TECH TIPS FROM FRED…(12/97, 1/98 Bits & Bytes)

By Fred Henning

Fast modems and Internet access. Many people are very interested in the Internet and want to go out and buy a faster modem so they can ride a faster wave! Actually, knowing the difference between a bit and a byte is necessary if you want to understand what you may or may not get!

A "Bit" is a single piece of binary data; a one or a zero. A "Byte" is a set of eight binary bits. Eight bits are needed to express a digit or alphabet character in the ASCII language that computers use. ASCII uppercase "A" would be the digits 6 and 4. Modem speed is stated in bps or bits per second NOT bytes or characters per second. Marketing!! 56,000 bps (bits/second) looks better than 7000 cps (characters/second). If you want to receive one megabyte of text from an Internet Web Site (Home Page) how long will it take? If there were no other limitation, a big if, then you could take your modem’s speed in bits per second and divide by 8 (8 bits to a byte) to see how many characters per second you can receive. If you have a 9600 bps modem, you could receive 9600/8 or 1200 characters per second. To receive our 1 meg. File it would take 1,000,000/1200 or 13.8 minutes with a 9600 bps modem. A 28,800 bps modem should be 3 times faster and would take 4.6 minutes. But it always takes longer! In our next issue, I will talk about Internet Access and some of the reasons it takes so long.

What about cable modems and satellite access?

With Satellite access, you still need to go out to the source of the data via your PC modem and telephone line. The speed of the download is fast ONLY if the source of the data you are trying to obtain is capable of high speeds. Remember, most sites won’t be able to respond at 56 kbs, let alone the speeds claimed by the satellite vendors!

Cable access should be faster than the telephone. If you think about how the volume changes from channel to channel and all of the other complaints you have about your cable, you should probably think twice about spending twice the cost of telephone access. Remember that once you get to the end of the cable you are going to be put on a telephone channel to get to the Internet!

56 kilobit modems:

  1. There is no standard for the 56 kbs PC modem yet (there are at least 3 flavors of 56 kbs modems).
  2. Only about 50% of Internet providers have any type of 56 kbs modem access (and it might not be your type!)
  3. It is only 56 kbs coming back to you if the originating site and all of the intermediate channels can support 56 kbs and your modem’s 56 kbs flavor.
  4. At present, it is never 56 kbs going out. At best it would be 28,800 bps.

Note: FAXing via modem is still limited by the FAX standards usually 9600 bps.

 

 

Modem Speed - Last time we talked about MODEM speed. Now its time to talk about why the Internet can be slow even when you have a fast MODEM.

What are the variables when using a MODEM to access the Internet? Your PC! (A 486 or Pentium should be plenty fast.) One is the Serial Port on your PC. Although you can set the port to some very fast speeds some cards cannot actually support the speeds they allow you to configure! (Although I prefer an external MODEM and like to see all of the lights, an internal MODEM should negate any limitations a serial port would present.)

The telephone line is the first big bottleneck. Residential lines were never meant to support high speed data. A little noise when you are talking or changes in the volume are things we tend to overlook but the computer needs all of the bits! (If you really want speed you need an ISDN phone line. It costs more per month and a lot more per minute.)

Internet Access: This is where things get even more complicated.

If you use AOL (America on Line), or a similar provider, you have several telephone numbers that you can dial. These numbers usually represent one or more Networks (ie. the AOL Network, Sprint Network, etc.). The numbers are further divided by their access speed. Numbers for 1200 bps, 4800 bps and perhaps 14,400 bps or 28,800 bps, etc. (Remember less then half of the providers have 56k access.) The access speed represents the capability of the MODEM at the telephone company office. Depending on the facility at the telephone company office your MODEM call may actually be combined with others and forwarded to another location before it ever gets to the main internet connection for this area. Very rarely does a direct internet connection exist in the telephone office that you dial. The speed or bandwidth of the communications channel between your telephone office and the Internet connection is a limiting factor along with the number of users trying to get connected via that telephone office. Depending upon who you have signed up with for internet access you may also go through several resellers with their MODEMS and line (bandwidth) limitations before you connect to the Internet.

The Host that you are connecting to (the home page you want to view) is another limitation on the actual speed. You could be connecting to Yahoo, a big site with powerful computers, yes multiple computers, with wide bandwidth access to the Internet capable of supporting thousands of simultaneous users at speeds only limited by the way the user accessed the site. You may also look at a small site that is actually in the back of a store or someone's home and is only connected to the Internet by a few MODEMs and then only when someone wants to connect to that site. If this small site only has 1200 bps MODEMs then regardless what you have the data only goes at 1200 bps.

The time it takes to view the same Home Page varies considerably from Internet provider to provider and with the same provider from city to city. In a recent test, of the Internet services of 34 different providers by a professional service that monitors the Internet and Internet sites, the time to load a 50 kilobyte Home Page ranged from 4.9 seconds to 18 seconds. There could be marked differences depending upon the city of the user or the Home Page Server location. The best provider could deliver the Home Page faster than your best 56k MODEM and the worst was no better then a 22k MODEM. Remember these were tests of how well the Big Boys did!