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#22
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Pegasus/SciSat Launch Cost
Ian Stirling wrote:
For the pretty fundamental reason that you've got to have a position solution in order to work out if you should blank the display... (well, there are some limits, but only well above the posted limits) Um, no. If the GPS engine knows there are limits, it obviously knows they are being exceeded, and refuses to send the data to the display. There is nothing fundemental about the blanking being done in the display vice the engine. D. -- The STS-107 Columbia Loss FAQ can be found at the following URLs: Text-Only Version: http://www.io.com/~o_m/columbia_loss_faq.html Enhanced HTML Version: http://www.io.com/~o_m/columbia_loss_faq_x.html Corrections, comments, and additions should be e-mailed to , as well as posted to sci.space.history and sci.space.shuttle for discussion. |
#23
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Pegasus/SciSat Launch Cost
Derek Lyons wrote:
Ian Stirling wrote: For the pretty fundamental reason that you've got to have a position solution in order to work out if you should blank the display... (well, there are some limits, but only well above the posted limits) Um, no. If the GPS engine knows there are limits, it obviously knows they are being exceeded, and refuses to send the data to the display. True, if they are seperate. There is often one microprocessor doing both the display driving, and the decoding of the GPS signal, hooked to the GPS reciever circuitry and the LCD. The reciever may do lots of signal processing, but probably won't go all the way to a position, as it's designed under the assumption there will be a micro somewhere in the system. Any limits from the reciever will typically be due to design limitations, such as loop stability/noise tradeoffs which give jerk limits, and VCO range which gives velocity limits. However, the velocity limits are with respect to the satellites, and if you are willing to ignore the ones you are moving away from, commercial recievers pretty much have to be able to cope with the 2000m/s (?) of relative motion, plus the ~500m/s of the artificial speed limit, for a total of 2500m/s. If you'r going towards a satellite going away from you, then you'll probably get a usable position up till well over 4Km/s. There is nothing fundemental about the blanking being done in the display vice the engine. Fundamental, no, but the economics tend to imply it for most of the chipsets I've looked at. You don't want to add a seperate micro just to do position calculation and pass it to a display micro. (for small GPS units, for really expensive ones where the display may be a much harder and more expensive task than the GPS decoding things may change) -- http://inquisitor.i.am/ | | Ian Stirling. ---------------------------+-------------------------+-------------------------- "I meant, have you ploughed the ocean waves at all?" Colon gave him a cunning look. 'Ah, you can't catch me with that one, sir' he said 'Everyone knows horses sink' -- Terry Pratchett - Jingo |
#24
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Pegasus/SciSat Launch Cost
"Colonel K" wrote in message om...
"Alex Terrell" wrote in message om... I think a lot of the above (not all) could be digitised, which would reduce cost and improve reliability. For telemetary transmitters, modify a satellite phone. You're silly. Your wit knows no bounds. Please explain what elements of telemetary cannot use a modified satellite phone. If launch costs were lower, people would design cheaper, less relaible satellites. Increased volume would again push the price down). Tremendously doubtful. Why spend $300 million on a comsat if I can launch it for $5 million? |
#25
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Pegasus/SciSat Launch Cost
"Alex Terrell" wrote in message om... "Colonel K" wrote in message om... "Alex Terrell" wrote in message om... I think a lot of the above (not all) could be digitised, which would reduce cost and improve reliability. For telemetary transmitters, modify a satellite phone. You're silly. Your wit knows no bounds. Thank you (takes a bow). Please explain what elements of telemetary cannot use a modified satellite phone. I'd like to see you qualify a satellite telephone for the job you just specified. It'd be cheaper and more reliable to use the products available now. If launch costs were lower, people would design cheaper, less relaible satellites. Increased volume would again push the price down). Tremendously doubtful. Why spend $300 million on a comsat if I can launch it for $5 million? Because that $300M buys a tremendous amount of long-lived capability. The launch price is not a factor in the equation. Quality and reliability of service to customers is. -Colonel K |
#26
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Pegasus/SciSat Launch Cost
"Colonel K" wrote:
"Derek Lyons" wrote in message ... AFAIK there are no GPS receivers outside of government hands that will perform in an accelerating booster. (There are hard limits inside commercial chips specifically to prevent provide cheap guidance systems to folks we'd rather not have.) OSC buys a COTS GPS unit for Pegasus. It's built by Honeywell and called SIGI - Space Integrated GPS/INS. http://www.ais.honeywell.com/dss/sgp...ts/gn-sigi.htm COTS does not mean anyone can walk in off the street and by them. It merely means that it is not a specially designed item. (It specifically does not mean an item in serial production.) D. -- The STS-107 Columbia Loss FAQ can be found at the following URLs: Text-Only Version: http://www.io.com/~o_m/columbia_loss_faq.html Enhanced HTML Version: http://www.io.com/~o_m/columbia_loss_faq_x.html Corrections, comments, and additions should be e-mailed to , as well as posted to sci.space.history and sci.space.shuttle for discussion. |
#27
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Pegasus/SciSat Launch Cost
"Derek Lyons" wrote in message ... COTS does not mean anyone can walk in off the street and by them. It merely means that it is not a specially designed item. (It specifically does not mean an item in serial production.) If you are a commercial customer and meet the criteria (a valid peaceful use for the device) you can buy one. In aerospace, that's COTS. If your idea of COTS means buying it at Radio Shack, then you should rethink your definition. -Colonel K |
#28
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Pegasus/SciSat Launch Cost
"Colonel K" wrote
"Derek Lyons" wrote COTS does not mean anyone can walk in off the street and by them. It merely means that it is not a specially designed item. (It specifically does not mean an item in serial production.) If you are a commercial customer and meet the criteria (a valid peaceful use for the device) you can buy one. In aerospace, that's COTS. If your idea of COTS means buying it at Radio Shack, then you should rethink your definition. True and true. It is, however, an interesting and sometimes instructive exercise to see what you *can* build (or at least design) using no-fooling, walk-in-and-buy-it equipment. |
#29
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Pegasus/SciSat Launch Cost
(Allen Thomson) :
"Colonel K" wrote "Derek Lyons" wrote COTS does not mean anyone can walk in off the street and by them. It merely means that it is not a specially designed item. (It specifically does not mean an item in serial production.) If you are a commercial customer and meet the criteria (a valid peaceful use for the device) you can buy one. In aerospace, that's COTS. If your idea of COTS means buying it at Radio Shack, then you should rethink your definition. True and true. It is, however, an interesting and sometimes instructive exercise to see what you *can* build (or at least design) using no-fooling, walk-in-and-buy-it equipment. For COTS I find my biggest problem is finding the correct supplier. Right now I am looking for a small all stainless-steel or all alumium rotary vane pump, just the pump - no motor - I need to pump low pressure H2O2 vapours. So far I have hit over a hundred online catalogs and called half a dozens local suppliers. No luck so far, I know such exist as the big industrial ones do, but all the companies I have called said they don't have any or any that small. I am also not sure the person at Fisher Science understood me right and may think they don't have something that infact they do have. And don't let me get in how bad *SOME* online catalogs are organized, some are missing critcal hyperlinks to needed data, but one site I was on *ALL* the hyperlinks only point to the same useless pages. Plus too many just point to thier sales force, I hate having to explain what I am doing to a saleman who often has no engineering background, he (usually) get lost the moment you leave the pre-planned sales script. Earl Colby Pottinger -- I make public email sent to me! Hydrogen Peroxide Rockets, OpenBeos, SerialTransfer 3.0, RAMDISK, BoatBuilding, DIY TabletPC. What happened to the time? http://webhome.idirect.com/~earlcp |
#30
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Pegasus/SciSat Launch Cost
In article ,
ed kyle wrote: That's $144,000 per kg! ... The spacecraft/mission cost seems quite reasonable by comparison. (Maybe Canada should develop its own space launcher, eh?) Believe me, some of us have thought about it. :-) Really hard to get the Canadian government to fund it, however. Partly there's an ingrained inferiority complex, a belief that Canada couldn't *possibly* do something that daring all by itself, so anyone who tries to sell Canada on it must be a con man. Partly there was a strategic decision made several decades ago that Canada would not build its own launchers, and whether or not the old reasons still apply, it has attained the status of religious dogma in the funding agencies -- even propulsion research tends to be dismissed as something that Canada Just Doesn't Do. Sigh. -- MOST launched 1015 EDT 30 June, separated 1046, | Henry Spencer first ground-station pass 1651, all nominal! | |
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