[amsat-bb] Re: ECHO duty cycle

Patrick Green pagreen@gmail.com
Thu Aug 31 22:56:27 PDT 2006

On 8/31/06, Gould Smith <gouldsmi@bellsouth.net> wrote:
> Pat,
> 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.

Is this why the change to "always on" TX  early on?  To make the power
budget more predictable than on demand keying up of the transmitter?

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
> major.
> 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.

More competition means more stations and the possibility of new grids.  I
see this as a good thing more than bad.  I need the higher power here to
overcome the urban noise floor on low elevation passes.  When I was away
from the city, I could easily hear the sat at it's normal power setting from
3 degrees and up.

Did UO-14 meet it's demise because of the TX power it was running?  Did it
run the 2+ watts 24h/day?

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.

My advice for a new op is a hand held beam with an HT.  It seems that coax
runs are the more important to keep under control.  I was able to hear SO-50
on my AOR AR 8200 scanner with a beam with a short run of coax, no preamp.
Then try a base setup.  I'll eventually get a base setup but for now, I'm
content with the single channel FM transponders.

> Gould

73 de Pat --- KA9SCF
Amsat #35741

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