Patent illustrations are free and copyright and royalty free! From the U.S.P.T.O. (external link) they come as 300 d.p.i. tiff files so you have enough detail to publish in hardcopy. These images show an early Motorola two way. Click on the left hand image for a "before" illustration and the one on the right for an "after" look. The right hand image was converted in Photoshop to a duotone, selecting a dark blue color. I then changed that duotone into a RGB file, to apply an "extrude edges" filter. Pretty neat, eh?

Searching takes the most time, not the processing, and these files require a broadband connection since they're so big. You may need QuickTime installed in your browser to accept the .tiff files the USPTO generates. You'll need a good graphics program, too, one that can do duotones and handle .tif files. But you need all of these things if you're interested in illustrating.

Wall telephone before

Wall telephone after (Vortex filter applied)

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Pick up your phone! You have a mobile call from Sweden. She's been dialing since the mid 1950's. Click to enlarge and to see the whole photo. (internal link to bigger picture)

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Here's a page to bookmark at my site: http://www.privateline.com/news.html (internal link) This page supplies current wireless and IT news, documents, and stock quotes. It's fed by an information stream from ITToolbox.com and changes daily. When you click on a report or news article a new window pops up in your browser. You're not taken away from this site. A good way to keep up.

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Wireless number portability begins today in the 100 most populated areas in the United States. Things to remember:

1) You can keep your number but probably not your phone. Different carriers use incompatible technologies which means you'll have to change phones when you go to a different wireless company. My cell phones and plans page has a link a group you can donate your old phone to. In The Future, consider a phone you can sync your PC to, so you don't loose your address book and contact information. Again.

2.) If you cancel your existing contract you may face early cancellation fees, sometimes a huge amount.

3.) The carriers won't make it easy for you to change. Don't start by asking your old carrier to switch your service and number to a new provider. No. If you bought your phone over the counter, take it to a store with the phone and plan you now want, along with a recent bill. That bill will have the account information they need to switch. I'd try the same approach with on-line cellular dealers. Start with the company you want to go with now, and let them do the work.

4.) You can now transfer your house telephone number to your wireless device if both have the same area code. I don't know how exactly how this will work. Seems to me your landline would have to die, you could not have both numbers ring when someone calls. I also don't understand how people get by without a hard wired phone. You'd have no fast internet connection and it's harder for emergency services to locate you.

5.) Starting out with wireless? Think about buying a cell phone on-line. You can't compare several companies at your local wireless store but you can on the web. I have more on this on my cell phones and plans page. Most web sites are easy: put in your zip code and back comes a list of carriers and phones and prices. One caution. Many of these sites overlook regional wireless companies which could offer good deals. Shop around.

Good luck on dealing with this historic change. It may provide you the incentive to upgrade your phone or to try a new wireless carrier. Now, if only service and coverage could be improved by simply setting a date.

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I sent our radio-telephone expert Geoff Fors the following paragraphs. I think they are from a 1985 article in Personal Communications Technology Magazine. I asked for his comments which you can read below:

"The earliest form of mobile telephony, unsquelched manual Mobile Telephone Service (MTS), was vulnerable to interception and eavesdropping. To place a call, the user listened for a free channel. When he found one, he would key his microphone to for service: 'Operator, this is Mobile 1234; may I please have 555-7890.' The operator knew to submit a billing ticket for account number 1234 to pay for the call. So did anybody else listening to the channel--hence the potential for spoofing and fraud."

"Squelched channel MTS hid the problem only slightly because users ordinarily didn't overhear channels being used by other parties. Fraud was still easy for those who turned off the squelch long enough to overhear account numbers."

"Direct-dial mobile telephone services such as Improved Mobile Telephone Service (IMTS) obscured the problem a bit more because subscriber identification was made automatically rather than by spoken exchange between caller and operator. Each time a user originated a call, the mobile telephone transmitted its identification number to the serving base station using some form of Audio Frequency Shift Keying (AFSK), which was not so easy for eavesdroppers to understand."

