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This has been suggested to pretty far, even light-years, plus have been turned into a subspace beacon or transponder especially if damaged to aid in finding the owner either to rescue a survivor or to recover the body in the event of death. Has someone any information on how this is supposed to theoretically work? What was the max distance mentioned in Star Trek canon (or non-canon)?

  • if you're hanging out with the Traveler and Kosinski, it can go beyond space and time to where "no one has gone before" ;) - ie - pretty far.... – NKCampbell Nov 13 '19 at 14:01
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    The real answer is that range is whatever limit the script calls for – Mohair Nov 13 '19 at 22:39
  • Well, it would be cheap enough for Enterprise to drop a few repeaters in orbit. They ould just be probe/torpedo casings with whatever advanced drive they have. Could even re-task (reposition) themselves for 100% coverage. Wouldn't even be worth mentioning narratively. – Harper - Reinstate Monica Nov 13 '19 at 23:38
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    @Mohair - They communicate at the range of plot. ;-) – T.J. Crowder Nov 14 '19 at 11:04
  • I felt my answer was pretty comprehensive, given the nature of the source. Is there anything else you'd want me to address before considering an acceptance? – Valorum Dec 4 '19 at 11:26
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Approximately 40,000 km (ground-to-ship)

Communications functions are carried out by tricorder through the subspace transceiver assembly (STA). Voice and data are uplink/downlinked along standard communicator frequencies. Transmission data rates are variable, with a maximum speed in Emergency Dump Mode of 825 TFP. Communication range is limited to 40,000 km intership, similar to the standard communicator badge.

...

The communicator is a line-of-sight device during away missions. Its planetside range may be improved if the magnetic field value is below 0.9 gauss, or mean geologic density is less than 5.56 g/cc.

Star Trek: The Next Generation Technical Manual

Approximately 500 km (ground-to-ground)

The range of the communicator is severely limited, mainly due to the small size of the STA emitter and power supply. In transmissions between two stand-alone communicators, clear voice signals will propagate only 500 kilometers. This is a tiny fraction of the 40,000 km required to contact an orbiting spacecraft, so it is the spacecraft that must become the active partner in order to receive the communicator's lower-power signals, and transmit correspondingly high-power signals to the communicator's receiver.

Star Trek: The Next Generation Technical Manual

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  • "Line of sight" implies that they can only communicate with an orbiting ship if it's relatively overhead. Have there been cases where they've lost communication because the line of sight was blocked by the planet? Or is it like short-wave radio where the signal can bounce around the ionosphere a few times and still be picked up on the other side? – Darrel Hoffman Nov 14 '19 at 16:18
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    40,000 km sounds like a geostationary orbit. Probably standard procedure so that they can always maintain line of sight with the away team. – Thomas Nov 14 '19 at 17:10
  • @DarrelHoffman I remember there having been situations where they were able to communicate with the ship while underground. However, the range seems to be affected, and being underground by sufficient numbers of km (well under 40,000 km) seems to block it until they can find a clearing. Direct line of sight may just be required for the full 40,000 km range. Perhaps the signal has to wind its way around solid objects, or is severely weakened by them. – trlkly Nov 14 '19 at 17:15
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    @Thomas 40K km might be geostationary for Earth, I imagine it's completely different for other planets - though considering I don't think they've ever been to a planet that had significantly different gravity than Earth, that might work in all cases? Would a smaller but denser or larger but looser planet (such that the gravity still equals Earth's) still have the same geostationary orbital distance? – Darrel Hoffman Nov 14 '19 at 18:02
  • @DarrelHoffman The gravitational field of a sphere (outside the sphere) only depends on the sphere's mass, not its radius. However, surface gravity depends also on your distance to the core, so you could have a smaller and less dense planet that has the same surface gravity as Earth. However, because such a planet has smaller mass, its geostationary orbit radius would be larger. Given that most planets visited in Trek are ahem very Earth-like in other aspects besides gravity though, I'd expect that they are all similar size and radius as well. – Thomas Nov 14 '19 at 18:39
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As shown in numerous episodes, a standard combadge can reach a ship in orbit; we see the Away Teams reporting to their ship as soon as they arrive on a planet's surface to confirm their arrival.

Communicating further away than orbit requires a boost or a modification of some kind to send the signal far enough.

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    I seem to recall episodes where the range was longer without specific mention of modification. The correct (out of universe) answer is "as far as the plot requires" – psubsee2003 Nov 13 '19 at 12:15
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    @psubsee2003, in Time's Arrow, Data is listing the composite materials of the combadge (the key ingredient for the scene was the gold, as it bought him a seat at a poker table), but I don't recall him mentioning Narrativium. – GeoffAtkins Nov 13 '19 at 13:21
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TNG S03E03 - The Survivors

RIKER: All right. I can't make you come with us. (takes off his comm. badge) Are you familiar with one of these? We'll be in the system for the next several days at least. If you reconsider, please contact us. RISHON: We'll be fine, Commander. We have each other.

So if everything was wiped out on Rana IV, there would be no equipment left to relay a ComBadge signal. If they are going to be in the system for several days (supposedly on there way out of the system), that would be quite some range on that ComBadge signal to still be able to reach the Enterprise across the Delta Rana star system.

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    I think he meant "in orbit" – Valorum Jan 11 at 1:22
  • A good find. I'm wondering if they'd be better able to detect a single combadge from within the solar system if there were no competing signals – Valorum Jan 11 at 1:42
  • I think Valorum has touched on it. I'd imagine Riker intended to have the ship keep a particular lock on his comm.badge frequency. In a star system with zero competition with other radio signals, I also imagine the computer could filter out a faint beep of that comm.badge being activated. And, a beep means Rishon is trying to activate the badge and would warrant a return visit just to see. – Blaze Jan 11 at 14:18

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