Question about Remotetech?

[makinyashikino]

Remotetech really confuses me, in the way of how satellites communicate with other, and their linkages, so if anyone is kind enough to answer my questions, that would be much appreciated.

1. I made a diagram to show my confusion(I cannot draw for my life though)

I have an SS-1(I think that's what it's called, the Duna dish one.) on the Duna probe, and the lesser range Mun dishes on the comms sat. I also have a small vehicle at the KSC with the Long range dish, the same as the one on the Duna probe. Even though there is a connection with both the commsat and the ground vehicle, It still says no connection on the probe. Any reason why, or at least an explanation of the mechanics?

2. What is the difference at pointing a sat at KSC or at Kerbin itself, if so, what are the benefits?

Thank you.

Edited December 17, 2013 by Cavenyanson
Typos

[jordanjay29]

Don't forget to point both dishes at each other (target the SS-1 to the comms sat, and the comms sat to the SS-1 on the Duna probe), otherwise they can't talk to each other. Mission Control is the only one you can just point at and have it work.

If you're low enough (geo-Kerbin Orbit is low enough) then consider using one of the omni-directional antennas for communicating to probes in Low Kerbin Orbit. Putting these on your comm satellites will erase the need to point dishes at Mission Control and each other, so long as the satellites are within range (GKO is under 3Mm, so any antenna but the Comm-16 should work). Then you can use your dishes to point at probes and things.

It took me some time to figure it out, too. If this is confusing, just ask. If you have more questions, just ask.

Honestly, I don't yet know what the benefit to pointing at a planetary body is. I thought it was intended to target the closest receiving relay around that body, but I haven't seen it work that way. I could be doing it wrong, so don't take my word for it.

[DeMatt]

Remotetech really confuses me, in the way of how satellites communicate with other, and their linkages, so if anyone is kind enough to answer my questions, that would be much appreciated.

1. I made a diagram to show my confusion(I cannot draw for my life though)

I have an SS-1(I think that's what it's called, the Duna dish one.) on the Duna probe, and the lesser range Mun dishes on the comms sat. I also have a small vehicle at the KSC with the Long range dish, the same as the one on the Duna probe. Even though there is a connection with both the commsat and the ground vehicle, It still says no connection on the probe. Any reason why, or at least an explanation of the mechanics?

Five things are needed to form a link:

1. Each end has power to run its antenna.
   
2. The antenna on each end has the range to reach the other end.
   
3. The antenna on each end is targeted on the other. (This step does not apply to omnidirectional antennas.)
   
4. There is a clear line of sight between the two ends.
   
5. One end has "command", that is it has a link path to Mission Control.

My bet would be that you don't have enough antennas on your commsat/vehicle, so when they're talking to your probe, they're not relaying to KSC.

2. What is the difference at pointing a sat at KSC or at Kerbin itself, if so, what are the benefits?

Targeting a dish on e.g. KSC will cause it to only attempt to form a link with KSC. Targeting a dish on Kerbin will, assuming the dish's field of view permits it, allow it to try linking with anything it can see, such as orbiting commsats.

[Hodo]

The funny thing is, being a former LOS communications tech in the Army I take these little things for granted and do them automatically. But Jordan is pretty much spot on with his answer.

The best way to handle long range missions like that is to have a secondary set of satellites that have REALLY long range broad band antenna on them for communications with probes that far out. I know for my Eve landing I used the dish that has the 25deg sweep on my CommSat 3K network which sits at 350km orbit around Kerbin. And the probe just had a simple Omnitech 32 and the other black collapsible one. I had a pseudo relay unit in orbit, the XI-2 craft which brought the probe, it was manned but wasn't a mobile command center, it only had a crew of 4 and no large remote control unit, but it did have the antenna to reach kerbin when it was in sight.

[Eric S]

If you're low enough (geo-Kerbin Orbit is low enough) then consider using one of the omni-directional antennas for communicating to probes in Low Kerbin Orbit.

Actually, while I agree with this idea, geo-kerbin orbit is not low enough if you're doing three satellites (or using the Communotron 16s, but you already covered that).

Here's a little geometry/trig for satellite setup in KSP for anyone that finds this thread at a later date (my math skills are a little rusty, so feel free to verify all of this):

Four satellites at a geosync altitude of 2868750m above a 600000m sea level, this gives a distance of 3468750 m from the center. At 90 degrees of separation, that gives you a satellite to satellite distance of 4905553.3m, which is just under the 5 Mm range limit of the 32s. At 120 degrees of separation, that gives you a distance just over 6 Mm, which is longer than the communication range of any omnidirectional antenna in RT2.

The obvious solution if you either don't have the Communotron 32 yet, or if you only want to use three satellites is to lower the orbit. Geostationary is used in reality because it's easier to communicate with a satellite that never moves. We don't have that issue in KSP with RT2, satellites are tracked as necessary. The only disadvantage for us is that all of the satellites have to be able to communicate with the ground. This would be an issue if we were using dishes, but not with omnidirectional antennas, since the same antenna that communicates with the other satellites can also communicate with mission control.

Since a synchronous orbit works for the Communotron 32 with four satellites, cutting the distance from the center in half will work for the Communotron 16, so your ceiling from the center becomes 1734375 m, or 1134375m altitude above kerbin sea level.

In the case of a three satellite network using Communotron 32s, your max distance from the center would be about 3468750 m / 6008051 * 5000000, or 2886751 m from the center or 2268751 m above Kerbin sea level.

For three satellites with communotron 16s, your max distance from the center would be half of that, or 1443375m, resulting in a max height of 843375m.

I should point out that those maximum height numbers for the three satellite configuration have no margin of error, so I'd orbit at least a few kilometers below that point.

There's a minimum orbit too for this, the point at which Kerbin is in the way of two satellites trying to communicate. With a radius of 600 km, for a 4 satellite configuration, you have to be at 248529 m above sea level to have line of site. For a 3 satellite configuration, that increases to 600000m.

In my career mode saves with RemoteTech 2, I've been using a three-satellite configuration where each satellite has a communotron 16 and three of the smallest dishes, aimed at active vessel, the Mun, and Minmus, at an altitude of 776.57km above sea level (a 1.5 hour orbit) with no issues. Once I start heading to other planets, I add another three satellites with a Communotron 16/32 and two big dishes, one set to active vessel and one to whatever planet I'm exploring. By the time I can put craft large enough to have enough long range antennas to cover the entire system without switching planet targetting, I'm usually so close to finishing the tech tree that I don't bother, since I start a new save as soon as the tree is finished (at least until we get more of career mode).

[makinyashikino]

Wow Thanks guys, you're really helpful!