Sunday, February 26, 2012

Coding schemes for digital modes

Jason Spence, KF6RGF writes:

Why don't more amateurs use coding schemes for digital modes? You don't have to transmit louder if you can transmit smarter. Recently, something called polar codes have been making the rounds in academia:

http://cnls.lanl.gov/~jasonj/poa/slides/urbanke.pdf

The idea behind polar codes provides a possible way forward for modems to maximize throughput over a noisy channel. Conveniently, they are much easier to implement than other schemes and simple implementations do not affect the design of the transceiver's analog parts.

But wait, you say. I can't just dump some power hungry DSP board in my solar powered packet node! I need something low power. Well, Freescale has been teasing us with a few details about this part for months now:

http://www.freescale.com/webapp/sps/site/prod_summary.jsp?code=MC13260&nodeId=0106B9B95C

Hey, you say, I need something now! Well, TI has you covered:

http://www.anaren.com/air-boosterpack/

$8.60 - 1x TI Launchpad
$20 - 2x AIR BoosterPacks

$28.6 gets you 2 modems which will do low speed packet over 300 meters for $14.30 each. They can use both the 440 and 900 mhz bands, and you even get protoboard space on each of the boosterpacks.

Why aren't more hams using these? Because the recommended tools cost $500 a seat to use the full capacity of the chips involved. Or do they?

https://sites.google.com/site/msp430ref/home

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