Difference between revisions of "CommNet"

From Kerbal Space Program Wiki
Jump to: navigation, search
(Range Calculation)
 
(54 intermediate revisions by 20 users not shown)
Line 1: Line 1:
'''CommNet''' is a relay and control communication system implemented first in KSP 1.2 pre-release. Probes now have limited attitude and thrust control if they are not linked back to Kerbin or a control point via a relay antenna. <ref name="commnet">https://docs.google.com/document/d/1Tu3KnB1alOMn_VXqF31BPDbAu24HdHLiYP2V1I6b6pU/edit</ref> Antennae have limited range from which control and transmission of science data is possible.
+
'''CommNet''' is a relay and control communication system implemented first in KSP 1.2 pre-release. With CommNet enabled (as a difficulty setting), antennae have limited range from which control and transmission of science data is possible. Vessels without a [[Pilot]] require a link to a control source for full control (valid control sources are a vessel with an operational [[Probe_Control_Point|Probe Control Point]], or more commonly the Deep Space Network on [[Kerbin]]). Locations may be linked either through a direct connection or indirectly via one or more relays.  
  
 +
The following table lists the maximum range for vessels with a single antenna signaling the Deep Space Network (note these change with Range Modifier in CommNet difficulty options):
 
{| class="wikitable"
 
{| class="wikitable"
 +
! colspan="2" rowspan="2" | '''Antenna Type'''
 +
! colspan="3" | [[Tracking Station]] Level (Rating)
 
|-
 
|-
! Tracking Station Level !! 5k (Probes / Manned)  !! 500k (Communotron 16)  !! 5M (HG-5 High Gain)  !! 2G (DTS-M1 / RA-5) !! 15G (HG-55 / RA-50) !! 100G (Communotron 88-88 / RA-100)
+
! '''1''' (2G) !! '''2''' (50G) !! '''3''' (250G)
 
|-
 
|-
| <center>'''1''' (2G)</center> || 3.1Mm (halfway to Mun) || 31.6Mm (Minmus) || 100Mm  || 2Gm || 5.5Gm  || 14.1Gm
+
| <center>'''5k'''</center> || <center>'''Command pods (Built-in)'''</center>
 +
| <center>3.16Mm (25% way to Mun)</center>
 +
| <center>15.81Mm (Mun)</center>
 +
| <center>35.36Mm (75% way to Minmus)</center>
 
|-
 
|-
| <center>'''2''' (50G)</center> || ~15.8Mm (Mun) || ~158Mm (Deep Space) || 500Mm || 10Gm (Duna if close) || 27.4Gm (Duna/Dres always, Jool if close) || 70.7Gm
+
| <center>'''500k'''</center> || <center>'''[[Communotron 16]] / [[Communotron 16-S|16-S]]''' <br> '''[[Probodobodyne Experiment Control Station|BG: Control Station]]'''</center>
 +
| <center>31.62Mm (67% way to Minmus)</center>
 +
| <center>158.11Mm (Kerbin SOI)</center>
 +
| <center>353.55Mm (Kerbin SOI)</center>
 
