"Larry, let me see if I understand what you said about x2.
If I only connect now at 24000 with a 33.6 modem that if I switch to a 56K that is not going to change?"
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Gary, I'm not certain I'd say it that way; I apologize if my explanation was vague about this. However, the fact that you are now connecting at 24000 allows me to make a guess about the condition of your phone connection, because of the channel requirements of x2 and similar technologies.
All V.34 modems take advantage of the fact that MOST phone systems in the U.S. have been upgraded over the years with digital technology. This yields more useable "bandwidth" than was originally specified for the phone system.(I will use the term "bandwidth" to refer to all analog factors of the line, including bandwidth but also signal levels, noise levels, distortion, etc.; this is commonly done simply to have one word, "bandwidth", which refers to all related terms, for convenience, and to prevent long sentences like this one from showing up all through the writing!). Any connection you get above 20,000 is certainly using this improved bandwidth to reach that speed. I have never calculated the absolute limit of a V.34 modem if the phone line has no extra bandwidth, though, so it could be even lower than 20000.
This is also why the phone companies aren't excited about upgrading their systems when some have trouble reaching 28,800 or 33,600 bps; the systems are ALREADY exceeding their specifications.
Back to your question: when you connect at "only" 24000, this reveals that your particular connection has less than the average amount of "extra bandwidth", which is why it can't run at 28800 or 33600. However, I would not say that this means that an x2 modem will not do better than 24000; what it DOES say is that you can be certain that the x2 modem will not run at 56000, since you already know, from your reduced V.34 speed over your phone line, that you don't have all the extra bandwidth many other phone lines have these days, and the 56K modem would also need this extra bandwidth to run full speed.
As I think more deeply about your question, I don't believe I see a way to directly determine what you could expect to see with an x2 modem. However, if you look at the experiences of most people who are using x2 now, some general trends can be seen. First, I don't know of anyone who is actually running at full speed (which at this point would be 53000 bps, since the FCC will not allow the power levels to be high enough to support 56000 yet). It is probably safe to assume most x2 users will actually get 48000 bps or less; I know of about a dozen x2 users, and only two of them have EVER gotten to 48000; those two rarely connect at that speed, they've only seen it a few times.
OK, so you won't be able to run at more than 48000, but what would be a reasonable guess of the best speed you might get on average? A VERY VERY rough estimate may be obtained if we assume that a V.34 modem running at 33600 uses the same bandwidth as an x2 modem running at 53000 uses. Then, in your case, since you are now getting 24000/33600 or about 70% of the maximum speed available to your modem, I'd GUESS that you wouldn't expect to see more than 53000 X 0.70 = 37800 with an x2 modem. That is, the BEST you could hope for with an x2 modem, if my assumptions are correct, would be something less than 38000 bps.
HOWEVER, of the dozen x2 modem users I have heard from, only one could not reliably get 28800 with the previous V.34 modem, and all but two could usually connect at 33600 bps. The average speed these people are seeing with x2 is not much better than the 33600 bps they were getting with their previous V.34 modems; I haven't actually calcualted the average but I believe it is in the range of 36000 bps. It is, technically, faster than their V.34 modems, and every little bit helps!
I'll make a "scientific guess" here and say that, in my opinion, you would PROBABLY see an improvement in your connection speed if you use an x2 modem; I'd guess that you may be able to get 30000 or more with an x2 modem, which in your case would be a significant improvement. If you buy the modem from someone who will let you return it if you aren't happy with it, it would certainly be worth a try. I am severely hampered in evaluating a situation like this, because I am working from a set of assumptions based on the THEORY behind x2 modems, and don't have any data about the way US Robotics acttually implemented them.
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"But I might experience a download or downstream as you refer to it of perhaps higher with a x2 then I presently receive??"
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My original message must have been unclear; I apologize. This refers only to the fact that x2 modems can RECEIVE at 53000 bps (maximum), but only TRANSMIT at 33600 (max). In your case, you would not see an increase in your TRANSMIT speed; that would remain at 24000. You may increase your RECEIVE speed if my assumptions are correct.
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"I looked at 56K modems yesterday, and if I received the correct information, it would connect just as my present 33.6 does even though it is a 56K, and would only switch to 56K if the server has the capabilities of 56K, is this correct assumption??"
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Yes, that is true. Both modems used to make the connection must support x2 56K speed; if one of them does not, you connect, in your case, at 24K. You would have to open an account with an ISP who has x2 modems for you to call.
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"I dont have a problem buying one, but want to make sure that it will work like my
present one, unless I connect to a 56K server."
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You are correct, that is the way it would work.
I hope I've helped a bit. Some of these questions can only be guessed at, but I've tried to guess using what I know of the technologies involved. This issue is confusing to me and everyone right now; it will take some time and a few good articles in magazines and on the internet before we know just how well x2 works in the real world. It's probably worth a try for you if you are adventurous!
Larry |
