Valueman:
I'm a rank amateur and poor "back of the envelope "guy when it comes to Satellites. I have been
peripherally involved in some satellite attempts, but only on the network side, not the fun side.
Satellite guys have birds, spot beams, dishes, transponders, and astronauts repairing them; in
telecom, we just have acronyms.
Thank you for the real data. Now let me try to understand the bottom line.
Each 36 MHz transponder has about a 45 Mbps capacity. A service like Gilat's Starband is
starting off with 14 transponders on
Loral's Telstar 7 satellite. A typical sat today has approximately 24 Ku-band, and 24 C-band
transponders. FYI, in Starband's S-1
filing, they have been getting 7,500 subs per transponder while maintaining their 150 Kbps
minimum. To wrap up this summary, a
sat costs ~$250 million to build, launch, and insure.
Other fun facts--a typical modern sat has about 1.2 Gbps throughput capacity. Birds being built
now, with frequency reusing spot
beams, will up that to 6-7 Gbps. Technology of ViaSat can be used to boost that capacity to
20-40 Gbps on a Ka-band spot beam
satellite.
I'm not clear on the potential for increase in capacity, so hold that off for now. Just taking 'todays'
new satellite numbers, let me try a crude business case.
Assume 150Kbps minimum with 7,500 subs per transponder and 24 transponders = 180,000 subs
per satellite, well over my raw guess.
The satellite cost $250 million to build and launch- I'm sorry, the bird costs $250 to fly (I must get
the verbiage right!). This is about $1,400 per subscriber.
Say another $200 for the modem. Assume the subscriber has all ready shelled out $500 for the
dish to get TV, so don't factor that in. This is about $1,600 per subscriber.
A rough rule of thumb says that the capital expense should be no more than 20 times the monthly
fee. Reverse engineering this means they have to charge $80 per month, even before add network
access equipment to make a business case. Not too bad, at first glance; I'd probably pay $80 for
150 kbps over a 56 kpbs link with a second phone at $40 per month.
Now of course, in satellite traffic disucssion, the fundamental problem of utilization is often overlooked.
You must put up a $250 satellite to handle even one subscriber. The only way the above numbers
work is if the satellite is fully utilized. If it is %50 utilized, you would have to spend $160 per month
per subscriber. I'm not sure I'd pay that. In fact, it would be cheaper to get three phone lines and
three modems and somehow glue them together (I think I've seen boxes that do this). This was one
of the many problems with 2b+d ISDN- one reason it failed was because it was more expensive
than getting two phone lines.
I don't see how to make a business case here, until the satellites can handle double the capacity you
noted.
On the other hand, in the bit I didn't understand, you seem to imply you can go from 1.2 G per
satellite to 20-40. Does that mean you can increase the number of subscribers per satellite by a
factor of 30?
That would do it. |
