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Re: AO-27 TEPR state explanation



I'm asked to explain TEPR about one a month. I also noticed that this
info isn't in the AO-27 spacecraft information area of the AMSAT site. It
should be added to the schedule and operation area in AO-27  spacecraft
information.

73 Jeff kb2wqm 



On Sun, 7 Nov 1999 07:51:42 -0500 "Chuck Wyrick" <cwyrick@mediaone.net>
writes:
> Here is a reprint of a previous posting explaining the TEPR meaning 
> on
> AO-27.
> 
> To summarize:  We set the bird to charge its batteries for "x" 
> number of
> minutes AFTER it enters the Sun.  This is TEPR state 4 expressed in 
> 30
> second increments, e.g. TEPR 42 means that the charging time is 21 
> minutes.
> We then set TEPR state 5 to the length of time, expressed in 30 
> second
> increments, that the transmitter would be on from the start of TEPR 
> 4 but
> not on until the completion of TEPR 4, e.g. TEPR 78 means that the
> transmitter will shut off 39 minutes after the start of TEPR 4, but 
> the
> transmitter will be on for 18 minutes. (78-42 =36, or 18 minutes)
> 
> AO-27 TEPR States Explained
> 
> AO-27 uses a method called Timed Eclipse Power Regulation (TEPR) to
> regulate the batteries.  In simple terms, TEPR times how long it has
> been in the eclipse or in the sun and decides what subsystems to 
> turn
> on or off.
> 
> The current software onboard AO-27 breaks an orbit into 6 different
> states as follows:
> 
> TEPR State 1:  Starts when the satellite enters the Eclipse
> TEPR State 2:  Starts a programmed time after TEPR State 1 (Still
> during the Eclipse)
> TEPR State 3:  Starts a programmed time after TEPR State 1 that's
> after State 2 (Still during the Eclipse)
> 
> TEPR State 4:  Starts when the satellite enters the Sun
> TEPR State 5:  Starts a programmed time after TEPR 4 (Still in the
> Sun)
> TEPR State 6:  Starts a programmed time after TEPR 4 that's after
> State 4 (Still in the Sun)
> 
> Current Subsystems by State:
> TEPR 1,2,3 - all unneeded Subsystems turned off (This is why there 
> is
> no Night time use of the satellite)
> TEPR 4     - AO-27 Transmitter is turned to exciter power only. All
> other Transmitters are off.
> TEPR 5     - AO-27 Transmitter is turned to 0.5 watts (low power)
> TEPR 6     - all unneeded Subsystems turned off
> 
> Using this Model, During a descending, day-time pass, AO-27 will 
> enter
> TEPR 4 after coming out of the eclipse and will start to recharge 
> its
> batteries.  We program the TEPR 5 time so the satellite will stay in
> TEPR 4 until the foot print reaches latitudes equal to the Northern
> United States.  At that time, it changes to TEPR State 5 and the
> transmitter turns on.  The duration of TEPR State 5 is set for the
> longest we can leave the transmitter on to keep the batteries in a
> state that will prolong their life time.  At the current time (June
> 1999) this is 18 minutes.  If we were to leave it on longer we would
> start to limit the life time of the satellite.  The TEPR 6 period
> needs to be long enough to recharge the batteries before we enter 
> the
> eclipse again (TEPR 1).
> 
> The time we need to stay in TEPR 6 is what places a limit on the
> southern latitudes we can work in.
> 
> 73
> Chuck, KM4NZ, Acting Control Operator
> 
> 
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