Difference between revisions of "Tutorial:RemoteTech2"

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{{Underlinked|date=April 2014}}
 
{{Underlinked|date=April 2014}}
  
RemoteTech 2 is a mod for KSP that modifies how unmanned probes work. Specifically, any unmanned probe must have a control link back to the [[KSC]] (or to a command ship, more on them later), requiring you to set up a satellite network to maintain links with your probes. RemoteTech 2 also simulates communications delay when giving commands to probes - while pottering around [[Kerbin]] this is merely irritating at around half a second, but interplanetary missions are seriously complicated by the several minute delays, necessitating the use of remotely executed commands. Transmitting [[science]] reports from any spacecraft, even manned ones, also requires a communications link back to the KSC.
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RemoteTech 2 is a mod for KSP that modifies remote operations of unkerballed probes by requiring the probes to have a telecommunications link back to Mission Control. Thus, to operate drones efficiently the player needs to set up a satellite network to relay and maintain communication with their probes. Transmissions of [[science]] reports will also require a comms link back to the KSC.
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Communications delay, caused by the speed of light, is also simulated. This could be a mere irritating 0.5s delay near [[Kerbin]] SOI, or a perilous 10-minute delay in interplanetary missions. To combat this, RemoteTech2 also provides advanced flight computers that can execute premeditated commands on mark.
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This tutorial seeks to inform the player on the details of this challenging mod, and to give pointers as to how to set up a functional relay network for the Kerbin system, and further interplanetary operations.
  
 
==Specifications==
 
==Specifications==
* Length: 45 minutes for "First Steps"
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* Length: 10 to 30 minutes for "First Steps"
 
* Difficulty: Advanced - This tutorial will assume you can already get a rocket in to orbit without Remote Tech 2 and are familiar with basic orbital mechanics.
 
* Difficulty: Advanced - This tutorial will assume you can already get a rocket in to orbit without Remote Tech 2 and are familiar with basic orbital mechanics.
* For version: KSP 0.23 and higher and RemoteTech 2 v1.3.3 and higher or Remote Tech 1.5 or higher.
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* For version: KSP 1.02 and higher and RemoteTech v1.6.5.
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==Introduction: Antennae and Links==
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First we need to understand the changes RemoteTech made to the existing probe/antenna mechanics. Unlike in vanilla KSP, where the player can control any craft at all times as long as there is a pilot or powered probe core onboard, here an unkerballed probe can only be controlled if it can communicate with KSC via antennae. Specifically, any two crafts can communicate if they have a direct line of sight between their respective antennae, which is not blocked by any celestial objects. ''This is known as forming a '''direct communication link'''.'' In practice, maintaining a direct link from crafts to KSC is not always feasible since planet rotates, but communicaiton links doesn't have to be direct, other crafts can relay the signal for the original craft, by-passing the blocking geometries of celestial bodies. Thus, a satellite relay network to reliably relay signals to KSC is highly desirable.
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There are two types of antennae - omnidirectional and directional (a.k.a. dish). Omnidirectional antennae can broadcast in every direction, tend to be very compact, and are typically light both in weight and power usage. They however lack the range for anything beyond low orbit communications. Dish antenna, on the other hand, have far greater range, able to communicate within and among planetary systems. But they must be targeted to function, they are also power intensive and comparatively unwieldy. Regardless, both make your satellite look totally awesome.
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At the very beginning, the only antenna we have is (somewhat) safely hidden in Mission Control, it is omnidirectional and has a range of 75 Mm. This is enough to reach the LKO, Mun, Minmus, and then some. Unfortunately the KSC is on one side of Kerbin and those links will be broken once line of sight is gone, likely on a daily basis at best. As we progress in career mode, we will acquire more options to better our communications network, which, at this point, is quite literally-- nominal.
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'''NOTE''': For reasons later explained, it is '''strongly''' recommended to set up a satellite network '''after''' the [[Electrics]] topic is researched.
  
==Antennae and links==
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===Types of Communication Links===
There are two main types of antenna - omnidirectional and dish. Omnidirectional antennae can broadcast to any other antenna in range, but they typically have limited range compared to dishes. Dishes have far greater range, but must be targeted at a receiver. Any link must be bidirectional and have unbroken line of sight to work. To keep control over a probe you must keep it connected to Mission Control, either directly or via other probes. A ship must have a probe core to relay a signal. Mission Control has a special omnidirectional antenna with around 75 Mm range, but it still only works with line of sight from the KSC.
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* Forward Link. A link from ground control to a mobile receiver.
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* Reverse Link. The reverse of a forward link.
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* Kerrestrial Link. A link among parties near the surface.
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* Uplink (UL). A link that is going toward a satellite network, or away from the surface of the pertinent celestial body.
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* Downlink (DL). The reverse of a uplink.
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* Inter-Satellite-link (ISL). A link among a satellite network, this can form the '''backbone''' of said network.
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* Planetary-Link (PL). A link among sub-systems within a planetary system, such as Kerbin to Mun, or Mun to Minmus communication.
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* Inter-Planetary-Link (IPL). A link among planetary systems across the solar system.
  
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==First Steps==
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The first build-able antenna we'll get is the [[Communotron 16]] (C-16), and is acquired upon researching Engineering 101 (2nd tier topic). The C-16 is omnidirectional, which means it does not need to be pointed at any direction to connect. This is useful for two reasons: one, this means a single C-16 can connect multiple signals with ease; and two, with less power cost per connection. On the other hand, the C-16 snaps under dynamic pressure, making it ill-suited for launching or landing purposes. The C-16 also have a limited ranged of 2,500 km, but that is more than enough to cover Kerbin.
  
==Antennae Specification Table==
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Despite its sufficient range, prior to any additional research, the C-16's only use at this point is to transfer scientific data nearby back to KSC. Which could speed up science gain if used properly.
  
{| class="wikitable sortable"
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The next available antennae are the Reflectron DP-10, unlocked by Flight control (4th tier topic); and the Comms DTS-M1, unlocked by Basic Science (another 4th tier topic), along with [[Stayputnik Mk. 1]], the first available probe core.
|-
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! Manufacturer !! Model !! Type !! Range !! Uses
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The DP-10 is also omnidirectional, but has a even more limited range of 500 km, it could form a 4-sat. network around the Mun and Eeloo, and a 3-sat. network for anything smaller, like Minmus. But it is difficult to form a network around Kerbin with the DP-10. Nonetheless, the DP-10 is built to withstand dynamic pressure, making it perfect for launching purposes. It could even work for landing operations, but the probe will need to be precision landed near KSC. For convenience, the DP-10 is activated by default, and the power cost for DP-10 is negligible, so it is always preferable if range is not an issue.
|-
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| Reflectron || DP-10|| Omni|| .5Mm|| Atmospheric launch/landing within uplink range, terrestrial links, short range drone comms, relay network for smaller-than-Kerbin celestial objects
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The DTS-M1 is the first available dish antenna, which means to be used they will need to be directed at a celestial body or craft. Although we do have the option to order dish antennae to cover currently active craft. They are also power-intensive and has greater range. Specifically, The DTS-M1 consume power at a rate 6-fold of that of C-16. But the DTS-M1 has a range of 50 Mm, capable of reaching Minmus.
|-
 
| Communotron || 16|| Omni|| 2.5Mm|| Initial Kerbin relay network, LKO vehicles
 
|-
 
| CommTech || EXP-VR-2T|| Omni|| 3Mm|| Relay network for non-giant celestial objects, KEO uplink; Objective upgrade to the Communotron 16
 
|-
 
| Communotron || 32|| Omni|| 5Mm|| High Kerbin space vehicles, luxury omnidirectional coverage
 