|-
 
|-
| <center>'''3''' (250G)</center> || 35.4Mm (halfway to Minmus) || 354Mm  || 1.1Gm || 22.4Gm (Dres if close) || 61.2Gm  || 158Gm (Jool always, Eeloo if close)  
+
| <center>'''5M'''</center> || <center>'''[[HG-5 High Gain Antenna|HG-5 High Gain]]'''</center>
 +
| <center>100Mm (Minmus)</center>
 +
| <center>500Mm (Interplanetary around Kerbin)</center>
 +
| <center>1.12Gm (Interplanetary around Kerbin)</center>
 +
|-
 +
| <center>'''2G'''</center> || <center>'''[[Communotron DTS-M1|DTS-M1]] / [[RA-2 Relay Antenna|RA-2]]'''</center>
 +
| <center>2Gm (Interplanetary around Kerbin)</center>
 +
| <center>10Gm (Moho, Eve & Duna when close)</center>
 +
| <center>22.36Gm (Moho always, Eve, Duna & Dres (barely) if close)</center>
 +
|-
 +
| <center>'''10G'''</center> || <center>'''[[Communotron Ground HG-48|BG: HG-48]]'''</center>
 +
| <center>4.47Gm </center>
 +
| <center>22.4Gm </center>
 +
| <center>50.0Gm </center>
 +
|-
 +
| <center>'''15G'''</center> || <center>'''[[Communotron HG-55|HG-55]] / [[RA-15 Relay Antenna|RA-15]]'''</center>
 +
| <center>5.48Gm (Eve when close)</center>
 +
| <center>27.39Gm (Always Moho & Eve, Duna & Dres if close)</center>
 +
| <center>61.24Gm (Dres, Jool & Eeloo if close, other planets always)</center>
 +
|-
 +
| <center>'''100G'''</center> || <center>'''[[Communotron 88-88]] / [[RA-100 Relay Antenna|RA-100]]'''</center>
 +
| <center>14.14Gm (Moho, Eve & Duna when close)</center>
 +
| <center>70.71Gm (Jool & Eeloo if close, other planets always)</center>
 +
| <center>158.11Gm (all bodies always)</center>
 +
|}
 +
 
 +
== Range calculation ==
 +
Individual vessels do not have a fixed maximum range: whether a connection is possible between two vessels that are a given distance apart depends on the transmission strength of the vessels at ''both'' ends of the connection. Each antenna has a "power rating", measured as a unitless number, which contributes to the overall power rating of the vessel it is attached to. A connection can be established between two vessels when the geometric mean of their power ratings is greater than their separation as measured in meters.
 +
This is calculated as follows:
 +
{{Formula
 +
|math code = <math> Range = \sqrt{Vessel_1 \times Vessel_2} </math>
 +
|where =
 +
*<math>Range</math> is the maximum distance in meters at which two vessels can connect with each other.
 +
*<math>Vessel_1</math> and <math>Vessel_2</math> are the power ratings for the vessels that are attempting to connect to each other.
 +
}}
 +
Power ratings for antennae range from '''5k''' for the integrated antenna available in every [[Command module]], to '''100G''' for the largest dishes. Kerbin's Deep Space Network can be treated as a vessel with a rating of '''2G'''/'''50G'''/'''250G''' (depending on the level of the [[Tracking Station]]) for the purposes of calculating range.
 +
 
 +
If (by difficulty setting) there is only one tracking station, a ship must depend on a CommNet relay manally placed around Kerbin, here are the general ranges between antennae.
 +
 
 +
{| class="wikitable" style="text-align:center"
 +
!
 +
! 5k
 +
! 500k
 +
! 5M
 +
! 2G
 +
! 10G
 +
! 15G
 +
! 100G
 +
|-
 +
! 5k
 +
| 5km
 +
|
 +
|
 +
|
 +
|
 +
|
 +
|
 +
|-
 +
! 500k
 +
| 50km
 +
| 500km
 +
|
 +
|
 +
|
 +
|
 +
|
 +
|-
 +
! 5M
 +
| 158.1km
 +
| 1.6Mm
 +
| 5Mm
 +
|
 +
|
 +
|
 +
|
 +
|-
 +
! 2G
 +
| 3.2Mm
 +
| 31.6Mm
 +
| 100Mm
 +
| 2Gm
 +
|
 +
|
 +
|
 +
|-
 +
! 10G
 +
| 7.1Mm
 +
| 70.7Mm
 +
| 223.6Mm
 +
| 4.5Gm
 +
| 10Gm
 +
|
 +
|
 +
|-
 +
! 15G
 +
| 8.7Mm
 +
| 86.6Mm
 +
| 273.9Mm
 +
| 5.5Gm
 +
| 12.2Gm
 +
| 15Gm
 +
|
 +
|-
 +
! 100G
 +
| 22.4Mm
 +
| 223.6Mm
 +
| 707.1Mm
 +
| 14.1Gm
 +
| 31.6Gm
 +
| 38.7Gm
 +
| 100Gm
 
|}
 
|}
  
=Range Calculation=
+
=== Combining antennae ===
Each antenna has a "power rating" measured in meters. It ranges from '''5k''' (5000m) for integrated default antennas available in every spacecraft, to '''100G''' (100 billion meters) for the largest dishes.
+
When a craft has multiple, combinable antennae, the antenna's power ratings stack in a way that provides diminishing returns using the following formula:
A connection can be established between two stations (craft to ground, or craft to relay) when the square root of the product of the strength ratings is greater than the distance between the two objects.
+
 