"Committing fraud under IMTS required modification of the mobile--restrapping of jumpers in the radio unit, or operating magic keyboard combinations in later units--to reprogram the unit to transmit an unauthorized identification number. Some mobile control heads even had convenient thumb wheel switches installed on them to facilitate easy and frequent ANI (Automatic Number Identification) changes."

Geoff here. The term squelch is a little misleading here, actually what is meant is "busy channel lockout." The MTS system went through a number of phases, and it depended upon where you were and what equipment the Telco installed in your car as to what you could do with it. Busy channel lockout was primarily a GE feature which lit a yellow lamp ("Busy") and wouldn't let you listen in if there was traffic on the channel. Older MTS sets didn't have that. I can put together some photos of assorted MTS control heads for you for future reference.

I think there was a busy channel lockout over-ride switch on the back of the control head on some GE models, intended for emergency use. The Motorola "Pushbutton Dial" system (not MTS and not IMTS but a proprietary scheme that laid an egg) had an emergency over-ride switch which also gave out a tone to let the parties using the channel know that someone was listening (as on the logo painted on the face of Nazi wartime military radios - "Feind hort mit." )

IMTS fraud wasn't widespread, maybe for one reason. The phones were so expensive that the general public had no access to them. The IMTS ANI is sent by the mobile at the beginning of the off-hook transmission. However, listening to traffic on the channels would pretty quickly reveal people giving their mobile number to the operator for various reasons. Smaller cities had a "block" of mobile numbers, and once you knew one, it would be easy to hack the others. For example, Chualar California (Salinas - Pacific Bell) had the mobile block of 679-5000 to 679-5100 as IMTS numbers. A crook could just pick one and away he went. It was also possible to park a scanner on the car to station channel in bigger cities and record calls, then slow the tape down and count the pulses of the ANI to determine the number. Then it would be obvious that any adjacent numbers were also IMTS. Not that I did this, but that's how it worked.

I never saw any control heads modified with thumbwheel switches by hackers. I suspect, frankly, that virtually all of the fraud was performed either by industry insiders or a few people who bought the equipment from them. Even though the mobile would have been hard to trace, the land side would not, as each call appeared on your bill with the number called and the time duration. Telephone company security did devote some time to this issue, with the usual result that the particular mobile number would get changed. I don't think they made much of a publicity issue out of it because 1) it would give others the idea and 2) bad for the company's shareholders to give out negative publicity.

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Hi,

I am a High School senior attending school in Maryland, and I had to do a research project on the effects of one technological advance on society. Well, as you may have guessed, I picked the telephone. I read the extensive history that was on your web site and I just wanted to say that it really helped me out a lot.

I actually became interested in the topic, and instead of considering it as just another boring research project I actually learned new things. The information was very helpful, and I just wanted to thank you for making it so interesting:-) H.W.

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Question: I'm interested in what a network engineer considers when purchasing or obtaining switching equipment. In the wireless/cellular network equipment world, what kind of common questions would likely need to be answered? I'm also confused about where the cellular switch is located with respect to the base stations.

Answer: Mark van der Hoek here. The switch sits at some telephone company central office, not necessarily even in the same state as the cell sites. The sites themselves have some intelligence. For digital technologies, there's an additional box called a BSC or base station controller that handles most of the low level call processing. It sits (logically, not geographically) between the sites and the switch. Typically there will be multiple BSCs on a switch, each BSC having up to a couple of hundred sites that talk to it. BSCs have pretty much the same power, AC, and maintenance requirements as a switch, so are often located in the same building. (Unlike everyone else, Lucent CDMA and AMPS switches incorporate the BSC function in the switch.)

(Network element description of above is here AND, with nice little pictures, here.)

Other than that, the switch dimensioning is pretty much the same with cellular. Number of cell sites and subscribers is the main factor. In other words, capacity. One big difference is that cellular switches are not necessarily interchangeable. It depends on the technology. GSM systems have excellent interoperability. Buy a site from Ericsson, a BSC from Siemens, and a switch from Nortel. No problem. Build a network with Siemens switches and add a couple of Nortel switches down the road a few years. No problem.

