HG-5 High Gain Antenna not working as a relay?

[Jashin]

Hi everyone,

I am playing a modded career in the new 1.2 version and I've set the difficulty to hard with no groundstations and about 0.25 DSN power in order to encourage me to build a communication network. Now in my early career I only have the HG-5 antenna to use as a relay, however it doesn't seem to work: I've launched a set in keo-stationnary orbit at an angle from KSC so it always has signal, yet it doesn't seem to be able to transmit anything.

When my other probes are behind Kerbin and do not receive signal from KSC anymore, my relay doesn't do anything even when there's a direct link between the two sats.

Here's the way it's set up now : the sat and its orbit

[WanderingKid]

What antenna do you have on the probe you're hoping to talk to the probe with the HG-5, and what level have you upgraded the tracking station to (that's mostly curiosity)?

Short form: The range is not 5million meters from the HG-5, it's a combination of two antennas.  Your Hermes satellite is at 2.7m range.  The average combination of an HG-5 relay and a Comm-16 antenna is ~1.5m.  Your antenna is way too high.  You want 3 of them ~500-600km up in my experience for the early comm net.

[Jashin]

Ah got it! My tracking station was still level 1 (the grind is real when you have to unlock parts with science + funds) so that's why my relay wasn't working as expected.

I followed your advice and set up intermediary relays and now it's all good. Thanks for your help!

[WanderingKid]

 

1 hour ago, Jashin said:

Ah got it! My tracking station was still level 1 (the grind is real when you have to unlock parts with science + funds) so that's why my relay wasn't working as expected.

I followed your advice and set up intermediary relays and now it's all good. Thanks for your help!

I'm glad it helped, but I just want to make sure you're clear.  the DSN on the ground isn't the problem directly.  The problem is that communications can only reach the square root of the two antenna's reach.  So, the range of the MG-5 is 5,000,000, the range of the Comm-16 is 500,000.  See http://wiki.kerbalspaceprogram.com/wiki/CommNet for details.  The square root of these is 1,581,138 (and change) in meters.  That's how close those two probes need to be to be able to communicate.

The DSN on the ground is a monster.  It starts at 2G, which is 2000M, or 2,000,000k.  It's huge.  Even at .25 you're looking at 500M.  For an MG-5, as long as it's in sqrt(500,000,000 * 5,000,000) = 50with direct line of sight, you're fine.  Plenty for Mun, you're stretching for Minmus.  I think you just miss. 

Now, for Kerbin, the Keo orbit is 2 863.35 km, which is around where you are.  If you want your probes with a single Comm-16 to reach them, you'll want to outfit your keosynchronous satellites with 2 MG-5's.  That gets you to 2.3 million (roughly).  From there, you equip your probes with a pair of Comm-16s, which gets you to 3.16 million, and they can all chat.

The reason I recommend setting up a tripod of satellites at ~600k is they should be able to stay in touch with each other and cover any probe in LKO as well, as a pair of MG-5's communicate at 5,000,000m and that's well within tolerance.  They can just spin around Kerbin up there without worrying about which one is in contact with the ground.

[Jashin]

Thank you so much for the detailed explanation! I had definitely not understood the square root part properly, it makes a lot more sense now. I also have tweaked down the antenna power in the difficulty option, which made it slightly more difficult to grasp the whole thing. I've been playing for years but I had never used RemoteTech or anything like it before, it raises some new questions and challenges.

I've now set up a tripod as well so I can have a constant signal from KSC in low Kerbin orbit. It looks very cool in the map view and functions properly. I think I've grasped the basics thanks to you, I can't wait to go bigger once I'll have interplanetary goals. Thanks again for your help @WanderingKid and have a great day