When a craft has multiple, combinable antennas, the antenna's power ratings stack in a way that provides a diminished return using the following formula:
+
<math> \text{Vessel Power} = \text{Strongest Antenna Power} \times \left ( \tfrac{\text{Sum of Antenna Powers}}{\text{Strongest Antenna Power}} \right ) ^ \text{Average Combinability Exponent} </math>
 +
 
 +
The vessel's Average Combinability Exponent is the average of the combinability exponent values of all antennas on the vessel, where each antenna is weighted proportionally to its respective power rating. Note that all antennae and relays have a combinability exponent value of 0.75 except for the Communotron 16 and the Communotron 16S, with values of 1.0 and 0.0 respectively. This means that the Average Combinability Exponent will always be 0.75 for a vessel containing neither of these antennae. For vessels with a Communotron 16 or 16S, the Average Combinability Exponent is calculated:
 +
 
 +
{{Formula
 +
|math code = <math>\text{Average Combinability Exponent} = \frac{P_1 C_1 + P_2 C_2 + \cdots + P_n C_n}{P_1 + P_2 + \cdots + P_n} </math>
 +
|where =
 +
*<math>\{P_1, P_2, \dots , P_n\}</math> are the power ratings of each antenna.
 +
*<math>\{C_1, C_2, \dots , C_n\}</math> are the combinability values of each respective antenna.
 +
}}
 +
For example, a vessel with a Communotron 88-88 (100G power, 0.75 combinability) and also a Communotron 16 (500k power, 1.00 combinability) would have the following as its Average Combinability Exponent:
 +
 
 +
<math> \frac{(100 \times 10^9) \times  0.75  + (500 \times  10^3) \times  1.00}{(100 \times  10^9) + (500 \times  10^3)} = 0.75000125 </math>
 +
 
 +
Antennae combinability exponent values can be found under "antennaCombinableExponent" in the part configuration files. If the value is missing, the default value of 0.75 is used.
 +
 
 +
== Signal strength ==
 +
 
 +
The length of a communication link relative to its maximum range is represented by signal strength. Signal strength for a single-hop link starts at 100% at a distance of zero and decreases as distance increases, down to a signal strength of 0% at the maximum range of the link. The relationship is non-linear: the true value requires plotting the relative distance on a [[w:Cubic Hermite spline|Bezier curve]] with the keys '0 0 0 0' and '1 1 0 0'. This can be calculated as follows:
 +
 
 +
* Calculate the relative distance between the vessels (the result should be between 0.0 and 1.0): <math> 1 - \frac{\text{Distance From Link Point}}{\text{Maximum Range}} </math>
 +
* Substitute the result above into the Bezier curve equation (cubic derivation): <math>-2x^3 + 3x^2 </math> or <math> (3-2x)x^2</math>
 +
 
 +
The result is the signal strength of the link at the specified distance. Note that the above applies to a single-hop link: if the signal is being bounced through one or more relays, the signal strength is the product of the signal strengths of each link making up the path to the control point.
 +
 
 +
=== Example ===
 +
Calculating the Signal Strength between a Level 3 DSN Tracking Center and a probe around Jool at a distance of 73.4Gm from Kerbin with two Communotron 88-88 antennas:
 +
 
 +
* Max Power of Lvl 3 DSN connection: <math> 250\,000\,000\,000 </math>
  
- Vessel Antenna Power = Strongest Antenna Power * (Sum of Antenna's Powers/Strongest Antenna Power)^(Average of Combinability Exponents for All Antennas)
+
* Max Power of Probe: <math> 100\,000\,000\,000 \times \left (\frac{200\,000\,000\,000}{100\,000\,000\,000}\right )^{0.75} = 168\,179\,283\,051 </math>
  