With other technologies, such as CDMA or AMPS, you buy a complete system. Buy a Lucent system, or buy a Nortel system, or buy a Motorola system. But you can't mix and match. It's all or nothing, from cell site to switch. The only part that can be interchanged is the HLR. That can be just about anything, as it interfaces via an industry standard protocol, IS-41.

Was that all wonderfully confusing?

Mark van der Hoek

Editor's note: I have diagrams and easy to follow text on these pages which outline different GSM architectures. Kind of pHun to puzzle over. See the example below and these different pages:

Generic GSM architecture by Scourias / Lucent GSM architecture / Ericsson GSM architecture / Nokia architecture / Siemen's GSM architecture

AXE: Automatic Exchange Electric: Ericsson's digital switch. They operate as either a landline or wireless switch. OSS: Operations support system EET: Ericsson engineering tool, network planning software. SOG: service order gateway BGW: billing gateway. MIN: Mobile intelligent network. SCP: service control point.

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I'm working on explaining the triode. Aside from the transistor it was the greatest help for the telephone system in the 20th century. Amplifiers developed from triode research enabled nation-wide calling for the first time in the mid-teens. I am drowning in pages and pages of information. A reader named Dante, a real radio expert, is helping me. I know the few sentences below won't make sense to most people, but I did want to show you that I am indeed working on what I said I would. Check back in another day or two. You'll find these paragraphs added to and modified to make them less cryptic.

I've written that a triode amplifies but this is wrong. A triode based amplifier certainly does make an audio frequency signal louder. But it takes a collection of components, arranged on a carefully designed circuit board, and, yes, the triode, to make amplifying possible. Think of the triode, for now, as a volume control, not an amplifier. The triode's "arrangement of filaments," modifies or regulates a current, it does not amplify.

When heated to incandescence the cathode begins to emit electrons, which flow from the negatively charged cathode toward the positively charged plate. The grid, where the original signal is introduced or injected , controls the electron flow. The result is that a tiny voltage, carrying the original signal, varies a much higher voltage at the plate or anode.

In our circuit high voltage drives a speaker. The amplifying, or better put, the gain, occurs when the audio frequency signals, say our voice, impinges on the existing current at the anode. These current variations act on the loudspeaker which then replicates speech. To sum up, you have a small current that varies a larger current. The triode itself regulates or modifies current, it does not amplify.

I write too much here today, it's back to work on the original article.

The grid. In this diagram the metal spiral where the unamplified signal is introduced. Located between the cathode and plate, the grid controls electrons passing through it by means of a negative electrostatic field.

Heater: Produces electrons by thermionic emission. Current passed through a filament-like heater makes it glow, boiling electrons off its surface.

Cathode: cylindrical, metal element in close proximity to and enclosing the heater. Electrons penetrate it easily and emit from its surface.

Anode or Plate: solid, cylindrical, metal element with high, positive potential, surrounding grid and heater/cathode assemblies. It accelerates electrons toward it and collects them for the external circuit.

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Question: I've found a great file on the net and I want to use it in print or at my site. But every e-mail I've sent to the copyright holder gets ignored. No replies. What now?

Answer: Make sure you offer to credit them, link back to their site, or both. Be very diplomatic. Keep copies of each e-mail you send. After your third or fourth attempt try language like this: "I've not received a response to use your file. Nor a response of any kind. While you haven't granted permission, you have certainly not objected. Unless you object now I will go ahead with the use I have planned. I consider this e-mail a release. Have a nice day."

Do you now have a legal copyright release? No. But you do have a nice paper trail that displays a good faith effort on your part. And a complete lack of vigilance to defend their copyright on their part. Go ahead and get on with your project.

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I don't like electrical symbols any more than mathematical equations. They're hard to remember, non-intuitive, and when first learning electronics, contribute more confusion than clarity. In the tube discussion I am writing it will be necessary to describe the triode in relation to the circuit it is wired to. A triode an amplifier or radio does not make, it is a collection of components that gives us our equipment.

