pml4791@rouge.usl.edu (Landry Patrick M) (12/12/89)
I am considering the purchase of a cellular phone for my father and would appreciate it if a couple of things could be explained to me. I will be purchasing a portable unit (as opposed to a car-mounted one). I understand the way cellular works but I don't know some of the admisistrative details. 1) Do the Bell Companies actually own the cells? 2) What is all the hubbub about subscribing with a certain carrier? What are the differences between different carriers? What questions should I be asking to find the right carrier for me? 3) What is the maximum power (watts) cellular phones are allowed to transmit? What kind of power can I expect to find in the consumer market? 4) How can I get my hands on a cell map? 5) Anything else a novice should know before purchasing? Thanks for the time. I can provide a condensation of replies if anyone is interested. patrick pml@cacs.usl.edu uunet!dalsqnt!usl!pml
sirakide%cell.mot.COM@uunet.uu.net (Dean Sirakides) (12/14/89)
pml4791@rouge.usl.edu (Landry Patrick M) writes: >I am considering the purchase of a cellular phone for my father and >would appreciate it if a couple of things could be explained to me. I >will be purchasing a portable unit (as opposed to a car-mounted one). >I understand the way cellular works but I don't know some of the >admisistrative details. >1) Do the Bell Companies actually own the cells? A quailfied *yes*. In each cellular service area there are two licenses, one wireline and one non-wireline (this is attempt to allow for competition in any given service area). The wireline licenses are used by the local Bell Companies, the other license is used by the company that was lucky enough to win the right in the FCC lottery. This brings us to your second question: >2) What is all the hubbub about subscribing with a certain carrier? > What are the differences between different carriers? > What questions should I be asking to find the right carrier for me? Each carrier may offer different features depending on which type of equipment they own (even though it is not uncommon for each to have identical CO equipment). The best question to ask is in regards to ROAMING: how much $, can your phone be tracked automatically when you leave your home area... >3) What is the maximum power (watts) cellular phones are allowed to > transmit? What kind of power can I expect to find in the consumer > market? Cellular phones come in there power levels: 4.0, 1.6, 0.6 watts (ERP). 4 watts is used by most car phones and bag phones. 0.6 watts is used by most portables. Bottom line: usually all phones of the same type use the same power levels. >4) How can I get my hands on a cell map? You got me with that one, I'm not sure they are public information. >5) Anything else a novice should know before purchasing? Buying a cheap cellular phone is like buying a cheap house phone don't kid yourself that "a phone is a phone". Ask the dealer which phones are always coming back for repair. Dean Sirakides uunet!motcid!sirakide Motorala Cellular Arlington Heights, IL Of course I speak for myself, not my employer...
john@bovine.ati.com (John Higdon) (12/15/89)
Landry Patrick M <pml4791@rouge.usl.edu> writes: > 1) Do the Bell Companies actually own the cells? In each cellular market, there are two sets of channels. One set, the "B" set is supposedly for use by "the landline telephone company". This could be a Bell Company, or more correctly a subsidiary of the Regional holding company. For instance, Pacific Telesis is the holding company for both Pacific Bell (my friendly telephone company) and PacTel Cellular, the abomination in Los Angeles that extorts money from people under the guise of providing mobile telephone service. Oops, sorry. The other set, the "A" channels, are for an independent company, such as an RCC or paging company. Therefore, there can be a maximum of two carriers in any given market. The distinctions are somewhat arbitrary, however. In San Francisco the wireline provider is GTE, who has an insignificant share of the telephone subscribers in this area; the non-wireline provider is Cellular One, owned primarily by Pacific Telesis, the major telephone service provider in the Bay Area. > 2) What is all the hubbub about subscribing with a certain carrier? > What are the differences between different carriers? > What questions should I be asking to find the right carrier for me? Shopping for carriers is like shopping for anything else. Who provides the best coverage in the areas you intend to travel in? What pricing packages do they offer? Ask customers in both systems how they like the service. > 3) What is the maximum power (watts) cellular phones are allowed to > transmit? What kind of power can I expect to find in the consumer > market? Car phones and transportables (luggables) all have a maximum of three watts. I say maximum because the unit does not always transmit at maximum power. Its output is under the direct control of the cellular system which will turn your transceiver's output power down to the lowest usable level to prevent it from interfering with other cells. Handhelds are limited to .6 watts. Power is not important. The design of the cellular system is much more significant. My handheld works just fine in this system with its 600 MW anywhere I go. > 4) How can I get my hands on a cell map? Unless you are an experienced RF engineer, a cell map won't tell you much. They use very directional antennas, massive beam tilt, and other tricks. If you weren't in on the design concept of the system as a whole, you would be wasting your time trying to find such a map. > 5) Anything else a novice should know before purchasing? Use it. If you like it, buy it. John Higdon | P. O. Box 7648 | +1 408 723 1395 john@bovine.ati.com | San Jose, CA 95150 | M o o !