The range can then be calculated as stated above by taking the square root of the product of the two Antenna Strength ratings
+
* Max Range of Connection: <math>\sqrt{(2.5\times 10^{11})\times (1.68\times 10^{11})} = 205\,048\,337\,625 \text{m} </math>
  
- Range = SQRT ( Antenna Strength 1 * Antenna Strength 2 )
+
* Relative distance between Link Points: <math> 1 - \frac{73.4}{205} = 0.642 </math>
  
Please Note: All Antennas and Relays have a Combinability Exponent value of 0.75 except for the Communotron 16 having a value of 1 and the Communotron 16S having a value of 0. These values can be found in the part config files.
+
* Signal Strength: <math> (3-2\times 0.642)\times 0.642^2 = 0.707 = 71% </math>
  
=Signal Strength=
+
Therefore the signal strength for this connection would be 71%.
  
To obtain your signal strength for a link at any given distance between the two points it is mostly the relative distance between the two points. The true calculation requires plotting the relative distance on a Bezier curve with they keys '0 0 0 0' and '1 1 0 0' to obtain the true Signal Strength. This can be calculated as follows:
+
=== Science Transmission ===
 +
If CommNet is enabled in the difficulty settings, then transmitting [[Science|science]] through a connection with high signal strength will give a bonus the transmission efficiency of up to 40% (to a maximum of 100% value). This bonus decreases non-linearly with signal strength. For example, a Gravity Scan from low Jool orbit would give 90*0.4=35 Science if transmitted with CommNet disabled or over a marginal connection, but if transmitted through a connection with an overall strength of 100% would give 90*0.4*1.4=50.4 Science.
  
- 1 - ( Distance away from 'Link Point' / Max Range of Antenna Link ) = 0 < x < 1 (as a fractional percentage)
+
== Connections through relays ==
  
- Substitute the result above into the Bezier Curve equation (Cubic derivation) of y = -2x³ + 3x² = (3-2x)x²
+
You can use ships with relay antennae to boost a weak signal or to transmit a signal when obstructed by a celestial body. You only need a ship with a probe core, a relay antenna, electricity and ways to generate it. You don't need to focus on your relay ship to relay a signal, it will be relayed automatically.
  
This will give you the Signal Strength between the link at your specified distance.
+
When considering the antenna power of your vessel, direct antennae and relay antennae combine to give you a 'Power' to calculate signal strength back to the KSC, however, if a different vessel is connecting through you to communicate with the KSC the direct Antennae are disregarded in any calculations made.
  
==Example==
+
=== Example ===
Calculating the Signal Strength between a Level 3 DSN Tracking Center and a probe around Jool at a distance of 73.4Gm from Kerbin with two Communotron 88-88 antennas.
+
* A vessel with a Communotron 88-88 direct antenna and a RA-100 relay antenna orbiting around Eeloo at a distance of 105Gm from the KSC, with a Level 3 DSN, will connect back to the KSC with a signal strength of 48% as both antennae combine to give an increased antenna 'Power' for its own direct connection.
  
- Max Power of Lvl 3 DSN connection: 250,000,000,000
+
* A vessel rendezvoused with the above craft with a measly Communotron 16 will have to communicate back to the KSC through the relay as its antenna is not strong enough to communicate with the KSC directly. As this small, probe craft will only consider the RA-100 Relay Antenna on the relay craft when calculating its connection back to the KSC, the power rating of the relay vessel drops and therefore the signal strength will drop to 26% (please note the calculations for these numbers have been obfuscated from the example for easy understanding of the concept).
  
- Max Power of Probe: 100,000,000,000 * (200,000,000,000 / 100,000,000,000)^0.75 = 168,179,283,051
+
Relaying data does not consume [[Electric_charge|electrical power]], in contrast to transmitting science directly from a vessel containing science.
  
- Max Range of Connection: SQRT( 2.5E11 * 1.68E11 ) = 205,048,337,625m
+
The game always favors a direct connection to Kerbin even if a more powerful relay is nearby.
  