|-
 
| Comms || DTS-M1|| Directional|| 50Mm|| Lightweight planetary system comms(Kerbin-Minmus reach), Jool relay network
 
|-
 
| Reflectron || KR-7|| Directional|| 90Mm|| Atmospheric planetary system comms(Kerbin SOI reach)
 
|-
 
| Communotron || 88-88|| Directional|| 40,000Mm|| Lightweight interplanetary comms(Kerbin-Duna reach), Solar relay network
 
|-
 
| Reflectron || KR-14|| Directional|| 60,000Mm|| Atmospheric launch/landing within downlink range, interplanetary comms(Kerbin-Dres reach)
 
|-
 
| CommTech|| 1|| Directional|| 350,000Mm|| Atmospheric Solar system wide comms
 
|-
 
| Reflectron|| GX-120|| Directional|| 400,000Mm|| Luxury lightweight Solar system wide comms
 
|}
 
  
==Kerbin Satellite Network Maximal Altitude Table==
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With the C-16, DP-10, and DTS-M1, we can now build a fully functional, fully unkerballed satellite network whose signal could reach Minmus. However, those satellites won't last very long, as we likely have no access to any solar panels yet, meaning the satellites can only last as long as the amount of their Z-100 batteries allow.
  
The following table shows the maximal and minimal altitude for a given set of satellite rigged with a specific type of antenna for interlink purposes on a equatorial orbit.
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This is why the player is advised to only consider making communication satellites once they have gotten the Electrics topic unlocked (5th tier topic)...
  
Note that a KEO-2-satellite-system will have some blind spots near Kerbin surface.
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===Maximal Altitude Table for an Initial Kerbin Satellite Network===
  
The Communotron 88-88, Reflectron KR-14, CommTech 1, and Reflectron GX-120 are always powerful enough to operate at the edge of Kerbin SOI.
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The following table shows the maximal and minimal altitude for a given set of evenly spaced satellites each rigged with a low tech antenna for interlink purposes on a Kerbin equatorial orbit.
  
 
{| class="wikitable sortable"
 
{| class="wikitable sortable"
 
|-
 
|-
! Interlink Antenna\Sat# !! 2 !! 3 !! 4 !! 5 !! 6+ Min.!! 6+ Max.!! Comment
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! Interlink Antenna !! 3 sat.!! 4 sat.!! Comment
 
|-
 
|-
| Minimal Altitude|| 2,869km(KEO)|| 600.000km|| 248.528km|| 141.640km|| 92.820km|| 70km (LKO)||
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| (Minimal Altitude)|| 600 km|| 249 km|| Caused by Kerbin Geometry
 
|-
 
|-
| Reflectron DP-10|| N/A|| N/A|| N/A|| N/A|| 130.951km|| 444.645km|| 9/13 sat. respectively
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| Communotron 16|| 843 km|| 1,167 km|| A 3-sat-sys. of this is the cheapest option overall and allows for easy expansion
 
|-
 
|-
| Communotron 16|| N/A|| 843.376km|| 1,167.767km|| 1,526.627km|| 1,900km|| 2,280.956km|| 6/7 sat.
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| Comms DTS-M1|| 28,267 km|| 34,755 km|| A 3-sat-sys. of this can also completely cover the Mun, at the cost of longer delay and night time
 
|-
 
|-
| CommTech EXP-VR-2T|| N/A|| 1,132.051km|| 1,521.320km|| 1,951.952km|| 2,400km|| 2,857.147km|| 6/7 sat.
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| Reflectron KR-7|| 51,361 km|| 63,039 km|| A 4-sat-sys. of this can yield almost complete coverage for the Kerbin system (Minmus will have temporary blind spots)
|-
 
| Communotron 32|| N/A|| 2,286.751km|| 2,935.534km|| 3,653.254km|| 4,400km|| N/A||
 
|-
 
| Comms DTS-M1|| 2,869km(KEO)|| 28,267.513km|| 34,755.339km|| 41,932.540km|| 49,400km|| N/A||
 
|-
 
| Reflectron KR-7|| 2,869km(KEO)|| 51,361.524km|| 63,039.610km|| 75,958.573km|| 83,559km (SOI Edge)|| N/A||
 
 
|}
 
|}
  
==First Steps==
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===Kerbal Relay Satellites===
The first antenna we'll get is the [[Communotron 16]], henceforth referred to as the C-16 for brevity, and is acquired upon researching Engineering 101(2nd tier topic). The C-16 is omnidirectional, meaning it does not need to be pointed at any direction to connect. This is useful for 2 reasons: one, this means a single C-16 can connect multiple signals with ease; and two, with less power cost per connection. The C-16 however does have a very limited ranged of 2,500km, or 2.5Mm. The C-16 will also snap under dynamic pressure, making it ill-suited for launching or landing purposes.
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Once the [[Electrics]] topic is unlocked, the [[OX-STAT Photovoltaic Panels]] will now be available, a far superior option to stuffing our satellites with batteries, which will still run down quite quickly powering several antennae. On a positive side note, this will also unlock the Reflectron KR-7 dish as well as the [[Probodobodyne OKTO]]. The OKTO drone core can provide basic SAS and the KR-7 has even more range than the DTS-M1 and isn't as fragile, so we can switch it on on the launch pad. More importantly, once our relay network is up, the KR-7 will grant control to a probe during Kerbin landing, without the need of precision landing in uplink range, unlike the DP-10.
 
 
Prior to any additional research, the C-16's only use at this point is to transfer scientific data nearby back to KSC. Which could speed up science gain if used properly.
 
 
 
The next available antennae are the Reflectron DP-10, unlocked by Flight control(4th tier topic); and the Comms DTS-M1, unlocked by Basic Science(another 4th tier topic), along with [[Stayputnik Mk. 1]], the first available probe core.
 
  
The DP-10 is also omnidirectional, but has a even more limited range of 500km. However, the DP-10 is built to withstand dynamic pressure, making it perfect for launching and landing purposes. In fact, due to this, the DP-10 is activated by default for convenience! Finally, the power cost for DP-10 is negligible, so we can feel free to just leave it on.
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With 4 antennae at our disposal and the capability of power generation, we can finally start with our satellite network! Our aim here is to put at least 3 relay satellites in Kerbin orbit so that we can bounce the signal from the KSC to anywhere around Kerbin, and, if we are feeling ambitious, to the Mun and Minmus.
 
 
The DTS-M1 is the first available dish antenna, meaning to be used effectively they will need to be directed at a celestial body or craft. Dish antennae also consume power more rapidly, meaning power management will be a serious concern with them. On the other hand, dish antennae has a much greater range when compared with omnidirectional ones, making them a must for missions beyond keostationary orbit. The DTS-M1 specifically, has a range of 50Mm, capable of reaching Minmus.
 
 
 
With the C-16, DP-10, and DTS-M1, we can now build a fully functional, fully unkerballed satellite network whose signal could reach Minmus. However, those satellites won't last very long, as we likely have no access to any solar panels yet, meaning the satellites can only last as long as the amount of their Z-100 batteries allow.
 
 
 
This means, the player is advised to only consider making communication satellites once they have gotten the Electrics topic unlocked(tier 5)...
 
 
 
===Relay Satellites===
 
Once the [[Electrics]] topic is unlocked, the [[OX-STAT Photovoltaic Panels]] will now be available, a far superior option to stuffing our satellites with batteries, which will still run down quite quickly powering several antennae. On a positive side note, this will also unlock the Reflectron KR-7 dish, which has even more range than the DTS-M1 and isn't as fragile, so we can switch it on on the launch pad. More importantly, once our relay network is up, the KR-7 will grant control to a probe during Kerbin landing, without the need of precision landing near KSC, unlike the DP-10.
 
