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Re: Mode-B vs Mode-J VERSUS Mode-S



My thoughts on the subject (for those that care...LOL):

Although I do not participate on the FM-Leo sats (much), this is the
easiest for the beginner with little or no new equipment to start on.  So I
think the combined mission of Echo fulfills a definite need for many.
Personally I am more convinced that small sats like Burninga's PCSat are
needed.  If small and inexpensive enough several cooperative and compatible
sats could provide a network (constellation) of Leos.

Personally I much prefer the open transponded bandpass satellites.  I'll
come back to the Heos in a minute.

But first I feel that the next step in ease to bring new hams or provide
sat opportunity to those who want it simple is the 10m/2m SSB Transponder
Sat.  One in Meo would be my thinking.  Mode-A is not too hard for a ham to
equip for.  Currently all of the mode-A birds are gone!

Heos:
AO-40:  Glad it is here.  My main interest in satellites.  Being far for
many Leo-meo footprints the Heo gives me access.
Since we now have a base developed of mode-S stations, future sats should
include it.  Mode-US still is easier than Mode-LS to achieve so that should
be continued.  But Mode-LS is the better in the long term.

Mode-U/V is much loved and missed.  I should be included on near-term Heos.
 There is a lot of off-shelf equipment that can be used.  I would suggest
that mode-U/V be included with say mode-US.  This would maximize
participation by the most hams.

The future should look higher in frequency:  Microwave is more efficient
than VHF/UHF for satellite links (its why the commercial sats are
there--also because of the spectrum availability).  Its clear that mode-S
incursion by Wi-Fi, cordless phones and other unlicensed users is going to
eventually make it unusable except by use of large dishes and sophisticated
NR techniques.

Mode-X is nearly as easy as mode-S for downlink (really this is true).
Mode-LX, Mode-SX, Mode-CX all should be on the drawing boards for next
satellites.  Many hams are unaware of a revolution and explosion of
terrestrial 10.368 GHz SSB/CW operation in the US.  Receiving is much the
same process as we have just done for mode-S/AO-40.  Equipment
manufacturers even built 10.450 GHz Rx converters in anticipation of AO-40
mode-X.  Too bad it hasn't turned out to be working (so far).

If mode-L/U is wanted then combine it with a Mode-L* microwave mode!  *
being S or X.

With a mix of Leos, Meos, and Heos, ham sats are achievable by any ham no
matter his pocket book or expertise!
And there is a progression for those that want the challenge.

I would recommend more smaller satellites and less "do-everything" birds.
For the obvious reasons:  Launch opportunity, cost, time to completion,
reliability.  Likewise diversity in organizations building ham sats...just
coordinate so they can all coexist!

73, Ed - AL7EB




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