Two antenas

[DJLeo]

Hi, I have designed a space ship to pick my man from Duna. It's build from "space part" and Lander. I really wanted to save space, so I used Communotron HG-55 to communicate with Kerbin and HG-5 to communicate with Landerm, which has Communotron 16-S. HG-5 should be a relay antenna, but I have no signal. Can a Probodobodyne HECS2 operate two antenas? Where is the problem?  Thx for answer

[Snark]

Hello, and welcome to the forums! 

Moving this question about how to play the game to Gameplay Questions.

20 minutes ago, DJLeo said:

Hi, I have designed a space ship to pick my man from Duna. It's build from "space part" and Lander. I really wanted to save space, so I used Communotron HG-55 to communicate with Kerbin and HG-5 to communicate with Landerm, which has Communotron 16-S. HG-5 should be a relay antenna, but I have no signal. Can a Probodobodyne HECS2 operate two antenas? Where is the problem?  Thx for answer

The problem is that your HG-5 isn't strong enough to reach Kerbin, so you can't use it as a relay antenna for your lander.

The HG-55 that you have on your spacecraft can talk directly to Kerbin from Duna, because at 15G, it's plenty powerful enough.  But it's not a relay antenna, so it can be used only for controlling that spacecraft.  You can't relay other craft's signals through it.

Your HG-5 is a relay antenna... but unfortunately it only has 5M antenna power, which means it's strong enough to talk from a Duna-orbiting spacecraft to Duna surface, but it's not even close to being powerful enough to reach Kerbin.  So you could use it for relaying signals from one near-Duna craft to another near-Duna craft, but you can't use it to relay signals all the way to Kerbin.

If you wanted to have a relay from a short-range antenna on the surface of Duna all the way back to Kerbin, then you'd need a powerful relay antenna, e.g. the RA-15 would have worked fine.

[HansAcker]

On 7/11/2019 at 9:05 PM, Snark said:

The problem is that your HG-5 isn't strong enough to reach Kerbin, so you can't use it as a relay antenna for your lander.

Isn't this the kind of situation where the "probe control point" comes into play?

If your ship can reach the lander via its relay antenna *and* you've got a pod or probe core with the probe control point feature on board *and* you packed the right amount of pilots, you could control the lander independently of any CommNet connection to Kerbin. Granted, I have seen the walkie-talkie icon for this type of control only in tests. I send a set of relays ahead of any manned mission.

[Daniel Prates]

Your relay craft talks to the probe via a normal antenna, so your probe needs only a direct antenna but the relay craft needs both a direct antenna (to talk to the probe) and a relay antenna (to talk back to kerbin). And of course, all of them must be within range of eachother.

There is a great mod, "antenna helper", that shows very easily the range of your current antenna setup. Worth a try.

[Snark]

2 hours ago, HansAcker said:

Isn't this the kind of situation where the "probe control point" comes into play?

If your ship can reach the lander via its relay antenna *and* you've got a pod or probe core with the probe control point feature on board *and* you packed the right amount of pilots, you could control the lander independently of any CommNet connection to Kerbin. Granted, I have seen the walkie-talkie icon for this type of control only in tests. I send a set of relays ahead of any manned mission.

Sure.  But that would only work if you have a pilot (not just crew, but a pilot) on the ship that has the probe-control-point feature, which doesn't sound like the OP's situation.  From the OP's description, it sounds as though what they're trying to do is to form a link from the lander back to Kerbin, in which case "probe control point" isn't in play.

1 hour ago, Daniel Prates said:

Your relay craft talks to the probe via a normal antenna, so your probe needs only a direct antenna but the relay craft needs both a direct antenna (to talk to the probe) and a relay antenna (to talk back to kerbin).

That's not how it works.  The relay craft talks to everything through the relay antenna.  It talks to the probe via the relay antenna, and it talks back to Kerbin via the relay antenna.

A direct antenna is only useful for controlling the currently piloted craft.

So, this statement is correct:

1 hour ago, Daniel Prates said:

your probe needs only a direct antenna

...but the following statement is incorrect:

1 hour ago, Daniel Prates said:

the relay craft needs both a direct antenna (to talk to the probe) and a relay antenna (to talk back to kerbin).

