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Das_Sheep

Optimal Comm Network

Question

Das_Sheep    7

So I recently started a new career game and along with a good whack of mods have decided to go with a slight difference in the set up for the comm network - 100% occlusion, no extra ground stations - so here's my question:

What's the better way to set up an orbital network around Kerbin? Low altitude constellation of 4 or 5 sats evenly spaced or 3 in KEO with 120° separation? Or a combination of both?

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Streetwind    3817
Posted (edited)

A better question is: what do you need it to do? And what do you have available to work with? A LKO constellation of five sats with a HG-5 is not going to support Mun missions. But perhaps you want to get that SCANsat thing going now, and not wait until you research SOI-spanning relay antennas.

Don't fall into the trap of designing something for the sake of designing a perfect system. First and foremost, you need a solution that's useful to you. You can still replace it with a better solution later-on.

Edited by Streetwind

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Streetwind    3817
Posted (edited)

Well then. Four satellites should give you a reasonable system in one launch.

First, you need two satellites in stationary Kerbin orbit. Position the first one so that it can barely still get a link back to KSC over the horizon; make sure that any error in orbital period you're unable to avoid causes a drift towards KSC, not away from it, to avoid losing comms a mere month later. Position the second as far around the planet as possible, but so that it can still talk to the first. This should result in a setup where any spacecraft above a certain altitude always sees at least one satellite or KSC itself. And even in a low orbit, the dark zone should only be maybe a dozen degrees or so - and then, perhaps you can bounce the signal across one of the other two:

One satellite each in orbit of Mun and Minmus. Position them in a medium polar orbit (~500 km Mun, ~300km Minmus). Their job will be to alleviate the signal shadow of the moons themselves. As the moons travel around Kerbin, the orbits stay fixed, so you get differing performance depending on the position. In the worst possible case, the polar orbit is edge-on with respect to Kerbin, and the satellite is useless while it passes in front and behind the moon, only able to properly do its job over the poles... but hey, it's better than having no comms at all on the far side. In the best possible case, the polar orbit is perpendicular with respect to Kerbin, and the satellite will be able to reach large parts of the far side at all times. On Minmus, it helps tilting your polar orbit in accordance with the inclination to Kerbin, but it's not strictly necessary since the inclination is small.

A prerequisite is, of course, having relay antennas that can talk between each other (not just with the much more powerful ground station) all the way from stationary Kerbin orbit to the edge of the SOI. That means the RA-2.

Edited by Streetwind

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Das_Sheep    7
1 minute ago, Streetwind said:

A better question is: what do you need it to do? And what do you have available to work with? A LKO constellation of five sats with a HG-5 is not going to support Mun missions. But perhaps you want to get that SCANsat thing going now, and not wait until you research SOI-spanning relay antennas.

Don't fall into the trap of designing something for the sake of designing a perfect system. First and f9oremost, you need a solution that's useful to you.

Mainly looking to put something together that can support un-manned missions within Kerbin's SOI - primarily Mun and Minmus probe orbiters / landers and to maintain links to planned bases on both. There might be the odd asteroid mission as well, so figure I'll need something in a polar orbit to account for weird movements across the ecliptic.

I can live with gaps in coverage as long as there are reasonably frequent connection windows and I've built other networks before, they just never seem to be terribly good. Mainly I'm looking to do as much as possible with as few launches as possible, although I do have a nice launcher that can lob 4 satellites at a time into LKO and they can boost themselves from there anywhere in Kerbin SOI.

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egoego    73

As @Streetwind said, design something that is usefull for you. In your early career you don't have very powerfull antennas, so if you put your relays in KEO your probes in LKO might not reach them unless they carry powerfull or plentifull antennas.

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Das_Sheep    7

Many thanks for advice folks - usually have just left the defaults on but fancied something a bit different this time that took some effort rather than just "launch giant relay dishes everywhere" and as I'm playing with the science rewards fairly low and community tech tree I have to be somewhat careful where I put science as there's something of a plan in place, at least for the first chunk of this career.

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Vive_moi    21
Posted (edited)

Hello,

I use RemoteTech but I guess the CommNet structure I use would also work with stock comm system.

For almost full coverage of the Kerbin system, I place 4 CommSat around Kerbin on a 700km height equatorial orbit with multiple (2-3) Comm16 and a dish (HG-5 ? Check the distance). Two opposite sats have their dish pointed to Mun, the other two to Minmus. Then I place 3 stats at also 700km height equatorial orbit around Mun and Minmus with Comm16 and a dish (all dish to Kerbin).

