About antennas

[PowderMonk]

Hi, first of all i'm new to the forum

 

Now about my doubt.

I made a relay sistem over kerbin consisting on 5 probes all with 2 x HG-5 antennas (that's the best I can afford for now). the relay system works ok, and dns level is 3, so I should cover all kerbin mun and minmus.

NOW... it is possible to relay to KSC(level 3 dns) over the range of my 5 probe system? i mean can I launch a probe with the best antenna and relay to ksc even when it's on the other side of the planet, or the antennas have to "see" each others?

 

 

i'm sorry if I explained myself bad, but not my language

Edited July 22, 2017 by PowderMonk

[ARS]

Hi there. First of all, welcome to the forum, glad to have you here

Regarding of your question, yes, the antenna must be on the line of sight of each other in order to relay the communication. If your probe is equipped with the best antenna, but it's on the other side of the planet, you will need a relay (another satellite in line of sight to relay the signal to KSC) to make that probe controllable.

Unless you enabled the extra groundstations (esc while in game> open settings> difficulty> commnet) you WILL need a relay satellite in formation around kerbin to relay signal to each other in order to maintain constant connection. Enabling extra groundstations will place several radar dish structure around kerbin to maintain constant communication (this means you don't have to set a relay in kerbin and never worried about losing connection around kerbin, so you can focus on making relay on another planet)

[PowderMonk]

Thank you, but my real problem is: can two antennas communicate if A (the best antenna) and B (the worst) are at a distance where A can reach B but B can't reach A? cause I'm worried I have to upgrade the relay system for future extra-kerbin system missions

[Kerbal101]

@PowderMonk Hello there and welcome to the forums, PowderMonk!

Now regarding your question, DNS on Kerbin is also a relay antenna. Let me provide you with a handy table:

 

Name	Tech Level	Range (in units)	Type	Combinable?
Communotron 16	1	500,000	direct	yes
Communotron 16-S (aerodynamic)	1	500,000	direct	no
Communotron DTS-M1	3	2,000,000,000	direct	yes
Communotron HG-55	4	15,000,000,000	direct	yes
Communotron 88-88	5	100,000,000,000	direct	yes
HG-5 High Gain Antenna	2	5,000,000	relay(+direct)	yes
RA-2 Relay Antenna	3	2,000,000,000	relay(+direct)	yes
RA-15 Relay Antenna	4	15,000,000,000	relay(+direct)	yes
RA-100 Relay Antenna	5	100,000,000,000	relay(+direct)	yes
DNS Level 1	-	2,000,000,000	relay	-
DNS Level 2	-	50,000,000,000	relay	-
DNS Level 3	-	250,000,000,000	relay	-

That means, if you have DNS level 3, the range is 250,000,000,000 units to any direct antenna. Edit: this range constitutes one half of the range in the chain segment, as Spricigo mentioned and as noted below. The rating of the other half is summed and square-rooted. Edit end. That is - if DNS is not blocked. However since DNS sits on Kerbin, its often blocked by planetary rotation.

In this case, DNS will try to relay the signal towards closest Relay and that Relay will further try to contact other Relays or Direct Antennas - but only using its power. The power of DNS will not play a role here.
That 2x HG-5 has maximum range of approximately 7,000,000 units (but can be combined with other relays, the formula, rule of thumb - up to 10 is practical).
Compare it to 250,000,000,000 units of DNS level 3 now. Again, the power of DNS will not play a role after signal jumps from first relay up one chain block - the power of relay and next relay/direct antenna matters. You can visualize it if you think about relays as chain segments.

This is why, I suggest:
- Place  4(300km) - 10(500km) HG-5 on your initial Relay Satellites around Kerbin, provide them enough power.
- On the automated vessels always prefer HG-5 instead of Communotron 16. All Relay capable antennas are also capable of direct communication.

And then, either:
- try to perform maneuvers (insertion, correction, landing) when between Mun and Kerbin, and exposed to DNS, or
- slowly expand the network further and further from Kerbin using blocks of RA-5, or
- upgrade to RA-2 series that allow much wider coverage and that include the Direct Antenna (Communotron DTS-M1) of similar quality to RA-2.

 

8 hours ago, PowderMonk said:

Thank you, but my real problem is: can two antennas communicate if A (the best antenna) and B (the worst) are at a distance where A can reach B but B can't reach A? cause I'm worried I have to upgrade the relay system for future extra-kerbin system missions

If A and B form the same chain segment, then yes. You should always upgrade sat. relay system, because Kerbin DNS is blocked for half a day due to planetary rotation, plus any stuff can get in-between your probe and signal.

If you take care, than you can fly towards and reach Kerbol using just "DNS Level 2 on Kerbin" and "8xDTS-M1 on the probe" without long range relay.
But the signal will be blocked half of the day. Building sufficient intra-Kerbin and intra-Kerbol relay network is always a safe option.

 

 

Edited July 22, 2017 by Kerbal101
Correction of oversight of chain range

[PowderMonk]

Ok, thanks, so to allow me to reach other planets, I just need few good antenna (2 should be good as there will alway one antenna in contact with the vessel) orbiting just over my relay system and i'm good.

so the vessel communicate with the good antenna wich then use the relay system of my 5 probes (if ksc isn't reachable directly)

sorry for all those doubt, but I always used manne vessels, and now I want to improve the gameplay using relays systems.

[Kerbal101]

@PowderMonk No problem   But reach does not mean "land", take care to perform maneuvers only when DNS is in line of sight, or bad stuff will happen!

I always use probes, because I play permadeath with life support mod (which is hard + no going back to previous save), so I can't reverse anything regardless how it goes.

Best of luck in your mission!