 
 
With 4 antennae at our disposal and the knowledge of power generation, we can finally start with our satellite network! Our aim here is to put at least 3 relay satellites in Kerbin orbit so that we can bounce the signal from the KSC to anywhere around Kerbin, and, if we are feeling ambitious, to the Mun and Minmus.
 
  
 
We'll want our satellites to have the following 5 capabilities, in addition to a rocket able to reach the designated orbit:
 
We'll want our satellites to have the following 5 capabilities, in addition to a rocket able to reach the designated orbit:
1) Control during launch. This can be a launch worthy antenna such as DP-10 or KR-7, or alternatively a kerballed lower stage, which will allow a level one pilot to execute prograde/retrograde hold. KR-7 is only recommended here if it also acts as connection to KSC in orbit. But it's hard to go wrong with DP-10 here.
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# Control during launch. This can be a DP-10 (initial uplink), or alternatively a kerballed lower stage, which will also allow a pilot to grant SAS. The KR-7 is also an option, but it will require another uplink as it needs to be targeted towards mission control prior to launch, specifically the [[TT18-A Launch Stability Enhancer]] can grant kerrestrial uplink prior to detachment.
2) Connection to KSC in orbit. Here, all 4 antenna could be viable, depending on the orbital altitude of course.
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# Connection to KSC in orbit (orbital uplink reciever). Either the KR-7, DTS-M1, or C-16 will do, depending on the orbital altitude and power generation.
3) Connection among the network. Again, all 4 antenna could do if the height is right. But a omnidirectional antenna will be very economical here, power wise. This is especially true if the omnidirectional antenna also covers the previous item.
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# Connection among the network (inter-satellite-link). Again, all 3 antenna could do. But a C-16 will be very economical on power consumption. This is especially true if the omnidirectional antenna also covers the previous item, as a single C-16 can deliver 3 links, and more should we want to expend the network. If we are using dish antennae though, we will need two of them due to cone angle, '''three''' if they also act as uplink receiver.
4) Connection to desired locations. Unless we are content with mere Kerbin coverage, we will want either/both of the dish antenna for the job. DTS-M1 has a shorter but wider range, whereas KR-7 is the reverse. Both takes the same amount of power, so the decision is purely goal-driven.
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# Connection to desired locations (downlink). Unless we are content with mere Kerbin coverage, we will want either/both of the dish antenna for the job. DTS-M1 has a shorter reach but lighter, whereas KR-7 has almost double the range but weighs half a tonne, on top of being not very aerodynamic. Although both takes the same amount of power. So the decision here depends upon our delta-v budget and desired reach. We will want at least one downlink antenna for the "active vessel", and, if we are committed, additional ones for '''each''' of the moons.
5) Enough power generation and storage. The night time of a given orbit needs to be consider here, the higher the orbit, the longer the night.
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# Enough power generation and storage. The night time of a given orbit needs to be considered here, the higher the orbit, the longer the night. For example, an equatorial LKO has a ten minute night, the KEO has a twenty-minute night, and an equatorial SOI-edge orbit will have a hundred minute night!
  
The possibilities here are endless, we could build a very economical 3 satellite network that uses C-16 for KSC and network connection, plus one or more dish antenna(e) each for further relays, at an altitude between 600km and 843km. Or We could use the dish antenna instead and build a network at keostationary orbit.
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The possibilities here are endless, we could build a very economical 3 satellite network that uses C-16 for KSC and network connection, plus one or more dish antenna(e) each for further relays, at an altitude between 600 km and 843 km. Alternatively, we could--if power demand is not an issue-- use the dish antennae instead and build a network at keostationary orbit.
  
Here's an example if you get stuck:
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Here's an example of the latter if you get stuck:
 
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Launch your first satellite over the KSC. As you leave the atmosphere, target one of your DTS-M1s at Mission Control and activate it. Remember you'll lose contact with the KSC if you go over the horizon, so make sure you get in to a stable parking orbit before then, or burn immediately for your target altitude, which should keep you more or less above the KSC. Circularise its orbit and that satellite is done for now.
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===Operational Details===
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We start by launching the first satellite for lower-than-target orbit, ideally during the day. If we are using a KR-7 as our uplink. we should target it towards KSC prior to launch. Once launched, Unless the vessel is kerballed, we will need to establish a stable orbit before it goes over the horizon, else we might not be able to control it again before it hits the ground and or air too hard. if we were using DP-10 as our uplink this is a good time to activate a more powerful antenna (remember to target KSC if it's directional!), after that and only after that we can deactivate the DP-10 to save power.if we have reached stable orbit and our uplink receiver is nominal, we will always, eventually, be able to maneuver the craft again when it is above KSC once more.
  
Launch your second satellite to the same altitude and target one of its DTS-M1s at Mission Control, and a second at your first relay satellite and activate them. Switch to your first relay satellite and target one of its DTS-M1s at your second satellite and activate it to make the link bidirectional. If your second satellite ends up close to your first, then you can leave its periapsis a little low when circularising at apoapsis; this will leave it with a slightly shorter orbital period than the first satellite, and it will move ahead of it a little each orbit. Once you're happy with its position relative to the first, burn to finish circularising your orbit. The most important thing is to get the satellites at matching altitudes, otherwise they'll drift relative to each other.
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But if comms link did break prior to our first satellite reaching stable orbit, there is one way to save it! By launching another one immediately after the link is broken, we can relay signals between KSC and the first satellite. Allowing the first satellite to finish stablizing its orbit. And if the second satellite went over the horizen itself, well, we can always launch another one! But we will probably need to launch one satellite that has a stable orbit prior to going over the horizen eventually.
  
Launch your third and final satellite, link it with the other two satellites (and them back to it) and mission control and place it in an orbit to make a triangle with the others. Hopefully your satellites now look something like this in the Tracking Station:
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If we havn't already, we should now launch the remaining satellites into stable orbit, as we did with the first satellite. If we are using dish antenna for inter-satellite-links, it would behoove us to target the satellites towards each other as soon as possible. As, by doing so we will extend the time window in which the satellites are controllable.
  
[[File:RT2-first-relay-sats.png|Ideally that triangle should be equilateral, but it's not essential]]
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Once stable orbit is reached for each satellite, we can now take our time in transfering the crafts to the intended orbit... But here's the tricky part, we want to put all of our satellites at a similar altitude as the first one but evenly spaced.
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The easy way to do this, is to simply put the satellite in the same altitude, and then lower or raise the orbit a bit to let the satellites "give chase" or "wait for" each other respectively, once in position, we can put the "chasing" or "waiting" satellite back into the previous orbit. This just like orbital rendezvous except we intend to miss the target for up to 120 degrees!
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Once the satellites are roughly evenly spaced, we can finalize the operation by reducing inclination and eccentricity by burning normal/anti-normal and radial/anti-radial, and finally synchronizing the satellites.
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To synchronize. the orbital period difference should be under a second, the higher the orbit, the longer the orbital period. Lowering the thrust limits will help with further precision. (We can calculate orbital period by doubling the difference of our time-to-apoapsis and time-to-periapsis, alternatively we can use mods that give us this information, such as MechJeb or Kerbal Engineer Redux)
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And that's it! Hopefully your satellites now look something like this in the Tracking Station:
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[[File:RT2-first-relay-sats.png|Ideally that triangle should be equilateral, but it's not essential, the higher the orbit, the more leeway we've got!]]
  