- Relative distance between Link Points: 1 - ( 73.4 / 205 ) = 0.64
+
== Effects of signal loss ==
 +
Depending on your difficulty settings, several effects occur when the CommNet signal is lost, either from the KSC or a probe control point. This could be due to either electricty loss, out of CommNet range, or an antenna destruction. There is also a setting where you can force the signal to blackout when entering a body's atmosphere too fast.
  
- Signal Strength: y = (3-2x)x² = (3-2(0.64))*(0.64)² = 0.704 = 70-71%
+
* '''Manned without a pilot''': You will lose the ability to create maneuver nodes, or delete existing ones
  
Therefore the Signal Strength for this connection would be ≈ 70%.
+
* '''Probe, require control unchecked''': Your probe will lose three capabilities : rotation control (roll, yaw, pitch), precise thrust control (only 0 or maximum), and the ability to create or remove maneuver nodes. If your probe is capable of locking a maneuver axis through SAS, it is advised to create a maneuver node before transmission blackout (passing behind a body) to allow the ship to perform the maneuver.
  
= DSN Strength =
+
* '''Probe, require control checked''': You will completely lose control of your probe. Either wait for it to go back to a CommNet range, or send a ship with a probe control point capability to do general maneuvers (deploy solar panels, precise control,...).
Each upgrade of the tracking center improves the strength of Kerbin's terrestrial-based Deep Space Network (DSN). Based on the provided figures, the Level 1 tracking station has an antenna strength of 2G, Level 2 is 50G, and Level 3 is 250G.
 
  
= Science Transmission =
+
SAS isn't transmitted by the KSC or a probe control point. If you cannot SAS, either look if your probe is controllable (batteries, CommNet range) or has a pilot onboard. The level of SAS depends on the ship itself (probe SAS levels or pilot level).
The same document from the KSP developers states that science returned via a relay satellite will have a bonus applied (some fraction of the difference between the recovery and transmission science potential). The exact amount of the bonus depends upon signal strength.
+
 
The amount of available Science Points you can transmit back to the KSC depends on your Signal Strength and the total potential value of the experiment.
+
== Difficulty Settings meanings ==
 +
 
 +
{| class="wikitable"
 +
! Setting
 +
! When OFF
 +
! When ON
 +
|-
 +
! Activate CommNet
 +
| All ships have full control and can plot maneuver nodes wherever they are. If they have an antenna they can transmit science from anywhere.
 +
| Ships behave differently depending on the CommNet status, see below
 +
|-
 +
! Required signal for control
 +
| When out of range, probe-only ships go into partial control (same as hibernation) where they can only lock to available SAS axis and throttle at 0 or 100%
 +
| When out of range, probe-only ships will completely lose control
 +
|-
 +
! Plasma blackout
 +
| Atmospheric re-entry has no effect on CommNet
 +
| Atmospheric re-entry lowers the signal strength, you can hover the network icon in the telemetry bar to see how many
 +
|-
 +
! Range Modifier
 +
| colspan="2"| The value of this slider is a multiplier value that is applied to the power levels of all antennae
 +
|-
 +
! DSN Modifier
 +
| colspan="2"| The value of this slider is a multiplier value that is applied to the power level of the DSN Network
 +
|-
 +
! Occlusion Modifier, Vac
 +
| colspan="2"| The value of this slider is a multiplier value that is applied to the effective size of atmosphereless bodies that can block signals between antennas.
 +
|-
 +
! Occlusion Modifier, Atm
 +
| colspan="2"| The value of this slider is a multiplier value that is applied to the effective size of bodies with atmospheres that can block signals between antennas.
 +
|-
 +
! Enable Extra Groundstations
 +
| Only one ground station has DSN: the [[Kerbal Space Center]]. Other [[List of bases on Kerbin|groundstations]] have a default antenna rating of ~36k*.
 +
| Kerbin has many groundstations that share the [[Tracking Station]]'s DNS rating.
 +
|}
  
Any experiments transmitted will be multiplied by the percentage of your connection, therefore an EVA Report high over the Mun (24 Science) at a Signal Strength of 68% would allow you to transmit a total of 16 Science points back to the KSC.
+
* Based on circumstantial evidence, the default '''DSN disabled''' groundstation antenna rating is approximately 36k, but CommNet prefers extra hops to the DSN on Kerbin, if a signal path is available.
  
