[extropy-chat] signals or noise?

[scerir]

From: "Dan Clemmensen" 

> If you are trying to maximize the 
> information rate of you signal 
> in the presence of noise for a particular 
> transmission power, your signal ends up 
> looking like noise. 

Good point. Optimal efficiency, for a
trasmission of informations, via e.m.
radiation, and with a reasonable and fixed amount 
of power, gives rise to a radiation with a 
spectrum like the 'blackbody' radiation 
spectrum.

(Btw, astronomical bodies show such a 'blackbody' 
radiation spectrum, if I remember well. Not sure 
though. So, an efficient signal could be indistinguishable
from a blackbody radiation).

If S is information, and dS/dt the information
transmitted, via e.m. carrier, per unit of time,
and P is a given power,

dS/dt = sqrt (4/3 * pi^2 * 1/h) * sqrt (P) 

and 1 Watt gives, more or less, 10^17 bits 
of information transmitted per second (hope so).

Another equation links dS/dt to the areas of the
transmitter (At) and of receiver (Ar), and to power,
and to the distance (d) between receiver and transmitter,

dS/dt = (const * Ar * At * 1/d^2)^1/4 * P^3/4

Ar = At = 1 square meter; P = 1 Watt;
-> a flux of 10^21 bits (hope so).