Bdale,

Thank you for careful review on this topic. I sincerely respect your 
feedback.

Glenn, KJ7SU


Bdale Garbee <[EMAIL PROTECTED]> writes:
> [EMAIL PROTECTED] (Glenn LeBrasseur) writes:
>
>   
>> Unfortunately no part of  802.11a is in the amateur spacecraft  
>> range. This kind of makes sense with regard to interference, since it  
>> would be so easy for a spacecraft to interfere with a large number of  
>> terrestrial 802.11a stations.
>>     
>
> The reverse is *far* more important, at least to me. ;-)
>
> A large body of unlicensed terrestrial transmitters bringing up the noise 
> floor could make it *very* hard to hear amateur satellite downlinks, which 
> are typically far too weak to cause any significant interference to 
> terrestrial stations.  In theory an uplink could cause interference to 
> 802.11a stations, but since highly directional antennas are typically used 
> aimed at the satellite, any real interference caused by an uplink is likely 
> to be rare.
>   
Yes, you are correct. I had my perspectives inadvertently biased toward 
the terrestrial. I understand and agree with the problems with noise 
pollution of extraterrestrial RF and light, and am an advocate to their 
reduction.

>> Power levels  
>> are limited to the license class [8], which for the technician class  
>> is 200 watts, and the overall power limit stated in CFR 47-97.313(a)  
>> and (b).
>>     
>
> I think you mis-read that part of the rules.  The actual power limit for all 
> licensed amateurs on that band should be 1.5kW PEP.  However, the restriction
> in the preceeding section on spread-spectrum transmissions likely applies, so
> the limit may be 100W.  In practice, these distinctions are not important, 
> because making gobs of power on C band requires *serious* heroics.  A watt is 
> pretty easy, a few watts is plausible, serious uplinks for things like EME
> typically involve TWT amplifiers, mongo amounts of heat sink mass, and/or 
> water
> cooling... you *really* don't want or need lots of watts for this task.
>
>   
Mis-read is too polite; I simply overlooked 802.11a is spread-spectrum 
(SS), which is a new privilege. However as you point out, we will mostly 
be dealing with power levels on a practical level that is well below any 
power limits of the law. I expect we will be able to work 1 to 3 watts 
into an antenna with maybe 0bB of gain, hopefully. We'll see.

>> The way I see it, using 802.11a will work for us up at larger amateur  
>> power levels until we actually get into space, and either need the  
>> higher power levels (more than 3 watts say) for the link budget, or  
>> our footprint increases and we actually become a spacecraft.
>>     
>
> When you become a spacecraft, you'll want/need to coordinate use of 
> frequencies
> in the amateur satellite sub-bands.  As long as you're on something like a 
> ballistic trajectory, the  should continue to apply.
>   
It is reasuring to confirm that you believe a ballistic trajectory 
follows terrestrial rules. We will probably be there for a while. 
However I expect we (PSAS) need to be thinking about the space segment 
sometime soon. How do you think we should proceed?
> 73 - Bdale, KB0G
>   
Bdale, Thank you sincerely  for your critique.
73 - Glenn, KJ7SU


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