 
If so, congratulations, you've made your first set of relay satellites!
 
If so, congratulations, you've made your first set of relay satellites!
  
Finally, switch to each of your satellites and target one of their KR-7s to Active Vessel and activate it. This will automatically keep one of their dishes targeted at whichever ship you're currently controlling.
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Finally, activate all of the downlink antennae, which ideally should be directional. If they are directional, pick "Active Vessel" under target selection, and the network will automatically cover the spacecraft currently under your control. For those more ambitious players who packed extra downlink antenna for Mun and/or Minmus communication, don't forget to target Mun and/or Minmus with your extra antennae!
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==Next Steps: Kerbal, Munar and Minmal Unkerballed-Missions==
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Now that we've got our first set of satellites up and running, we can control a probe within our downlink range, depending on our downlink antenna, this can be either low Kerbin space (C-16), from Kerbin to Minmus (DTS-M1), or almost anywhere within Kerbin [[sphere of influence]] (KR-7).
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To use this downlink coverage we have just set up, we need to equip our probes with a set of appropriate antenna as downlink receiver. Remember that links need to be bidirectional.
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If we are using dish antenna as our downlink receiver, when the probe is physically within the network satellites, we will need to target it towards a nearby relay satellite, and maybe switch to a closer one if the original relay satellite has drifted away. A very useful example of this would be a probe equipped with a KR-7, which is flight worthy in Kerbal atmosphere, meaning we could control the landing of a probe almost anywhere on Kerbin!
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If the probe is far enough away from Kerbin, we can switch it to simply target Kerbin, this will trigger cone mode, and our receiver will link with anything that's in range, just like an omnidirectional antenna, except that it has a field of view limit. The Target selection menu will helpfully point out if the cone mode would cover anything, so if it says zero then we are not far away enough. Alternatively, having a omnidirectional antenna as downlink receiver will greatly simplify operations nearing the relay network.
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As a probe leaves Kerbin, we will start noticing mild signal delays. Near the mun this will likely only be a 0.1s or so signal delay, a probe around Minmus can easily end up with around 0.5s signal delay, which is enough to become noticeable. Be careful when landing or docking when that far out, because fine control movements can be difficult. Within the Kerbal system, signal delays, however annoying, should still be manageable.
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With only a single set of satellite network, there are inevitably some blinds spots, such as the space behind Mun and Minmus, as well as the polar regions of Kerbin and its moons.
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if we want coverage behind the moons, we can launch a further set of satellites out beyond their orbit, which will allow us to bounce a signal out and back behind them, or give them their own relay network just like we did for Kerbin.
  
==Next Steps==
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If we want coverage for the polar areas, we will need to launch another set of Kerbal relay satellites on a polar orbit. By doing so we could also cover polar regions of the moon that is facing Kerbin. If we want to be extra thorough, we can even give the moons their own polar relay networks!
Now that you've got your first set of satellites equipped with KR-7s, you can control a probe almost anywhere in the Kerbin [[sphere of influence]]. Equip any probe with 3 KR-7s and point them at your relay satellites and activate. Your relay satellites will already target one of their KR-7s at your probe because you set it up to target your active vessel. Despite their appearance, KR-7s don't need to be physically faced towards the target. You should now be well set to send a probe to the Mun. There are still two places your communications network can't reach, and that's directly behind the Mun and [[Minmus]], so make sure you plan your route so you don't need to make a burn when behind them.
 
  
If you're doing your first Mun probe without the Electrics topic unlocked then you'll be using DTS-M1 or Communotron-16s for your long range communications. This has the unfortunate problem that these antennae will burn up on reentry, causing you to lose control of your probe and be unable to open parachutes or fine tune your landing. You can solve this problem two ways:
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===Advanced Discussion===
* Perform any actions required for landing, such as opening chutes and deploying landing legs in the upper atmosphere. KSP doesn't simulate reentry heating, so your parachutes won't be destroyed.
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Although we have already covered the basics on how to set up a relay network, one might wonder if the one they've got is the best for them, here we will discuss about the pros and cons of different network configurations.
* Re-enter within 500 km of the KSC. This will allow your DP-10 antenna to link with the KSC and keep control of the probe.
 
  
While your probe to the Mun will likely only have 0.1s or so signal delay, a probe around Minmus can easily end up with around 0.5s signal delay, which is enough to become noticeable. Be careful when landing or docking when that far out, because fine control movements can be difficult.
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In this case, there are three primary types of cost to be concerned about: '''financial''', '''power''', and '''opportunity'''. Financial cost covers the funds required to set up and maintain a network, this is likely not an issue if we are not in career more. Power cost is the energy needed for the satellites to run. And opportunity cost is the player's time, a difficult network configuration for example will force the player to constantly waste their time on maintaining the network.
  
If you want perfect coverage around Kerbin, including behind the Mun and Minmus, you can launch a further set of satellites out beyond their orbit, which will allow you to bounce a signal out and back behind them, or deploy a set of satellites around the Mun and Minmus like you did around Kerbin.
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Here are some factors that could influence these costs:
 +
 
 +
* '''Network Satellite Number'''. The more satellites a network has, the more altitude margin it has. a C-16 3 Kerbal satellite network for example only has a margin of 600km to 843 km in altitude. But a 4 satellite one can work from a altitude of 248km to 1,168 km. However, having more moving parts also means more things could go wrong, and the player is required to pay for, support and setup a higher amount of satellites.
 +
* '''Orbital Altitude'''. The higher the altitude is, the more leeway we have in terms of spacing, and will also grant more polar coverage, if the network is equatorial. Higher orbits also means longer nights, and thus greater battery capacity is needed. But a lower one will have shorter days, making greater power generation necessary.
 +
* '''Antenna Amount and Type''' A more powerful and greater amount of antennae will likely mean higher energy consumption, at the very least they would be heavier so more funds is needed for the rocket carrying the satellite, but this could save the player some time down the road as less upgrade is required, as long as the satellites are well-designed.
 +
* '''Network Completeness'''. A truly total coverage of a celestial object from its network will require at least 2 sets of 3-satellite-networks. But it is entirely possible that a partial network will do. For non-Kerbin celestial objects, a single relay satellite will already grant near-full coverage half of the time. And two relay satellites in Lagrangian points will grant near perfect coverage. Nevertheless a disconnection at the wrong place or time could cause mission failures.
  
 
==Going Interplanetary==
 
==Going Interplanetary==
Your KR-7s can talk to any satellite in Kerbin's sphere of influence, but they won't reach much beyond that. For that you'll need to unlock the Reflectron KR-14, with its 60 Gm range. The KR-14 can reliably reach [[Moho]], [[Eve]] and [[Duna]] and just about reach [[Dres]], but it can't reliably reach [[Jool]]. To reach Jool and [[Eeloo]] you'll need to unlock the Reflectron GX-128 or CommTech-1 with massive 350 Gm+ ranges. Remember links need to be bidirectional, so you'll need the strong antenna on the probe you send AND launch some satellites in to Kerbin orbit with the strong antenna on them to relay between the probe and the KSC.
+
The KR-7 and DTS-M1 are great for communications within the Kerbal system, but they can't do much more than that. For interplanetary communications we will need to unlock the Communotron 88-88 and Reflectron KR-14, these have a reach of 40Gm and 60Gm respectively.
 +
 
 +
For perspective, a 40Gm range 88-88 in Kerbin orbit will permanently grant [[Moho]], [[Eve]] and [[Duna]] coverage. And a 60Gm range KR-14 will also permanently cover [[Dres]]
 +
 
