Radio and Tightbeam Comm Range

[rgrove0172]

Im thinking I read somewhere in one of the rulebooks or sourcebooks that radio communications, and tight beam laser communications, were effective out to a certain distance. (If you can recall where, let me know - I cant find it!)

Ive read where standard radio transmissions could be recieved up to 20 light years away - and thats with today's technology (not that a 20 year old message would do you much good in a game for the most part)

In that they both travel at the speed of light, what would the advantage of a tightbeam rig be over conventional radio in the space environment?

 

[shaunhilburn]

In that they both travel at the speed of light, what would the advantage of a tightbeam rig be over conventional radio in the space environment?

Signal power is transmitted in all directions with a broadcast. If you intend only a single recipient for the signal, then all that broadcast power is wasted. It's more efficient to concentrate it into a beam and direct it at the recipient. Watt-for-watt, a tight beam as greater reception range than broadcast.

Tight-beam signals are more secure. They're nearly impossible to eavesdrop on since the intruder has to both A) be aware of the signal's existence and B) position himself in the beam path in time to intercept the signal.

 

[rgrove0172]

Ok so I get security. As for signal strength...what's a good rule of thunb? Radio out to....km and tightbeam out to....km

 

[shaunhilburn]

Ok so I get security. As for signal strength...what's a good rule of thunb? Radio out to....km and tightbeam out to....km

It depends on the power of the transmitter and the sensitivity (gain) of the receiver. We're still receiving signals from Voyager 2, over 100 AU distant. They're exceedingly weak signals but still contain intelligible data. On the other hand, we're receiving them with very sensitive, very large antennas.

Dish antennas are probably the best prospect for ship-ship interplanetary communication over a distance of a few AUs. I'm thinking of the old largish satellite TV dishes from the 1980s, the ones about 8 feet in diameter. I used to be a radio & radar repair tech many years ago, and I've forgotten all the formulas, but I still have textbooks around. I'll have to dig them out.

I'm pretty sure it comes down to :
- transmitting power (probably in kilowatts)
- transmitting antenna gain (beam tightness)
- attenuation (in db) due to beam-spread over distance D
- receiver gain (sensitivity) in db.

 

[McPerth]

In any case, I guess trying to send a message in thight beam to a ship that moves so fast, and that is tunneling thousands of times per second may be quite difficult, IMHO, as you must keep the beam focused to something that is there and is not and whose position changes quite fast, even id STL. So, I guess messages must be quite comprised and be sent several times repeated, hoping that it can be "puzzled" to a whole message by the computer.

 

[rgrove0172]

Theres a bit somewhere (probably in the same place as the other commentary IM still looking for) that describes how stutterwarp ships can dial in to another friendly ship's cycle, essentially compensating for the fragmented signal, if they know the precise specifics. The signal would be so much garble to anyone else without the appropriate 'coding' but would make perfect sense when recieved by the target ship. I cant recall if this was assumed a tight beam communique or not, but I doubt it, for reasons you give about trying to hit the damned thing with your laser!

Where is that article? ugh

 

[shaunhilburn]

Theres a bit somewhere (probably in the same place as the other commentary IM still looking for) that describes how stutterwarp ships can dial in to another friendly ship's cycle, essentially compensating for the fragmented signal, if they know the precise specifics. The signal would be so much garble to anyone else without the appropriate 'coding' but would make perfect sense when recieved by the target ship. I cant recall if this was assumed a tight beam communique or not, but I doubt it, for reasons you give about trying to hit the damned thing with your laser!

Where is that article? ugh

Since the jump takes zero time, and the passage of time is apparently unaffected by stutterwarp, it follows that there is a brief recovery interval between jumps of a few or perhaps a dozen microseconds.

If communication takes place during jump intervals, the transmission & reception need not be choppy since the duration of the jump is zero.

 

[rgrove0172]

Yes, but I think the gist of the article I was reading was that longer transmissions can be linked, if the appropriate intervals were programmed in. A millisecond doesnt give you much time to get any information across, unless its some form of hyper-burst or something. Certainly a possibility, even today's technology permits a great deal of data in only a second of connection.

 

[shaunhilburn]

Yes, but I think the gist of the article I was reading was that longer transmissions can be linked, if the appropriate intervals were programmed in. A millisecond doesnt give you much time to get any information across, unless its some form of hyper-burst or something. Certainly a possibility, even today's technology permits a great deal of data in only a second of connection.

The duration of the jump is zero, therefore there is zero interruption in the transmission.

The transmission just carries over on into the next interval without interruption, so it doesn't matter how brief the jump intervals are as long as the jump takes zero time.

To visualize it, take the phrase "Hello Earth!", and chop it up into a thousand pieces. Now arrange them so that there is absolutely zero space (zero jump duration) between the pieces.

 

[rgrove0172]

Aha! Found it... Challenge 30, page 40... Stutterwarp Technology - refering to communications;

"Thus, the second method is a quite complex system which is used commonly on many military vessels. When such a vessel wishes to transmit a message to an object which is relatively stationary, it sends the message along with a pulsed signal which gives the ship's exact cycle rate and velocity vector relatvie to a standard inertial reference point. The receiver than runs the trasnmission through a computer which decodes the ship's vector information signal (called a DDB or Dynamic Data Burst) and corrects for any distortions. Now, if the stationary reciever wishes to transmit a signal back, it sends out its response in a chopped form fashioned for thes ship to read with no computer assistance, that is, unless they have changed thier heading, speed or cycle rate since their initial transmission. The same mechanics apply to two ships using stutterwarp, except the inital message is just the DDB. The reciever ship reads the DDB and alters its cycle rate slightly to mesh with the transmitting ship's. It then sends a confirmation signal that it is ready to recieve and meaningful communication can occur."

