[reprinted from IEEE - Fort Worth Section Signals July 1996]
by Jeff Carrell, Electronic Communications Chairman
You finally convinced the person who controls the expenses (home or work) that you *really* needed a 28.8Kbps modem. You may have even had a separate phone line installed, so as not to disrupt the normal in-bound calls. But now that you've had a taste of what 'surfing' is all about it just isn't fast enough. (this is the Tim Taylor syndrome - need more power/speed) So, what do you do now...
As always, there is new technology becoming available, literally the next day after you've spent money. I always tell folks, don't look back - look forward (and redeploy where ever possible) and be thankful that you still have "more speed" than your neighbor :-)
Today, the basic technology available for dial communications is using analog phone lines. You use a modem that could support speeds up to 33.6Kbps (brand specific), but you are still using analog technology or POTS (plain old telephone system) and therefore line noise and EMI/EMF play a part of your less than stellar performance. The next level of dial technology is using digital signals and lines, providing for clearer and more stable dial connections.
Recently, ISDN (integrated services digital network) has been made available in the DFW area. Although the monthly bill is high, at speeds of 64-128Kbps you wait less time, file transfers are very fast, and most importantly the connection is usually solid. But, is 128Kbps fast enough...
There are a couple of options, mainly for business use, that provide very fast connection speeds. Satellite links can provide data rates up to 400Kbps (outbound only) but a dial link is still needed for downloads. Another option would be leased-lines. You can get speeds up 1.5Mbps bi-directionally, but the monthly bill can be *very* expensive.
Enter a new talked about technology - cable modems. Cable modems and cable TV systems are being trial tested in a few select areas in the eastern US, but currently is expensive. Also, most cable TV systems can only support communications one way - inbound. Because of that, cable TV companies will have to do major system re-designs in order to support bi-directional communications. Also there are currently no standards for this technology, so until these are set there will be different implementations. But the trade offs might be worth it. Connections speeds range from 500Kbps-30Mbps inbound and 100Kbps-10Mbps outbound! (talk about more speed :-)
Lastly, ADSL (asymmetric digital subscriber line) is the newest 'buzz' technology in the phone company arena. ADSL can use the existing copper cabling the phone companies have in place, and it provide faster speeds than ISDN. At 16-500Kbps outbound and 1.5-9Mbps inbound and hopes of prices comparable to ISDN, you can see why everyone is excited about this new technology. ADSL is being used by some telephone companies to distribute digital lines, but it is more of an infrastructure implementation. Currently there are serious distance limitations in its deployment (half that of ISDN). Until these issues are resolved, don't look for ADSL to your office/house soon.
Have a question or want to know more details about e-mail, the Internet, electronic communications or related technologies? Send a note to me or Signals editor and we will try discuss it in a future article. If your society, company or other organization would like an Internet presentation, demo, discussion, etc., let me know. (no commercial pitch, just plain 'ole techie talk :-)
Copyright 1996 Jeffrey L. Carrell. All Rights Reserved