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Mobile Rotary Telephone From Bell

Started by Craig T, April 25, 2010, 09:07:52 PM

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Craig T

Yeah, I wish! I stumbled on this site today with various mobile phones from Bell starting in 1946. Great illustrations to go with articles also Lots of very early mobile phones some are rotary too.

http://www.wb6nvh.com/Carphone.htm

Jim Stettler

I have one of those briefcase phones. It has a rotary handset.
When I dig it out again I will take a photo.
Jim
You live, You learn,
You die, you forget it all.

Russ Kirk

Here's a photo of my IMTS phone.

Russ
- Russ Kirk
ATCA & TCI

AET

I tried to buy one just like that Russ, but it got too rich for my blood.
- Tom

savageje

That site is pretty interesting stuff.  I had to chuckle when I saw the picture of the Motorola "Deluxe" system in the back of the cab from 1948.  If technology hadn't advanced, mobile telephone service would be out of reach for anyone with a Mini or a Prius.   :) 

McHeath

Great posting Craig, very informative.  I noticed that very few people ever signed up for this mobile service, it said that Pac Bell in California only had about 12,000 subscribers in the early 80's.  I never saw or knew anyone with a mobile phone in the their back then, but I knew of a good number of companies, dad's included, that used two-way radios. 

Kind of miss those days, it was pretty cool to pick up the mic and call in.  "2C to base, 2C to base, over"


Craig T

Russ thanks for posting that great phone!

Heath, I had never seen such a setup before. I didn't see a cell phone up here until some time in the second half of the 90s. I also thought it was a great read.

If you had a complete and intact system, would any of you run it in your current vehicle? If I could make it work I would be willing to give up the trunk :)

Bill

I had an IMTS phone in those days, albeit an illicit homebrew one. I worked for Motorola Communications and Electronics Division in Chicago, which worked closely with the Bell System on a lot of communcations challenges. The photo above shows a Motorola IMTS set, for example. Because of that relationship, Chicago was the test area for a lot of new (and sometimes experimental) communications services.

Anyway, an interesting lesson came out of the MTS and IMTS deployments. At that time, Motorola was king of two-way vehicular radio communication, with thousands of installations in police cars, taxicabs, delivery trucks, and so forth. All of these were single frequency systems, of course - the FCC assigned a frequency, and the radio tech for the police department or cab company set up all company's radios on that frequency.

It was commonly accepted in both mobile and fixed communications that if you needed to achieve greater range (more coverage) in these systems, the way to do it was to increase transmitter power or antenna height - receivers weren't usually the problem. It was common, and annoying, for the mobile phone customer to drive out of the coverage area, so the initial deployment of MTS and IMTS followed the bigger-transmitter model.

By increasing the mobile phone system's transmitter power, the individual user could continue his conversation over a larger area, which was good. But at the same time, that one user would tie up one of the limited number (12) of telephone frequencies over a larger and larger geographical area, denying the use of that frequency to any other user. And it was quickly apparent that the mobile phone market could not be served by a system that would support a maximum of 12 phone conversations in the entire Chicago area.

What to do? Aside from getting FCC approval for more frequencies, the problem was considered intractable. Then someone - a Bell Labs engineer? - concluded that if bigger and bigger transmitters, each covering more and more area, were the problem, then maybe the answer was to use smaller and smaller transmitters, each covering less and less area. This was counter-intuitive, and required them to simultanously figure out what to do when the customer drove out of the smaller area. In this way, the concept of the cell system - small transmitters, but more of them, and automatic handoff of the conversation from one to the next small area - was born.

The implementation of a cell system is immensely more complicated that a conventional point-to-point system, because it has to determine which cell the customer is in, and then hand off the conversation to the next cell when the customer moves - no matter what direction he moves in. In those days, there were no really practical computers to handle the job. Bell Labs struggled with the problem for a while, and developed some hardware to do it. The original approaches were crude compared to today's systems - but they worked, and served as the basis for the much more capable systems we enjoy today.

The out-of-the-box thinking - smaller transmitters rather than larger - was what Bell Labs was so good at, and I'm sad that we have lost it. But without it, we would not have cell phones today.

Bill

Jim Stettler

Quote from: McHeath on April 26, 2010, 11:53:23 PM
Great posting Craig, very informative.  I noticed that very few people ever signed up for this mobile service, it said that Pac Bell in California only had about 12,000 subscribers in the early 80's.  I never saw or knew anyone with a mobile phone in the their back then, but I knew of a good number of companies, dad's included, that used two-way radios. 

Kind of miss those days, it was pretty cool to pick up the mic and call in.  "2C to base, 2C to base, over"


In the early 90's,. 90-93. my boss had a radio phone  the first 1 minute was free then very high. He was "rude" to customers to avoid the fee.
The next company I worked for 93-94  had Big brick cell phones that he paid $2-3 K each plus service.
Jus' reminiscing,
Jim
You live, You learn,
You die, you forget it all.