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Short for Cellular Phones, which is a description of how the phones work. A number of access points offer connection to the phone, with the communication being between the phone and the cell with the strongest connection.
The problem with CellPhones so far is that they are analog, which means that conversations are over the air and in the clear. That is, they are unencrypted. Unsafe, the way you don't want your credit card number to be sent to an online store.
Digital phones are better in a couple of ways:
- Digital encoding and decoding, combined with error correction, should mean that you have longer range from a cell before signal degradation. But this just marketing non-sense as anyone with a digital/analog cell phone knows, or anyone who has compared "real audio" to FM radio knows.
- Digital communication cannot be trivially eavesdropped, so your communication is more secure.
The coming US standard is PCS. The main standard for the rest of the world is GSM. GSM is better, I've heard, with a wider set of features and (of course) acceptance by the rest of the world. Of course, the bandwidth GSM uses elsewhere is used already in America. I think by PCS.
CellPhones might be considered the first thing after pocket calculators and digital watches to spread PervasiveComputing, and it is the most common access to VoiceRecognition UserInterfaces.
- Almost everyone I know has a [cell phone]. None have VoiceRecognition. I suspect that this is a matter of local popularity — you generally see 2 brands of cell phone here, Nokia and Motorola. I actually know more people with ViaVoice? on their computer than VoiceRecognition phones (I've heard of the phones, but never seen someone use one...).
- Experience in this area shows that digital transmission doesn't give you clues when your signal drops — silence on the other end of the line may mean the person is not speaking, or it may mean their cell phone connection is not transmitting properly. Signal degradation is presented to the user as a boolean — you have a connection, or one or both directions is not functioning (typically a PCS phone will be able to initiate a call, and receive audio from the person who answers, but is unable to transmit strongly enough for the signal to get through).
Actually, since digital phones use technology akin to streaming audio on the internet, you get a lot of static on the line as well, which is dumb. After all, instead of playing random bits in the buffer, one could just play nothing. On the other hand, constant and frequent (dozens of times a second) drops in signal will make the audio sound like static as well.
- There is a technical issue with that. You drop the noise, you get silence. Silence sounds like a dropped call. So a little bit of noise getting through is a good thing, because it shows there's still an open line of communication. --DaveJacoby
As for security of phones, I don't think that really matters to anyone. Why would it matter who was eavesdropping on your line if you're talking in the middle of a restaurant?
- I once heard someone talking about firing someone at a restaurant. He might've thought he wasn't announcing it to everyone. He might not.
- Security matters to some people. It doesn't matter to everyone. Someone browsing or texting in the middle of a restaurant would have different expectations of privacy. Or someone talking on the phone in the back seat of a limo. For me, I'm an SSH user. I want protocols to exist so any insecurity is clearly on the user (using stupid passwords, talking loud in a restaurant) and not on the technology. --DaveJacoby
Here's [another application of cell-phones]. You use GPS on GSM phones to track someone's position, and you can make an SMS message asking "Are You OK?". This is planned for people like social workers and the like, who often travel solo. What I find interesting is that this is built on non–telephone-connected technology grafted to the telephone in its mobile form. This is pretty much a dictionary definition of convergence.
CategoryPervasiveComputing