= Example Orbits =
+
The CommNet ranges of '''DSN disabled''' groundstations are:
Example orbits for setting up a planetary network can be found at: [[Tutorial:Ideal Orbits for Communication Satellites]]
+
{| class="wikitable"
 +
!
 +
!5k
 +
!500k
 +
!5M
 +
!2G
 +
!10G
 +
!15G
 +
!100G
 +
|-
 +
! 36k
 +
| 13.42km
 +
| 134.16km
 +
| 424.26km
 +
| 8.49Mm
 +
| 18.97Mm
 +
| 23.24Mm
 +
| 60Mm
 +
|-
 +
|}
  
= Difficulty Settings =
+
== Tutorials, Calculators and Examples ==
 +
A Google Sheets document that can help calculate Signal Strength and Ranges for you can be found here: [http://forum.kerbalspaceprogram.com/index.php?/topic/149099-commnet-signal-strength-calculator-antenna-selector/ CommNet Signal Strength Calculator & Antenna Selector]
  
- Range Modifier = The value of this slider is a multiplier value that is applied to the power levels of all Antenna and Relay parts.
+
Example orbits for setting up a planetary network can be found at: [[Tutorial:Ideal Orbits for Communication Satellites]]
  
- DSN Modifier = The value of this slider is a multiplier value that is applied to the power level of the DSN Network.
+
One method of setting up a full-system network can be found at [[Tutorial:Setting up a CommNet system]].
  
These figures may change with the final release of 1.2.
+
[[Category:Communications]]
= References =
 
<references />
 

Latest revision as of 17:08, 7 January 2021

CommNet is a relay and control communication system implemented first in KSP 1.2 pre-release. With CommNet enabled (as a difficulty setting), antennae have limited range from which control and transmission of science data is possible. Vessels without a Pilot require a link to a control source for full control (valid control sources are a vessel with an operational Probe Control Point, or more commonly the Deep Space Network on Kerbin). Locations may be linked either through a direct connection or indirectly via one or more relays.

The following table lists the maximum range for vessels with a single antenna signaling the Deep Space Network (note these change with Range Modifier in CommNet difficulty options):

Antenna Type Tracking Station Level (Rating)
1 (2G) 2 (50G) 3 (250G)
5k
Command pods (Built-in)
3.16Mm (25% way to Mun)
15.81Mm (Mun)
35.36Mm (75% way to Minmus)
500k
Communotron 16 / 16-S
BG: Control Station
31.62Mm (67% way to Minmus)
158.11Mm (Kerbin SOI)
353.55Mm (Kerbin SOI)
5M
HG-5 High Gain
100Mm (Minmus)
500Mm (Interplanetary around Kerbin)
1.12Gm (Interplanetary around Kerbin)
2G
DTS-M1 / RA-2
2Gm (Interplanetary around Kerbin)
10Gm (Moho, Eve & Duna when close)
22.36Gm (Moho always, Eve, Duna & Dres (barely) if close)
10G
BG: HG-48
4.47Gm
22.4Gm
50.0Gm
15G
HG-55 / RA-15
5.48Gm (Eve when close)
27.39Gm (Always Moho & Eve, Duna & Dres if close)
61.24Gm (Dres, Jool & Eeloo if close, other planets always)
100G
Communotron 88-88 / RA-100
14.14Gm (Moho, Eve & Duna when close)
70.71Gm (Jool & Eeloo if close, other planets always)
158.11Gm (all bodies always)

Range calculation

Individual vessels do not have a fixed maximum range: whether a connection is possible between two vessels that are a given distance apart depends on the transmission strength of the vessels at both ends of the connection. Each antenna has a "power rating", measured as a unitless number, which contributes to the overall power rating of the vessel it is attached to. A connection can be established between two vessels when the geometric mean of their power ratings is greater than their separation as measured in meters. This is calculated as follows:

Where:
  • is the maximum distance in meters at which two vessels can connect with each other.
  • and are the power ratings for the vessels that are attempting to connect to each other.

