Mail Archives: geda-user/2015/09/25/15:17:34
Chris Smith (space DOT dandy AT icloud DOT com) [via geda-user AT delorie DOT com] wrote:
> My problem is that I'm developing the code blind, based on
> intellect and reasoned guesswork and I don't like that. There are
> many wireless products out there which are quite robust and I'm
> sure they weren't developed by guesswork either. What I'm looking
> for are any texts or references that discuss the principle of
> digital encoding for wireless transmission, which algorithms and
> strategies are used in what circumstances and why.
This is the topic of RF modulation and demodulation; digital signal processing.
One good tool for measuring the ether is an SDR, a Software Defined Radio.
For 433 MHz all you need is a DVB-T USB stick supported by the RTL-SDR
project, then you get spectrum analysis and demodulators for free (as
in software). Look for the Pentoo Linux distribution, which is created
specifically for RF experiments.
> As I said, I can't influence the RF part, only the ones and zeros
> that are encoded onto the carrier. I also can't change at this
> stage the simplex operation.
Simplex is fine, the modulation is what matters. There is a very real
risk that the modulation used by these modules simply will not be able
to provide the data bandwidth that you require. You can try to compensate
with bit patterns and so on, but that can't really make up for the "wrong"
modulation..
> I wasn't looking for lengthy discourse anyway, just a few pointers.
Look around for more open source modems like FLdigi. :)
//Peter
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