doug@letni.uucp (Doug Davis) (12/17/89)
In article <2155@accuvax.nwu.edu> motcid!sirakide%cell.mot.COM@uunet.uu.net (Dean Sirakides) writes: >>3) What is the maximum power (watts) cellular phones are allowed to >> transmit? What kind of power can I expect to find in the consumer >> market? >Cellular phones come in there power levels: 4.0, 1.6, 0.6 watts (ERP). >4 watts is used by most car phones and bag phones. 0.6 watts is used >by most portables. Bottom line: usually all phones of the same type >use the same power levels. Er, I believe that *three* watts is the maximum legal power that a cellular radio may transmit. >>4) How can I get my hands on a cell map? >You got me with that one, I'm not sure they are public information. Most companies publish a simple one as part of their sales brochures. Depending on who you talk to sometimes it's just a phone call away. At least thats what it took me, with Southwestern Bell. I'm sure your milage may vary. >>5) Anything else a novice should know before purchasing? >Buying a cheap cellular phone is like buying a cheap house phone don't >kid yourself that "a phone is a phone". Ask the dealer which phones >are always coming back for repair. Also, call the carrier, or better yet write them a letter. Most dealers will sell you the unit they are getting the best spiff off of this week. Most of all shop around, have several different places show you the same unit, ask about where accesories for that unit may be purchased. You'ed be suprised how many companies sell just the phone, and can't even *ORDER* an extra antenna, or battery pack for it. Also, and I hate to company bash here, (except for GTE) especially since a representive of the company I am about to bash gave very good answers to your questions.. But... Motorola cellular customer service *sucks* *rocks*.. (whew, that felt good) Let me explain, I am the ideal cullular customer, I constantly run bills in the 500-800 minute a month range. I have sold several phones to associates of mine and they too run rather large bills. At the time I purchased my phone I shopped around and the general consenses was that Motorola made the best/most reliable phones. This may be quite true, my phone still functions just fine after well over 100,000 hours of time. But.. When I purchased this phone I was assured that it would take an adapter that would allow hands free communication in a car, (like a normal telephone speaker box) In the box with my phone was a brochure that has a picture of and about 1/2 dozen other options I could buy for it. Now then, this Christmas I was going to treat myself to a hands free adapter, I called the same people I purchased the phone up and had them order me one. They called back a few hours later and said that Motorola, NEVER MANUFACTURED THE HANDS-FREE ADAPTER FOR THIS PHONE. Needless to say I was a bit miffed over this and gave Motorola a call about it. The nice lady on the phone proceeded to explain to me that *they* didn't put that brochure in the box with the phone, the fact that it was sealed in the same plasic as the owners manual, in a sealed box, and it was pretty much obvious that it was the first time the box had been opened when the dealer pulled it from stock for me. Didn't seem to phase her one bit. Matter of