[amsat-bb] Re: ECHO duty cycle

Gould Smith gouldsmi@bellsouth.net
Thu Aug 31 18:37:11 PDT 2006


The command team is constantly working on optimizing the Battery 
Charge/Discharge system.  This is the most critical system in a satellite. 
One of the tricks is to reach your battery discharge depth at the same time 
you come out of eclipse, a non-trivial task and one that requires a constant 
tweaking process.  Add mode, transmitter and power changes to the mix and it 
becomes a fine tuning act.

The team is analyzing and compiling the information from the testing a few 
weeks ago.  The control software is not something that
gets changed very often due to the extensive effort needed to test it. 
There is NO simple change.
As mentioned many times, we are all volunteers and we need to maximize our 
efforts for the things that effect the health and well being of the 
satellite.  While there may be a some additional information that people may 
want published, there is just so much volunteer time in a day/night.

There may appear to be many 'simple' solutions to power management and 
transmit power issues, but most of them fall back to changing control 
software which is not a simple solution.  As with any control software, 
adding a feature is usually pretty straight forward, it is the inadvertent 
change/effect to some other part of the system that causes a problem, often 

AO-51 will be in high power mode Sept 4-11.  You may see that more is not 
necessarily better, the fact that more people can hear the satellite means 
there is more competition for the satellite.  You may experience more 
difficulty getting through the satellite.  The BEST advice for any satellite 
operation is to maximize your receive system - i.e.  beam antenna, AZ/EL 
rotor, and preamp.  For LEO operation a small downlink yagi at a fixed 
elevation and AZ rotor will work very well and is inexpensive.


----- Original Message ----- 
From: "McGrane" <tmcgrane@suffolk.lib.ny.us>
To: "Amsat BB" <amsat-bb@amsat.org>
Sent: Thursday, August 31, 2006 7:42 PM
Subject: [amsat-bb] ECHO duty cycle

> hello again-
> Does anyone know what percentage of a day or orbit the echo transmitters
> are ON?
> I've been thinking about the battery depth of discharge issue.
> Being that they are as a whole 4 amp hours, a 10 percent discharge would
> equate to about 1.6 amps for one quarter of an orbit on-time.
> According to drew, the transmitters are drawing about .8 amps.
> I hope people are viewing depth of discharge as a function of amp-hours
> more than voltage ( I realize also important ).
> Any comments are welcome.
> Thanks, pat n2oeq
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