A comment was posted on an answer to another question:

there will always be a time delay caused, the speed of light dictates the minimum delay between a signal being sent and received after all.

This is in reference to Starfleet com badges. It made me wonder: what's to say com badges use conventional radio, rather than subspace communications? I haven't given it a lot of thought, but I was under the impression that com badges were subspace.

  • Is it ever explicitly stated what communications technology is used "under the hood" by the com badges?
    • If it is explicitly stated, then what is it?
    • If it is not explicitly stated, then what can we derive from what we see on screen as well as other authoritative sources?
  • Also, does this change over the course of the series?
  • When Janeway and Checotay are left behind by the voyager and Janeway gave her final speech to the crew - doesn't she do it using her combadge? If so, that would imply ftl since voyager is far away at that time.
    – Einer
    Commented Apr 29, 2014 at 9:47
  • @Einer You're right, I'm pretty sure they did. Of course, they could simply be using the combadge to relay to a subspace transmitter on the site (which could also have more power available). I'm more interested in the combadge itself.
    – user
    Commented Apr 29, 2014 at 9:49
  • Intraship communication is via conventional radio. Ship-to-ship or ship-to-shore communication is via (fictional) subspace radio allowing FTL conversations
    – Valorum
    Commented Apr 29, 2014 at 9:50
  • @Richard Well, yes, subspace is fictional. So is Starfleet. :) If you can cite any sources for that comment though, it could probably make a good answer.
    – user
    Commented Apr 29, 2014 at 9:51
  • 1
    I'm at work. The answer will be in the "communication" section of the TNG Technical Manual but I've not got access to it from here.
    – Valorum
    Commented Apr 29, 2014 at 9:55

2 Answers 2


It's explicitly stated in both the TV series (Voy: "Time and Again") and the TNG Technical Manual that the communicator badges contain "subspace" technology allowing faster-than-light communication.

JANEWAY: We can assume that Voyager will be looking for a way to reach us. I'll set my combadge to emit a subspace beacon...

I've edited the relevant sections in the picture below. There's also a handy constructor's guide showing the internal workings of the combadge.

enter image description here


From quick research this is what I've gathered the Star Trek Wikia memory alpha.


I don't think it's clearly stated what form of communication it uses but there are some limitations to it such as range.

The Starfleet combadge was a crystalline composite of gold, microfilament, silicon, beryllium, and carbon-70. (TNG: "The Last Outpost", "Time's Arrow"; VOY: "Hope and Fear") Due to the size of the combadge, its working range was limited to five hundred kilometers, although a starship could boost the signal to bridge larger distances. (TNG: "11001001")

There's also no explicit mention of what's "under the hood" except other than what it's composed of and what the combadge can be modified / taken apart to achieve.

In emergency situations, a combadge could be modified for use in other applications. It could be converted into a subspace distress beacon, or the tiny power cell could be extracted for other uses. (DS9: "Rocks and Shoals") Lieutenant Worf used it to power a homemade field generator for several seconds. (TNG: "A Fistful of Datas") In 2374, Captain Kathryn Janeway of the USS Voyager was able to modify Seven of Nine's Borg implants to escape the brig of the USS Dauntless using pieces of her combadge. (VOY: "Hope and Fear") If the casing of the combadge was ever cracked, an emergency distress signal was emitted, mainly to help searchers locate victims. (TNG: "A Fistful of Datas"; VOY: "Time and Again") Combadges, when destroyed by an electrical force, could cause damage to the wearer's clothing. (TNG: "Thine Own Self")

As far as I can tell not much has changed in the combadges other than the designs.

2360's photo of combadge.

enter image description here

2370's photo of combadge

enter image description here

  • If you're going to quote heavily from memory-alpha it's considered polite to credit them.
    – Valorum
    Commented Apr 29, 2014 at 13:28
  • Sorry didn't have my coffee forgot to link it XD Commented Apr 29, 2014 at 13:40
  • If it's limited to five hundred kilometers, ftl doesn't make much sense since even on its limits it would take 0.00167 secs for the signal to travel at lightspeed. There is little use in speeding that up, is there?
    – Einer
    Commented Apr 29, 2014 at 14:17
  • @Einer: well, subspace presumably bypasses most EM interference. Commented Apr 29, 2014 at 14:31
  • Still, 500 km ? This can't be right. Don't people talk to colleague far away on the planet and in orbit all the time? Commented Apr 29, 2014 at 14:32

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