RT 2 question

[7499275]

Right now I'm in career and don't have any powerful comms unlocked yet. So I'm setting up a crappy satellite array at 1.5 million meters. (150km?) Once I have the biggest sat dish I want to throw it at the edge of Kerbins SOI and have one dish point at a geo satellite above KSC. The geo sat will always have connection to KSC and then have the 2nd dish on the large sat point at Kerbin itself. with this method I should be able to connect to any craft I need almost right?

I'll throw in a little pic to explain what I want to do a little better.

The black lines represent the coverage area by the dish. Arrows point to which way the dish coverage is going.

Lastly... Can a dish connect to an omnidirectional sat and the reverse be true as well?

Edited January 7, 2014 by 7499275

[Dwight_js]

Your layout will work until Kerbin is blocking your ship's view of the Large sat. The GEO sat will also orbit faster than your Large sat, so there will be times when Kerbin gets between them and they won't be able to communicate. The most common comm sat constellation for this situation would be three GEO sats spaced evenly around Kerbin. The three sats can always see each other, and together they cover all space around Kerbin. There's a good wiki on how to set up comm networks:

http://wiki.kerbalspaceprogram.com/wiki/Tutorial:RemoteTech

The omni antenna is able to communicate with a directional dish, but both have to have enough range to reach the other. This is a main principle that you have to remember - you need two way communication. The dishes/antennas both have to have enough range to reach each other. Coverage angle is also important if you want to have a dish pointed at Kerbin so it can communicate with vessels orbiting the planet. You need to make sure that the dish has a wide enough cone (can't remember what they call that in the mod). The really big, long range dishes have very narrow cones, and if placed too close to Kerbin, your coverage area will be tiny and ineffective.

Edited January 7, 2014 by Dwight_js

[Eric S]

1.5 million meters would be 1500 km. This is low enough that the satellite could contact KSP with an omnidirectional antenna, and satellites can talk to each other provided you have four satellites 90 degrees apart instead of three 120 degrees apart. However, it's not at an altitude that would produce a synchronous orbit, so you'll need multiple satellites.

Actually, unless you're just communicating between places on Kerbin, you'll wind up wanting multiple satellites. With a single geostationary satellite, there will be times when the satellite is on the far side of Kerbin from whatever it is you want it to communicate with unless what you want it to communicate with is also in a geostationary orbit. Also, if what you want it to communicate with is either not in Kerbin's SoI or has an apoapsis above the Mun's orbit, it's quite likely that at some point the Mun (and other bodies as well) may be blocking line of sight between the geostationary satellite and what you want to communicate with.

In early career mode, I usually do three satellites each with a Communotron 16 and three or four of the DTS-M1 dish in identical circular orbits in the 650-800 km altitude range. At that height, one of them can always see KSC (though not the same one), they're close enough that the other two can communicate to the one that can see KSC through the Communotrons. The dishes on the satellites target the active vessel, the Mun, and Minmus. That gives me reasonable coverage within Kerbin's SoI, though sometimes I also put up three satellites around the Mun or Minmus, with just a Communotron 16 and a single DTS-M1 dish, with the dish aimed at Kerbin.

When I start entering the solar SoI, I usually either put up another three satellites with a Communotron and two long range dishes, or just replace the three existing satellites with satellites with four dishes, two short range and two long range. By this time, I'll have Communotron 32 antennas, which means that I can place the satellites at a higher altitude (though still not geostationary if I'm doing a three satellite constellation).

Finally, I believe a dish can communicate with an omnidirectional antenna, though you don't get the full range of the dish. Depending on the version of RT2 you're using (and possibly configuration settings), you may only get the range of the omnidirectional antenna.

[7499275]

ok thank you guys so much but I have one last question that I thought of...

If you have a dish that is pointed at the Mun or Minmus, and have one sat with a dish in orbit around the Mun or minmus that ios pointed at Kerbin and not the Kerbin satellite will they communicate?

[Dwight_js]

If both dishes have enough range and a wide enough field of view (cone, or whatever that is really called), and nothing is blocking their line of sight, then yes, they will communicate.

[Eric S]

Dwight_js is correct. basically, the longer range the dish, the more focused the transmission strength. Some dishes have fairly wide cones, 45 degrees or so, so half a right triangle, but some have a width of 0.01 degrees, so you wouldn't want to use that for the Mun or Minmus, because even at 47 Mm, the beam width would be less than 2km across, so you couldn't target Kerbin and expect to hit satellites in orbit around Kerbin with any kind of consistency. For that matter, Eve at it's closest point to Kerbin is about (wild guess not taking inclination into account) 3800000 km, which with a 0.01 degree spread gives it a spread that's still narrower than Kerbin itself even at that distance.

[7499275]

Awesome thanks guys! with your help I have set up working comms for the Mun and Kerbin!

[match]

One other detail regarding Dish antennae and targeting a body instead of a specific target... even if the intended vehicle is within the cone of the dish, it will not connect until it joins the SOI of the target.

ie A satellite in orbit around Kerbin has a dish pointed at Mun. Another satellite is en route to the Mun and is within the cone of the dish from the Kerbin satellite. If the dish is targeting "Mun", there will be no connection until the traveler enters the Mun's sphere of influence.

Hope this helps!