos Aires, Argentina
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http://www.nxtbook.com/nxtbooks/newbay/ ... 130417/#/6


Jeff from Vorsis on multipath..good read
interesting article

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PostPosted: Sat Apr 27, 2013 5:34 am 

Joined: Thu Mar 14, 2013 5:54 pm
Posts: 56
great discussion. just had a conversation with our engineer tonight about how SSB seemed to help our multipath...

tried it for the first time today. his first response: low cloud bank and rain....try again tomorrow and report back.

thx for sharin the article.


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PostPosted: Sat Apr 27, 2013 6:08 am 
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Quote:
http://www.nxtbook.com/nxtbooks/newbay/ ... 130417/#/6


Jeff from Vorsis on multipath..good read
Ah! I talked to him about SSB at the NAB, will read the article!


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PostPosted: Sat Apr 27, 2013 6:14 am 
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Performance improvement: "Clipping Strength" is now automatically determined per sample! So the slider setting is ignored (in Composite mode; I can probably make the same change in the traditional clipper).

I'm now getting similar clipping strictness at Strictness 11 as I got at 16 with the previous version. So I think (not really tested much yet) that you can probably reduce Strictness by about 5 points in this new version.
Per step the CPU load is *slightly* higher than before but it should be a very small difference.

For some extra performance improvement, disable the new '16x oversampling in pre-clipping' button; if there are no drawbacks to this (ie. if noone hears anything bad) I'll remove the button and make that the default behavior.

Stand alone: http://www.stereotool.com/download/ster ... 20-009.exe
Winamp DSP: http://www.stereotool.com/download/dsp_ ... 20-009.exe
VST: http://www.stereotool.com/download/vst_ ... 20-009.dll

IMPORTANT: To get a good sound from the composite clipper:
1. Enable it :) It's an option under Advanced Clipper
2. Under Advanced Clipper -> CPU, set 'Strictness' at 11 or higher (higher is better; there's probably not much gain above 15 anymore though; 11 looks pretty good already so a bit lower values should still be ok).

Warning:
You will need a license update to use this! Otherwise the 'unregistered options in use' thingy will pop up, and you'll get messages through the music (every 4 hours).


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PostPosted: Sat Apr 27, 2013 7:58 am 
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Joined: Thu Oct 25, 2012 3:22 pm
Posts: 237
Location: Poland
Quote:
http://www.nxtbook.com/nxtbooks/newbay/ ... 130417/#/6


Jeff from Vorsis on multipath..good read
This is good article :)
Many new car recivers have implemented in hardware multipath and noise detection and canceling witch of course affect audio image, but nobody litsten in car with headphones (expect me) so it's ok ;) Detection multipath in recivers is based on complete composite and with SSB may work not good or very poor.

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PostPosted: Sat Apr 27, 2013 8:28 am 
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Joined: Thu Oct 25, 2012 3:22 pm
Posts: 237
Location: Poland
Hans, can you add some limit of maximum demodulated signal in new clipper? now peaks are 165%

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PostPosted: Sat Apr 27, 2013 12:40 pm 
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I see I didn't even mention how to compare the old and new versions.

Higher "Clipping Strictness" values mean that you'll get less spikes above 100% in your MPX signal BEFORE Hard Limit. The higher the spikes in this signal are, the harder Hard Limit needs to work, causing reductions in audio level.

So how to check:
1. Turn Hard Limit off
2. Look at the output waveform. You'll see (small) spikes there
3. Increase Strictness and you'll see less spikes. Decrease it and you'll see more.

In the new version, spikes are much smaller at the same Strictness setting.

Note: You can debate about how bad these spikes really are. For small numbers, every percent in overshoot costs approx. 0.1 dB in loudness - so 10% spikes (which is extreme!) would cost 1 dB (at the place of the spike, not overall). I've tested with Strictness 11 in the new version; the spikes are almost always below 2% (0.2 dB loss). With the old version at Strictness 11 it was 4 or 5%.


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PostPosted: Sat Apr 27, 2013 12:40 pm 
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Quote:
Hans, can you add some limit of maximum demodulated signal in new clipper? now peaks are 165%
I probably should!


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PostPosted: Sat Apr 27, 2013 12:59 pm 
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Joined: Tue Sep 28, 2010 10:56 pm
Posts: 326
Location: Usa
unfortunately i cant compare much cause my cpu cant handle SSB but as far as i could sounds great.
The cpu from 31-35% with SSB enabled goes up to 20% up.!

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PostPosted: Sat Apr 27, 2013 3:24 pm 
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Joined: Tue Mar 17, 2009 2:56 pm
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Strictness 16


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