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The following is my reply to a private email from a forum member, who
suggested that I post it for the possible benefit of others.
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I have a satellite feed for my incoming real time data, is Internet
faster?
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The Internet is not the issue. That is just the set of protocols with which
your connections and data are sent and received.
For incoming speed, there is a split second or greater delay on satellite
data coming to you. That can be 1/2 second to 2 seconds or more. It is
caused by the distance from earth stations up to the satellite then the
distance from the satellite to your receiving dish. It is a speed of light
limitation. Plus the switching delays by the earth stations.
There are two speeds involved. One is latency, the time from the real event
until you begin to receive data about the event. The second is the transfer
rate once each message or piece of data transmission has begun.
For outgoing speed, all of your outgoing data is sent through the dial up
connection that you must use with the satellite connection. You can only
receive data from the satellite, you do not send data back to the satellite,
at least if you are using a normal office or home satellite connection.
There are expensive exceptions to this. But even those exceptions have the
same latency delay problem as for incoming data.
xDSL (the x means whichever of several DSL standards you can get) can be
faster or slower for transfer rates, but will always have lower latency for
the start of any incoming data or message. It will always be considerable
faster than dial up in transfer speeds for outgoing data.
There are multiple types and speeds of xDSL to choose from. Choice depends
upon the luck of how good or bad your local Telco is, and how far away you
are from a Telco xDSL relay or switch.
Cable can be the fastest. Depends upon your local choices. Also depends
upon how many other folks are on the same cable data channel as you are at
the same time, since everyone shares the available bandwidth within a
variable area.
Have found that very few folks in my area use the cable modem during the
day, so, until AT&T broadband put a governor on the speed, I was measuring
rates several times faster than a T1 line. Now it is speed limited by AT&T
to between 200 to 400 mbs on a sustained basis.
So, which one is faster?
For real time trading data, both xDSL and cable modems are almost always
going to be a lot faster than satellite.
Satellite is impacted by weather, whereas xDSL and cable modems are usually
not.
If you have a good local Telco, xDSL may be more reliable and a bit faster
than cable modem. It depends.
I use a cable modem because we have fiber optic cable up to our home. xDSL
is only available over copper wires, so we cannot get xDSL.
I've found AT&T cable to be fairly unreliable, with one or two failures
longer than a couple minutes each month, and with several shorter failures
per month. That will always be a function of the cable modem provider and
how good the local server farm and physical cables are in your particular
location.
It happens that I live in an area with a lot of new road, home and major
business construction, which seems to affect connection reliability. Have
considered satellite, which would likely be more reliable, but the satellite
speed issues always lose out to cable, for me.
So, suggest that you get the specs for your available choices and simply
compare those and the costs for each service. Sometimes cable companies
provide extra discounts for TV cable subscribers, and vice versa, when you
also get the data service.
There are some other alternatives.
One is VPN or Virtual Private Networks. These are usually much more costly.
Another is a T1 line. Very expensive.
Vince Heiker
Flower Mound, Texas
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