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March 6, 2004

Q. What is the phone doing while it is "searching for service" when it connects to a CDMA network? Also, how do network messages (SMS or VM notification) get to CDMA phones? More specifically, how does the network address a specific phone when it's not in a call, since there's no specified control channel? Does it still use the pseudo code sequence or does it just address it by ESN?

A. (By Mark van der Hoek)

Every phone, regardless of technology, has to "find" the network. It has to find the right frequency, decode a control channel of some kind, announce its presence to the network, and be ready to receive a call or to place a call. The real question is not why CDMA phones display this message, it's why the other technologies DON'T, since they have to perform the same basic functions.

In the case of CDMA, it has to get synchronized with the system timing. Oddly enough, it does this by looking for the SYNC channel. Once it's in sync, it moves to the access channel/ paging channel (access channel is where the phone transmits, paging channel is where the network transmits, where it registers (announces its presence - - "Hey everybody! I'm here! Let the party begin!") , then parks itself to wait for further commands.

I suppose it's possible that CDMA phones take longer to acquire the network than other phones, and that's why we see the difference in the display. I don't know what typical times are for acquiring the network.

I've shown a similar photograph before, now here is the story. It was taken by an engineer who wishes to remain anonymous. Mark van der Hoek writes, "This photograph was taken by someone I know. The monopole was in St. Louis. The engineer was driving the network trying to find the cause of one site dropping a lot of calls when he got a call from the NOC (Network operation center) telling him that the site had gone off the air. They wanted him to investigate since he was in the area. He drove over to see what was going on, and that’s when he took the picture."

March 4, 2004

Added much more great reading from Don Kimberlin on early radio-telephony. Read both of his pages (internal link). Anchors aren't working properly on those pages, I am trying to fix them now.

March 3, 2004

Added more discussion on cell shapes and frequency re-use patterns to the second page of the cellular basics series.

March 1, 2004

More thoughts on answering obscure telephone questions. Try this wonderful search engine, it's a great resource for serious researchers:

February 29, 2004

Q. I have an obscure telephone technology question. Nothing on the net. Now what?

A. You must do hardcopy research. That research can begin on the net but it will not finish there. No technology historian, writer, or researcher relies exclusively on the net, it is impossible and will continue to be until every paper document is digitized and put on line. Due to manpower, technological, and copyright constraints, this will not happen in our lifetimes. But you can at least start with the net, even with the most difficult questions.

Many people ask about cell phone interfaces: the way a keypad and the buttons on the phone are arranged. If you can't find cell phone design resources on the net then get good with patent searching. A patent will describe not only itself but also the background of its field. You'll often find good bibliographies and links to other related patents which in turn have more information.

Spend at least a day or two looking through the USPTO on-line to get familiar with this valuable resource. If you can't find the magazine articles and trade brochures listed in a bibliography you can order a copy of the entire patent file which will then give you copies of those documents. Ordinary patents are fairly easy to search, if difficult to read, but design patents are more hard to research.

Here's a good way then to browse design patents. Put in what you want to look for and then add the important phrase: ornamental design. Select the quick search option at the patent office:

http://patft.uspto.gov/netahtml/search-bool.html (external link),

and you'll see this form:

Put in what you are looking for, say, the words ornamental design, and then your date range. Only patents from 1976 on can be searched this way. The patents before then haven't yet been made keyword searchable. Try as many different keywords as you can think of.

After the net, it's back to the library, the largest technical library you can find. More later . . .

February 24, 2004

The Wireless Local Loop

The first fixed wireless radio-telephone service for individual customers began in 1946 near Cheyenne Wells, Colorado. While radio-telephony wasn't new to the Bell System, this was the first time subscribers had radio-telephones installed at their premises. It was the first local wireless loop in the country, possibly the world. And it was a party line, too, since only one frequency was available and all customers had to share. Click here to read a very entertaining interview with the people and customers involved. (464K in .pdf) By the way, do you collect salt and pepper shakers?

Full URL:

A. (From Mark van der Hoek) The answer has to do with frequency planning and vehicle traffic. . . . Click on the link above to go to this discussion.

February 19, 2004

I've set up a preliminary page for Dr. Richard Ling, an industrial sociologist for Telenor. He writes about the uses and social impact of the mobile telephone. He has a new book coming out in April that should interest anyone working in wireless. On his page is an internal link to a well researched paper on teenagers, their parents, and how wireless is changing the relation between them. Good reading with many keen insights.

February 17, 2004

Q. How do I learn about repairing mobile telephones?

A. Get hired by a company that makes them. They're the only ones that do the work. Today's mobile phones use surface mount technology, which means that individual components cannot be easily removed or replaced. What's more, any repair work done by you would invalidate or void the warranty of the phone. There may be factory authorized repair shops but I am unaware of a single operation.

I am sure the factory itself does not try to repair most defective phones, rather, they would simply replace the entire unit. New models come out frequently and I am sure there is little economic sense or reason to repair a mobile that will be out of date in three or four months. Some of the new, very expensive camera phones may be refurbished or repaired, along with satellite phones, but I do not know about this. Again, this would be work done at the factory.

February 16, 2004

Dial a Buoy

Telephone to find out conditions at your favorite off shore and Great Lake Buoy. Check out this web page first:

http://www.ndbc.noaa.gov/dial.shtml

Dial (228) 688-1948 and enter your buoy number, such as 46013 for Bodega Bay, California. Or enter the longitude and latitude you're interested in and the service will give you a report from the nearest buoy. That includes air temperature, wave height, water temperature, and so on. Even a forecast. Dial when a really big storm hits. A reporter might not go twenty miles out to sea in a gale, but this automated system will patiently report back conditions.

February 15, 2004

What did you think about on Valentine's Day? Telephones, I hope. On February 14, 1876, Anthony Pollok and Marcellus Bailey, two Washington D.C. lawyers, filed Alexander Graham Bell's original telephone patent application. They did so under direction of Gardiner Hubbard, Bell's chief promoter. At the time Bell did not know what Gardiner had ordered; A.G. was waiting for foreign patents on the telephone to be taken out first, what he thought was necessary before filing in the United States. Gardiner had tired of waiting and a good thing his impatience was, that application resulted in the most valuable patent ever issued. For more on telephone history click here.

February 13, 2004

Permissions and releases

Q. I keep e-mailing the Right People for permission to reproduce an article or an image without success. They never reply. Any suggestions?

A. After your third polite e-mail has been ignored, try language like this:

"Dear So and So,

I've e-mailed you several times regarding permissions but have received no reply. Unless you answer this e-mail I will consider your silence as permission to reproduce the material since you have raised no objection."

That should get you a response but if not I would use the information or graphics as you wanted to, providing all proper credits to the copyright holders. Link to their site if they have one or if you can. Keep a record of your e-mails to show good faith. Then let them contact you if they want the file or picture pulled.

February 11, 2004

More stuff off my site!

Excellent, easy to read series on RFID or Radio Frequency IDentification devices. They're those tiny, autonomous tags that WalMart is thinking of using to electronically track its inventory and possibly for checking out. You'd take your shopping cart to a RFID enabled register and it would scan by radio each product's tag. The whole cart at one time! Put your credit card in the register and off you go. This same technology lets cars zoom by toll booths without stopping. A RFID device communicates between your car and the electronic toll booth. When you pass by the toll gets taken out of your account. Neat stuff:

http://www.mobilein.com/RFID/RFID-1.htm (external link)

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