electro_aLex
Member
- Joined
- Aug 15, 2011
- Messages
- 14
Hello together,
i had I discussion with a good friend about some analog-audio theory, especially our discussion was about PeakProgramMeters.
My thoughts were: the old peak meters we know, measure the "real peaks" (full-wave-peak-rectifyeng) and multiply it with 0,71 (RMS-value).
My friends opinion: the signal runs through a full-wave-peak-rectifier, which simultaneously generates the RMS-value.
We are agreed that:
This works good for perfect sine-signals, but not for music- or human language -signals (problems with short and high signals).
Which opinion is correct?
With the new EBU Recommendation R128, witch is the new standard in television broadcasting since 31.08.2012
these old Quasi Peakmeters are worn-out.
The old QPPM-values are load-related - what is the background in relation to this fact?
Are there any advantages in measuring this way?
My question is: is it possible to bypass the RMS-converter of the old QPPM's to display the "true" peak, like the new EBU-standart recommends?
Or is there just a (adjustable) gain adjusted to x0,71 that can be set to x1?
Is there someone who can explain exactly the processes inside a QPPM (like the often used NTP/RTW plasma QPPM's)?
I think I misunderstand a lot of this stuff, for example:
I saw a camparison grapic between QPPM and TPPM, the 1Khz sine test tone gives exactly the same level on both meters - but why?
Isn't the QPPM-value just 71% instead of 100%?
Best regards,
Alex
i had I discussion with a good friend about some analog-audio theory, especially our discussion was about PeakProgramMeters.
My thoughts were: the old peak meters we know, measure the "real peaks" (full-wave-peak-rectifyeng) and multiply it with 0,71 (RMS-value).
My friends opinion: the signal runs through a full-wave-peak-rectifier, which simultaneously generates the RMS-value.
We are agreed that:
This works good for perfect sine-signals, but not for music- or human language -signals (problems with short and high signals).
Which opinion is correct?
With the new EBU Recommendation R128, witch is the new standard in television broadcasting since 31.08.2012
these old Quasi Peakmeters are worn-out.
The old QPPM-values are load-related - what is the background in relation to this fact?
Are there any advantages in measuring this way?
My question is: is it possible to bypass the RMS-converter of the old QPPM's to display the "true" peak, like the new EBU-standart recommends?
Or is there just a (adjustable) gain adjusted to x0,71 that can be set to x1?
Is there someone who can explain exactly the processes inside a QPPM (like the often used NTP/RTW plasma QPPM's)?
I think I misunderstand a lot of this stuff, for example:
I saw a camparison grapic between QPPM and TPPM, the 1Khz sine test tone gives exactly the same level on both meters - but why?
Isn't the QPPM-value just 71% instead of 100%?
Best regards,
Alex