Doesn't Microsoft have a significant investment stake in DirectWay? Or DirectTV?
Thanks
Robert L. Cochran
-----Original Message-----
From: dsavage@peaknet.net [mailto:dsavage@peaknet.net]
Sent: Wednesday, October 23, 2002 11:24 AM
To: psyche-list@redhat.com
Subject: Re: Direct TV Satellite connections
On Wednesday, October 23, 2002 Thom Paine wrote:
> If it is similar to the one Bell offers here in Canada, you get a card
> that plugs into the computer. There is special software that brings the
> card online and reconfigures your browsing. You still need a phone line
> and a dial-up isp. Any outbound packets go through the dialup to the sat
> station which then directs incoming information down the DTV stream. I'm
> not sure if two way is supported as of yet. If you have DTV at home, you
> can check channel 227 I think. They have the DWAY info channel on there.
> That might answer some preliminary questions. www.directv.com may also
> have some info on it.
Thom,
Here in the Lower 48 DirectWay is a pure satellite system, unlike its hybrid
predecessor which required a land line modem for all outbound traffic.
The biggest problem with DirectWay is the speed of light. The minimum one-way
distance to a geosynchronous satellite is still 23,500 miles, which is about 1/8
light-second. That means the absolute minimum time required for a full duplex
character echo from the distant end is at least 1/2 second (up & down outbound
followed by up & down return). To that time you must add in the arctangent
multipliers for each of the two look angles, and the absolute delays along any
terrestrial path segments.
Aside from the human interface difficulties this delay presents, it can have all
sorts of wierd effects on protocols which expect ping times in the 100 msec
range. I remember how we had to change the cryptographic resync pattern from
10101010... to 11111111000000001111111100000000... for 50 kbps analog modems on
military satellite links. I can well imagine how HTTP acceleration and FTP might
be very adversly affected by such lengthy absolute delays.
If you are trying to connect to the Internet from someplace so remote that
satellite is your only means available, then I think DirectWay may be a
tolerable solution. As an engineer, however, I believe DirectWay's designers
must have been sitting on their collective brains when they packaged their
product exclusively for USB + Windows.
--Doc Savage
Fairview Heights,
IL
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