|
|
Thread Tools | Display Modes |
#1
|
|||
|
|||
What Is Soyuz Using For Comm These Days?
Anyone know? Do they have a TDRSS system as part of the ISS
agreement? |
#2
|
|||
|
|||
What Is Soyuz Using For Comm These Days?
Rand Simberg wrote:
Anyone know? Do they have a TDRSS system as part of the ISS agreement? No - they have a TDRSS-like system called Altair, and there may be a satellite or two from that system still running, but Soyuz isn't equipped with an antenna for it. It relies on ground stations for comm, and all the ground stations are in Russian territory. (For that matter, I don't think the Lira antenna on the Zvezda module intended to communicate via Altair was ever fully deployed.) |
#3
|
|||
|
|||
What Is Soyuz Using For Comm These Days?
On Tue, 20 May 2008 23:21:16 -0500, in a place far, far away, "Jorge
R. Frank" made the phosphor on my monitor glow in such a way as to indicate that: Rand Simberg wrote: Anyone know? Do they have a TDRSS system as part of the ISS agreement? No - they have a TDRSS-like system called Altair, and there may be a satellite or two from that system still running, but Soyuz isn't equipped with an antenna for it. It relies on ground stations for comm, and all the ground stations are in Russian territory. (For that matter, I don't think the Lira antenna on the Zvezda module intended to communicate via Altair was ever fully deployed.) Actually, I got an email response from Oberg: "Mir used to have a TDRSS-like system called 'Luch', and a dish antenna capable of communicating with the GEO relay satellite is installed on the Service Module now linked to ISS. But it's never worked. The old system broke down and wasn't replaced in the 1990's. There are one or two payloads already built, at the Reshetnev plant in Krasnoyarsk, but they won't deliver them until the Russian Space Agency pays cash -- and by now, their components have probably exceed their warranties anyway. The Russians have a voice relay capability through the NASA TDRSS, but can't relay TV or telemetry, so they conduct how-criticality operations such as dockings or spacewalks only when passing over Russian ground sites. They don't even have ocean-going tracking ships any more -- all sold for scrap [one is in drydock as a museum]." |
#4
|
|||
|
|||
What Is Soyuz Using For Comm These Days?
|
#5
|
|||
|
|||
What Is Soyuz Using For Comm These Days?
On May 21, 12:47 pm, Damon Hill wrote:
Are there any commercial GEO data link services that could serve low orbit satellites? Seems like there'll be a market sooner or later where store-and-dump doesn't cut the mustard. --Damon market for what LEO spacecraft? |
#6
|
|||
|
|||
What Is Soyuz Using For Comm These Days?
|
#7
|
|||
|
|||
What Is Soyuz Using For Comm These Days?
Rick Jones wrote:
I wonder how much of Iridium still works, or how many satellite ISP's there are around the globe and how well a "base station" moving across/below them at 17000 MPH would work...assuming the base station kept a dish pointing at one or another of the ISP's satellites in GEO. Terrestar perhaps if it manages to launch? (although that would be NA only I guess) All of Iridium works. The whole constellation isn't up there, but you can pick up the phone anywhere in the world and get a call through. Iridium is pretty heavily used. There are actually a lot of satellite phone services and ISPs around the globe, but most of them are using satellites that target only a very small area. Iridium works anywhere, and it's a hell of a lot cheaper than INMARSAT. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#8
|
|||
|
|||
What Is Soyuz Using For Comm These Days?
In sci.space.history Scott Dorsey wrote:
All of Iridium works. The whole constellation isn't up there, but you can pick up the phone anywhere in the world and get a call through. Iridium is pretty heavily used. That got me looking them up on the web - the production rate they achieved with the satelites was impressive if the wikipedia article is at all accurate. Almost like the satellite equivalent to a liberty ship 21 days to make a satellite, one coming off the line every 4.3 days. That starts to sound like "responsive" in the context of some of the other posts in the group. The 1500 millisecond latency quoted for TCP was equally astounding if not as positive I wonder how much of that is bandwidth and how much of that is hopping around. IIRC 1500 milliseconds is enough time for 6 GEO hops - ~250 milliseconds for each up and down to GEO - so that makes me wonder where all that latency happens to be if the satellites are only 480 odd miles up. Perhaps it is the baud rate. rick jones -- denial, anger, bargaining, depression, acceptance, rebirth... where do you want to be today? these opinions are mine, all mine; HP might not want them anyway... feel free to post, OR email to rick.jones2 in hp.com but NOT BOTH... |
#9
|
|||
|
|||
What Is Soyuz Using For Comm These Days?
Rick Jones wrote:
The 1500 millisecond latency quoted for TCP was equally astounding if not as positive I wonder how much of that is bandwidth and how much of that is hopping around. IIRC 1500 milliseconds is enough time for 6 GEO hops - ~250 milliseconds for each up and down to GEO - so that makes me wonder where all that latency happens to be if the satellites are only 480 odd miles up. Perhaps it is the baud rate. It's all latency from hopping around, that's not related at all to the bandwidth limitations. There are some tweaks you have to do with some TCP/IP parameters (and that includes cranking buffers way up and using the dynamic window size stuff), but you can actually get some pretty good throughput for file transfers. It's no fun for a telnet connection, though. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#10
|
|||
|
|||
What Is Soyuz Using For Comm These Days?
In sci.space.history Scott Dorsey wrote:
It's all latency from hopping around, that's not related at all to the bandwidth limitations. There are some tweaks you have to do with some TCP/IP parameters (and that includes cranking buffers way up and using the dynamic window size stuff), You mean the RFC 1323 "large window" extensions (window scaling)? Assuming that 1500 milliseconds is a round-trip latency, the ever fun: Tput Window/RTT Would suggest that the classic TCP window of 65535 bytes would limit one to: Tput 65535Bytes/1.5S or ~42KB/s (K == 1024) no matter how much more bandwidth there was out there. Still, I thought the wikipedia article was claiming a rather lower baudrate than that? but you can actually get some pretty good throughput for file transfers. It's no fun for a telnet connection, though. Indeed. rick jones -- oxymoron n, commuter in a gas-guzzling luxury SUV with an American flag these opinions are mine, all mine; HP might not want them anyway... feel free to post, OR email to rick.jones2 in hp.com but NOT BOTH... |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
What Is Soyuz Using For Comm These Days? | Rand Simberg[_1_] | Policy | 20 | May 30th 08 10:05 AM |
Comm Check | Brian Webb | Amateur Astronomy | 3 | April 3rd 06 06:14 AM |
timeline of Navy Comm birds | David Lesher | History | 22 | October 24th 05 08:38 PM |
Soyuz w/ Exp-10 Delayed "5-10 days" for "docking system problem" | Jim Oberg | Space Station | 3 | September 19th 04 08:13 PM |
Soyuz w/ Exp-10 Delayed "5-10 days" for "docking system problem" | Jacques van Oene | News | 0 | September 15th 04 02:09 PM |