As Dante writes to me, "There is nothing magical about vacuum tubes or transistors in general. They have no unique properties that allow them to take a small signal and amplify it's amplitude and/or power. They are part of an entire process that involves a low power input circuit controlling a higher power output circuit. A common analogy for an amplifier is to think of it as a black box with two input leads and two output leads. It doesn't matter what is inside. For now."

For now. But we need to explain the triode to state why it was so important. Only the transistor was a greater development than an electron tube. And these two devices, the tube and the transistor, were the most important inventions in the history of the telephone system. Describe we must. In my upcoming articles I will try to supply pictorial diagrams and not just electrical symbols.

Look also at the diagram below these first two graphics. Exploded diagrams are used often to portray mechanical things, like cars. And model cars. Why not electrical circuits?

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Corrected and refined some material in the DSL pages. Take a look. DSL or digital subscriber line is a very misleading name. The technology isn't truly digital, it just has that name.

On September 17, 2003, California Highway Patrol Officer Mike Terry was badly hurt in a motor vehicle accident while on the job, riding his bike. His recovery will be long and expensive. If you can send him a greeting, make a donation, or attend a November 14th fund raiser in the Sacramento, California area, I'm sure his family would appreciate it. To sign his guest book or to get further information, please visit his website: http://officerterry.com/ (external link)

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Gravity keeps loose objects grounded. Pencils on a desk, books on a shelf, water in a pond, would all be floating free if weren't for gravity, that downward pull to the earth's center. But what keeps attached objects grounded? Why don't buildings and rocks and trees fall to the planet's core? What keeps our own bodies from falling apart? It's because gravity is a wimp. Electromagnetism, that essential friend of telephony, is 10 to the 42'd power stronger than gravity. Sky and Telescope magazine's Stuart Goldman writes that, "It's this mutual repulsion of billions of electrons that prevent . . . everything . . . from plunging to the center of the Earth." Stuart was reviewing the new PBS series, The Elegant Universe, based on Brian Greene's book of the same name. Here's a paragraph from that book, along with a link for a much longer excerpt:

"The electromagnetic repulsion [compared to gravity on the Earth] is about a million billion billion billion billion (10 to the 42th) times stronger! If your right bicep represents the strength of the gravitational force, then your left bicep would have to extend beyond the edge of the known universe to represent the strength of the electromagnetic force. The only reason the electromagnetic force does not completely overwhelm gravity in the world around us is that most things are composed of an equal amount of positive and negative electric charges whose forces cancel each other out. On the other hand, since gravity is always attractive, there are no analogous cancellations -- more stuff means greater gravitational force. But fundamentally speaking, gravity is an extremely feeble force."

http://www.wwnorton.com/catalog/fall03/

greene1.htm (external link)

Unrelated graphic but still neat (Click for larger image 249K)

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Wireless has many odd terms, especially for measurement and test. Aslan Technologies performs the tests below. I wrote to Mark van der Hoek (not an Aslan employee) for an explanation. He writes,

"Sweep testing involves injecting a signal into an antenna system (cables with or without the antenna attached) and measuring the reflection. In theory, we want all of the energy to go out of the antenna into space. But in reality, some gets reflected, and these reflections indicate mis-matches in the system. If they are too severe, corrective action is needed."

"Antenna Loss, Return Loss, Fault Location, Insertion Loss, VSWR Measurement are all part of sweep testing. The 'sweep' part comes from the fact that the signal is 'swept' across the frequency band of the intended application, and results recorded. Sometimes you'll find that an antenna system has a bad spot at one frequency. Or it may fail across a wide band. Typically the cable is tested first, then the antenna is connected and the whole system is tested. The antenna may be tested by itself on the ground first, but some don't like this approach as nearby objects can affect the results.

"Backhaul Testing is testing the link back to the switch, whether that is a T-1 from the local telco or a microwave link."

"Base Station Testing is simply putting the site hardware through some diagnostics."

"Ground Resistance Testing is a standard test for any telecommunications site. It's testing the quality of the system's ground."

