[aprssig] Pulse Position Modulation
magne at samfundet.no
Tue Jan 13 02:23:15 CST 2009
Andrew Rich wrote:
> Has anyone played with Pulse Position Modulation for transmission of
> position reporting technolgies ?
The aero industry does it all the time. The Mode-S transponder system
use 1Mbps, with two positions per bit, PPM as the downlink mechanism.
Transmission consists of frames of 56 or 112 bits, and usually conveys
aircraft id, 3D position, and other flight related information.
I'm not convinced that PPM was chosen because it was the best
technology available, but rather because it was fairly compatible with
the older Mode A and C transponder systems, and that the industry
felt comfortable with pulse technology.
--Magne / LA1BFA
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