Quick Question about Commnet Relay Antennas

[Wovejulio]

I'm trying to plan a trip to Duna, and I figured I'd send along a pod of communication satellites. I'm kind of murky on how relays affect signal strength.

As of now, I've only unlocked the RA-2, which will sometimes reach Duna but sometimes won't. I figured I could get around this by attaching 5 RA-2's to my satellite, thereby giving me the signal strength to connect to KSC always (~40 Gm). But what if my line of sight to KSC is blocked - say it's on the opposite side of the planet from me. I have comsats around kerbin to avoid this issue, but does my probe have enough juice to connect to another RA-2 at Kerbin? If the range between the two satellites is calculated the same as that between a satellite and KSC, then it seems I'd actually need something like 50 RA-2s on EACH satellite to guarantee the signal can travel the maximum distance between Kerbin and Duna, which isn't particularly feasible. I could, of course, wait to unlock the next tier antenna, but if I'm doing the calculations right then I'll still need 4 of those on each satellite if I want to cover the extreme case. This is doable, but it requires my satellites to be much beefier than I've been making them. On the wiki, it says the RA-15 will always reach Duna, but after accounting for the fact that you may not have LOS to KSC, do you need more power to meet this requirement?

tl;dr: Does every hop in the communications network have to be close enough such that the two antennas in the hop can communicate with each other independently of what's going on in every other hop, or does a relay's proximity to KSC somehow boost its power? If going through a relay to reach KSC does that relay also have to have the power to perform the next hop on its own?

[bewing]

In default commnet mode, Kerbin has ground transmission stations all around the planet. I assume you turned the ground stations off?

1 hour ago, Wovejulio said:

Does every hop in the communications network have to be close enough such that the two antennas in the hop can communicate with each other independently of what's going on in every other hop

Yes. That's exactly it. That's how it works IRL, and in the game.

If you turn off the groundstations, then you need to provide a string of relays between KSC and Duna where every relay has the range to communicate with the next relay. And with 2 RA-2's on each sat, that basically means that they can't be more than 3.5 Gm apart. (Or a bit further if you use five.)

However, if you just include a pilot in your craft, then you do not need continuous signal back to KSC to do anything. Or even if you want to do this as a robotic probe, you can control enough robotic functions to complete (for example) a satellite contract -- unless you decided to be a masochist and you also clicked the "no control without signal" button in the game settings.

[Wovejulio]

Thanks! I was writing that at 4 AM so I had forgotten about the many ground stations on Kerbin but the point still stands that without LOS I’m going to need multiple antennas on every satellite, so thank you! 

 

I DO have no control without signal on, thought it was a cool difficulty setting and I thought I could be Scott Manley . But now sending unmanned probes is so much harder than manned missions. Maybe I’ll buff the communication range or download a life support mod...