fact, the *ONLY* thing she could do for me was sell me another phone for 4000.00 that WOULD do hands free in the car, of course that little option was a mere 1500.00 more. Oh yeah she also told me that I should *NEVER* buy a phone from a dealer since they obviously wouldn't know if the phone could support hands free. (I guess that must be right if they look at the brouchures that come in the box with the phone.) Well at 5500.00 dollars I can buy several portable phones from almost anywhere and most of those have hands free adapters for < 100.00. Anyway, now that I've vented my frustrations a bit, I will say that I have put this unit through h*ll and it still works like the day I bought it. So, technically the phone is great, just that Motorola doesn't know the meaning of the word's "customer service." Oh, yeah, I did write a very nice letter, including a photo-copy of the brochure, to several places inside of Motorola, if something interesting comes back I will be sure to follow up with it to Telecom. Doug Davis/1030 Pleasant Valley Lane/Arlington/Texas/76015/817-467-3740 {texsun, motown!sys1, uiucuxc!sys1 lawnet, attctc, texbell} letni!doug
sirakide%cell.mot.COM@uunet.uu.net (Dean Sirakides) (12/20/89)
doug@letni.uucp (Doug Davis) writes: >>>3) What is the maximum power (watts) cellular phones are allowed to >>> transmit? What kind of power can I expect to find in the consumer >>> market? >>Cellular phones come in there power levels: 4.0, 1.6, 0.6 watts (ERP). >>4 watts is used by most car phones and bag phones. 0.6 watts is used >>by most portables. Bottom line: usually all phones of the same type >>use the same power levels. >Er, I believe that *three* watts is the maximum legal power that >a cellular radio may transmit. Er, I believe that *four* watts is the maximum legal power that a cellular radio may transmit. This is what is meant by ERP--Effective Radiated Power. The *three* watts refered to by most ads is the *chasis* power of the device. However, after antenna gain this is increased, but should not exceed 4 watts nominal ERP. Sorry I didn't make that clear. Dean Sirakides | Cellular Infrastructure Division ...uunet!motcid!sirakide | Motorola, Inc. | Arlington Heights, IL Of course I speak for myself, not my employer...
lars@salt.acc.com (Lars J Poulsen) (12/22/89)
In article <2319@accuvax.nwu.edu> motcid!sirakide%cell.mot.COM@uunet.uu.net (Dean Sirakides) writes: > ... *four* watts is the maximum legal power that a >cellular radio may transmit. This is what is meant by ERP--Effective >Radiated Power. The *three* watts refered to by most ads is the >*chasis* power of the device. However, after antenna gain this is >increased, but should not exceed 4 watts nominal ERP. If 3 watts of power goes into the transmitter, I do not see how the laws of physics would allow 4 watts to be radiated into the electro- magnetic field ? Or is "4 Watts ERP" a derated number sortof like "the power that would be radiated out of a 4-watt transmitter using 1930's technology", meaning that the energy content of the field is really more like 1.5 Watts ? / Lars Poulsen <lars@salt.acc.com> (800) 222-7308 or (805) 963-9431 ext 358 ACC Customer Service Affiliation stated for identification only My employer probably would not agree if he knew what I said !!
