by July 7, 2000 0 comments

Year after year, we’ve said that the performance of a modem depends on the
condition of the telephone line that it’s working on. We’ve emphasized that
no amount of testing elsewhere can guarantee performance on your telephone line.

Let’s understand why. Broadly, the performance that a modem
delivers is a function of the characteristics of the modem, and those of the
telephone line it’s working on.

Till the V.34 protocol (28.8 kbps, later extended to 33.6
kbps) came along, there was a huge difference between modems in performance. The
V.34 protocol delivers a much more superior and robust performance across all
line conditions. V.90 and K 56 Flex support 56 kbps, but in most cases, you’d
actually be running at 33.6 kbps. Add to this the fact that a vast majority of
modems ship with the same Rockwell chipset. When both these combine together,
you come across situations like we started seeing in our previous modem
shootouts, where there was hardly a three percent difference between the best
performing modem and the worst.

Thus, you have two factors – a protocol which is very stable
(plus, all modems have the same chipset), and a telephone line whose condition
varies widely across the country. So, today, the performance of a modem is
overridingly determined by the quality of your telephone line.

Let’s take a brief look at this deciding factor. There are
several different types of noise that can happen, either individually or in
combination, in a telephone line. Different modems react differently to these.
And there’s no way you can identify which of these conditions affect your
line. So, nobody can correctly predict which modem will work the best on your
line. For example, during the ISP shootout the PCQ review team carried two
different brands of modems to nine cities across the country. While one worked
well on all the lines it was tried on, another popular brand just refused to
even connect properly on some of them. Same modem, same PC, different telephone
lines, and vastly differing performance.

So, how do you decide which modem to buy?

The answer is simple. Test the modem on the telephone line
you plan to use it on.

We can see the doubt in your eyes. Will the vendor come and
test the modem at my place? Will he replace the modem with a different brand if
it doesn’t work?

Frankly, there’s no other way out. As users, we have to
demand that the vendor agree to test the modem at our place, and take it back if
it doesn’t work properly.

Believe me, it can be done. After all, you’re paying for
the modem. Test it before you accept it.

Atul Chitnis

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