How far can transmissions go in space?

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cellurl
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NASA's New Horizons probe can send us communications from Pluto.

Q: How far can that transmitter communicate? Twice, 3 times, not much further?

To me, electromagnetic signals must disperse, but this one seems to have no loss...

I am fascinated by the technology, be it directional antennas?, QAM? Any leads appreciated!
 

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cellurl said:
NASA's New Horizons probe can send us communications from Pluto.

Q: How far can that transmitter communicate? Twice, 3 times, not much further?

To me, electromagnetic signals must disperse, but this one seems to have no loss...

I am fascinated by the technology, be it directional antennas?, QAM? Any leads appreciated!
The antenna on New Horizons transmits at about 10 watts. A typical radio station transmits at 50,000 watts. The only reason that we can pick up the signal from that distance, is we have really big ears listening. And it isn't even science fiction. :wink:

SRI_Dish_radio_antenna.jpg
 
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At some point the signal gets lost in background noise, but technology has made great strides recently and that limit continues to be improved.
 
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cellurl said:
NASA's New Horizons probe can send us communications from Pluto.

Q: How far can that transmitter communicate? Twice, 3 times, not much further?

To me, electromagnetic signals must disperse, but this one seems to have no loss...

I am fascinated by the technology, be it directional antennas?, QAM? Any leads appreciated!
Further to what people have said, when the distance is doubled the received power will be a quarter. That sounds a lot, but it means that when the probe is twice as far as Pluto (another nine years?) the signal will have dropped by just 6 decibels.