john@bovine.ati.com (John Higdon) (12/22/89)
Lars J Poulsen <lars@salt.acc.com> writes: > If 3 watts of power goes into the transmitter, I do not see how the > laws of physics would allow 4 watts to be radiated into the electro- > magnetic field ? Antenna "gain" is most common in the RF world. It involves the amount of energy radiated in a given direction from the antenna. In a given azimuth, a 5/8 wave antenna (as used in cellular mobile phones) radiates more energy than a 1/2 wave reference dipole for a given RF input. An easy way to visualize this is to refer to the case of an FM broadcast antenna (oh, no, Martha, here it comes!). If you take a single "bay" or element and you could see the energy being radiated from it, it would appear as somewhat spherical, coming off in every direction. Unfortuately, the receivers are all out at some horizontal distance from the antenna. There are hardly any listeners in the sky or under the ground, so all that energy is being wasted. If you place a second bay on the tower exactly one wavelength's distance above or below the first and divide the energy between the two, the formerly spherical pattern will now "flatten out", with more energy being radiated out horizontally and less going up and down. The antenna is now said to have "gain" over the standard dipole. No energy was created, just redirected in a more useful manner. The ERP (Effective Radiated Power) from a standard dipole equals the Input Power to the antenna which is close to the transmitter output power. The ERP from a "gain" antenna is equal to the Input Power times the power gain of the antenna. In the case of our FM example above, adding that second element would give the antenna a gain of 2. The gain of a 5/8 wave antenna is approximately 1.3 referenced to the standard 1/2 wave (I think--don't work with those much). I know more about FM antennas than cellular, but the principle is the same. John Higdon | P. O. Box 7648 | +1 408 723 1395 john@bovine.ati.com | San Jose, CA 95150 | M o o !
"Robert P. Warnock" <rpw3%rigden.wpd@sgi.com> (12/28/89)
In article <2382@accuvax.nwu.edu> John Higdon <john@bovine.ati.com> writes: +--------------- | Antenna "gain" is most common in the RF world. It involves the amount | of energy radiated in a given direction from the antenna. In a given | azimuth, a 5/8 wave antenna (as used in cellular mobile phones) | radiates more energy than a 1/2 wave reference dipole for a given RF | input... +--------------- [...and more good tutorial stuff about Effective Radiated Power (ERP) and how you get effective gain...] Except that I thought the "reference" for ERP was the hypothetical isotropic radiator, not a dipole. An isotropic radiator's pattern *is* a uniform sphere; a 1/2-wave dipole is more like a doughnut with a really small hole in it. (The dipole "threads" the hole. That is, the maximum power from a dipole is broadside to the antenna.) A 1/2-wave dipole has (I think) about a 3dB gain (factor of 2 power gain), due to the fact that it doesn't "waste power" radiating off the ends. Even a 1/4-wave whip has some gain (as long as you hold it "up" and don't actually point it at the cellular site!). A properly phased stacked array of a ground plane plus 1/4-wave plus 1/2-wave (which is what I think you're calling a 5/8-wave, which is *about* what it is after the account for the shortening due to the loading-coil effect of the phasing coil between the two sections) has an (advertised) gain of about 5dB, or a power gain of 3.2 or so. This is how Radio Shack et al. get away with calling a 1/2-wave whip (the funny thing which is really *center*-fed 'cause the bottom half is the folded-back shield of the feed line) a "3dB gain" antenna, even though ita gain is barely a dB or so more than a 1/4-wave whip. It's 3dB with respect to an *isotropic* antenna. Rob Warnock, MS-9U/510 rpw3@wpd.sgi.com rpw3@pei.com Silicon Graphics, Inc. (415)335-1673 Protocol Engines, Inc. 2011 N. Shoreline Blvd. Mountain View, CA 94039-7311
tad@ssc.UUCP (Tad Cook) (12/28/89)
Lars Poulsen asked how a 3 watt transmitter could put out 4 watts ERP (Effective Radiated Power). 4 watts ERP would result when the transmitter is connected to an antenna with an overall gain of 12.5 db. Broadcast stations are also regulated like this. If they are allowed 50,000 watts ERP, they may have 12.5 KW into a 6 db gain antenna system. Tad Cook tad@ssc.UUCP MCI Mail: 3288544 KT7H @ N7HFZ.WA.USA.NA
tad@ssc.UUCP (Tad Cook) (12/31/89)
I was shocked to read my posting on antenna gain and ERP. It looks like I moved a decimal point. It should have said that going from 3 watts to 4 watts implied 1.25 db, not 12.5! Tad Cook tad@ssc.UUCP