Power ratings for antennae range from 5k for the integrated antenna available in every Command module, to 100G for the largest dishes. Kerbin's Deep Space Network can be treated as a vessel with a rating of 2G/50G/250G (depending on the level of the Tracking Station) for the purposes of calculating range.

If (by difficulty setting) there is only one tracking station, a ship must depend on a CommNet relay manally placed around Kerbin, here are the general ranges between antennae.

5k 500k 5M 2G 10G 15G 100G
5k 5km
500k 50km 500km
5M 158.1km 1.6Mm 5Mm
2G 3.2Mm 31.6Mm 100Mm 2Gm
10G 7.1Mm 70.7Mm 223.6Mm 4.5Gm 10Gm
15G 8.7Mm 86.6Mm 273.9Mm 5.5Gm 12.2Gm 15Gm
100G 22.4Mm 223.6Mm 707.1Mm 14.1Gm 31.6Gm 38.7Gm 100Gm

Combining antennae

When a craft has multiple, combinable antennae, the antenna's power ratings stack in a way that provides diminishing returns using the following formula:

The vessel's Average Combinability Exponent is the average of the combinability exponent values of all antennas on the vessel, where each antenna is weighted proportionally to its respective power rating. Note that all antennae and relays have a combinability exponent value of 0.75 except for the Communotron 16 and the Communotron 16S, with values of 1.0 and 0.0 respectively. This means that the Average Combinability Exponent will always be 0.75 for a vessel containing neither of these antennae. For vessels with a Communotron 16 or 16S, the Average Combinability Exponent is calculated:

Where:
  • are the power ratings of each antenna.
  • are the combinability values of each respective antenna.

For example, a vessel with a Communotron 88-88 (100G power, 0.75 combinability) and also a Communotron 16 (500k power, 1.00 combinability) would have the following as its Average Combinability Exponent:

Antennae combinability exponent values can be found under "antennaCombinableExponent" in the part configuration files. If the value is missing, the default value of 0.75 is used.

Signal strength

The length of a communication link relative to its maximum range is represented by signal strength. Signal strength for a single-hop link starts at 100% at a distance of zero and decreases as distance increases, down to a signal strength of 0% at the maximum range of the link. The relationship is non-linear: the true value requires plotting the relative distance on a Bezier curve with the keys '0 0 0 0' and '1 1 0 0'. This can be calculated as follows:

  • Calculate the relative distance between the vessels (the result should be between 0.0 and 1.0):
  • Substitute the result above into the Bezier curve equation (cubic derivation): or

The result is the signal strength of the link at the specified distance. Note that the above applies to a single-hop link: if the signal is being bounced through one or more relays, the signal strength is the product of the signal strengths of each link making up the path to the control point.

Example

Calculating the Signal Strength between a Level 3 DSN Tracking Center and a probe around Jool at a distance of 73.4Gm from Kerbin with two Communotron 88-88 antennas:

  • Max Power of Lvl 3 DSN connection:
  • Max Power of Probe:
  • Max Range of Connection:
  • Relative distance between Link Points:
  • Signal Strength:

Therefore the signal strength for this connection would be 71%.

Science Transmission

If CommNet is enabled in the difficulty settings, then transmitting science through a connection with high signal strength will give a bonus the transmission efficiency of up to 40% (to a maximum of 100% value). This bonus decreases non-linearly with signal strength. For example, a Gravity Scan from low Jool orbit would give 90*0.4=35 Science if transmitted with CommNet disabled or over a marginal connection, but if transmitted through a connection with an overall strength of 100% would give 90*0.4*1.4=50.4 Science.

Connections through relays

You can use ships with relay antennae to boost a weak signal or to transmit a signal when obstructed by a celestial body. You only need a ship with a probe core, a relay antenna, electricity and ways to generate it. You don't need to focus on your relay ship to relay a signal, it will be relayed automatically.

When considering the antenna power of your vessel, direct antennae and relay antennae combine to give you a 'Power' to calculate signal strength back to the KSC, however, if a different vessel is connecting through you to communicate with the KSC the direct Antennae are disregarded in any calculations made.

