Is this the deepest underground payphone in the world? The photo is from Larry Johnson's Heritage of Time: The People and Times of GTE Southwest 1976- 1988. It shows an underground payphone at 750 feet below sea level. It was installed in 1956 but the original line had been run in the late 1920s.

I understand a newer model still exists at Carlsbad Cavern. But it might not be the lowest payphone of any kind. The Dead Sea near the Israel/Jordan border is 1,312 feet below sea level. Does anyone know of a public payphone there? Write me! Click the image for a bigger picture:

Click for a larger picture

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Q. I can't stand cell phones going off in my theatre. Any way to jam their signals?

A. Yes, but it's illegal to do so. You can't interfere with any radio transmission authorized by the F.C.C. You can ask people to turn off their cell phones or radios but you can't physically interfere with a properly authorized, licensed signal. And it's not the small F.C.C. fines you should worry about. If someone has a heart attack and people can't call 911 because you are jamming their cell phones, well, you and your theatre will be sued out of business.

Although products like this can be had, I am sure they are illegal to use in the United States:

http://www.suresafe.com.tw/showroom1.html (external link)

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Ranch work today instead of web work. We're getting the property and equipment ready for spring.

It's too bad about the Martian Rover. It's having problems and NASA/JPL aren't sure what's wrong. See their press release below. Today it did communicate with Earth using a satellite orbiting Mars. Story from JPL below. This nice graphic from the San Francisco Chronicle shows how that communication link works. Click here to view. (147K).

"NASA's Spirit rover did not go to sleep today even after ground controllers sent commands twice for it to do so.:

"Shortly before noon, controllers were surprised to receive a relay of data from Spirit via the Mars Odyssey orbiter. Spirit sent 73 megabits at a rate of 128 kilobits per second. The transmission included power subsystem engineering data, no science data, and several frames of 'fill data.' Fill data are sets of intentionally random numbers that do not provide information."

"Spirit had not communicated successfully through Odyssey since the rover's communications difficulties began on Wednesday."

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Q. What are the connectors called that join the handset to the telephone? They're different than the ones that join the telephone to the wall.

A. (From Cowboy Frank:)

Howdy,

It took just a bit of research, but the handset connectors are referred to as 4P4C. RJ11 (the standard phone jack) and RJ45 (the Ethernet jack) are actually construction standards and not the plug shapes themselves. I have never bothered with looking up the standards before, but it would appear they refer to such things as the general shape, use and position of the little lock tab, spacing of contacts, insulation qualifications, acceptable voltage levels and so fourth of the connectors.

This web site is excellent for finding different connectors. It links to a which actually has some technical specs for the 4P4C plugs this company offers:

http://exw.en.alibaba.com/group/0.html

It was actually lucky you asked now instead of 6 months ago. I have just recently bought a crimping tool for handset cords and it had the number on the side which allowed me to look it up :-)

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I've written below on communication between Earth and the Mars' Rover. But this wonderful graphic from the Chronicle tells the story in a more pictorial form. Click here to view. (147K). Quite nice.

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While you can't use your cell phone in flight on commercial airliners now, that may soon change. I'm working on a preliminary page that explains this.

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Added an article by Julian Macassey, N6ARE, to the site. It's the essential article on how telephones work. It is technical but if you want to learn telephony then you need to understand this page. It was first published in Ham Radio Magazine, September 1985.

Mark van der Hoek explains antenna polarization, db's and the mysterious image below in yet another page in the cellular telephone basics series. Scroll all the way down to the bottom of the page.

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Hanjoo Kim of the IITA (Institute of Information Technology Assessment), Daejoen, South Korea, supplies this nice outline of wireless in Korea. He adds that number portability has been required for some time and that, as in America, many problems and much confusion have resulted.

Brief history of mobile communications in Korea

From mid-1960s : IMTS service for government use only. [Editor's note: Motorola sold IMTS systems throughout the world.)

March 1984 : Inauguration of KMT (Korea Mobile Telecommunications Co.,) as a subsidiary of KTA (Korea Telecommunications Authority; the government-owned communication service carrier. It is now KT (Korea Telecom), a privatized telecom company)

May 1, 1984 : KMT begins AMPs service.

June, 1994 : KMT privatizes, with SK (Sun-Kyung Group) becoming the 1st major stockholder of KMT.

January, 1996 : Shinsegi Telecom (the second cellular service carrier in Korea) begins CDMA service in the Incheon area (very near to Seoul).

April, 1996 : KMT begins CDMA service in Seoul area. (Sun-Kyung Group Telecom)

March, 1997 : KMT changes name to SK Telecom.