 +
Remember links need to be bidirectional, so we'll need these strong antennae to be on both the probe, and a relay satellite. If we've built the Kerbal relay network with omnidirectional inter-satellite-link, We can simple slap both a C-16 and a 88-88/KR-14 on a amplifier satellite and park a pair of those each on the opposite side of LKO.
 +
 
 +
We can also extend these interplanetary antenna's range by establishing a solar, or keliocentric, relay network. This are similar to the Kerbal relay network we just did, except instead of orbiting Kerbin, it is orbiting the sun. Such a network will have a orbit among the planets. The 88-88 for example can form a network near Dunanian orbit, and by doing so extends its range to cover Dres permanently. The KR-14 can also form a Solar relay network, and it can be near Dresser orbit, which will give permanent [[Jool|Joolian]] coverage!
 +
 
 +
Alternatively, we can unlock the Reflectron GX-128 or CommTech-1(CT-1 for shot). These ridiculously long ranged antennae can just about reach anything within the solar system, as long as the planets, or the sun, don't literally align. Note that, even though the 88-88, KR-14,GX-128, and CT-1 all have great reach, they have a very limited field of view, so they are ill-suited for planetary linking.
 +
 
 +
Also notice that, just like back in Kerbin, without further relays we will not have access to the far side of another celestial object. Depending on how thorough we want to be, we could give every single planet and moon their own partial, or even full relay network, which would be quite an achievement!
 +
 
 +
===Signal delays===
 +
Other than needing the more powerful antennae, once we send probes to interplanetary distances the signal delay will reach several minutes, making interactive control unfeasible. To properly maneuver, we should use the Flight Computer, which comes with every probe core and can be accessed with the calculator icon next to the signal delay display.
 +
 
 +
The simplest way to execute a burn with the flight computer is to create a [[maneuver node]] and plot out the intended maneuver, then instruct the computer to NODE, this will prompt the probe do a maneuver hold. After that, hit EXEC to schedule a burn of the correct length at the correct time. By clicking the >> icon we can see the commands being sent to the probe and the time it'll take for them to get there.
 +
 
 +
Signal delay affects most operations on your probe, such as using science instruments, ejecting a stage, extending solar panels, etc. If something doesn't seem to have worked, check the flight computer to see if the command has been delayed.
  
Other than needing the more powerful antennae, once you send probes to interplanetary distances the signal delay will reach several minutes, making interactive control of your probe unfeasible. To make burns you'll need to use the Flight Computer, which comes with every probe core and can be accessed with the calculator icon next to the signal delay display. The simplest way to execute a burn with the flight computer is to create a [[maneuver node]] with the maneuver you want, instruct the computer to NODE, which will pre-orient the spacecraft in the burn direction of the next maneuver node, then EXEC to schedule a burn of the correct length at the correct time. By clicking the >> icon you can see the commands being sent to the probe and the time it'll take for them to get there. Signal delay affects most operations on your probe, such as using science instruments, ejecting a stage, extending solar panels, etc. If something doesn't seem to have worked, check the flight computer to see if your command has been delayed.
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Landing probes on a planet with minutes of signal delay can be extremely difficult. Atmospheric landings are easier due to areobreaking, and parachutes eliminates the need for responsive input, at least somewhat. Though do remember to take in to account the time delay of the command to open the parachutes.
  
Remember that you'll lose contact with your probe while on the far side of the planet from Kerbin. You can solve this problem by stationing a satellite in high orbit over your destination planet (either send it as a second craft or decouple it from your main craft) to bounce a signal off.
+
Landing on planets and moons without atmospheres is likely to be an exercise in frustration, but killing surface horizontal velocity and instructing the flight computer to point straight up while applying suicide burn just might work. Alternatively we could just build a sturdy enough craft that lands horizontally and let gravity and friction do the rest, I believe this is called "lithobreaking"... I mean "lithobraking".
  
Landing probes on a planet with minutes of signal delay can be extremely difficult. Planets and moons with atmospheres are easier because you can use parachutes for the final descent, making control inputs unnecessary, or at least less important. Remember to take in to account the time delay of the command to open your chutes. Landing on planets and moons without atmospheres is likely to be an exercise in frustration, but killing your surface horizontal velocity and instructing your flight computer to hold the spacecraft directly up while applying a constant burn to slow your descent may work.
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===Antennae Specification Table===
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{| class="wikitable sortable"
 +
|-
 +
! Brand !! Model !! Type !! Range !! Uses
 +
|-
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| Reflectron || DP-10|| Omni|| 0.5 Mm|| Atmospheric flight (including launch and landing) near KSC, Kerrestrial links, local drone comms, relay network for smaller-than-Moho celestial objects (This includes the Mun and Minmus, needs 4 sat. for Mun and Eeloo)
 +
|-
 +
| Communotron || 16|| Omni|| 2.5 Mm|| Relay network for smaller-than-Jool celestial objects (Including Kerbin, and 3 sat.-sys. for Mun and Eeloo)
 +
|-
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| CommTech || EXP-VR-2T|| Omni|| 3 Mm|| KEO uplink above KSC, straight upgrade to the Communotron 16
 +
|-
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| Communotron || 32|| Omni|| 5 Mm|| High Kerbin orbit/KEO relay network, luxury omnidirectional coverage
 +
|-
 +
| Comms || DTS-M1|| Dish|| 50 Mm|| Lightweight planetary system comms (Kerbin-Minmus reach), Joolian relay network
 +
|-
 +
| Reflectron || KR-7|| Dish|| 90 Mm|| Atmospheric flight within downlink coverage, Heavy-duty planetary system comms (Kerbin-SOI reach)
 +
|-
 +
| Communotron || 88-88|| Dish|| 40 Gm|| Lightweight interplanetary comms (Kerbin-Duna reach), Solar relay network near Duna orbit (Sun-Dres Reach)
 +
|-
 +
| Reflectron || KR-14|| Dish|| 60 Gm|| Heavy-duty interplanetary comms (Kerbin-Dres reach), Solar relay network near Dres orbit (Sun-Jool Reach)
 +
|-
 +
| CommTech|| 1|| Dish|| 350 Gm|| Heavy-duty Solar system wide comms
 +
|-
 +
| Reflectron|| GX-120|| Dish|| 400 Gm|| Luxury lightweight Solar system wide comms
 +
|-
 +
| [[TT18-A Launch Stability Enhancer|LSE]]|| TT18-A|| Land|| N/A|| The Stability Enhancer will provide land line connection prior to detechment
 +
|-
 +
| Core Upgrade|| N/A|| Omni|| 3 km|| Obtained through researching "unmanned tech" after that it is completely free, can replace the land line from [[TT18-A Launch Stability Enhancer]], also replaces the DP-10 for local comms purposes
 +
|-
 +
|}
  
 
==Remote Mission Control==
 
==Remote Mission Control==
Once you unlock the Large Probes topic you'll get access to the [[RC-L01 Remote Guidance Unit]]. This probe core is special because it contains a Command signal processor, which allows a ship equipped with it to act as remote Mission Control to any probes connected to it, however to do this the ship must also be crewed by 6 or more [[Kerbals]]. The main advantage of this is that a command ship can control probes near it with very little signal delay, even if far from Kerbin. Note that transmitting science results back to Kerbin still requires a link to the KSC.
+
If the signal delay is unmanageable, there is a solution. Once we unlock the Large Probes topic we'll get access to the [[RC-L01 Remote Guidance Unit]]. In RemoteTech, this probe core is special because it contains a Command signal processor, which allows a ship or base equipped with it to act as remote Mission Control to any probes connected to it, however to do this the ship must also be crewed by 6 or more [[Kerbals]]. The main advantage of this is that a command ship can control probes near it with reduced signal delay, even if far from Kerbin.
 +
 
 +
Note that to gain science the reports still need to be sent back to KSC, to even suggest that six Kerbals can replace the entirety of R&D might give Wernher von Kerman a heart attack!
  
