It was the regular mobile telephones that were so big and used so much electricity that they were trunk mounted. This was prior to cellular phones.
Commercial cellphones didn't get commercially going til about 1983 when the AMPS ("Advanced" Mobile Phone Service) was introduced commercially (in Chicago I believe.)
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I think some of the early cellular phones were made to fit the same mountings and use the same antenna cables as their MTS and IMTS predecessors, so they may have been "bulky" in order to fit the old hardware. Since cellular came long after transistorized RF decks were common, cell phones never had to support the power demands of vacuum tubers: ergo, they never had to be the same size unless there were compatibility issues.
Any Motorola/GE/? techs care to chime in?
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IMTS used much lower frequencies and higher power than AMPS, so it's hard to see how you could use the same cables. See
Also, IMTS phones were big, briefcase size or bigger. My first portable AMPS phone was a bag phone that would fit in a shoebox. The guts of an IMTS phone took up a significant part of the trunk, but even the first generation AMPS would fit under the seat and had all the controls in the handset.
Per Mr. Levine's post, the earliest "AMPS" (early cellphones) were much smaller than the old systems, but still--in most cases--too big to be hand held; so a separate box and antenna was still required in the vehicle, even if the box was smaller than the prior models. (I believe the early hand held "bricks" were very expensive to make). I suspect the earliest cellphones were seen as successors to car phones; not for walkers, after all, in those days walkers were mostly in cities or buildings where there was convenient landline phones everywhere. I recall how the earliest cellphone centers had a garage so that the car gear could be installed by them.
Perhaps the cell phones installed in cars had a more powerful signal and antenna; from the early wireless literature it appears initially there weren't as many cell towers and the extra power was necessary. As time went on and customers increased, they added more towers. I believe people going into remote areas had to continue using either a car phone or bag phone with its extra power.
A few years after cell service introduction they got the handset size down small enough to be genuinely portable; and the garages were dismantled. At the same time there were many more subscribers justifying many more antennas.
It is important to remember that in _any_ telephone service, there is always an overlap between old and new technologies, everyone does not switch overnight at once. There was a transition from car-mounted to hand held, and a transition from analog to digital. Early digital phones could also do analog. There will be transitions as they migrate from one digital mode to another. (Today C.O.s still support pulse dialing because there are many pulse phones out there.). In looking back, we have to remember that a date of introduction is "fuzzy".
Separately we discussed the mobile telephone serviced installed on the original Metroliner trains in 1969. This was a pioneer effect at cell service in that calls automatically found an open channel and were automatically routed from one cell to another along the way (in most but not all cases the cells were large). To the passenger the phone looked like a standard pay phone. But there was considerable extra equipment mounted on the train.
One curious question--on the pre-cellular mobile phones, did the units use a standard "G" handset, or did it have special transmitter and receiver elements designed for radio service. The ringer sounded like a standard telephone ringer and the dial looked conventional.
AMPS phones could transmit up to 3 watts, while digital handhelds are limited to 0.75 W, one of the reasons they're so much smaller than the old brick and bag phones.
I used to have a cottage in rural Vermont where until we got a landline phone, the way to make a phone call was to drive up onto a hill where we could get a signal from a tower 25 miles away with the
3W AMPS phone. You can still get car kits with amplifiers to boost your GSM or CDMA signal, and Motorola still makes a car phone, the M930, that you permanently install in a vehicle and install an external antenna, which transmits at up to 2W.
Is there any point in having a digital phone transmitting at any great power *if* the corresponding base station also doesn't respond in kind?
My understanding is that digital phones only transmit with just enough power to ensure reliable reception at the base station they are attached to, and I would imagine that the base station would do something similar on the return signal - with all of this being constantly monitored and adjusted as the path conditions change (this is on the assumption that base stations don't want to be flooding their surrounds with maximum RF output when they don't need to - such things seem to be unpopular with people who live near these things....)
I can understand using a higher gain antenna which would improve both paths, but if the phone put out a higher signal then the base station may decide to "back off" on the assumption that the signal it was receiving indicated a far closer location of the phone and therefore it can reduce its power accordingly.
Of course not, but base stations have always had higher power than mobiles, because mobiles are transmitting to the well engineered antenna on the base station, but the base is usually transmitting to a junk 1cm antenna inside the phone.
Modern (AMPS and later) mobiles have always done that. The base station adjusts its own power and tells the mobile to adjust its power as well.
Ah, the power of silly urban legends about RF danger from mobile towers. I've never seen a mobile base station that transmitted above
100W total, although people seem to have no trouble with radio and TV towers broadcasting at 50,000 or 100,000W. The tower adjusts its signal to minimize interference with other towers using the same frequencies. That's one of the ways they make cellular phones work.
I believe it tells the mobile to adjust power to the lowest level that the tower can receive reliably. Why would it do anything else?
Somewhat unrelated anecdote: there are towers along the French coast that have a lot of users on ferries between France, the UK, and various islands. Signal strength isn't an issue since salt water is an ideal ground plane and if the tower is reasonably high it's line of sight. But since the mobiles are so much farther from the tower than normal, the round trip time for the signal is a lot longer than usual. GSM uses time-division multiplexing to share each channel, and the extra time makes the conversation not fit in the usual time slots. So on those towers, they have half as many slots of double length, so the GSM phones on the ferries work.
All my phone are CDMA; I one tried one of those antennas that you stick on the rear or side window with a small one on the inside that are supposed to help the signal improve, but I did not see any difference. My biggest problem seems to be between California and Las Vegas on Interstate 15 and on 395, both have major dead spots; other phone I had would switch to Analog and work, but new ones don't. I don't use the phone when I am driving even hands free, but at times I have needed to.
I have already deleted the original post, but is it possible he was referring to thru-glass antennas? For example, patent 6661386 describes a thru-glass coupler. While the coupler does have loss, it requires drilling no holes in the automobile. But these do not work if the glass is coated with a conductive coating like tin oxide for defrosting.
On Fri, 24 Apr 2009 20:50:27 -0400 (EDT), Steven Lichter
The analog systems have been shut off for a while (year or maybe two). My 2004 GM vehicle came equipped with OnStar, which at the time used only analog cell phone service. I got a notice from OnStar that the analog service was being shut down per FCC orders. If I wanted to continue OnStar, I had to have my GM dealer swap out the analog receiver with a digital one. I chose not to spend the money to make the switch.
The notice from OnStar said that although digital cell phone service did exist in 2004, there were competing systems and OnStar didn't know which would be around long enough to base their system on, so they in effect defered the decision until the analog got shut off.
For what they do though I actually consider the price to be rather low. These are specialized radio repeaters after all with two sets of radios in them rather than just the one set as in your cell phone.
That is the type of antenna I tried. It did not seem to make much of a difference at all, I put it both on the back window, not near the defroster wires and on a side window. A poster told me about another type of antenna, but the price is out of sight.
I understand that, but I don't need it that much, beside I pulled my old hand held Ham radio, if an emergency comes up I'm sure I can reach someone, Last week on a trip to Las Vegas I tested it, I used the external antenna and an Amp, and reached a base in New York.
It's under $200 which is pretty reasonable for that kind of kit. It's probably no more than your phone cost your carrier.
If you're eligible for a new subsidized phone, you might see about getting one with an antenna plug, then get a glass mount or magnetic roof antenna with a cable you can plug into the phone. That should be under $50.
I have not seen one from Sprint, besides I use a Palm 755P and will stick with them since they work fine with my Macs. I saw the new one at the CES in Las Vegas in January and liked it except they now only offer it with Windows mobile but am told it will still work with my Macs.