October, 1997 : Three PCS service carriers (KT Freetel, LG Telecom, Hansol PCS) begin CDMA service at 1.7GHz.

April, 2000 : SK Telecom acquires Shinsegi Telecom. Retires the Shinsegi Telecom name.

October, 2000 : cdma2000-1x service launches.

December, 2000 : SK Telecom and KT Freetel get IMT-2000 licenses for W-CDMA.

May, 2001 : KT Freetel acquires Hansol PCS. KT Freetel retires the Hansol name.

August, 2001 : LG Telecom gets the IMT-2000 license for cdma2000 technology.

May, 2002 : cdma2000-1x EV-DO service begins. (SK Telecom insists that this service began in January 2002. But in the official statistics, subscribers to cdma2000-1x EV-DO first appear in May, 2002.)

December 2003 : Launch of W-CDMA service for field trial.

Editor's note. Some additional, though dated material was at the external link below:

http://www.3gnewsroom.com/country/south_korea.shtml

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The lead article in the new Ericsson Review discusses mobile communications and health. Well written and researched:

http://www.ericsson.com/about/publications/review/

And Ericsson continues to publish the well done On, a chatty, colorful read that focuses on current and soon to be wireless offerings:

http://www.ericsson.com/about/publications/onmagazine/

Alcatel devotes their latest quarterly entirely to wireless:

http://www.alcatel.com/atr/

Each magazine offers free subscriptions free through the mail, a great service. I like my information electronically available, to have an online version, but I still prefer reading a regular, non .pdf magazine.

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Consumer Reports is out with their annual cell phone plan report. It's in the February issue which should be going on newstands now. I have their summary here which makes for interesting reading. No carrier comes out well in their survey, and each service plan seems deliberately confusing so that subscribers can't easily compare rates and services.

The wireless industry continues to promise more than they can deliver, and this has been happening every year since 1984. Customers want large coverage areas, few dropped calls, and good audio quality. The industry responds by providing deceitful coverage maps, routinely dropped calls, and connections filled with static, no sidetone, or voices that make us sound like Donald Duck. Yes, cellular radio technolgogy is wonderful and I am glad it is here. I just wish the wireless industry would conduct itself in a more honest way, explaining radio's limitations as well as its benefits.

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The line art below is from a 1960's Bell System ad detailing their efforts with communication satellites. The ad shows an early computer simulation, possibly drawn on a plotter, quite a contrast from today's marvelous, animated, full color renderings. Click here to view the entire ad in much finer detail. Warning: it's quite a large file.

I've had difficulty finding out exactly how long it takes for a radio signal to go from Earth to Mars. Turns out that many answers can be correct since the distance from our planet to Mars varies so greatly. Here's the problem well explained:

Question

How long does it take for a radio signal to go from Earth to Mars?

Asked by: Richard Boulais

Answer

Radio signals are electromagnetic waves, such as light or X-ray. The speed of electromagnetic waves in vacuum, is 300000km/sec (approximately).

In order to calculate the time of travel with this speed from Earth to Mars, we need to know the distance.

When the Mars and the Earth are at the opposite sides of the Sun, the distance is the largest: approximately: 378 million km. The time needed for an electromagnetic wave to cover this distance is approximately: 21 minute.

The closest distance between Mars and Earth is 78 million km, the time in this case is: 4.3 min.

So the time of travel between Earth and Mars is between 4.3 minutes and 21 minutes, depending on the actual distance between the two planets.

Answered by: Ferenc Szekely, Ph.D., Physicist, ELTE, Budapest, Hungary

Source: http://www.physlink.com/Education/AskExperts/ae381.cfm

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The United States has again returned to the Red Planet. The Rover's radio gear communicates directly with earth or to orbiting satellites above Mars. At a data rate equal to most terrestrial cellular networks!

This wonderful graphic from the Chronicle tells the story in a more pictorial form. Click here to view. (147K). Quite nice.

Sending data over cellular networks has always been slow. Cellular radio was built on low bandwidth rates to conserve spectrum and because voice was the first priority. Only now are technologies like EDGE and GPRS slowly improving data transfer speeds.

But a typical file transfer on a present cellular radio system, today, while driving about in a car or truck, gets no better results than NASA does from Rover, millions of miles in space: from 3,500 bits per second to 12,000 bits per second. Remember that old 14.4 modem you used to have? NASA would love that top speed and you might too, getting that new picture phone of yours to work.

At the bottom of this page I write about how telephony is no longer possible when distances stretch far into space:

http://www.privateline.com/TelephoneHistory/soundwaves.html

And there's a mention of Britney Spears so you really should check it out. :-)

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