T-Mobile's Brodman Not a Fan of Subsidized Devices > other three ?

reply to MovieLover76

Re: other three ?

There should be no push to standardize. They should be allowed to innovate freely as they have been.

This is not Europe.

reply to plencnerb
It's a bit more complicated than a Superheterodyne FM receiver. In your standard FM radio. Your FM radio really only "receives" one frequency, 100.1MHz or something to that effect. To make it really, really simple, incoming signals are "mixed" with a locally generated signal of a different frequency, so that the resulting output is the actual radio station you want. 97.1FM "The Drive" to your radio's internals is on 100.1MHz, just as 103.5FM "Kiss FM) is seen by your radios internals on 100.1MHz, just that the locally generated frequency changed. (It may not be 100.1, just using that as an example)

Since FM radios work in an extremely narrow swath of bandwidth (20MHz, 88-108MHz in the US), this is a great solution and allows for precise tuning (since the tuner really only has to see 100.1MHz). Cell phones are much, much different.

Not only do you have a receiver, you also have a transmitter. This means that there must be internal antennas tuned to the exact frequency range for each band you wish to use. Different bands will require different kinds of antennas. You need separate antennas for transmit and receive. Some cell phones even incorporate antenna diversity for greater call clarity. This will require two sets of antennas for each band. See where this is going?

Now, There are so many different ranges, for example:
Cellular-Americas (824-849, 896-894MHz)
Cellular-Europe (880-915, 925-960MHz)
PCS-Americas (1850-1910, 1930-1990MHz)
AWS-Americas (1710-1755, 2110-2155MHz)

And it goes on from there. There are a whole different set of frequencies for LTE networks. There are 1800MHz European networks, SMR Bands (Sprint-Nextel 800MHz), and on and on and on.

Then throw in that on whichever given frequencies you are using, you need to support the technology/frequency combination in your chipset for whichever carrier you are compatible with, CDMA, GSM, WCDMA/HSPA (3G GSM), EVDO, LTE, WiMax...it's nothing short of an engineering miracle that we have even the most basic interoperability that we do today. For example, my current phone, the HTC Rezound, supports the following that I am aware of:

700MHz USA LTE
800MHz USA Cellular (CDMA)
800MHz USA Cellular (EVDO)
800MHz USA Cellular (GSM)
1900MHz USA PCS (CDMA)
1900MHz USA PCS (EVDO)
2100MHz European 3G (WCDMA/HSPA)
900MHz European GSM
1800MHz European GSM

To me, that's a modern miracle!!

If only it were a matter of "just make a phone that works everywhere", it would have been done already. Not only are carriers, especially in the USA, scared of customers being able to take their (subsidized) phone to a competitor, it's also a RF section/chipset/support nightmare for engineers. It's not just as simple as changing from "The Drive" over to "The Loop" when you're tired of hearing the Beatles and want to hear some Black Sabbath!

Thanks for the detailed explanation. I did not know it was that complex.



Have a great weekend!

--Brian

reply to fifty nine
+1

They'll be standardized sooner or later without any Governmental mandate. See LTE....

reply to plencnerb
No problem. The more you know, the better! Plus, sometimes I just get the urge to write a book on the forums. Have a great weekend too!

reply to Crookshanks
Oh really? So then tell me why Apple is selling 2 COMPLETELY DIFFERENT iPads for LTE...

reply to clone

said by clone:

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WCDMA/HSPA (3G GSM), EVDO, LTE,

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reply to fifty nine