ResslynHalvik
Cosmic Mongoose
Hmmm. I'm struggling to work out how to use a single satellite in orbit over the equator to determine position...
Rules Clarification: Agent Programs (CSCp69)
- Thread starter Yenaldlooshi
- Start date
ProfGrizzlyJon
Cosmic Mongoose
A Geo-Ranging Navigation System (GRNS) is a radio-navigation method that uses a geostationary satellite as a fixed reference point in space. By timing a radio signal’s round trip to the satellite, it determines range—the distance between the receiver and that orbital beacon. Combined with azimuth (compass bearing), elevation (angle above the horizon), and the satellite’s known longitude, the GRNS can precisely locate a vessel or surface station on a planetary body. The azimuth shows direction, the elevation shows height above the horizon, and the range defines distance to the satellite.
If that is the case why is it any more challenging to get a bearing than with GPS? It either provides the data automatically or you cannot get LOS to the stationary satellite and it doesn't. The positional fix is as accurate as the receiving system makes it.
To the roll to plot a course is the skill to use that positional fix. Whether you can get the fix itself is entirely determinable by the referee or the setting (such as the comms satellite coverage in the Tarsus setting book).
To the roll to plot a course is the skill to use that positional fix. Whether you can get the fix itself is entirely determinable by the referee or the setting (such as the comms satellite coverage in the Tarsus setting book).
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ResslynHalvik
Cosmic Mongoose
I've never heard of that.
The individual device would need to know precise orbit information for the satellite, and from the description the device needs to be transmitting to the satellite as well, and it needs a way for measuring angular elevation. The transmission would probably be something of a power sink, but that's overcomeable. I don't understand how measuring the elevation works. And it can all only work in a very small circle on the surface below the orbit point, surely?
Edit: correcting myself - no not a relatively small circle. Assuming a perfectly even sphere with no terrain, a satellite in GSO is geometrically visible from approximately 42% of the body's surface. (Assuming the same relationship between gravity and body radius that we have on Earth). So even allowing for some terrain, 3 geostationary satellites with 100% service availability cover the entire planet between ±81°
But I still don't understand how a handheld device is able to measure precise elevation to a satellite at an altitude of (on an earth size and mass body) of 36,000km
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Standard GPS technology to a single satellite gets a line of bearing. You know you are somewhere along that line. The normal route is to compare other Lines of bearing to other satellites and from that you triangulate your position.
An alternative method to finding where you are on that line is to measure the round-trip time of the radio signal and calculate it. You could do that by sending a signal and waiting for the response. Alternatively if you both have synchronised time signals the satellite just needs to broadcast the precise time. You only need to be able to receive the time signal and you just compare it to your own time to see how out of date it is. That tells you how long it took to get there and thence how far away along that line of bearing you are. There are complications of course, you need to account for the processing time, you'll need to compensate for the curvature of the earth etc. Keeping the clocks in synch is also necessary, but probably trivial in the future.
ResslynHalvik
Cosmic Mongoose
I disagree with this. If my phone picks up just one GPS satellite, it has no idea what direction that signal's coming from. Ignoring altitude and clock drift the signal from one satellite gives me a circle on whose circumference I could be anywhere.
ProfGrizzlyJon
Cosmic Mongoose
Exactly.
GPS satellites transmit continuously, but they send one-way timing signals rather than responding to two-way range pings. Each GPS satellite broadcasts a precise time code and orbital ephemeris (position and velocity), allowing the receiver to measure how long the signal took to arrive. With signals from four or more satellites, the receiver can solve for both position and clock error without ever transmitting anything.
By contrast, the Geo-Ranging Navigation System (GRNS) concept is a two-way ranging system — the receiver sends a brief, coded pulse to the satellite, which immediately echoes it back. The round-trip time gives the exact range to that single satellite. This means GRNS can fix position from one satellite, provided it also determines azimuth and elevation, but it does require the receiver to transmit, unlike GPS’s purely passive design. This takes advantage of the ubiquitous nature of transceivers in electronics (e.g, any transceiver with Regional Range of 500km can reach orbit fairly easily)
GRNS can also work from a ship in orbit. Once they cancel out the ground speed with some acceleration, the ship is basically parked and can act like the satellite.
(Sorry, I am a Position/Navigation/Timing nerd and spent a lot of brainpower trying to figure out various analogs to the old LORAN/VOR/GPS systems for use in Traveller games- functionally, GRNS is a planetary-scale extension of TACAN/DME and was the precursor to the Inner System-Ranging Navigation System aka ISRNS that provides the same function for interplanetary travel)
ResslynHalvik
Cosmic Mongoose
On earth, GSO is 36,000km, though.
And, I don't understand how you precisely measure angle of elevation from a device on a planet's surface to something you can't see 36,000 to 42,000km away.
I can just about see the ISS with the naked eye, but (1) I know where to look to find it because I know where I am, (2) it's only about 400 km away, (3) it moving so easier to spot and (4) it's huge
If there needs to be two-way communication then presumably band-width is a limitation of the system (whereas broadcast GPS can be received by everyone in range).
I am more used to Tactical Datalinks where each participant transceiver measures round-trip timing to all others in LOS and their best-guess positions (GPS, INS or blend), and then working out the relative separations and correcting. This requires at least one participant to "know" the actual time though as Net Time Reference and everyone needs to be honest about how good their positional accuracy or the algorithms can never solve the complex calculation.
