Emergency Beacon Detection Range
- Thread starter Terry Mixon
- Start date
The simple answer about EM vs gravity is that gravity is MUCH MUCH weaker and harder to detect. You can transmit radio with a wire coat hanger as the antenna. Detectable gavity waves come from stuff like close orbiting black holes.
Both propogate at the speed of light in a vacuum, so neither has an advantage there.
Both propogate at the speed of light in a vacuum, so neither has an advantage there.
MasterGwydion
Emperor Mongoose
Yeah, but each of those ships can install them and they have exactly the same sensor ranges.
Arkathan
Emperor Mongoose
Same. But longer.
Fluffy Bunny Feet
Cosmic Mongoose
How big is the heat radiator for getting rid of the heat from the losses? Not to mention the power plant in that life pod and its fuel consumption.
Fluffy Bunny Feet
Cosmic Mongoose
Built and sold by a low bidder and never expected to be used. Not any more powerful or reliable than the law requires. Unlike the probe which cost a fortune and designed to handle anything the scientists could think of.
I am the person suggested the interplanetary transciever be added to an escape pod. I feel unlimited jump detection range is silly. It's clearly a case of Mongoose trusting refs to do what is reasonable in thier game. I feel a transponder or distress beacon are intended for use inside a 100 D limit but not a full system. Full system cover is the province of fleet bases and A class ports. I have made several assumptions.
1. An interplanetary transciever and ship's transponder are roughly equivalent.
2. A ship's transponder is detectable at greater ranges than the ship itself.
3. Designers thought in terms of 100 D limits for ships.
Page 26 of High Guard redefines the distant range band to 50,000 km to 300,000 km and introduces very distant (300,000 - 5,000,000 km) and far (over 5,000,000 km). Page 66 of the Starship Operators Guide mentions that ships can classify objects as ship or not ship at a few million km.
Page 73 of the Starship Operators Manual has a section on system wide sensors and even mentions that sensor nodes operating across an entire could achieve a resolution of 1 meter at 1500 parsecs.
While not explicitly stated, an interplanetary transciever and standard ship's transponder are likely similar in power. As a house rule for both transponders and distress beacon detection ranges, I would use 10,000,000 km x the total hardware DM if it is positive or 1 over the DM if it is negative.
At the high end, a ship with advanced sensors and Enhanced Signal processing will have a detection of 60,000,000 Km. That would cover even Jupiter out to 450D but insufficient to reach other plants except during close approaches. At the low end, civilian sensors will receive a distress call at 2,500,000 km. That is sufficient to cover the entire 100D limit of even the largest terrestrial world from anywhere inside it.
Additionally, the use of a distributed array, extended array, or rapid deployment extended array will increase the base range five fold. Most C class starports will have such an array combined with improved sensors and improved signal processing for a total range of 150,000,000 km. That is sufficient to cover about a quarter of the inner system and may be combined with a few watch towers throughout inner system to achieve full coverage.
B class ports will be able to monitor the entire inner system through either improved sensors or remote platforms. Additionally, major celestial bodies in the outer system will at least have remote sensors but the outer system lacks full coverage. An A class port will have substantial sensors and be capable directly monitoring both the inner and outer systems but coverage of the Kuiper belt will limit remote platforms on dwarf planets at best.
Fleet bases and Scout Bases will be able to cover both the inner and outer systems fully but only the most vital systems will cover the Kuiper belt.
This only covers distress beacons and transponders but might also be a reasonable metric for detecting jump signatures. If every ship can easily communicate across an entire system, it changes to many story dynamics.
1. An interplanetary transciever and ship's transponder are roughly equivalent.
2. A ship's transponder is detectable at greater ranges than the ship itself.
3. Designers thought in terms of 100 D limits for ships.
Page 26 of High Guard redefines the distant range band to 50,000 km to 300,000 km and introduces very distant (300,000 - 5,000,000 km) and far (over 5,000,000 km). Page 66 of the Starship Operators Guide mentions that ships can classify objects as ship or not ship at a few million km.
Page 73 of the Starship Operators Manual has a section on system wide sensors and even mentions that sensor nodes operating across an entire could achieve a resolution of 1 meter at 1500 parsecs.
While not explicitly stated, an interplanetary transciever and standard ship's transponder are likely similar in power. As a house rule for both transponders and distress beacon detection ranges, I would use 10,000,000 km x the total hardware DM if it is positive or 1 over the DM if it is negative.
