#10789 LOW 11.2.0-: Measure activity should be calibrated on all active XO platforms

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#10789: Measure activity should be calibrated on all active XO platforms
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           Reporter:  greenfeld         |       Owner:  arjs                             
               Type:  task              |      Status:  new                              
           Priority:  low               |   Milestone:  11.2.0-M4                        
          Component:  measure-activity  |     Version:  Development build as of this date
         Resolution:                    |    Keywords:                                   
        Next_action:  diagnose          |    Verified:  0                                
Deployment_affected:                    |   Blockedby:                                   
           Blocking:                    |  
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Comment(by greenfeld):

 To clarify, I am not looking to create an infrastructure which is super
 precise.  There's no need to have the XO start generating a square wave of
 known voltage which I can then use to tweak my attenuating XO oscilloscope
 probe to guarantee I've got +/- 1% accuracy.

 It would be nice to at least have 10% accuracy at room temperature if we
 know the components in the chain are of the 10% accuracy sort.  {Yes I
 know that this comparison is invalid, and better component tolerances are
 available; no I haven't looked at the schematic, and I probably would be
 terrible at it as I haven't done analog circuit development for years.}

 What I would like to do is use Measure {or something similar} as a proxy
 to determine if recording levels are within a decent percentage of each
 other between OS versions and across XO platforms, and not several
 dB/orders of magnitude off.  The ability to use Measure for Measuring with
 actual instead of relative units then comes as a bonus.

 Trying to do this by recording and then playing things back involves the
 output audio path, and hearing is subjective and logarithmic.

 As long as Measure does not change the mixer controls itself or try to do
 too much platform-specific compensation this may or may not be possible.

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Ticket URL: <http://dev.laptop.org/ticket/10789#comment:3>
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