All very complicated
ResslynHalvik
Cosmic Mongoose
Sure - by very skilled users, using high magnitude, well-known stars, to a low degree of precision.The sextant fixed position by the position of stars above the horizon and they are gazillions of miles away
ResslynHalvik
Cosmic Mongoose
I just don't understand how the traveler knows exactly (or even vaguely) where to point their mobile computing device or whatever it is to measure the elevation. During daylight there's definitely not going to be anything to look at. Even during night how are they distinguishing the near invisible dot of a tiny satellite about 40,000 kilometers away from the stars around them?
I don't think they need to point it. The device can have an omni directional antenna. If it had a uni-directional all it needs is a signal strength indicator. Or it could have a spinning antenna and it could work it out itself. All you need to do it keep it still (or put it down).
The sun is also broadcasting in all directions, but you can detect where it is. I don't think there would be any problem getting latitude from a single point transmission in a geostationary orbit, if you know the world's radius. If you have the latitude that puts you on one of two points on the range circle that Resslyn is thinking of... but since it's in a geostationary orbit, not off thataway and moving across the sky like a star, you should also be able to work out if you're east or west of the satellite too. Which gives a location.
(Note that satellite can determine its OWN position in any number of ways, but likely by sighting celestial objects. And it can broadcast that without needing to know where any mobile devices are).
All the rest is just precision.
(Note that satellite can determine its OWN position in any number of ways, but likely by sighting celestial objects. And it can broadcast that without needing to know where any mobile devices are).
All the rest is just precision.
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ResslynHalvik
Cosmic Mongoose
We seem to be getting at crossed purposes. My comment was on https://forum.mongoosepublishing.co...ion-agent-programs-cscp69.125603/post-1020199, where Jon says that the user needs to know azimuth and elevation to use his GRNS.
This sub-part of the thread seems to have got muddled, so I'll back out of it now.
I would like to return to the orinal thread of Agent, Intellect, etc software, though, as I have realised I am still unclear on some parts of that.
As was discussed a lot earlier, the terminology is half the problem, and you have the original CRB rules modified by CSC further confusing it.
Interface is just Windows. (Name checks out. But maybe Basic Interface would be better)
Intelligent Interface allows voice control and makes decisions about how data is displayed. Required for a meatbag to use Expert software but IS NOT ACTUALLY A THINKING MACHINE. Maybe Google assistant. (I'd change this to Advanced Interface.)
Expert software is the Skill stuff. Meatbags can use it to improve their skill roll, whether they know the skill or not. AI can use it to do stuff. (I'd change this to Skill software)
Agent software is AI that only knows how to do Electronics (computer) stuff, but is quite capable of working things out within its skill limitation. Note however that Electronics (computer) can be used to interface with stuff that might be able to do a whole lot more. It's not totally clear if this counts as Electronics 0 for the other specialties, but I wouldn't object to an Agent program using communications or remote ops at that level, especially if instructed to. (Name checks out, but maybe Basic Agent would be better)
Intellect software is general AI you can plug Expert software into. (I'd change this to Advanced Agent)
Intelligent Interface software and Intellect software both make use of Expert software, which is where a lot of the confusion arises, I think. But the former is for a user, while the latter is a user.
Interface is just Windows. (Name checks out. But maybe Basic Interface would be better)
Intelligent Interface allows voice control and makes decisions about how data is displayed. Required for a meatbag to use Expert software but IS NOT ACTUALLY A THINKING MACHINE. Maybe Google assistant. (I'd change this to Advanced Interface.)
Expert software is the Skill stuff. Meatbags can use it to improve their skill roll, whether they know the skill or not. AI can use it to do stuff. (I'd change this to Skill software)
Agent software is AI that only knows how to do Electronics (computer) stuff, but is quite capable of working things out within its skill limitation. Note however that Electronics (computer) can be used to interface with stuff that might be able to do a whole lot more. It's not totally clear if this counts as Electronics 0 for the other specialties, but I wouldn't object to an Agent program using communications or remote ops at that level, especially if instructed to. (Name checks out, but maybe Basic Agent would be better)
Intellect software is general AI you can plug Expert software into. (I'd change this to Advanced Agent)
Intelligent Interface software and Intellect software both make use of Expert software, which is where a lot of the confusion arises, I think. But the former is for a user, while the latter is a user.
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ResslynHalvik
Cosmic Mongoose
Yes, that would help the initial understanding. And diagrams.
My current questions are about what the different levels of the assorted interface packages mean, and also what appear to be pretty basic contradictions between CRB and CSC. I'm going to look back through the older parts of the thread to see if they already got covered.
My current questions are about what the different levels of the assorted interface packages mean, and also what appear to be pretty basic contradictions between CRB and CSC. I'm going to look back through the older parts of the thread to see if they already got covered.
Yeah, sorry allowed myself to get sucked in there on my own tangent. Sorry.
ResslynHalvik
Cosmic Mongoose
You and me both - if there's a loose thread, I'll pull on it 
MasterGwydion
Emperor Mongoose
Sadly, me three...You and me both - if there's a loose thread, I'll pull on it
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