"System Drive Test is getting into my area. Test phones and (often a special scanner) are mounted in a vehicle and driven around the area. Usually an engineer has mapped out a drive route. The data is downloaded continuously into a laptop, along with GPS data. Then the data can be plotted out and analyzed. That's where Data Analysis comes in. Problems like Pilot Pollution and Missing Neighbors show up here."

"If phones from several different operators are used, you are doing Competitive Comparison Analysis."

Mark.

Thanks, Mark! I note that Ericsson says Missing Neighbors are incorrectly configured neighborhood cell relations. And that Pilot Pollution means evaluating the primary Common Pilot Channel or CPICH. The Common Pilot Channel is fine tuned to balance cell call loads or volume. Increasing power means accepting more calls into a cell, decreasing power to the CPICH means taking fewer. The URL was here:

http://www.ericsson.com/services
/tems/articles/March_02_Investigation-WCDMA_SE.pdf (external link)

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IT&T tried being the world-wide equivalent to AT&T. In some ways they succeeded. Little exists about IT&T on the web but you'll find many good books about them in any large library. They had two eras, the first, founding and development, led by the Behn brothers, and the second, a rebirth and expansion, led by Harold Geneen. How did they start?

In 1925 Western Electric sold its overseas manufacturing plants to a small company with a big name and even bigger ideas: International Telephone and Telegraph. A controversial decision within the Bell System. AT&T sold factories in 11 countries, fearing a United States anti-trust lawsuit. Western kept one foreign company: Canadian Northern Electric, holding it until 1957. AT&T would not return officially to the international market until 1977.

ITT's owners, the curious, conspiratorial Behn brothers, Sosthenes and Hernand, bought Western Electric International for 30 million dollars and renamed it International Standard Electric. Their purchase, backed by J.P. Morgan's bank, included Western's large British manufacturer, renamed Standard Telephones and Cable. The Behns agreed not to compete in America against Western Electric, and to be the export agent for AT&T products abroad. AT&T agreed in return not to compete internationally against the Behns. Now equipped with a large manufacturing arm, IT&T spread across the globe, buying and influencing telephone companies (and their governments) on nearly every continent.

IT&T reorganized and moved into new industries in the late1950s after Sosthenes Behn died. Harold Geneen, an obsessive and ruthless man, at times criminal, took charge. Don Kimberlin relates,

"Harold Geneen's arrival put accountants clearly in charge. During my own time there, the engineers were still reeling from the way in which Geneen trashed all their technology heritage, both figuratively and literally. If it didn't make money in the current accounting cycle, it wasn't worth having around."

"I have my own perfect example, having been the project engineer who found a revolutionary way to improve telegraphy on the then worldwide Telex network. My technique was highly successful, and increased the capacity of an analog voice channel from at first 24 TTY's, then 46, then 92, and ultimately 184 as the serial data modems that supported it increased in capacity from 2400 to 4800 and then 9600 bps."

"That project impressed Park Avenue enough that they featured that 'ITT World's First' on the cover of the annual report....then forgot about it. Geneen was the sort who'd say, 'OK, so what did you do for me this year?' He wouldn't invest in people whose creativity didn't match the accounting cycle. I left ITT to utlimately work for a developer who had me take the new technology to Africa and the Mid-East."

"In that regard, we had to solve a number of marketing problems. One of them was Saddam Hussein, who wanted our Time Division Multiplexing technique because we'd proved and sold it to the Saudis. However, Iraq had alrady embargoed American goods."

"Cable and Wireless stepped into the transaction to broker it and sanitize the deal. At the time, it was interesting because the Iraqis actually came to us, even visiting our company and factory run by American Jews, but then they backed off to have CandW make the purchase and install the goods. No small part of it was the Arab embargo on components from 'corporate supporters of Zionism.' That included most of our semiconductor suppliers -- Fairchild, Motorola and such. The Iraqis sent people from their embassy to our plant, negotiating the price and having us paint out all offending parts ID's in the product, the drawings and the parts lists, to make a special product for them. They paid dearly for us to make our products acceptable to their inspectors -- and CandW benefited from the increased cash flow in the deal."

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