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BobWeaver

Two-way satellite

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Just got back from a client site where they have recently installed a two-way satellite internet connection. The dealer who installed it normally does satellite TV installations, and this was his first ever datacom installation. So, he was on the phone to the ISP a lot trying to get things configured. Results were disappointing. Speed is barely any better than the old 56K modem/router setup. In fact, loading of web pages is actually worse.

The ISP says the minimum average file download speed should be 200kb/sec and as high as 2000kb/sec. The best we got was 20kb/sec.

Obviously, something is seriously wrong. Has anyone had any experience with these systems, and if so, what sort of things do we need to check?

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I once worked for a company that installed telecom satellite dishes in between apartment buildings. It was a disaster. First, the job was done during the winter in MO., so horrible weather stopped work many times. Then, there was not a clear line of sight between dishes and communication was dropped on a regular basis. Finally, at the time, the transmitter boxes were <10Mbps. I wish I could put my finger on one single thing, but it turned out to be just bad all around

Ken

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I'd check to make sure you paid on a charge card with charge back rights. wink.gif Here satellite is still expensive and as Anatoli says, the delays to orbit is limited by the 22,500 synchronous orbit to about 0.3 seconds theoretical. Before the cable company offered high speed internet access, I look into satellite a little and never found an installer who had actually done an internet installation.

I'd probably put mega pressure on the parent company to resolve the problem. I'm sure given enough pressure they have specialists that can be sent out to "help" the local installer.

-bd

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Guess this is getting a bit off of the Filemaker topic, but...

We realized there would be a latency problem, but I wouldn't expect that to affect the download speed of a large file. Maybe as Ken says we have a bad signal and we are losing a lot of data packets. Could be on the edge of the satellite footprint or something like that.

We have put the heat on the ISP to fix the problem. No telling how soon they are likely to come up with an answer though. Pretty sure they'll get the hardware dumped back on their doorstep if they don't come up with something soon. My client has less patience than me, and I don't have much.

BTW, I found a pretty good source of info at www.dslreports.com on tweaking TCP/IP parameters for different types of connections (including satellite). I tried the tweaks, and they seemed to give some improvement on the host computer. The host computer is a PC running win98, and serves as a router (using Internet Connection Sharing) for the rest of the office which is all Macs. According to the above web site, tweaks should be applied not only to the host, but to all client computers on the local net too, but it seems that parameters like RWIND and MTU etc. are not accessible on MacOS9.x which is what is being used on site. Does anyone know if these parameters are accessible? Apparently they can be adjusted on OSX, but we don't want to open that can of worms yet.

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For anyone else who may be considering a satellite internet connection, here is an update on what happened.

The system is based on a satellite modem which is connected to the host computer via USB. That means that it's incompatible with the normal bunch of routers, hubs and switches. It must be directly connected to a PC running Windows. That host computer then acts as server/router to the rest of the office LAN. The download performance when working directly on the host computer is comparable to DSL/Cable. The problem arose when we tried to share the connection over the LAN. Apparently, the TCP/IP parameters which are optimum for communication between the host and the satellite are very bad for communicating on the LAN. When we used ICS to share the connection, it did not do any data buffering and just passed the data packets on. This led to very bad performance. I estimate that this bottleneck reduced the throughput by a factor of 8.

We tried one commercial internet sharing software product that did not help at all, and then finally tried Orbitnet from www.orbitsat.com

This seems to have solved the problem. It has built-in buffering and caching which helps match the LAN timing to the satellite timing. The client computers now seem to communicate on the internet at nearly the same speed as the host.

Just in case you ever get into this situation, now you know.

Also, don't be misled by satellite ISP claims of performance exceeding DSL/Cable. Actual performance will depend on a lot of factors such as where you live and the local subscriber load. We find that our local DSL and Cable ISPs have better performance than what we are currently getting on satellite.

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Thanks for the update Bob.

Except for hosting where a decent DSL connection is better, cable can be impressive (most cable uplinks are blocked at 128K). We see download speeds that peak at over 2 Mb, although the speed browsing most sites is still dominated by the site.

-bd

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Yes. I have cable internet at home and at my office, and am very happy with it. I'm getting download speeds similar to you. I've never checked to see what kind of cap there is on our uploads since I don't do a lot of big uploads.

Out of curiousity, are your local DSL ISP and Cable ISP the same or separate companies? A co-worker on my current project is from Portland OR, where the cable and phone co are both AT&T. He says that with the monopoly, their monthly charges are way higher than ours. Our local high speed ISPs are separate companies and quite competitive. I pay C$43/month (U$29) for the connection.

Unfortunately, the installation where the satellite connection is, is out in the country 20 miles from the nearest town that has DSL.

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P.S.

Note the important difference between kbps and kB/s in ISP promotional material. I always think in bytes, but bits make for more impressive sounding numbers (factor of 10). I was a little muddled up by that initially. I wonder how many other people have been misled.

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Competition is the key. In San Diego and Riverside counties the cable companies include Adelphia and Cox. DSL is by SBC PacBell, Verizon, Qwest and others. Cable rates for internet service hover around $43.

-bd

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