Force a satellite to use a relay

[rpayne88]

I am building a comm network so I can send a rover to Duna.  I have three comm sats in orbit, one about 45 degrees ahead of kerbin, the other two 45 and 90 degrees behind.  The one 45 degrees behind Kerbin has a 78% signal strength and the 90 has a 30% signal strength direct to Kerbin.  How do I force it to relay signals off the other satellite so as to get a better signal?  I am using 2x RA-2s, 2x DTS-M1s, and 1x 16-S.

[AlamoVampire]

3 hours ago, rpayne88 said:

I am building a comm network so I can send a rover to Duna.  I have three comm sats in orbit, one about 45 degrees ahead of kerbin, the other two 45 and 90 degrees behind.  The one 45 degrees behind Kerbin has a 78% signal strength and the 90 has a 30% signal strength direct to Kerbin.  How do I force it to relay signals off the other satellite so as to get a better signal?  I am using 2x RA-2s, 2x DTS-M1s, and 1x 16-S.

Howdy there! I was taking a look in the VAB at the communication relay antennae and a few things spring up in my mind. Now, before I go further, I am not sure which game mode you are in, and will make my reply take 2 forms, the first being as if you are in just sandbox where kerbucks and science are meaningless metrics for doing anything and the second will be as if you are in either career or science mode. Oh one other thought before my suggestions is that I think the comms net just picks which ever relay sat meets a few criteria <at least this is my guess, and a guess as to the criteria> such as what relay is in LOS, How potent is the signal. I imagine its more complicated, but, the guess I made seems to fit logically to me.

My first suggestion is to replace your relay set around Kerbin with a set < I myself have a triad in orbit, seems to work well enough for me in sandbox > of RA-100 Relay Antenna <the heavier of the two> or a set of Communotron 88-88 <the lighter of the two, and its animated, smaller package, but identical stats other than weight and some basic transmission differences, but those are negligible as far as I can see . Both can reach a max range of 158GM. As to the arrangement around the planet Kerbin, that I leave to you, but, suggest a similar setup around Duna as a rover will not always have a LOS to Kerbin, but, odds are good at least 1 relay will be in LOS <depending again on setup> of the rover on the ground.

Ok, lets say you are in career or science mode. It may be more expensive <I honestly have no idea as I only do sandbox as for me career and science really do not draw me in that well> as it may take more relay steps, but, the principle I think is sound. Pick which ever relays you can afford and are the strongest you can afford and put up several relay sets. One set around Kerbin, another perhaps between Kerbin and Duna and another at Duna itself. 

I am sorry if this came off as an incoherent mess, so, perhaps a TL:DR translation?

1. I do not think its possible to force a connection, as I think the relays just pick the best that they can see/talk to.

2. If sandbox use either the RA-100 Relay Antenna or the Communotron 88-88 <both are nearly identical in terms of data transmission and range with minor differences in transmission size/rate. Major differences are the weights and the fact that the Communotron 88-88 is smaller <physically> and can be deployed from a stowed position.

3. If career or science, just pick the strongest available to you at the moment <that you can afford of course> and place as many as needed to bridge the gap between Kerbin, Duna and the surface of Duna.

Hope this helps.

Posted at 0221 central, on 4142020

[jimmymcgoochie]

 

1 hour ago, AlamoVampire said:

2. If sandbox use either the RA-100 Relay Antenna or the Communotron 88-88 <both are nearly identical in terms of data transmission and range with minor differences in transmission size/rate. Major differences are the weights and the fact that the Communotron 88-88 is smaller <physically> and can be deployed from a stowed position.

The 88-88 is not a relay antenna. While it will be just as good for transmitting data directly, it won't help you as part of a relay network (unless I'm completely misunderstanding how the antennae work in KSP). 

If your second satellite has 30% signal direct to Kerbin, that probably means the signal via the first satellite is worse. I'm going to guess your tracking station is either level 2 or 3, I think level 2 has 50Gm range and level 3 has 250Gm or something similar- in either case this is far more than a pair of RA-2s can manage (~3.5Gm at best). Signal strength is the square root of the combined antenna powers of the two objects multiplied together, so a RA-2 and a level 2 tracking station has (50 * 2 = 100 sqrt = 10 ) 10Gm total communication range, whereas two RA-2s talking to each other have (2  * 2 = 4 sqrt = 2) 2Gm total range, and a level 3 tracking station has (250 * 2 = 500 sqrt = 22.4) 22.4Gm range.

I'll repeat a suggestion I made to someone else on a similar topic- until you unlock RA-15s, skip Duna and focus on Eve which is closer, easier to orbit and land on (with enough heat shields!) and closer to the sun so solar panels are more effective, whereas on Duna you get less power.

You might find this page useful, it has a diagram showing what types of antenna you'll need to communicate from all the planets:

[AlamoVampire]

@jimmymcgoochie on the 88-88 its my understanding that it can still receive a relayed signal. I say this because I have or had (sorry its 0400 and im kinda on vapors from a long day and cant recall if its a current save or a past save) a probe in orbit of duna with the 88-88 on it and it was listening to my ra-100’s en route and at duna. 
 

I admit my wording above could have been clearer, but i think the 88-88 should be fine for the rover itself, i think. 

posted at 0406 central on 04142020

[jimmymcgoochie]

2 minutes ago, AlamoVampire said:

@jimmymcgoochie on the 88-88 its my understanding that it can still receive a relayed signal. I say this because I have or had (sorry its 0400 and im kinda on vapors from a long day and cant recall if its a current save or a past save) a probe in orbit of duna with the 88-88 on it and it was listening to my ra-100’s en route and at duna. 
 

I admit my wording above could have been clearer, but i think the 88-88 should be fine for the rover itself, i think. 

posted at 0406 central on 04142020

Agreed that any antenna can START a signal that gets relayed back to Kerbin, but only a relay dish can be one of the links in the middle. With a couple of smaller RA-2 equipped relays in low-ish Duna orbit and a larger RA-15/RA-100 relay in a high and inclined orbit to slingshot the signal back to Kerbin, rovers can get away with less powerful (and cheaper!) antennae than 88-88s and the more compact DTS-M1 would be sufficient to reach any of the Duna relays.

@rpayne88 use the best relay antenna you have on your relays at all times, there's no such thing as too strong a signal!

[AHHans]

5 hours ago, rpayne88 said:

How do I force it to relay signals off the other satellite so as to get a better signal?

As @AlamoVampire already hinted at: you cannot. If a vessel has a direct connection to the KSC then it will use that, even if using a relay would result in a better connection. (I had the situation that one of my probes got a better connection to the KSC once it got in the Mun's radio shadow.)

But if another craft is using that "90 deg relay" then it will use the best connection, even if it means adding more hops to the connection. So it should give you the better connection through the 90 deg and 30 deg relays - in case that will indeed result in a better connection.

[TheFlyingKerman]

Sometimes retracting and then deploying the antenna works. But even the relay can have multiple ways to call home and it may not select the strongest path...