Greetings.

This e-mail reviews developments at TelecomWriting.com over the last two weeks. The HTML version is here:

I. Wireless

II. History

III. Miscellaneous

I. Wireless

Macrocells and Microcells

1. Steve Punter, of the excellent Steve's Toronto Area Cellular/PCS Site Guide:

http://www.arcx.com/sites/

took the time to send in a correction to my digital wireless basics article. It has to do with macrocells and microcells. The key is that macrocells control microcells, the two do not exist independently. Cells are overlaid upon each other with the mobile switch controlling when your call gets put on each.

Macario describes a business park or college campus as a typical situation. In those cases a macrocell provides overall coverage, especially to fast moving mobiles like those in cars. A microcell might provide coverage to slow moving people between large buildings and a piconet might cover an individual lobby or the floor of a convention center.

A macro cell is typically built to first provide coverage and microcells are added to provide capacity.

Here's the text of his comments along with his illustrative photographs:

"I believe are misusing the term "Microcell" in your section on cell splitting. The proper definition of a microcell is a small independent site designed tocover a small geographic area UNDER a larger macrosite. Typically microcells are employed along the sides of busy highways or on street corners.

I have attached pictures of two typical microcells in the Toronto area.

[Microcell 1 (70K)] [Microcell2 (71K)]

Each directional "piece" of a split cell is called a SECTOR, but they are NOT referred to as microcells. Further proof of the above comes from the following quote directly from your article: "a macrocell costs $500,000 to $1 million to build, a microcell one-third as much and you don't have to build a room around it."

What this AT&T engineer is referring to is that the typical electronics for a microcell are small enough to be put in a small metal box, whereas a full macrosite usually requires a full equipment shelter (what he refers to as "a room").

Cell Splitting has usually referred to the process of SECTORIZING an omni-directional site into 3 or 6 distinct areas (120 and 60 degrees around the site respectively). This approach dates back to the late 1980's.

The practice of installing Microcells takes a different approach to the problem by "unloading" some users from the overcrowded Macrosite. By placing these short-range microcells along busy highways or at busy street corners, you effectively reduce the strain on the PRIMARY macrosites by a substantial margin.

Some networks are build TOTALLY around the microcell, such as Omnipoint's GSM coverage on Manhattan Island, but this approach is extremely rare. In fact, I believe this represents the ONLY such implementation in North America."

2. Bluetooth Continues to Move Ahead

With the introduction of a developers' kit Tuesday, the Bluetooth consortium continues to make progress. I don't write about data communications often because I find it boring. But Bluetooth is interesting because it is practical and, well, cool. Bluetooth allows any enabled device: a printer, cell phone, headset, mouse, or a laptop, to take part in a wireless network on the fly. What Ericsson calls ad hoc networks. Walk into a room with Bluetooth enabled desktop and laptop computers and you could all start sharing information. People could work on the same document, surf the web together, or communicate with other similar small networks. All without wires or cables or connectors. Now that's cool. To go further, download this .pdf file. It's a copy of an excellent Ericsson Review article:

http://www.ericsson.com/about/publications/review/1998_03/files/1998031.pdf

(Thanks to Remco Enthoven from the Netherlands for providing the current link for the file above. Please visit Remco's excellent site, The Dutch Online Telephone Museum. It's at:

http://www.telefoonmuseum.com)

And to answer your question in advance, the Bluetooth name comes from Harald Blatand, an early middle ages' Danish Viking king. Obviously!

3. Cell phone coverage

I got two e-mails yesterday regarding cell phone coverage:

Should any cellular phones work inside metal buildings, such as in a farm operation?

There are no guarantees. Conventional analog phone service will probably work best but it all depends on how close the building is to the nearest base station and where you are within the building. Take a look at the signal strength meter on your cell phone and you'll find it bounces up and down in every part of the building, metal framed or no. Get to a window and it should climb.

PCS phones are the most fragile because they use higher frequencies whose radio waves are more easily disturbed and because they use weaker signals to begin with. Inside building performance is so unreliable that the newest systems such as IS-136 permit incorporating base stations within a structure itself, an expensive arrangement for high rise office buildings and such.

A high powered cordless phone might be a better choice or even the walkie talkies made for industry and plant use like the ones Motorola and many others make. One thing I haven't heard much about are add on antennas for cell phones that might help reception. But you really need to be able to count on a solid connection since dropped calls are expensive and bad business for everyone. Best, Tom Farley

Dear Tom,

With all the different types of phones that are available today, I've yet to get any clear information on what type and frequency have the best reception - I'm not talking about coverage, but a more local reception issue - which can be quite variable from between two locations separated by a very short distance; also the ability to receive calls inside a building or a tunnel. . . .

Conventional analog service may offer the best reception. An analog communication link can keep going despite heavy static or interference. A digital signal gives up when it encounters too many errors in the bit stream, a point which, if one had analog, one could keep talking despite the noise on the line. Unfortunately, most carriers have switched their old analog channels to digital ones to increase capacity.

Some people use car mounted mobiles instead of hand held units. Power helps. Car mounted ones are allowed the most power, hand helds the least. An old brick phone is in the middle of the power band. A really good antenna helps even more. Sometimes two, depending on how your installer sets things up.

Even with the best equipment you are still limited by your carrier's infrastructure. Maybe they don't cover that tunnel well or at all. Maybe there are gaps on your route that would be too expensive for them to fill in. Even a big truck or a billboard or 100 feet or less can make a difference in coverage.

