Antenna

[Guest]

I have a planned Eve mission, and I need help with calculating signal strength. I have a level 2 tracking station, 2 com sats in 100km orbit with 2g com antenna. The satellite has 1 hg55, and 2 communitron 16. Will this be enough? I cant experiment, no reverts allowed.

[ThreePounds]

I have made this spreadsheet to help you calculate. You can download it and modify it to do your calculations.

If you have questions about how to use it, just ask. I'll be glad to assist.

LINK: https://docs.google.com/spreadsheets/d/1PLS1UkVRR-qqUluIlyEweaqRFZqAJjp4sLgIiixqdFY/edit?usp=sharing

Edited July 31, 2017 by Three_Pounds

[Snark]

Moving to Gameplay Questions.

20 hours ago, dundun92 said:

I have a level 2 tracking station

Do you have the extra ground stations turned on or off?  This is important:  if they're on, then you don't need comsats at all (since any craft anywhere will have direct LOS to Kerbin, if it's not blocked by the local celestial body), whereas if they're off, you won't get the benefit of that high tracking-station power unless Kerbin happens to be facing the right direction.

20 hours ago, dundun92 said:

2 com sats in 100km orbit with 2g com antenna.

Sorry, are these satellites in orbit around Kerbin or Eve?

20 hours ago, dundun92 said:

The satellite has 1 hg55, and 2 communitron 16.

Is this your probe that's going to Eve?

20 hours ago, dundun92 said:

Will this be enough?

The short answer is:

• When your probe can directly see KSC:  Yes, it's enough.
• When you have to relay the signal through your comsat:  It's enough when Eve is close to Kerbin.  Not enough when Eve is far away.

 

Okay, here's the longer answer:

There are basically three levels of availability you might be concerned with:

1. Unavailable, i.e. a setup that can never reach Eve from Kerbin and is doomed to failure.
2. Partially available, i.e. a setup that works some of the time but not all (i.e. only works when Eve is relatively close to Kerbin, and/or when Kerbin is facing the right direction)
3. Completely available, i.e. a setup that provides continuous coverage even when Eve is at its farthest, and/or Kerbin is facing the wrong way.

To answer the question "Is it enough?", we need to care about two things:  distance and antenna power.

Distance:  Kerbin orbits at a radius of 13.6G meters.  Eve is 9.8G.  That means that the distance between the two planets can range anywhere from 3.8G to 23.4G meters, which is quite a range-- that's why it's important which "availability scenario" you're concerned with.

Antenna power:

• Your probe-- the one with the HG-55 and the Communotron-16-- has an antenna power of 15G from the HG-55.  (Plus a smidgeon from the Communotrons, but their power is so microscopic relative to the HG-55 that it's not worth the bother to include them in the math.  So I'll ignore them as irrelevantly insignificant.)
• Your level-2 tracking station has an antenna power of 50G.

So, the max range for a connection directly between your probe and the tracking station will be sqrt(15G * 50G) = 27G.  That's farther than the greatest distance that Eve ever gets from Kerbin.

Therefore, if your probe has a direct LOS to the tracking station, then yes, it's enough-- your signal will reach, for any part of Eve's orbit.  The only time it would be unavailable would be in the following circumstances:

• if your probe is on the far side of Eve, so Eve blocks the signal
• if you don't have extra ground stations enabled, and KSC is facing away from Eve
• if Kerbin & Eve are exactly on opposite sides of the Sun and the Sun itself is blocking the signal (a situation so rare that we can probably just ignore it).

 

Okay, so what if you don't have direct LOS and need to relay through a comsat?  Then the answer depends on where the comsats are-- around Kerbin, or around Eve?

• If the comsats are orbiting Kerbin:  then the long-distance link is between 15G probe and 2G comsat, for a max range of 5.4G.  That's enough to reach Eve only in the nearest part of its orbit, i.e. when it's closet to Kerbin.
• If the comsats are orbiting Eve:  then the long distance link is between 50G KSC and 2G comsat, for a max range of 10G.  That reaches a larger portion of Eve's orbit... but still not all of it.

 

 

[Kryxal]

There's also this: you're launching the mission with a L2 tracking station, but are you planning not to do much until the mission arrives?  By the time it gets to Eve, you can easily have a L3 station by doing other missions for income.

[Guest]

3 hours ago, Snark said:

Moving to Gameplay Questions.

Do you have the extra ground stations turned on or off?  This is important:  if they're on, then you don't need comsats at all (since any craft anywhere will have direct LOS to Kerbin, if it's not blocked by the local celestial body), whereas if they're off, you won't get the benefit of that high tracking-station power unless Kerbin happens to be facing the right direction.

Sorry, are these satellites in orbit around Kerbin or Eve?

Is this your probe that's going to Eve?

The short answer is:

• When your probe can directly see KSC:  Yes, it's enough.
• When you have to relay the signal through your comsat:  It's enough when Eve is close to Kerbin.  Not enough when Eve is far away.

 

Okay, here's the longer answer:

There are basically three levels of availability you might be concerned with:

1. Unavailable, i.e. a setup that can never reach Eve from Kerbin and is doomed to failure.
2. Partially available, i.e. a setup that works some of the time but not all (i.e. only works when Eve is relatively close to Kerbin, and/or when Kerbin is facing the right direction)
3. Completely available, i.e. a setup that provides continuous coverage even when Eve is at its farthest, and/or Kerbin is facing the wrong way.

To answer the question "Is it enough?", we need to care about two things:  distance and antenna power.

Distance:  Kerbin orbits at a radius of 13.6G meters.  Eve is 9.8G.  That means that the distance between the two planets can range anywhere from 3.8G to 23.4G meters, which is quite a range-- that's why it's important which "availability scenario" you're concerned with.

Antenna power:

• Your probe-- the one with the HG-55 and the Communotron-16-- has an antenna power of 15G from the HG-55.  (Plus a smidgeon from the Communotrons, but their power is so microscopic relative to the HG-55 that it's not worth the bother to include them in the math.  So I'll ignore them as irrelevantly insignificant.)
• Your level-2 tracking station has an antenna power of 50G.

So, the max range for a connection directly between your probe and the tracking station will be sqrt(15G * 50G) = 27G.  That's farther than the greatest distance that Eve ever gets from Kerbin.

Therefore, if your probe has a direct LOS to the tracking station, then yes, it's enough-- your signal will reach, for any part of Eve's orbit.  The only time it would be unavailable would be in the following circumstances:

• if your probe is on the far side of Eve, so Eve blocks the signal
• if you don't have extra ground stations enabled, and KSC is facing away from Eve
• if Kerbin & Eve are exactly on opposite sides of the Sun and the Sun itself is blocking the signal (a situation so rare that we can probably just ignore it).

 

Okay, so what if you don't have direct LOS and need to relay through a comsat?  Then the answer depends on where the comsats are-- around Kerbin, or around Eve?

• If the comsats are orbiting Kerbin:  then the long-distance link is between 15G probe and 2G comsat, for a max range of 5.4G.  That's enough to reach Eve only in the nearest part of its orbit, i.e. when it's closet to Kerbin.
• If the comsats are orbiting Eve:  then the long distance link is between 50G KSC and 2G comsat, for a max range of 10G.  That reaches a larger portion of Eve's orbit... but still not all of it.

 

 

No extra ground stations, comsats are in kerbin orbit.

3 hours ago, Kryxal said:

There's also this: you're launching the mission with a L2 tracking station, but are you planning not to do much until the mission arrives?  By the time it gets to Eve, you can easily have a L3 station by doing other missions for income.

Hmm, never thought of that. Will try!