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Re: 11/4 SEDSAT Update(possible spurious data in current sensor



At 09:49 PM 11/4/98 -0500, Mark Maier wrote:

>Chris and I talked about some potential issues in the apparent differences
>in the impled current from the AHI readings versus the recorded main bus
>currents. I don't know if this has been conclusively resolved. One
>explanation is that the satellite sends its current sample, which can be
>effected by the PTT being on to send the data, even though in the
>intervening time PTT is off. Hence main current and AHI readings shouldn't
>necessarily track.

Something else to keep in mind is that the kernel executes an HLT in the
idle loop.  If the current is measured when the CPU is running, the current
will be higher than when it is in HLT.  On the microsats this results in a
100-200ma difference, in the larger P3D Rudak it results in 800ma per CPU.
We see the difference on microsat because the current is measured
asynchronously by the AART- sometimes the CPU is asleep. On RUDAK we can
monitor one CPU's current from the other.

If you always measure with the CPU running, then you will be measuring
high.  The kernel when just running PHT is asleep most of the time.  This
assume that you are using the version of the kernel that sleeps - there was
a version for testing on the ICE at UAH that had the HLT patched out.

Harold

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