 
== Related Links ==
 
== Related Links ==
 
* [[Tutorial: Basic Probe And Satellite Building]]
 
* [[Tutorial: Basic Probe And Satellite Building]]
  
[[Category:Tutorials|Tutorial:RemoteTech2]]
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[[Category:Tutorials|RemoteTech2]]

Latest revision as of 20:22, 2 May 2019

This page has been requested to be moved to Tutorial:RemoteTech.

The given reason is: Mod renamed from Remote Tech 2 to just Remote Tech

This page needs more links to other articles to help integrate it into the Kerbal Space Program Wiki

RemoteTech 2 is a mod for KSP that modifies remote operations of unkerballed probes by requiring the probes to have a telecommunications link back to Mission Control. Thus, to operate drones efficiently the player needs to set up a satellite network to relay and maintain communication with their probes. Transmissions of science reports will also require a comms link back to the KSC.

Communications delay, caused by the speed of light, is also simulated. This could be a mere irritating 0.5s delay near Kerbin SOI, or a perilous 10-minute delay in interplanetary missions. To combat this, RemoteTech2 also provides advanced flight computers that can execute premeditated commands on mark.

This tutorial seeks to inform the player on the details of this challenging mod, and to give pointers as to how to set up a functional relay network for the Kerbin system, and further interplanetary operations.

Specifications

  • Length: 10 to 30 minutes for "First Steps"
  • Difficulty: Advanced - This tutorial will assume you can already get a rocket in to orbit without Remote Tech 2 and are familiar with basic orbital mechanics.
  • For version: KSP 1.02 and higher and RemoteTech v1.6.5.

Introduction: Antennae and Links

First we need to understand the changes RemoteTech made to the existing probe/antenna mechanics. Unlike in vanilla KSP, where the player can control any craft at all times as long as there is a pilot or powered probe core onboard, here an unkerballed probe can only be controlled if it can communicate with KSC via antennae. Specifically, any two crafts can communicate if they have a direct line of sight between their respective antennae, which is not blocked by any celestial objects. This is known as forming a direct communication link. In practice, maintaining a direct link from crafts to KSC is not always feasible since planet rotates, but communicaiton links doesn't have to be direct, other crafts can relay the signal for the original craft, by-passing the blocking geometries of celestial bodies. Thus, a satellite relay network to reliably relay signals to KSC is highly desirable.

There are two types of antennae - omnidirectional and directional (a.k.a. dish). Omnidirectional antennae can broadcast in every direction, tend to be very compact, and are typically light both in weight and power usage. They however lack the range for anything beyond low orbit communications. Dish antenna, on the other hand, have far greater range, able to communicate within and among planetary systems. But they must be targeted to function, they are also power intensive and comparatively unwieldy. Regardless, both make your satellite look totally awesome.

At the very beginning, the only antenna we have is (somewhat) safely hidden in Mission Control, it is omnidirectional and has a range of 75 Mm. This is enough to reach the LKO, Mun, Minmus, and then some. Unfortunately the KSC is on one side of Kerbin and those links will be broken once line of sight is gone, likely on a daily basis at best. As we progress in career mode, we will acquire more options to better our communications network, which, at this point, is quite literally-- nominal.

NOTE: For reasons later explained, it is strongly recommended to set up a satellite network after the Electrics topic is researched.

Types of Communication Links

  • Forward Link. A link from ground control to a mobile receiver.
  • Reverse Link. The reverse of a forward link.
  • Kerrestrial Link. A link among parties near the surface.
  • Uplink (UL). A link that is going toward a satellite network, or away from the surface of the pertinent celestial body.
  • Downlink (DL). The reverse of a uplink.
  • Inter-Satellite-link (ISL). A link among a satellite network, this can form the backbone of said network.
  • Planetary-Link (PL). A link among sub-systems within a planetary system, such as Kerbin to Mun, or Mun to Minmus communication.
  • Inter-Planetary-Link (IPL). A link among planetary systems across the solar system.

First Steps

The first build-able antenna we'll get is the Communotron 16 (C-16), and is acquired upon researching Engineering 101 (2nd tier topic). The C-16 is omnidirectional, which means it does not need to be pointed at any direction to connect. This is useful for two reasons: one, this means a single C-16 can connect multiple signals with ease; and two, with less power cost per connection. On the other hand, the C-16 snaps under dynamic pressure, making it ill-suited for launching or landing purposes. The C-16 also have a limited ranged of 2,500 km, but that is more than enough to cover Kerbin.

Despite its sufficient range, prior to any additional research, the C-16's only use at this point is to transfer scientific data nearby back to KSC. Which could speed up science gain if used properly.

The next available antennae are the Reflectron DP-10, unlocked by Flight control (4th tier topic); and the Comms DTS-M1, unlocked by Basic Science (another 4th tier topic), along with Stayputnik Mk. 1, the first available probe core.

The DP-10 is also omnidirectional, but has a even more limited range of 500 km, it could form a 4-sat. network around the Mun and Eeloo, and a 3-sat. network for anything smaller, like Minmus. But it is difficult to form a network around Kerbin with the DP-10. Nonetheless, the DP-10 is built to withstand dynamic pressure, making it perfect for launching purposes. It could even work for landing operations, but the probe will need to be precision landed near KSC. For convenience, the DP-10 is activated by default, and the power cost for DP-10 is negligible, so it is always preferable if range is not an issue.

The DTS-M1 is the first available dish antenna, which means to be used they will need to be directed at a celestial body or craft. Although we do have the option to order dish antennae to cover currently active craft. They are also power-intensive and has greater range. Specifically, The DTS-M1 consume power at a rate 6-fold of that of C-16. But the DTS-M1 has a range of 50 Mm, capable of reaching Minmus.

With the C-16, DP-10, and DTS-M1, we can now build a fully functional, fully unkerballed satellite network whose signal could reach Minmus. However, those satellites won't last very long, as we likely have no access to any solar panels yet, meaning the satellites can only last as long as the amount of their Z-100 batteries allow.

This is why the player is advised to only consider making communication satellites once they have gotten the Electrics topic unlocked (5th tier topic)...

Maximal Altitude Table for an Initial Kerbin Satellite Network

The following table shows the maximal and minimal altitude for a given set of evenly spaced satellites each rigged with a low tech antenna for interlink purposes on a Kerbin equatorial orbit.

Interlink Antenna 3 sat. 4 sat. Comment
(Minimal Altitude) 600 km 249 km Caused by Kerbin Geometry
Communotron 16 843 km 1,167 km A 3-sat-sys. of this is the cheapest option overall and allows for easy expansion
Comms DTS-M1 28,267 km 34,755 km A 3-sat-sys. of this can also completely cover the Mun, at the cost of longer delay and night time
Reflectron KR-7 51,361 km 63,039 km A 4-sat-sys. of this can yield almost complete coverage for the Kerbin system (Minmus will have temporary blind spots)

Kerbal Relay Satellites

Once the Electrics topic is unlocked, the OX-STAT Photovoltaic Panels will now be available, a far superior option to stuffing our satellites with batteries, which will still run down quite quickly powering several antennae. On a positive side note, this will also unlock the Reflectron KR-7 dish as well as the Probodobodyne OKTO. The OKTO drone core can provide basic SAS and the KR-7 has even more range than the DTS-M1 and isn't as fragile, so we can switch it on on the launch pad. More importantly, once our relay network is up, the KR-7 will grant control to a probe during Kerbin landing, without the need of precision landing in uplink range, unlike the DP-10.