 

[BMonnery]

Aha! Found it... Challenge 30, page 40... Stutterwarp Technology - refering to communications;

"Thus, the second method is a quite complex system which is used commonly on many military vessels. When such a vessel wishes to transmit a message to an object which is relatively stationary, it sends the message along with a pulsed signal which gives the ship's exact cycle rate and velocity vector relatvie to a standard inertial reference point. The receiver than runs the trasnmission through a computer which decodes the ship's vector information signal (called a DDB or Dynamic Data Burst) and corrects for any distortions. Now, if the stationary reciever wishes to transmit a signal back, it sends out its response in a chopped form fashioned for thes ship to read with no computer assistance, that is, unless they have changed thier heading, speed or cycle rate since their initial transmission. The same mechanics apply to two ships using stutterwarp, except the inital message is just the DDB. The reciever ship reads the DDB and alters its cycle rate slightly to mesh with the transmitting ship's. It then sends a confirmation signal that it is ready to recieve and meaningful communication can occur."

Yes, but it requires the warping vessels to maintain exactly the same course and speed, and preferably be moving "across" the sky rather than changing distance.

We have to take it as read comms are possible, but it is an extremely non-trivial problem - especially if the vessel has to maneuver (i.e. in combat). Hence the need really to have a manned station each end adjusting the comms laser (and at any real range it's almost certainly a laser as the radio can't be collimated enough) and then shifting the packets into usable data. As distances increase and also pseudovelocity (and course) bandwidth drops, possibly quite dramatically. Voice is probably unlikely with warping ships. Even sensor returns from a reasonable array (a few thousand transmit/receive modules) seem problematic.

 

[McPerth]

Yes, but it requires the warping vessels to maintain exactly the same course and speed, and preferably be moving "across" the sky rather than changing distance.

We have to take it as read comms are possible, but it is an extremely non-trivial problem - especially if the vessel has to maneuver (i.e. in combat). Hence the need really to have a manned station each end adjusting the comms laser (and at any real range it's almost certainly a laser as the radio can't be collimated enough) and then shifting the packets into usable data. As distances increase and also pseudovelocity (and course) bandwidth drops, possibly quite dramatically. Voice is probably unlikely with warping ships. Even sensor returns from a reasonable array (a few thousand transmit/receive modules) seem problematic.

I fully agree. IMHO maintaining thigh beam communications among maneovering ships (e.g. in combat) would be so difficult that most communications would be in fully compressed, multiple repeated radio, as told before, so even if a ship gets just some fractions of it its computer may convert those into a full ininetilgible message.

Unless the ships are in paralel courses and at same speed, the messag will always arrive in pieces, as the change in place for a ship, being instantaneous, puts the ship at different nanosecond of the relayed message.

See that this precludes visual teleconferences among warping ships, and makes the communications a message-answer matter, more akin to email communication tan to chat, so to say.

 

[rgrove0172]

I assume periodic (perhaps once a minute) lulls of a second or two in order to allow sensor returns, comm burst or what have you to catch up, realign etc. The nav computer performs these "Stutter Lags" or "hiccups" as the star jocks like to call them, automatically. They arent even noticed by the crew.

 

[McPerth]

If the messages must be compressed and coded before sending them, and mounted from pieces (as I said before), decompressed and decoded before reading them, I'd expect a little more, a minute being the minimum time (more if the ships are far away, as the waves go at light speed).

 

[shaunhilburn]

I assume periodic (perhaps once a minute)comm burst or what have you to catch up, realign etc.

I don't get it. Why do you have to catch up & realign?

 

[rgrove0172]

Well I suppose if you assume computers are capable of making the necessary computations thousands of times a second with each new position the ship occupies after each intantaneous stutter jump, and that whatever sensor data is being recieved is instantly available and processed, then you wouldnt.

 

[shaunhilburn]

Well I suppose if you assume computers are capable of making the necessary computations thousands of times a second with each new position the ship occupies after each intantaneous stutter jump, and that whatever sensor data is being recieved is instantly available and processed, then you wouldnt.

Assume you're stuttering through STL space. Why would computations be necessary for signal reception?

 

[BMonnery]

Assume you're stuttering through STL space. Why would computations be necessary for signal reception?

To make the system work, unless it's low bandwidth morse - that works but is more like a signal light.

 

[shaunhilburn]

To make the system work, unless it's low bandwidth morse - that works but is more like a signal light.

Something is interrupting the signal, requiring synchronization and signal processing. A stutter cycle is instantaneous - zero time, so its not the tunneling action.

What is it?

 

[aramis]

Assume you're stuttering through STL space. Why would computations be necessary for signal reception?

Because you're losing signal during the microsecond gaps, and because you're also leaping several hundred meters... a µLS is 2.96km, so at any pseudospeed in excess of about 0.01c, you need to account for the leaps because it's going to significantly affect the apparent gap length.