Example

  • A vessel with a Communotron 88-88 direct antenna and a RA-100 relay antenna orbiting around Eeloo at a distance of 105Gm from the KSC, with a Level 3 DSN, will connect back to the KSC with a signal strength of 48% as both antennae combine to give an increased antenna 'Power' for its own direct connection.
  • A vessel rendezvoused with the above craft with a measly Communotron 16 will have to communicate back to the KSC through the relay as its antenna is not strong enough to communicate with the KSC directly. As this small, probe craft will only consider the RA-100 Relay Antenna on the relay craft when calculating its connection back to the KSC, the power rating of the relay vessel drops and therefore the signal strength will drop to 26% (please note the calculations for these numbers have been obfuscated from the example for easy understanding of the concept).

Relaying data does not consume electrical power, in contrast to transmitting science directly from a vessel containing science.

The game always favors a direct connection to Kerbin even if a more powerful relay is nearby.

Effects of signal loss

Depending on your difficulty settings, several effects occur when the CommNet signal is lost, either from the KSC or a probe control point. This could be due to either electricty loss, out of CommNet range, or an antenna destruction. There is also a setting where you can force the signal to blackout when entering a body's atmosphere too fast.

  • Manned without a pilot: You will lose the ability to create maneuver nodes, or delete existing ones
  • Probe, require control unchecked: Your probe will lose three capabilities : rotation control (roll, yaw, pitch), precise thrust control (only 0 or maximum), and the ability to create or remove maneuver nodes. If your probe is capable of locking a maneuver axis through SAS, it is advised to create a maneuver node before transmission blackout (passing behind a body) to allow the ship to perform the maneuver.
  • Probe, require control checked: You will completely lose control of your probe. Either wait for it to go back to a CommNet range, or send a ship with a probe control point capability to do general maneuvers (deploy solar panels, precise control,...).

SAS isn't transmitted by the KSC or a probe control point. If you cannot SAS, either look if your probe is controllable (batteries, CommNet range) or has a pilot onboard. The level of SAS depends on the ship itself (probe SAS levels or pilot level).

Difficulty Settings meanings

Setting When OFF When ON
Activate CommNet All ships have full control and can plot maneuver nodes wherever they are. If they have an antenna they can transmit science from anywhere. Ships behave differently depending on the CommNet status, see below
Required signal for control When out of range, probe-only ships go into partial control (same as hibernation) where they can only lock to available SAS axis and throttle at 0 or 100% When out of range, probe-only ships will completely lose control
Plasma blackout Atmospheric re-entry has no effect on CommNet Atmospheric re-entry lowers the signal strength, you can hover the network icon in the telemetry bar to see how many
Range Modifier The value of this slider is a multiplier value that is applied to the power levels of all antennae
DSN Modifier The value of this slider is a multiplier value that is applied to the power level of the DSN Network
Occlusion Modifier, Vac The value of this slider is a multiplier value that is applied to the effective size of atmosphereless bodies that can block signals between antennas.
Occlusion Modifier, Atm The value of this slider is a multiplier value that is applied to the effective size of bodies with atmospheres that can block signals between antennas.
Enable Extra Groundstations Only one ground station has DSN: the Kerbal Space Center. Other groundstations have a default antenna rating of ~36k*. Kerbin has many groundstations that share the Tracking Station's DNS rating.
  • Based on circumstantial evidence, the default DSN disabled groundstation antenna rating is approximately 36k, but CommNet prefers extra hops to the DSN on Kerbin, if a signal path is available.

The CommNet ranges of DSN disabled groundstations are:

5k 500k 5M 2G 10G 15G 100G
36k 13.42km 134.16km 424.26km 8.49Mm 18.97Mm 23.24Mm 60Mm

Tutorials, Calculators and Examples

A Google Sheets document that can help calculate Signal Strength and Ranges for you can be found here: CommNet Signal Strength Calculator & Antenna Selector

Example orbits for setting up a planetary network can be found at: Tutorial:Ideal Orbits for Communication Satellites

One method of setting up a full-system network can be found at Tutorial:Setting up a CommNet system.