Ralph Smith wrote:
O
We are not syncing time slots for communications. The timing requirement
is for determining aircraft position by multilateration. Timing errors
translate into position uncertainty.
What's your carrier freq? In mountainous regions you'll probably have
better luck at the lower end. Please tell me you're not trying this at
GHz freqs at higher, rocky elevations.
Signal emitted by the aircraft is 1090 MHz, pulse-position modulated
transponder squitter (Mode C/Mode S). Radio stations receive signal,
determine time of reception, and forward the timestamped transmission via
landline to a central facility for correlation and position determination.
and presumably, you have only one interrogation transmitter, and many
listeners? (otherwise you could pulse each one in turn and essentially
get a set of 2 way ranges to solve with)
I realize you're trying to do multilateration.. BUT, if you measure
angle of arrival too, then you can throw that into the solution, and you
can tolerate a greater uncertainty in the range measurement.
There's also the whole "using physics constraints"... combine multiple
measurements, and model the vehicle dynamics.
You've basically got a "make a bunch of measurements and combine them,
hoping to get a root(N) improvement" problem. As you've noted, to get
from 1000 ft to 30 ft requires a 30 fold improvement, implying a 1000
measurements.. Yow..
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