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View Full Version : Strange looking analysis.. Could anybody have a look?


Dizcipline
2010-01-30, 06:34 PM
I got this strange looking file, could anybody tell me what that could be? Why does it cut at 18khz and not 16 or 20.5? And what's that purple stripe? Thanks in advance!

Dizcipline
2010-01-30, 06:37 PM
The 2nd pic is a 2 second sample, btw.

AAR.oner
2010-01-30, 06:52 PM
that stripe is a pilot tone [shows as a spike in the FA]...looks to be from a TV source since its in the 15-16kHz region...a pilot tone at 19kHz indicates a FM source

Dizcipline
2010-01-30, 06:55 PM
I thought about that as well, but i'm pretty sure this show was never broadcasted, neither TV nor FM. :hmm:

lintoni
2010-01-31, 03:27 AM
I thought about that as well, but i'm pretty sure this show was never broadcasted, neither TV nor FM. :hmm:

Useful info (http://www.solorb.com/dat-heads/digests/V3.100/D153#Msg2)

Dizcipline
2010-01-31, 05:02 AM
That's quite interesting... And it makes kinda sense... Thanks for that info, lintoni!

But what about the cut off frequencies? Would you consider this 100% lossy? Is the cut at around 18khz just the result of a high bitrate mp3 conversion? Thanks so far, guys! ;)

lintoni
2010-01-31, 06:32 AM
If you could post a spectral screenshot of 2-3 seconds, that might help.

Dizcipline
2010-01-31, 08:13 AM
Like this? That's a two second snippet from the file.

lintoni
2010-01-31, 04:45 PM
Hmm... looks ok to me. Possibly somebody has used some noise reduction, which is why there's the 18k cut off. Strange that they didn't take care of the spike at 15.7kHz while they were at it.

Dizcipline
2010-01-31, 05:29 PM
Cool, thanks. See, that's the kind of stuff i didn't think of. Never knew that NR could lead to such a "clean" cut. Thanks for your help! :)

lintoni
2010-02-01, 02:30 AM
Or simply used a brickwall filter at 18kHz to cut everything off. But it looks like a lossless source to me.