Emergency Beacon Detection Range

[Terry Mixon]

I was building a life pod and when I posted it on Facebook, someone said I should add an Interplanetary range transmitter as the rescue beacon. I was open to the idea but I’m not sure about the comment he made about the 500,000 km transmitter being detectable anywhere in the system. That’s not covered in the rules and I’m not sure I would grant detecting it at more than a million kilometers. I’d like to see what y’all think.

 

[MasterGwydion]

Sending an SOS in morse code bursts of transmitting power is vastly different than providing two-way near-instaneous communication. So, a beacon, sure. Speed of light and it is detectable anywhere in the system. Two-way communication, not so much.

 

[rinku]

Detection at interplanetary distances will depend a bit on sensor setup, but I'd expect even Civilian grade could pick up the general direction of a distress call and work on boosting detection until they have a better plot.

You're starting from "I'm detecting a faint distress signal" and working up.

It's just a radio signal, being ACTIVELY broadcast. The usual rules to detect apply - but pretty much every sensop in the system listening will get the minimal information that a distress signal is coming from that bearing.

The comms range really would just be the limit on it being able to talk to someone two way. Sending out a signal and hoping someone hears it should be fine.

Put it another way... if you can detect a ship trying not to be found at interplanetary ranges, you can definitely pick up active transponders and distress calls.

Further... there should be radio bands specifically restricted for emergency signals, which every ship's computer would routinely monitor and alert the sensop about as a priority.

 

[Condottiere]

There should be designated emergency frequencies.

First responders are likely to have a fast acceleration spacecraft available.

If it's too far, they might do a microjump.

I have no idea how powerful a transmitter you need to reach half way across a solar system.

Though, how about morse code with the turretted laser?

 

[Arkathan]

How far away are the Voyager probes, operating on 220 watts of power after losing slightly more than half their original power levels due to radioactive decay?
While we have big honking antenna arrays listening, they are old. I'd expect at least similar (and most likely much better) communications array capabilities from any TL 12+ Starport installation

 

[Terry Mixon]

How far away are the Voyager probes, operating on 220 watts of power after losing slightly more than half their original power levels due to radioactive decay?
While we have big honking antenna arrays listening, they are old. I'd expect at least similar (and most likely much better) communications array capabilities from any TL 12+ Starport installation

But those receivers are directional. I hear the part where the signal would be weakly detectable, but it would have to be detectable in non directional receivers. I’m still working on grasping that.

 

[Arkathan]

Compare the power level of a Traveller modern broad transmitter to 220 watts of the entire Voyager spacecraft.
Then factor in whether the lifeboat occupants know which dot out there is the main world, and if any of them can use Comms skill to boost signal/ make it (semi-)directional.

 

[Arkathan]

Also, It is a beacon. Assume the transmitter is rapidly rotating like a 3D light house on crack to make sure it can be more easily detected.

Edit: from anywhere in the system, not just the main world.

 

[Terry Mixon]

Also, It is a beacon. Assume the transmitter is rapidly rotating like a 3D light house on crack to make sure it can be more easily detected.

Edit: from anywhere in the system, not just the main world.

It’s an unmanned pod so omnidirectional is the goal.

 

[phavoc]

How far away are the Voyager probes, operating on 220 watts of power after losing slightly more than half their original power levels due to radioactive decay?
While we have big honking antenna arrays listening, they are old. I'd expect at least similar (and most likely much better) communications array capabilities from any TL 12+ Starport installation

Voyager signals are a bit of a cheat. Because they know exactly where to look and what to listen for the deep space network is able to pick up the signals. Had they been sent with no knowledge on Earth of when or where to listen for them, it's debatable whether or not they'd get picked up. There's actually only one antenna (in AUS) that is capable of talking to Voyager (but only one of them I think).

The radio on Voyager doesn't have 220 watts of power, just about 22. I forgot which one is the furthest now, something like 23 light hours away.

 

[rinku]

Yeah, Voyager is a special case, although it does help demonstrate how weak a signal can be detected at what are well past normal interplanetary ranges now.

But for this I think it's fair to assume a pretty strong signal at source. It's JUST a transmitter and can use whatever modulation makes sense.

We're talking a distress signal maybe from Jupiter, not the heliopause.

Using the 500,000km communicator as a base works for me.

Also...

Whatever the signal strength is at 500,000km, it will be 1/4 that strength at 1,000,000km, 1/9 that strength at 1,500,000km, 1/16th strength at 2,000,000km and so forth, under the inverse square law. And that applies to omnidirectional broadcasts.

 

[Arkathan]

Voyager signals are a bit of a cheat. Because they know exactly where to look and what to listen for the deep space network is able to pick up the signals. Had they been sent with no knowledge on Earth of when or where to listen for them, it's debatable whether or not they'd get picked up. There's actually only one antenna (in AUS) that is capable of talking to Voyager (but only one of them I think).

The radio on Voyager doesn't have 220 watts of power, just about 22. I forgot which one is the furthest now, something like 23 light hours away.

I stipulated that all of Voyager only had 220 watts. It is reasonable to assume that an emergency beacon would use more power than that. A repeated signal, on an emergency frequency transmitting a Signal GK is going to be something the computer(s) in the comm system is going to be programmed to detect and boost.

 

[agentwigggles]

How can a life pod in use be unmanned? Or am I confusing a life pod with an escape pod?

 

[MasterGwydion]

How can a life pod in use be unmanned? Or am I confusing a life pod with an escape pod?

These are not the droids you're looking for...

 

[rinku]

Ultimately, the pod doesn't have to detect itself.

It just has to shout loud enough to be heard by people listening.

 

[Terry Mixon]

How can a life pod in use be unmanned? Or am I confusing a life pod with an escape pod?

Escape pod (with emergency low berth) might be more accurate. I was also making lifeboats with low berths and might be mixing terms. The two seem interchangeable to me in this context but I can be convinced I’m wrong.

 

[Condottiere]

Smoke signals.

If they're looking into the infra red spectrum, release that heat in an obviously artificial way.

 

[rinku]

Radio works better. Even longer wavelength.

 

[Sigtrygg]

Add sensor range to comms range - that's the range at which you can detect a signal.

 

[MasterGwydion]

Add sensor range to comms range - that's the range at which you can detect a signal.

Yet a ship can see a star on their sensors from thousands of parsecs away. That doesn't really jibe with the sensor rules either.

Also, jump detection range is unlimited. You can detect a ship entering or exiting jumpspace from a thousand parsecs away as well. So, by the rules, I can detect a 100-ton ship exiting jumpspace on the other side of Charted Space, but a supernova can't be detected at that distance with Traveller rules.