Re: Radios for higher speeds,

[Phil Karn <karn@qualcomm.com>]

>Why it is nessesary to have a 15KHz bandwidth for 9.6Kb, when in the wireline
>case it is sufficient a 2.4KHz for 28.8Kb ??

There's a fundamental tradeoff between bandwidth and S/N ratio. On a phone
line where you have high S/N, you can use higher-order modulation schemes
to get many bits/sec per Hz.

You *could* apply these same schemes to radio channels but, as Richard
Nixon once said, "that would be wrong". Modulation schemes that give many
bits/sec/Hz are inherently more sensitive to noise and interference, which
is much more of a problem on radio than on phone lines.

Phil