[sdiy] generators/antennas analogy?

[sasami at blaze.net.au]

Audience detecting is a lot simpler than that. Two common 
ways are used in Australia. 

1) servey a percentage of people, then multiply the results.
2) In the case of TV a small sampling of people are set up 
with monitoring boxes, (as few as 500 people) and the 
results multiplied.

All rather suspect!

Ken

>Whilst I am familiar with the idea of 'back emf' in a 
generator there is
>something I have never understood which Im sure someone can 
clear up.
>
>I once heard that Radio and TV stations can judge audience 
figures by the
>amount of power 'absorbed' ie the Watts or MWatts they have 
to pump out. On
>one level this makes sense. A popular station would need 
only the weakest of
>transmitters if this were not so. But can the resonance of 
millions of tuned
>circuits really indicate power usage that accurately? And 
if not then how do
>they judge audience figures? I don't really buy the 
argument that grid power
>usage can accurately reflect these things when so many 
programmes start at
>exactly the same time.
>
>Lincoln