[amsat-bb] Re: ECHO duty cycle

[Gould Smith]

Hello Pat,

>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? 
There are a number of factors involved in the TX always on function, predictability is certainly one of them.

>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. 
My point is simply that with more people attempting to use the one channel on the satellite at the same time, the more difficult it is to complete QSOs.  There are benefits as well as downsides.

>Did UO-14 meet it's demise because of the TX power it was running?  Did it run the 2+ watts 24h/day?
UO-14 was a much larger satellite with more power generating capacity. It had a very long lifetime, it was launched in 1990.  I don't recall how it failed.

>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.
Your advice is exactly right, it is an excellent starting place.  That was a major factor in deciding to build it.  Coax is important, there is higher loss per foot at 430 MHz than 2M. As your satellite operating interests increase, moving toward a good fixed station is a natural progresssion.

73,
Gould

  ----- Original Message ----- 
  From: Patrick Green 
  To: Gould Smith 
  Cc: McGrane ; AMSAT-bb@amsat.org 
  Sent: Friday, September 01, 2006 1:56 AM
  Subject: Re: [amsat-bb] Re: ECHO duty cycle





  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. 



    73,
    Gould
    WA4SXM

  73 de Pat --- KA9SCF
  Amsat #35741