[amsat-bb] Re: Geostationary Satellite
Tom Schaefer, NY4I
ny4i at arrl.net
Tue Oct 11 08:07:15 PDT 2011
I ask this in all seriousness though. Is a giant repeater in the sky with no need to handle Doppler shift really something that would be used? That would take some of the magic out of it. Having to follow a schedule and have the computer and radio synced to correct for the shift is part of the operating fun. Sure we hear some of the same people but it is the station that pops in on the low elevation passes that make it special.
This seems like the same idea of explaining to a "hamshack on the belt" type the magic of HF. Yes, you have to check the propagation and MUF. What is the best band to talk on. All the things that lead to making contacts with different places on HF. While it would be nice to push up North American VUCC numbers, I just don't see why anyone would want a geo-stationary satellite for ham activities. I can guarantee at least two of my friends are on the local repeater right now. That is great if I have to get ahold of them for something or if I am on the side of the road in a ditch (although the auto club on my cell phone is my preferred mode of choice in that situation).
Due to the costs, the is clearly academic, but as we frequently hear rumblings of a GEOSYNC bird (from me too in the past), when I really look at why I like operating satellites, that type of bird would have none of that.
I am glad someone brought this up though as it caused me to re-examine my own beliefs about it.
Tom Schaefer, NY4I
ny4i at arrl.net
Monitoring EchoLink node KJ4FEC-L 489389
DSTAR Capable APRS: NY4I-15
On Oct 11, 2011, at 10:23 AM, Joe wrote:
> Too bad we can't get one of the TV sat people to allow us to have one of their channels. It would be wide enough to hold hundreds of QSO's at the same time for sure. And I bet they have at least one that isn't doing anything at all.
> But of course thats not a ham band either bummer!
> Joe WB9SBD
> The Original Rolling Ball Clock
> Idle Tyme
> On 10/11/2011 9:01 AM, Howie DeFelice wrote:
>> I agree with much of what Dan, N8GFV, says. Our best hope of a high altitude satellite is probably a hosted payload on a GEO sat. To make that viable we need to consider the entire mission. GEO satellite operators are a for-profit business and every aspect of a commercial satellite has a dollar value. The major items are spectrum, power and fuel. Since hams bring their own spectrum, that is a no cost item for us. If we need to use satellite power then we would need to pay the market rate for the percentage of the total satellite resource used for the design lifetime of the satellite, typically 15 years. If the payload can be disabled by the operator we may be able to negotiate a pay as you go plan so that we don't have to pre-pay 15 years worth of power. Developing very power efficient transponder systems will reduce our costs. Trading bandwidth for power by using digital encoding, strong FEC, regenerative transponders with DSP signal enhancement will all aid in the reduct!
>> n of the power required to close a link.
>> The other big cost factor is fuel. As previously stated here, station keeping is a critical element in GEO satellites and with the advances of component technology, a satellites lifetime in orbit is determined primarily by the amount of station keeping fuel it can carry. The more fuel, the longer the satellite life, the more time the operator can use to recover their investment and make money. Every ounce added to the satellite affects the cost of the launch and possibly the amount of fuel that can be carried on board. Whether this is the case or not, the added satellite weight WILL add to the launch cost that we would have to pay.
>> The good news is that the AMSAT community and the satellite operators have common interests in making satellites less expensive and more efficient. By building on the technology pioneered in ARISSAT-1 we MAY be able to get some cooperation from a commercial operator to deploy a technology demonstration package as a hosted payload. This might be more probable than one thinks. Satellite operators are EXTREMELY conservative and don't deploy new technology until it is thoroughly proven. The commercial satellite market is running out of real estate. Many of the big operators are at over 80% capacity. Since they are for-profit organizations, they are running out of product quickly and will not be able to grow their business. All the major operators are investing large amounts of money to promote a hosted payload business where government and scientific users can bring their own bandwidth to a transponder or payload on the operators platform. A low cost, high performance, innovat!
>> e payload COULD be a great advertising tool for a commercial operator. The operator would get the payload for zero cost and could also get part of the launch cost subsidized by AMSAT in return for a real world, open source demonstration tool.
>> If we build this payload along the lines of Tom Clark's C-C rider concept with a 5 GHz up/ 3 GHz. down transponder we can probably even use the satellites low gain telemetry antenna, further reducing payload costs.
>> Sorry for the lengthy post but I have been thinking about this for a while and this seemed like a good opportunity to finally put it in writing.
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