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Re: AM on MILITARY built Satellites!



Bob and the group.  It was NOT clear when first writing about the use of AM
on satellites that this was to be placed on a military built satellite of his
design.  Obviously all of the BB members were not at Toronto where this idea
was first released.  His paragraphs below specifically illustrates this. 
     I support Bob in this idea under a military funded framework and continue
to insist that old fashioned full carrier double sideband AM has no place on
existing OSCAR satellites!  With effort even this can be misinterpreted as well!
Cliff K7RR


> We like to think outside of the box so to speak... We chose an AM uplink
> for our mode A satellite as follows:
> 
> UPLINK (UHF AM):
> 1) Its what our boats have and what they are currently authorized to use.
> 2) The lack of efficiency of AM on the uplink is meaningless, since the
>    power is on the earth side of the link and the boats have 25W xmtrs.
> 3) With AM there is no Doppler tuning required on the AM uplink which on
>    UHF otherwise would be almost 18 KHz
> 4) AM (6 KHz) is 3 times better in spectrum efficiency than FM (18 KHz)
> 
> DOWNLINK (HF SSB):
> 1) The downlink is very efficient SSB mode A in the 24 to 29 MHz band.
> 2) We can close the link with only 1 Watt from the satellite.
> 3) The boats also have HF SSB radios so there is 0 cost to the users.
> 4) We have $$$ to build a satellite, we dont have a dime to spend on
>    upgrading the boats with SATCOM radios. (at $20,000 each)
> 
> We are quite proud of the project, especially since there are tens' of
> thousands of low value assets like jeeps, tanks, trucks, and aircraft that
> still only have a UHF AM tactical radio.  They will never be upgraded at
> $20,000 each to SATCOM capability.  And even if the radios were free,
> there is no way the current SATCOM channels can support communications for
> these low priority users.
> 
> Thus, we found a niche to fill (demonstration only) and were able to make
> a satellite project out of it..  Since many Hams are also members of MARS
> organizations, we figured this satellite could also be made available to
> them for experimentation.  After all, what good is a satellite if you
> can't play with it..
> 
> http://www.ew.usna.edu/~bruninga/marscom.html
> 
> Unfortunately, it will only last 6 months or so due to the low orbit
> opportunity... (and is more than a year from now)...
> 
> de WB4APR, Bob
> Naval Academy Satellite Lab
> 
> ----
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