[liberationtech] Efficient digital one-way communication

Jens Christian Hillerup jens at hillerup.net
Mon Mar 4 09:53:05 PST 2013


Whoops, we're drifting off-list. I've included the relevant parts (and
committed a stereo fix to the main repo that fixes the bug from my
second mail).

On Mon, Mar 4, 2013 at 6:46 PM, Kurtiss Hare <kurtiss at gmail.com> wrote:
>> Also, couldn't having a large frequency span be challenging to carry
>> over FM? I should probably grok
>> http://en.wikipedia.org/wiki/Frequency_modulation before discussing
>> that detail further.
>
> My naive model of the idea here is to consider the number of audibly
> distinct (and computationally discernible) instruments capable of delivery
> through FM. For a given note, each one has a distinct overtone series which
> lends it a unique timbre. Depending on the sophistication of your decoder, I
> would think the number of euphonic sounding configurations to be quite high.

Well, instruments get their timbre from the *weighting* of the
overtones, not their existence or non-existence. I'm concerned that if
we go into the game of actually weighting these overtones (rather than
just choosing whether they should be there or not), decoding becomes
too difficult. We're already spanning three octaves as it is, so
they'd definitely need to have less amplitude than the fundamentals.
I'll do some experiments when I get the time...

JC



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