^ No. The relay craft only needs one antenna.  And that antenna must be a relay antenna.  And it must be powerful enough to reach Kerbin.

[Daniel Prates]

That has never crossed my mind @Snark. I always put both kinds in the relay craft, but that is because I always want to control it for whatever reason. Guess I just got used to that and never really tried just the relay antenna.

If the relay is out of control, does it still function properly?

[Snark]

35 minutes ago, Daniel Prates said:

I always put both kinds in the relay craft, but that is because I always want to control it for whatever reason.

Yah, not needed.  As long as you have a relay antenna on there that has a big enough power for the range, that's all you need.  There's usually no reason to put a direct antenna on a craft that already has a relay one.

Relay antennas also work as direct antennas.  The reverse is not true.

 

36 minutes ago, Daniel Prates said:

If the relay is out of control, does it still function properly?

Not sure what you mean by that.  A relay antenna provides a link between any other craft that are within LOS.  If it's so far that it's out of range for control purposes, then it'll also be so far that it's out of range for relay purposes, too.

[Daniel Prates]

7 minutes ago, Snark said:

Not sure what you mean by that.  A relay antenna provides a link between any other craft that are within LOS.  If it's so far that it's out of range for control purposes, then it'll also be so far that it's out of range for relay purposes, too.

What I mean is, if my relay has a relay antenna but not a normal antenna, it will be uncontrollable, right? Even out of control it can still relay? You see I ask this, because ever since the new signals system came out years ago, I always placed both kinds of antennas on all relay craft and never really tried without both, in the understanding that craft-to-craft comms demanded both having direct antennas.

[Snark]

4 minutes ago, Daniel Prates said:

if my relay has a relay antenna but not a normal antenna, it will be uncontrollable, right?

Huh?  What are you talking about?  Why would it be uncontrollable?

Relay antennas do everything that direct antennas do, plus they can also serve as relays.

The only reason a craft with a relay-antenna-and-nothing-else would be uncontrollable would be if it's either out of range from a control source, or if there's something blocking LOS to a control source.  Exactly the same as with a direct antenna.

4 minutes ago, Daniel Prates said:

Even out of control it can still relay?

I'm a little fuzzy on what you're picturing, here.  If you have a craft that's out of control, it means it's got no signal, right?  (Either because the range is too big, or some planet or something is blocking line-of-sight.)

And if it's got no signal, that means it also can't relay anything.

[Daniel Prates]

@Snark with 1000+ game hours I shoukd know if a craft is out of range or something like that.

I see what is happening. Some versions ago I must have used some mod, maybe kerbalism or remote control, that demanded direct antennas for craft dialoguing with eachother, and in my mind I must have made a "note to self" marking that as a general, stock rule. You know how you sometimes you adopt a rule and it lingers on, after it becoming obsolete?

Thanks for correcting me, I was adopting an unnecessary procedure without it noticing.

[Snark]

Just now, Daniel Prates said:

I see what is happening. Some versions ago I must have used some mod, maybe kerbalism or remote control, that demanded direct antennas for craft dialoguing with eachother, and in my mind I must have made a "note to self" marking that as a general, stock rule. You know how you sometimes you adopt a rule and it lingers on, after it becoming obsolete?

Yeah, been there, done that.    Perhaps you were using RemoteTech?  That has a completely different model for relaying and inter-ship communication, and requires that antennas be specifically aimed at a target (so if you want to talk to N different craft, you need N different antennas.)

But anyway... stock CommNet doesn't work that way, it's a much simpler model.

[Daniel Prates]

49 minutes ago, Snark said:

Yeah, been there, done that.    Perhaps you were using RemoteTech?  That has a completely different model for relaying and inter-ship communication, and requires that antennas be specifically aimed at a target (so if you want to talk to N different craft, you need N different antennas.)

But anyway... stock CommNet doesn't work that way, it's a much simpler model.

Yes! Remote tech. That's the one. There are many mods I have stopped using over the years, for instance, now I use TACLS + kerbal health to give me what Kerbalism used to. But some habits remain and it's tough to remember  that the rule does not apply anymore. Here I think something like that happened, probably some rule from remote tech that I have incorporated into my accumulated "knowledge", if you  can call it that!

Again, thanks for bringing me up to date!