Looks like option 3 would work with the eventual 28, 145, 430 and 2400 MHz options planned for installation. That will provide 4 bands for 4 different modes.
Keep in mind that the primary goal is to support school contacts. Keeping them on 2 meters greatly simplifies the task for a lot of first timers working a space based radio station. Additional objectives must fall in line with that goal.
Another difference is that the ISS is setup more like a club station than a satellite. Future enhancements could convert it into a more satellite-ish operation but we have a lot of those orbiting already.
Kenneth - N5VHO
-----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Robert Bruninga Sent: Wednesday, May 02, 2007 11:07 AM To: sar[email protected] Subject: [sarex] Re: Future ISS amateur radio modes
Once the planned hardware is aboard and installed, having each system dedicated to a specific operation will minimize the need for mode changes and crew interaction.
But this can only be true if all systems operate with clear isolation of all uplinks from all downlinks on separate bands. It is impossible to have independent systems operating with uplinks in the same band which may be used for downlinks.
Until ARISS commits to a permanent dedicated downlink band which then guarantees other known bands for non-interfering uplink bands, future planning is stymied by crew-required mode changes and lack of independence of systems.
Current use of 2m for both uplink and downlink, prevents its use by any other system for any other purpose without crew intervention on every such use. There are really only three choices...
1) make 2m the downlink band for simplicity of reception around the world. Even the least advantaged country should be able to at least borrow an ARISS UHF uplink radio for a school contact. But it does require Doppler tuning in the blind on the uplink. Tuning a radio +/10 KHz is not a hard skill to learn.
2) Make UHF the downlink band so that recipients can simply tune the Doppler to best sound, and then uplink on 2m is fixed frequency with no problems. Less interference with UHF radars...
3) Continue status-quo, and use 2m for both uplink and downlink for school contacts and either require crew intervention with every mode change for use of 2 meters for anything else, or require all other systems to not use 2m for anything, so they can be independent of crew issues.
Until there is a permanent commitment to one of these three possibilities, uplinks and downlinks can not be planned without conflicts, and crew intervention is required in every mode change on every system that might want to share 2m for anything.
Of 60+ amateur satellties, few (with more than one mode on board) use monoband operation. There is a good reason for that. Uplinks and downlinks are in different bands for operating independence of modes. Just what we need on ISS.
Just a thought. Bob Bruninga
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