This way, except for the pole at low altitude or landed, you have full and permanent coverage.

All mission vessels will only have omni antennas. So you will lose transmission during transfert. But, I usually don't have to do any maneuver during it and you will recover control before entering Mun/Minmus SOI.

See you,

Vive_moi

EDIT: oups did not see the previous answer. Post not usefull...

Edited by Vive_moi

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Blaarkies    234

Put a ground relay probe on the mountains west of KSC. The 5km extra altitude seriously help with the occlusion on 100%, and it is very easy to get there. As others have pointed out, just build enough so that you can do Mun missions, after that you will have better relay dishes. With those, put a relay in a polar orbit with an Ap above the north pole at just below 84 000km(tip of Kerbin SOI), and Pe at south pole 70km. This satellite spends 40days above the north pole with connection to KSC, and swings around Kerbin in about 40 minutes. This covers everything except the south pole of every kerbin body(and their dark side), and can be greatly improved by lobbing another ground relay to the mountains north of KSC

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Das_Sheep    7
1 hour ago, Blaarkies said:

Put a ground relay probe on the mountains west of KSC.

Also sounds like a fantastic test of the massive Munar tracked rover I'm planning on building- just replace ore payload section with a dish array.

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Streetwind    3817
Posted (edited)
2 hours ago, Vive_moi said:

I use RemoteTech but I guess the CommNet structure I use would also work with stock comm system.

It wouldn't, no. Stock antennas make no distinction between omnis and dishes; none of them require pointing. Furthermore, the ranges of the individual antennas are very different - both on a part stats level, as well as how range between two antennas is calculated. For example: using a HG-5 in a 700 km orbit would let you talk to geostationary orbit spacecraft, but not much further. Unless your spacecraft around the Mun are using much stronger antennas, but that kinda leads the concept of having commsats ad absurdum.

Edited by Streetwind

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PrathamK    6

GrouddStations Instead, Two communicates KSC and other Relay, while others Make a network while self Communicating and connect all the probes on far side.

My 1st and only Mun GroundStation (1 dish, 50G) helped me no Blackouts on My first Duna Mission.

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10 hours ago, PrathamK said:

GrouddStations Instead, Two communicates KSC and other Relay, while others Make a network while self Communicating and connect all the probes on far side.

My 1st and only Mun GroundStation (1 dish, 50G) helped me no Blackouts on My first Duna Mission.

Except early on you have neither wheels, large antennae nor good structural parts to make a nice ground station. Ground stations also get occluded by the Mün and you will require relays anyway to get the signal from the KSC to the stronger ground relay. It's anything but an efficient solution.

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Vive_moi    21
17 hours ago, Streetwind said:

It wouldn't, no. Stock antennas make no distinction between omnis and dishes; none of them require pointing. Furthermore, the ranges of the individual antennas are very different - both on a part stats level, as well as how range between two antennas is calculated. For example: using a HG-5 in a 700 km orbit would let you talk to geostationary orbit spacecraft, but not much further. Unless your spacecraft around the Mun are using much stronger antennas, but that kinda leads the concept of having commsats ad absurdum.

Thanks for this information. Did not know that.

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maculator    241

I'm playing the first time with occlusion set to 1.

There is no need for KEO sats. Right now I have 6 Sats in 1800km orbit. 3 with 0° inclination and 3 with 90°. The next mission will put 5 sats at the edge of kerbins soi (80000km) and that should 100% cover the whole kerbin system.

But is need t oget more science to get the right dishes first...

And by the way I started with a octo sat and a hg-5 antenna strapped to every ship that went to orbit. In orbit I dumped the octo and continued my mission. That left me with 36 octo-sats in lko.

A waste of resources and coverage was really bad, don't do it that way.

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GoSlash27    3048
Posted (edited)

Das_Sheep,

 My back-of-the-envelope says you could set up a relay to Mun pretty easily using 3 twin HG-5 relays in an equilateral constellation. Each sat would have 2 antennae. Final orbit would be at 5.17 Mm altitude. The 3 sats would be seeded in a single launch, Pe 2.44Mm x Ap 5.17Mm. 2 daughter sats with 140 m/sec DV each, and the bus would serve as the 3rd relay sat. The bus/ sat would have a DV of 1,250 m/sec from LKO @ 70 km altitude.

 Unfortunately, HG-5s would be impractical for a relay to Minmus without employing an RA-2 in Minmus orbit.

Best,
-Slashy

Edited by GoSlash27

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