At the high end, a ship with advanced sensors and Enhanced Signal processing will have a detection of 60,000,000 Km. That would cover even Jupiter out to 450D but insufficient to reach other plants except during close approaches. At the low end, civilian sensors will receive a distress call at 2,500,000 km. That is sufficient to cover the entire 100D limit of even the largest terrestrial world from anywhere inside it.
Additionally, the use of a distributed array, extended array, or rapid deployment extended array will increase the base range five fold. Most C class starports will have such an array combined with improved sensors and improved signal processing for a total range of 150,000,000 km. That is sufficient to cover about a quarter of the inner system and may be combined with a few watch towers throughout inner system to achieve full coverage.
B class ports will be able to monitor the entire inner system through either improved sensors or remote platforms. Additionally, major celestial bodies in the outer system will at least have remote sensors but the outer system lacks full coverage. An A class port will have substantial sensors and be capable directly monitoring both the inner and outer systems but coverage of the Kuiper belt will limit remote platforms on dwarf planets at best.
Fleet bases and Scout Bases will be able to cover both the inner and outer systems fully but only the most vital systems will cover the Kuiper belt.
This only covers distress beacons and transponders but might also be a reasonable metric for detecting jump signatures. If every ship can easily communicate across an entire system, it changes to many story dynamics.
You still have light speed lag.
A ship should be able to send a message to the outer system, but we are talking hours for the signal to get there and the same time for it to be sent back.
Detectability isn't the major bottleneck - it's bandwidth. But for the purposes of a distress beacon, you barely need any . It can communicate by simply turning itself on and off.
We've discussed before about the issues with reacting to anything that happens in the outer system. Jump takes a week. Realspace interception takes at least days. Even realising something is happening at all takes hours, which may well be enough time for intruders to do what they came for and leave.
A ship should be able to send a message to the outer system, but we are talking hours for the signal to get there and the same time for it to be sent back.
Detectability isn't the major bottleneck - it's bandwidth. But for the purposes of a distress beacon, you barely need any . It can communicate by simply turning itself on and off.
We've discussed before about the issues with reacting to anything that happens in the outer system. Jump takes a week. Realspace interception takes at least days. Even realising something is happening at all takes hours, which may well be enough time for intruders to do what they came for and leave.
CordwainerFish
Emperor Mongoose
It's not power that decides the size of your antenna, it's the wavelength you want to operate at.
On that note, there might be unsuitable frequencies to use for a space distress beacon. Gas giants can be mighty radio sources, so any beacon that operated in typical wavelengths for those might be almost useless if near one (which you'd think would be a common scenario). Stars may be another consideration, but I'd guess there's some frequency that would work.
Arkathan
Emperor Mongoose
Harder to get away with that in a fabricator economy.
Condottiere
Emperor Mongoose
1. Jump flashes detection (and range thereof) should be based on the energy input of the jump drive.
2. Lowest, currently, is two and a half power points, from default ten.
3. Megatonne freighter at likely factor/three, three hundred thousand power points.
4. Knowing how far you want that detected, will let you know the range.
5. As long as you have fuel and a functioning fusion reactor, you can divert energy every turn into a transmitter, whatever energy it outputs.
2. Lowest, currently, is two and a half power points, from default ten.
3. Megatonne freighter at likely factor/three, three hundred thousand power points.
4. Knowing how far you want that detected, will let you know the range.
5. As long as you have fuel and a functioning fusion reactor, you can divert energy every turn into a transmitter, whatever energy it outputs.
Fluffy Bunny Feet
Cosmic Mongoose
Not really. In a fabricator economy you may reduce the amount of the more valuable elements thereby reducing quality and cost but increasing your output for the same value input.
As a point, nothing in the HG section that talks about extreme range sensors and mentions jump flashes as being detectable precludes extreme range detection of active transmissions.
No one is saying you can get much information at that range, but detection makes sense, especially for a signal that is designed to be noticed.
No one is saying you can get much information at that range, but detection makes sense, especially for a signal that is designed to be noticed.
ottarrus
Emperor Mongoose
Radio waves travel at the speed of light out to infinite ranges. The trick is to separate a transmission from the ambient noise. The more powerful the transmitter, the stronger the signal, the less it resembles background noise.