With 4 antennae at our disposal and the capability of power generation, we can finally start with our satellite network! Our aim here is to put at least 3 relay satellites in Kerbin orbit so that we can bounce the signal from the KSC to anywhere around Kerbin, and, if we are feeling ambitious, to the Mun and Minmus.

We'll want our satellites to have the following 5 capabilities, in addition to a rocket able to reach the designated orbit:

  1. Control during launch. This can be a DP-10 (initial uplink), or alternatively a kerballed lower stage, which will also allow a pilot to grant SAS. The KR-7 is also an option, but it will require another uplink as it needs to be targeted towards mission control prior to launch, specifically the TT18-A Launch Stability Enhancer can grant kerrestrial uplink prior to detachment.
  2. Connection to KSC in orbit (orbital uplink reciever). Either the KR-7, DTS-M1, or C-16 will do, depending on the orbital altitude and power generation.
  3. Connection among the network (inter-satellite-link). Again, all 3 antenna could do. But a C-16 will be very economical on power consumption. This is especially true if the omnidirectional antenna also covers the previous item, as a single C-16 can deliver 3 links, and more should we want to expend the network. If we are using dish antennae though, we will need two of them due to cone angle, three if they also act as uplink receiver.
  4. Connection to desired locations (downlink). Unless we are content with mere Kerbin coverage, we will want either/both of the dish antenna for the job. DTS-M1 has a shorter reach but lighter, whereas KR-7 has almost double the range but weighs half a tonne, on top of being not very aerodynamic. Although both takes the same amount of power. So the decision here depends upon our delta-v budget and desired reach. We will want at least one downlink antenna for the "active vessel", and, if we are committed, additional ones for each of the moons.
  5. Enough power generation and storage. The night time of a given orbit needs to be considered here, the higher the orbit, the longer the night. For example, an equatorial LKO has a ten minute night, the KEO has a twenty-minute night, and an equatorial SOI-edge orbit will have a hundred minute night!

The possibilities here are endless, we could build a very economical 3 satellite network that uses C-16 for KSC and network connection, plus one or more dish antenna(e) each for further relays, at an altitude between 600 km and 843 km. Alternatively, we could--if power demand is not an issue-- use the dish antennae instead and build a network at keostationary orbit.

Here's an example of the latter if you get stuck:

Spoiler:
Needs more solar panels?

An upper stage of two FL-T400 Fuel Tanks attached to an LV-909 Liquid Fuel Engine. A middle stage of two FL-T400s attached to an LV-T30 Liquid Fuel Engine and the first stage consisting of 6 FL-T400/LV-T30s attached with TT-38K Radial Decouplers. There are of course many other ways of designing this rocket, this is just an example if you get stuck. Note the single DP-10, 3 DTS-M1s and at least one KR-7. This rocket will just about reach KEO with a well executed ascent through the atmosphere, though a lower orbit will do.

Operational Details

We start by launching the first satellite for lower-than-target orbit, ideally during the day. If we are using a KR-7 as our uplink. we should target it towards KSC prior to launch. Once launched, Unless the vessel is kerballed, we will need to establish a stable orbit before it goes over the horizon, else we might not be able to control it again before it hits the ground and or air too hard. if we were using DP-10 as our uplink this is a good time to activate a more powerful antenna (remember to target KSC if it's directional!), after that and only after that we can deactivate the DP-10 to save power.if we have reached stable orbit and our uplink receiver is nominal, we will always, eventually, be able to maneuver the craft again when it is above KSC once more.

But if comms link did break prior to our first satellite reaching stable orbit, there is one way to save it! By launching another one immediately after the link is broken, we can relay signals between KSC and the first satellite. Allowing the first satellite to finish stablizing its orbit. And if the second satellite went over the horizen itself, well, we can always launch another one! But we will probably need to launch one satellite that has a stable orbit prior to going over the horizen eventually.

If we havn't already, we should now launch the remaining satellites into stable orbit, as we did with the first satellite. If we are using dish antenna for inter-satellite-links, it would behoove us to target the satellites towards each other as soon as possible. As, by doing so we will extend the time window in which the satellites are controllable.

Once stable orbit is reached for each satellite, we can now take our time in transfering the crafts to the intended orbit... But here's the tricky part, we want to put all of our satellites at a similar altitude as the first one but evenly spaced.

The easy way to do this, is to simply put the satellite in the same altitude, and then lower or raise the orbit a bit to let the satellites "give chase" or "wait for" each other respectively, once in position, we can put the "chasing" or "waiting" satellite back into the previous orbit. This just like orbital rendezvous except we intend to miss the target for up to 120 degrees!

Once the satellites are roughly evenly spaced, we can finalize the operation by reducing inclination and eccentricity by burning normal/anti-normal and radial/anti-radial, and finally synchronizing the satellites.

To synchronize. the orbital period difference should be under a second, the higher the orbit, the longer the orbital period. Lowering the thrust limits will help with further precision. (We can calculate orbital period by doubling the difference of our time-to-apoapsis and time-to-periapsis, alternatively we can use mods that give us this information, such as MechJeb or Kerbal Engineer Redux)

And that's it! Hopefully your satellites now look something like this in the Tracking Station:

Ideally that triangle should be equilateral, but it's not essential, the higher the orbit, the more leeway we've got!

If so, congratulations, you've made your first set of relay satellites!

Finally, activate all of the downlink antennae, which ideally should be directional. If they are directional, pick "Active Vessel" under target selection, and the network will automatically cover the spacecraft currently under your control. For those more ambitious players who packed extra downlink antenna for Mun and/or Minmus communication, don't forget to target Mun and/or Minmus with your extra antennae!

Next Steps: Kerbal, Munar and Minmal Unkerballed-Missions

Now that we've got our first set of satellites up and running, we can control a probe within our downlink range, depending on our downlink antenna, this can be either low Kerbin space (C-16), from Kerbin to Minmus (DTS-M1), or almost anywhere within Kerbin sphere of influence (KR-7).

To use this downlink coverage we have just set up, we need to equip our probes with a set of appropriate antenna as downlink receiver. Remember that links need to be bidirectional.

If we are using dish antenna as our downlink receiver, when the probe is physically within the network satellites, we will need to target it towards a nearby relay satellite, and maybe switch to a closer one if the original relay satellite has drifted away. A very useful example of this would be a probe equipped with a KR-7, which is flight worthy in Kerbal atmosphere, meaning we could control the landing of a probe almost anywhere on Kerbin!

If the probe is far enough away from Kerbin, we can switch it to simply target Kerbin, this will trigger cone mode, and our receiver will link with anything that's in range, just like an omnidirectional antenna, except that it has a field of view limit. The Target selection menu will helpfully point out if the cone mode would cover anything, so if it says zero then we are not far away enough. Alternatively, having a omnidirectional antenna as downlink receiver will greatly simplify operations nearing the relay network.

As a probe leaves Kerbin, we will start noticing mild signal delays. Near the mun this will likely only be a 0.1s or so signal delay, a probe around Minmus can easily end up with around 0.5s signal delay, which is enough to become noticeable. Be careful when landing or docking when that far out, because fine control movements can be difficult. Within the Kerbal system, signal delays, however annoying, should still be manageable.

With only a single set of satellite network, there are inevitably some blinds spots, such as the space behind Mun and Minmus, as well as the polar regions of Kerbin and its moons.

if we want coverage behind the moons, we can launch a further set of satellites out beyond their orbit, which will allow us to bounce a signal out and back behind them, or give them their own relay network just like we did for Kerbin.