There are some cell discussion groups on the USENET that discuss specific carriers or operators. Go to

http://www.dejanews.com

to look. Radio is really tough to get flawless coverage; signals tend to line themselves along street axes, that is, up and down the street at right angles, like a cross. All sorts of issues there. And buildings are really tough to provide coverage. In addition, calls get dropped if the caller is too far away from the base station, even if there is a useable signal. The "near -far" problem that I can discuss sometime else. Let me know if this reply is confusing or if it has led to more questions. It may be possible that as we move to all digital wireless that coverage will decrease until all networks are built out.

4. Cell Basics article correction

Dwayne Rosenburgh (N3BJM) sends in these two important corrections to the cellular basics article:

"In the section 'The SAT, you state 'You don't hear it since the signal lasts less than 300 ms. and because it's muted during transmission. "

The fact that the signal lasts just 300 ms has nothing to do with why you don't hear the SAT. In fact you can hear tones/signals of less than 300 ms. Perhaps you should say 'You don't hear it since the signal is muted during transmission.'

In the next paragraph, you state 'The signaling tone is a very high audio frequency tone that you can't hear. Maybe your dog can but not you. It's 10kHz tone.' Well, humans can hear from 20 Hz - 20 kHz. So, the reason that we cannot hear the ST is not due to its frequency."

Dwanyne is correct on both points and I've accordingly revised both the English and Spanish versions of the basics article:

http://www.TelecomWriting.com/Cellbasics/Cellbasics.html

Please, please please -- if you have any corrections or comments with any of my writing please send it in and I will look at it. My goal is to put out the most accurate information I can, and it's only with your help that I can do it.

5. The Joint Spectrum Center

The FCC manages United States commercial and amateur radio spectrum. But have you ever wondered who manages the spectrum the military uses? It's the United States military Joint Spectrum Center:

http://www.jsc.mil/

Although the site is mostly limited to specific military programs, it does have a couple of nice resources for the rest of us. The first is a beautiful but big (374k) electromagnetic spectrum chart at:

http://www.jsc.mil/images/speccht.jpg

And the second is a great links page to, seemingly, everything military and radio.

http://www.jsc.mil/relhompg.htm

6. Hacking Authentication -- Or Trying to

Difficult but informative Russian hacker site. Has many good links.

http://www.semionoff.com/cellular/hacking/phreaking/

II. History --

1. Step by Step and Early Dial Systems Articles Go On-Line

I've posted "Early Work on Dial Telephone Systems" by R.B. Hill:

http://www.TelecomWriting.com/Switching/EarlyWork.html

That's in addition to "The Early Years of the Strowger System:" by Bell Labs' R.B. Hill which I got on line two days ago:

http://www.TelecomWriting.com/Switching/EarlyYears.html

I've since corrected a few spelling mistakes to it and put it into a larger font to make it easier to read. Published in 1953 it is the first of a two part series on early switching technology. Although I have other things to do today, I may get the second part on line tonight or tomorrow morning. If you've been baffled by step by step operation I think you'll understand it better after reading this article. But it's more than just this article that I'm excited about, rather, it's the power of the internet to rescue a great piece of writing from obscurity and uselessness.

Defunct telephone magazines like the Zodiac, the Bell Laboratories Record, Automatic Electric's Journal, and the Lenkurt Demodulator, all featured great writing but now remain largely unread or even unheard of. Their volumes sit on university or telephone museum bookshelves, most often on reserve, sometimes on a basement floor or in a distant reference room. As such these works have little life and even less chance to help people understand technology -- the whole purpose they were written for. Until the internet came along.

An author like Roger B. Hill, who wrote the article I just put on line, probably accepted that his excellent two part series would move into obscurity over time, becoming a research paper to a few telephone historians, like himself, who, had in turn, used other authors' older papers and books to complete his writing. I'm sure he could never have imagined that nearly fifty years later his articles would become part of a vast electronic library, living again, and educating anyone interested in telephones.

Again, I thank John Donovan of Bell Labs/Lucent:

http://www.lucent.com/ideas2/perspectives/trends/

Another link now dead!

for arranging permission to put this article and several articles to come on line. We are building this electronic library together; the future is bright indeed.

2. The Cyber Telephone Museum

Ron Christianson's telephone site (designed by George Triant) features many great photographs and informative pages. Concentrates on individual telephone photographs which is what most people want to see:

http://www.museumphones.com/ (external link)

The site is also promoting an "Illustrated Antique Telephone Identification And Price Guide."

3. Cable and Wireless

I am right now checking out the history pages of Cable and Wireless. Their site is excellent:

http://www.cwhistory.com/

And for an easy way to view the site, download the main docs (for the Mac) from here -- and yes, they do have a Windoze version -- go to the site!

http://www.cwhistory.com/TeacherPack/teachimages/teachpk.sit

Another dead link. But I archived those files, so I may post them at my site. Sometimes you wind one.

4. The definitive Alexander Graham Bell resource site?

Yes! The ACCESS INDIANA Teaching & Learning Center provides a wonderful set of materials and links to all thing A.G.B:

http://tlc.ai.org/bellalex.htm#lp Connection rrefused

III Miscellaneous

1. SecureRoot's H/P links page

Good links page of H/P zines. Unfortunately, they refer to private line as a phreaking zine. Sigh.

http://secureroot.m4d.com/category/zines/ Dead link. You guys know better.

2. More outside plant information

Matthew Sadler (KF4LHP), of the Coaxial & Microwave Telephone Page

http://www.qsl.net/kf4lhp/telco/index.html

sent in this great URL for looking up OSP information:

http://www.relteccorp.com/d0000004.cfm

Both links above now dead. Thanks again to all of you webmasters who have helped wipe out our technological history. . .

This company produces all sorts of cabinents, pedestals, and splice cases. Their enormous catalog of PDF files give plenty of names and photographs with which to identify OSP equipment.