So yes, a more powerful transmitter matters.
So yes, a more powerful transmitter matters.
Are we assuming omi-directional transmission? If the life pod is on a course somewhere then it has an idea of destination. If so it can concentrate it's transmission in that direction. If it uses a Marx generator or something similar that pulse can be very high powered as a long as it is brief and the briefer, the more powerful.
An outer system SAR antenna grid can be as large as you like (or afford). In the outer system it can be better shielded against system radio traffic (blind to the habitable zone) meaning it can amplify a great deal without interference.
The limit to all this will be how much infrastructure a system is willing to dedicate to the hopefully infrequent incident of a life pod being released so far out that it cannot make it's own way in before life support fails (as then it becomes a far lower priority recovery operation). The lifeboat indicates months of life support. How long will people be actively looking for the little lost pod that tried? With M-Drive, how far can you actually effectively go seek? Can you actually jump/navigate to a tiny pod in the middle of nowhere. I would suggest that will determine the design range of the beacon and the systems to detect the beacons.
Years of life support whilst entirely possible seems excessive, there is little point in sustaining life if the chances of rescue are low. Once you are thinking in terms of years or decades, then the pod will need to make its own way in without intervention and a long range beacon is irrelevant.
TLDR:
Beacons can usually be detected within the 1000D limit of any system bodies (with a space port) as beyond that no credible response is possible anyway. Unusual astronomical phenomena might limit this (or in rare cases extend it). Basically this is Referee fiat. If you want it to happen it will.
An outer system SAR antenna grid can be as large as you like (or afford). In the outer system it can be better shielded against system radio traffic (blind to the habitable zone) meaning it can amplify a great deal without interference.
The limit to all this will be how much infrastructure a system is willing to dedicate to the hopefully infrequent incident of a life pod being released so far out that it cannot make it's own way in before life support fails (as then it becomes a far lower priority recovery operation). The lifeboat indicates months of life support. How long will people be actively looking for the little lost pod that tried? With M-Drive, how far can you actually effectively go seek? Can you actually jump/navigate to a tiny pod in the middle of nowhere. I would suggest that will determine the design range of the beacon and the systems to detect the beacons.
Years of life support whilst entirely possible seems excessive, there is little point in sustaining life if the chances of rescue are low. Once you are thinking in terms of years or decades, then the pod will need to make its own way in without intervention and a long range beacon is irrelevant.
TLDR:
Beacons can usually be detected within the 1000D limit of any system bodies (with a space port) as beyond that no credible response is possible anyway. Unusual astronomical phenomena might limit this (or in rare cases extend it). Basically this is Referee fiat. If you want it to happen it will.
Arkathan
Emperor Mongoose
Your only realistic difficulties are:
Low tech, low communications infrastructure systems;
Anomaly zones that block/distort signals;
Gas Giant radiation/magnetic fields;
Stellar corona;
Planetary/stellar occlusions.
If you have no deep space assets, and your boat is stranded around a moon of a distant, unused/undeveloped gas giant, you are going to be delayed for days or weeks if the moon is on the wrong side of the gas giant. Similarly, if you are on the wrong side of a star, you could wait months or if the only occupied world is an outer planet (again with no deep space relays), years before the signal has a clear path to anything that might detect it.
Low tech, low communications infrastructure systems;
Anomaly zones that block/distort signals;
Gas Giant radiation/magnetic fields;
Stellar corona;
Planetary/stellar occlusions.
If you have no deep space assets, and your boat is stranded around a moon of a distant, unused/undeveloped gas giant, you are going to be delayed for days or weeks if the moon is on the wrong side of the gas giant. Similarly, if you are on the wrong side of a star, you could wait months or if the only occupied world is an outer planet (again with no deep space relays), years before the signal has a clear path to anything that might detect it.
I'd expect Imperial tech to provide a much more powerful transmitter using batteries, or even a 52nd century RTG equivalent (though that had more power).
ottarrus
Emperor Mongoose
Radio waves emit in the 360 degrees, even directional radar signals. If you emit a radio signal, you're emitting 'in the round' so to speak. A directional transmitter greatly increases the signal strength along the transmission axis, but it should not be forgotten that you're transmitting in a circle.
This is why Traveller specifically differentiates 'tightbeam' signals via laser or meson beam.
Similar threads