If we want coverage for the polar areas, we will need to launch another set of Kerbal relay satellites on a polar orbit. By doing so we could also cover polar regions of the moon that is facing Kerbin. If we want to be extra thorough, we can even give the moons their own polar relay networks!

Advanced Discussion

Although we have already covered the basics on how to set up a relay network, one might wonder if the one they've got is the best for them, here we will discuss about the pros and cons of different network configurations.

In this case, there are three primary types of cost to be concerned about: financial, power, and opportunity. Financial cost covers the funds required to set up and maintain a network, this is likely not an issue if we are not in career more. Power cost is the energy needed for the satellites to run. And opportunity cost is the player's time, a difficult network configuration for example will force the player to constantly waste their time on maintaining the network.

Here are some factors that could influence these costs:

  • Network Satellite Number. The more satellites a network has, the more altitude margin it has. a C-16 3 Kerbal satellite network for example only has a margin of 600km to 843 km in altitude. But a 4 satellite one can work from a altitude of 248km to 1,168 km. However, having more moving parts also means more things could go wrong, and the player is required to pay for, support and setup a higher amount of satellites.
  • Orbital Altitude. The higher the altitude is, the more leeway we have in terms of spacing, and will also grant more polar coverage, if the network is equatorial. Higher orbits also means longer nights, and thus greater battery capacity is needed. But a lower one will have shorter days, making greater power generation necessary.
  • Antenna Amount and Type A more powerful and greater amount of antennae will likely mean higher energy consumption, at the very least they would be heavier so more funds is needed for the rocket carrying the satellite, but this could save the player some time down the road as less upgrade is required, as long as the satellites are well-designed.
  • Network Completeness. A truly total coverage of a celestial object from its network will require at least 2 sets of 3-satellite-networks. But it is entirely possible that a partial network will do. For non-Kerbin celestial objects, a single relay satellite will already grant near-full coverage half of the time. And two relay satellites in Lagrangian points will grant near perfect coverage. Nevertheless a disconnection at the wrong place or time could cause mission failures.

Going Interplanetary

The KR-7 and DTS-M1 are great for communications within the Kerbal system, but they can't do much more than that. For interplanetary communications we will need to unlock the Communotron 88-88 and Reflectron KR-14, these have a reach of 40Gm and 60Gm respectively.

For perspective, a 40Gm range 88-88 in Kerbin orbit will permanently grant Moho, Eve and Duna coverage. And a 60Gm range KR-14 will also permanently cover Dres

Remember links need to be bidirectional, so we'll need these strong antennae to be on both the probe, and a relay satellite. If we've built the Kerbal relay network with omnidirectional inter-satellite-link, We can simple slap both a C-16 and a 88-88/KR-14 on a amplifier satellite and park a pair of those each on the opposite side of LKO.

We can also extend these interplanetary antenna's range by establishing a solar, or keliocentric, relay network. This are similar to the Kerbal relay network we just did, except instead of orbiting Kerbin, it is orbiting the sun. Such a network will have a orbit among the planets. The 88-88 for example can form a network near Dunanian orbit, and by doing so extends its range to cover Dres permanently. The KR-14 can also form a Solar relay network, and it can be near Dresser orbit, which will give permanent Joolian coverage!

Alternatively, we can unlock the Reflectron GX-128 or CommTech-1(CT-1 for shot). These ridiculously long ranged antennae can just about reach anything within the solar system, as long as the planets, or the sun, don't literally align. Note that, even though the 88-88, KR-14,GX-128, and CT-1 all have great reach, they have a very limited field of view, so they are ill-suited for planetary linking.

Also notice that, just like back in Kerbin, without further relays we will not have access to the far side of another celestial object. Depending on how thorough we want to be, we could give every single planet and moon their own partial, or even full relay network, which would be quite an achievement!

Signal delays

Other than needing the more powerful antennae, once we send probes to interplanetary distances the signal delay will reach several minutes, making interactive control unfeasible. To properly maneuver, we should use the Flight Computer, which comes with every probe core and can be accessed with the calculator icon next to the signal delay display.

The simplest way to execute a burn with the flight computer is to create a maneuver node and plot out the intended maneuver, then instruct the computer to NODE, this will prompt the probe do a maneuver hold. After that, hit EXEC to schedule a burn of the correct length at the correct time. By clicking the >> icon we can see the commands being sent to the probe and the time it'll take for them to get there.

Signal delay affects most operations on your probe, such as using science instruments, ejecting a stage, extending solar panels, etc. If something doesn't seem to have worked, check the flight computer to see if the command has been delayed.

Landing probes on a planet with minutes of signal delay can be extremely difficult. Atmospheric landings are easier due to areobreaking, and parachutes eliminates the need for responsive input, at least somewhat. Though do remember to take in to account the time delay of the command to open the parachutes.

Landing on planets and moons without atmospheres is likely to be an exercise in frustration, but killing surface horizontal velocity and instructing the flight computer to point straight up while applying suicide burn just might work. Alternatively we could just build a sturdy enough craft that lands horizontally and let gravity and friction do the rest, I believe this is called "lithobreaking"... I mean "lithobraking".

Antennae Specification Table

Brand Model Type Range Uses
Reflectron DP-10 Omni 0.5 Mm Atmospheric flight (including launch and landing) near KSC, Kerrestrial links, local drone comms, relay network for smaller-than-Moho celestial objects (This includes the Mun and Minmus, needs 4 sat. for Mun and Eeloo)
Communotron 16 Omni 2.5 Mm Relay network for smaller-than-Jool celestial objects (Including Kerbin, and 3 sat.-sys. for Mun and Eeloo)
CommTech EXP-VR-2T Omni 3 Mm KEO uplink above KSC, straight upgrade to the Communotron 16
Communotron 32 Omni 5 Mm High Kerbin orbit/KEO relay network, luxury omnidirectional coverage
Comms DTS-M1 Dish 50 Mm Lightweight planetary system comms (Kerbin-Minmus reach), Joolian relay network
Reflectron KR-7 Dish 90 Mm Atmospheric flight within downlink coverage, Heavy-duty planetary system comms (Kerbin-SOI reach)
Communotron 88-88 Dish 40 Gm Lightweight interplanetary comms (Kerbin-Duna reach), Solar relay network near Duna orbit (Sun-Dres Reach)
Reflectron KR-14 Dish 60 Gm Heavy-duty interplanetary comms (Kerbin-Dres reach), Solar relay network near Dres orbit (Sun-Jool Reach)
CommTech 1 Dish 350 Gm Heavy-duty Solar system wide comms
Reflectron GX-120 Dish 400 Gm Luxury lightweight Solar system wide comms
LSE TT18-A Land N/A The Stability Enhancer will provide land line connection prior to detechment
Core Upgrade N/A Omni 3 km Obtained through researching "unmanned tech" after that it is completely free, can replace the land line from TT18-A Launch Stability Enhancer, also replaces the DP-10 for local comms purposes

Remote Mission Control

If the signal delay is unmanageable, there is a solution. Once we unlock the Large Probes topic we'll get access to the RC-L01 Remote Guidance Unit. In RemoteTech, this probe core is special because it contains a Command signal processor, which allows a ship or base equipped with it to act as remote Mission Control to any probes connected to it, however to do this the ship must also be crewed by 6 or more Kerbals. The main advantage of this is that a command ship can control probes near it with reduced signal delay, even if far from Kerbin.

Note that to gain science the reports still need to be sent back to KSC, to even suggest that six Kerbals can replace the entirety of R&D might give Wernher von Kerman a heart attack!

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