Sunday, November 15, 2009
The Phone Network, an 80-year-old dog
Why has it been so hard to teach that old dog, the phone network, the new trick of sound quality that's as good as what we hear?
In 1930, the goal of the phone system was stated like this: “In the Bell system the general objective which has been set up for the transmitted frequency range for new designs of telephone message circuits is a range having a width of 2,500 cycles, extending from about 250 cycles to about 2,750 cycles.”
The performance of the public telephone network has not gotten much better - even a little worse, in some ways, over the years. As recently as 1984, the higher end was still about 2.7 kHz for long-distance calls, and 280 Hz at the lower end. It’s hard to take something like the global phone network, one with fundamental goals set eighty years ago, and change its underlying fidelity in any meaningful way.
This why telephones are moving to VoIP, Voice over Internet Protocol (or internet telephony), to make better fidelity possible for most people. The internet carries data, and since any kind of signal can be converted into data, this means the internet can carry almost any kind of signal. Did you get that?
1. The Internet Carries Data
2. Any Signal can be turned into Data
Therefore: The Internet Carries Any Signal
Signals can be HD Voice, desktop video, Immersive Videoconferencing, and most other kinds of information you may want to share. Because the Internet can be made arbitrarily versatile and fast, it can keep up with the needs of live human communication for a long time to come.
Reference: “Transmitted Frequency Range for Telephone Message Circuits,” W.H.Martin, Bell System Technical Journal July 1930 Ref. JR1/11