[something]

The DNS consists of a variety of stations scattered around Kerbin. (Have a look at where the green communication lines end in map view). You have full control as long as any station receives a signal. This basically means that planetary rotation for deep space missions is less of an issue on Kerbin.

The algorithm will always use the strongest link as the preferred way of signal relay, so you don't have to worry about removing old satellites.

Edited July 22, 2017 by something

[Spricigo]

3 hours ago, PowderMonk said:

Thank you, but my real problem is: can two antennas communicate if A (the best antenna) and B (the worst) are at a distance where A can reach B but B can't reach A? cause I'm worried I have to upgrade the relay system for future extra-kerbin system missions

seem that you (and also @Kerbal101 ) are under (unfortunatelly very common) misundertandment of how antenna ranges works. Maybe take a look at what the wiki says about commnet.

 

In short:

• each antenna have an [antenna rating], and can be of Direct or Relay type.
• Each craft will have a [vessel antenna power] that will depends on the antenna rating and combinability expoent of all antennas in the vessel. Also there will be a [relay antenna power] that will take in account only relay antennas and used when the that vessel is used as a relay (aka is not the craft you are in control)
• Range  between two crafts or a craft and a ground station will deppend on the vessel antenna power of each side.

the important bits of math:

Vessel Antenna Power = Strongest Antenna Power * ( Sum of Antenna's Powers / Strongest Antenna Power ) ^ ( Average Weighted Combinability Exponent for Vessel )

Range = SQRT ( Antenna Strength 1 * Antenna Strength 2 )

you arre using 2x HG-5 in your relays, that gives you VAP=RAP=8.4M

It can talk to a lvl3 ground station up to 1.45Gm away (way out of kerbin SoI but not even close to a Duna or Eve)

Two of those relay can communicate to each other Up to 8.4Mm away (about 2/3 of the distance between Kerbin and Mun)

A craft with a singlle communotro 16 (VAP=500k) can communicate with this relay up to 2Mm away (90% Minmus SoI radius)

 

4 hours ago, PowderMonk said:

Thank you, but my real problem is: can two antennas communicate if A (the best antenna) and B (the worst) are at a distance where A can reach B but B can't reach A? cause I'm worried I have to upgrade the relay system for future extra-kerbin system missions

As mentioned above Range depend on the Antenna power of both craft (or craft and ground station). Important to notice there is the difference of VAP and RAP. Vessel Antenna Power is the power of your current vessels and take in consideration the contribution of all* antennas. Relay Antenna Power is the power of the vessel that is just actin as a mid point in between your active vessel and KSC only relay antennas are take in consideration.

And yes you need to uprgrade for interplanetary mission. In fact the whole idea of build a relay network in kerbin's orbit make little sense considering how the system works, the ground station will have stronger signal and reach further (except if you disable extra ground station or refuse to upgrade the tracking station). Relay anennas are usefull for two motives:1.  to deal with LoS issues 2.to allow the use of smaller antennas on ligther vesssel.  Relays near Kerbin will not provide significant bettter field of view or range. So you should build the relay network near your destination, where they can reach the opposite side of the celestial body and the vessels with low VAP.

*Just happens that the built in antennas and the Communotytron 16S don't make any contribution if others stronger antennas are present.

 

 

[Kerbal101]

@Spricigo Could you please be more specific about what I potentially misunderstand? I don't see any contradiction between your post and mine.

Edit: Thats an article I've written on antennas, perhaps there is something which could be improved:

 

[Spricigo]

@Kerbal101

Antenna Ratting vs Max Link Range

Antenna Ratting is a value used to determine Vessel Antenna Power *(how powerful a particular point in the chain is) . For a craft with a single antenna VAP is equal to Antenna Ratting. 

Max Link Range is how far two craft can be and still communicate.  It depend on the VAP of both crafts. 

So you are wrong when you say :

Quote

if you have DNS level 3, the range is 250,000,000,000 units to any direct antenna.

In fact a craft with only the built-in antenna (VAP=5k) in minmus will be out of range and even one with a Communotron 88-88 will only be I'm range up to 158Gm away. 

*Relay Antenna Power is the same but without taking Direct antennas in consideration.  

[Kerbal101]

@Spricigo Ah, yes, this is an oversight. 250,000,000,000 is of course DNS range - a part of the two-vessel chain. Thank you!

[Snark]

On 7/22/2017 at 7:33 AM, PowderMonk said:

Thank you, but my real problem is: can two antennas communicate if A (the best antenna) and B (the worst) are at a distance where A can reach B but B can't reach A? cause I'm worried I have to upgrade the relay system for future extra-kerbin system missions

Some very detailed explanations above ... but just to summarize in case this important detail got lost in the shuffle:  it doesn't matter which one is more powerful.  Because a better antenna is more powerful to transmit, but also more sensitive to receive.  It's symmetric.

To find the max range at which two antennas can communicate with each other, it's sqrt(A*B).  That is, take A's power, multiply by B's power, and take the square root of that.  That's the max range, for communication in both directions.

You can boost the antenna power of a vessel, somewhat, by stacking multiple antennas.  The Communotron-16S doesn't stack.  The Communotron-16 stacks linearly (that is, if you have N of them on a vessel, it's N times more powerful.)  All other stock antennas are stackable, but with diminishing returns.  If you have N of them, they will be N^0.75 times more powerful than having just one.

There's an enormous quantum leap in power from the HG-5 to the next level up of antenna; it's a factor of 400.  So you can use the HG-5 for exploring Mun and Minmus, if you have a direct LOS to Kerbin.  If you stack a few HG-5 antennas, then you can communicate from one ship to another between Kerbin and the Mun.  But that's pretty much it-- you need better antennas to go interplanetary.

[PowderMonk]

Thanks to all guys, this helped a lot, now definitely know how to use antennas