[amsat-bb] Selection of satellite (ham and non-ham) frequencies
jim at coloradosatellite.com
Tue Mar 14 23:51:37 UTC 2017
For the US: If the satellite owner is a government organization the NITA
controls the frequencies and assignments. For large agencies like NASA
they have a team of people who do nothing but this and blocks of
frequencies that NTIA lets them manage themselves (for the most part).
All others are managed by the FCC. For example a commercial TV
broadcast satellite must obtain an FCC license. There are many
categories of FCC licenses and many blocks of frequencies that are more
or less dedicated to certain uses.
Let me provide the following on how Amateur satellites and Experimental
satellites that may be licensed in spectrum allocated to the Amateur
Radio Service works. This again applies to the US (other countries have
other methods and procedures).
If someone like AMSAT builds a satellite for the use of Amateur
licensees, and it wants to use frequencies allocated to the ARS, it
first obtains coordination from the IARU then follows the notification
procedures in part 97. The FCC part is pretty straight forward. The
transmitter(s) in the satellite are operated under someones existing ARS
license much like a mountain top repeater is operated under the license
of a person (or perhaps a club). The frequencies to be used are
coordinated by the Satellite Advisor to the IARU and his international
committee of advisors. What that means is the builder provides the info
on what freqs they would like to use, the nature of the satellite, their
commanding methods and other technical details to the IARU on their
form, and the IARU coordination team gets together and 'coordinates'
those frequencies. Coordination means they look at all other sats using
those bands and work at keeping them on separate frequencies so they
don't interfere with each other (or cooperatively share them). In the
notification process to the FCC you must include the info from the IARU
that you have coordinated your frequencies. The IARU team does this for
all amateur sates from all countries (to the extent those countries
cooperate and participate, not all do.)
If someone wants to use frequencies in ARS allocated spectrum for
something other than an Amateur satellite, like scientific or
Experimental cubesats from universities or commercial companies, they
can ask the FCC Experimental branch for an experimental license. But
the FCC Experimental brance won't give them a license unless the IARU
has coordinated their proposed frequencies (again, keeping them apart so
they don't interfere with Amateur or other experimental usage).
Experimental licensees must accept any and all interference from
licensed operations and must not interfere with any licensed
operations. There is no assurance that the IARU will agree with the
frequencies chosen or that they will provide coordination at all. Those
experimental licensees and operations are something between guests and
interlopers in the Amateur allocated spectrum. The IARU endeavors to
keep the experimentals separated from the Amateur by sort of using one
end of a band for Amateur and the other for Experimentals.
The IARU has done a great job of this very complicate and difficult task
over the years as the number of both Amateur and Experimental satellites
proposed and on orbit has increased hugely. It's very hard. And most
of those building experimantals don't know how this works or what they
must do. Sometimes they buy hardware (radios and antennas) for their
satellite without understanding how this works to find they can't get
licensed where they want to be. That's costly.
In the past month I've sat as a reviewer for three university small
satellite projects none of which understood this and one of which has
radios they are not going to be able to use because they can't get an
experimental license in that band.
We could certainly use local AMSAT folks with satellite experience as
mentors for the COMM part of most of the university driven small and
cubsats. It's a great opportunity to educate some young people and keep
them from making technical and regulatory errors. And some of these
projects can turn into Amateur satellites after their experimental or
science mission is over. I'm working with one right now that has the
potential to be a great Amateur on orbit resource - the owner is done
with it and looking to turn it over to AMSAT if we can get it fully
working in various modes again.
Colorado Satellite Services, LLC
wd0e at amsat.org
jim at coloradosatellite.com
On 3/14/2017 4:59 PM, Philip Jenkins wrote:
> I'm helping teach a Technician licensing class, and one of the students has
> asked a question I can't answer :-) (And please correct any misinformation
> in this email)
> My understanding is that agencies/governments - by gentleman's agreement?
> policy? - are supposed to request frequency coordination for satellites
> with inputs/outputs in the amateur bands from IARU, whether the primary
> payload is ham radio or not. I remember an entity a couple of years ago
> which launched a satellite(s) who did NOT go through IARU for satellite
> downlink(s) on the ham bands, and there was some dust-up over this. (Again,
> please help me understand this better if I'm mistaken.)
> My student's question is this; who is responsible for frequency assignments
> for non-ham satellites, specifically, missions like Cassini and
> Voyager/Pioneer? Is it ITU?
> I'm sure the military - and government (and commercial interests) - in
> other countries have their own satellite frequencies, but for scientific
> payloads, who is responsible for frequency allocation/coordination in near
> Earth orbits and intra-galactic ones? Is is ITU?
> (This started a whole new thought bubble in my head about what would be the
> best/appropriate frequencies for missions like Cassini (antenna size and
> Doppler considerations, but that is for a different email, as I want to
> wrestle with those questions in my head first :-) )
> Philip N4HF
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