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vvanders
on April 10, 2020
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First trans-Atlantic contact made on 432 MHz
The term you're looking for is Forward Error Correction, send extra bits so you can lose a few along the way.
devxpy
on April 10, 2020
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That takes care of lost information, but how do you reliabiliy filter out signal from noise? Can a simple FIR filter work in this situation?
vvanders
on April 10, 2020
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FT8 syncs everyone's clock on 15s intervals, you can also send well known sequences at the start of a transmission and search for those.
ruslan
on April 10, 2020
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FIR filter alone cannot do this, but combined with special coding like Direct Sequence Spread Spectrum (DSSS) does it pretty well. For example, CDMA and GNSS benefit from using DSSS.
sizzzzlerz
on April 10, 2020
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More accurately, extra bits are added to the transmitted stream so that bit errors in the received signal can be corrected.
andbberger
on April 10, 2020
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See also: information theory and channel capacity
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