[amsat-bb] Re: Fluctuating AO-40 TLM values

["Stacey E. Mills" <w4sm@xxxxxxxxxx>]

>Some of the values decoded seem to fluctuate.  For instance, the S2 TX
>temperature displays predominantly two values as I type this:  15.97
>(mostly) and 22.56 , though there are others as well.  I can eliminate some
>on reasonableness, such as when it shows the S1 transmitter is warmer, but
>is there a less judgment-intensive way to sort out the real values?  All
>have good CRC checks.
>
>Alan
>WA4SCA

Hi Alan,
If the CRCC's are truly OK then all the values should be "real" (excluding 
8 known failed temp. sensors after the December event).  I have not seen 
the phenomenon that you are describing.  I just  graphed the telemetry from 
Orbit 765 and the S2 Tx occasionally shows a "one bit" dither and a change 
of several bits over the orbit, but is otherwise stable.  I have not looked 
carefully at the telemetry from Orbit 766.  Remember that the ADC is only 
8-bit, so the precision we have on the thermistors is about 0.66 deg.  You 
may often see dithering of this order of magnitude, but you should not see 
the several degrees that you are indicating.



-- 
  ________________________________________________________________________
  Stacey E. Mills, W4SM    WWW:    http://www.cstone.net/~w4sm/ham1.html
    Charlottesville, VA     PGP key: http://www.cstone.net/~w4sm/key
  ________________________________________________________________________

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