Antenna Questions

[Long Finger]

The HG-5 has: Antenna Rating 5.00M (combinable). What unit is this? Does it mean 5Mm? I have a L2 tracking station so I assume I can connect to an HG-5 from KSC up to 500Mm. So if I want to remote control a ship not in sight of KSC I need it to be within 5Mm of the HG-5? Does the ship I'm using also have to have a relay antenna or can it be a regular Communotron? The Mun is 11.4Mm away so I don't see any way to remote control anything around the Mun with HG-5's as they have such poor combinable range. Finally is there any benefit to putting multiple HG-5's on one satellite? I imagine the range won't increase but does it give better signal strength?

Thanks. 

[FullMetalMachinist]

23 minutes ago, Long Finger said:

Antenna Rating 5.00M (combinable). What unit is this? Does it mean 5Mm?

Yes, but that's only half of the story. The formula for finding range between two antennas is: sqrt(antenna1 * antenna2). 

25 minutes ago, Long Finger said:

So if I want to remote control a ship not in sight of KSC I need it to be within 5Mm of the HG-5?

Not quite, see the formula above. 

25 minutes ago, Long Finger said:

Does the ship I'm using also have to have a relay antenna or can it be a regular Communotron?

Regular antenna will work on the controlled ship. 

26 minutes ago, Long Finger said:

Finally is there any benefit to putting multiple HG-5's on one satellite? I imagine the range won't increase but does it give better signal strength?

The range does increase. That (combinable) tag after the range means that you can combine multiple for more range. Unfortunately, I forget what the formula for combining antennas is, but I'm pretty sure it's not linear (i.e. 2 of the same antenna don't get you twice the range). 

[Long Finger]

15 minutes ago, FullMetalMachinist said:

The formula for finding range between two antennas is: sqrt(antenna1 * antenna2).

Okay so the relay range of HG-5 with a Communotron 16-S is 1.5Mm [Sqrt (5000000 * 500000)] or between two HG-5's is 5Mm [Sqrt (5000000 * 5000000)].

Thanks that helps explain why my ship is out of range when I thought it should be in range.

15 minutes ago, FullMetalMachinist said:

The range does increase. That (combinable) tag after the range means that you can combine multiple for more range. Unfortunately, I forget what the formula for combining antennas is, but I'm pretty sure it's not linear (i.e. 2 of the same antenna don't get you twice the range). 

Ah, so does that also apply to the range between the tracking station and the relay satelite?

Edited October 16, 2016 by Long Finger
mistake

[FullMetalMachinist]

2 minutes ago, Long Finger said:

Ah, so does that also apply to the range between the tracking station and the relay satelite?

I believe it does. 

[Plusck]

43 minutes ago, Long Finger said:

The Mun is 11.4Mm away so I don't see any way to remote control anything around the Mun with HG-5's as they have such poor combinable range.

If I've understood it correctly, an HG-5 in Munar orbit will happily relay the connection to a communotron-bearing craft on the far side of the Mun.

[Long Finger]

Thanks for the help!

About the range increase I just found this by Valerian:

Quote

Now the new thing with the current build is that you can increase the range by putting more antennas/relays on a vessel, with a diminishing return formula.

To explain it simply in the case where you have multiple instance of the same antenna, you have to do (range of the antenna) * ((amount of antennas)0.75 ) to get the range.

A few examples:

3 antennas = range x 2.3

10 antennas = range x 5.6

50 antennas = range x 18

 

3 minutes ago, Plusck said:

If I've understood it correctly, an HG-5 in Munar orbit will happily relay the connection to a communotron-bearing craft on the far side of the Mun.

Yes I think so but you'd need the lvl 3 tracking station.

[Plusck]

12 minutes ago, Long Finger said:

Yes I think so but you'd need the lvl 3 tracking station.

Not as far as I understand it - with level 2 you get out to 50Mm (i.e. Minmus) with the HG-5. The HG-5 to communotron-16 is 1500km or so. So one well-placed HG-5 in Mun or Minmus orbit can relay to any craft not in KSC LoS.

Also, these figures are for full reception and all the associated benefits. I've been sending ships to the Mun without any antenna with a level-2 tracking station, and though the signal is very weak it works well enough for control.

Edited October 16, 2016 by Plusck

[Long Finger]

18 minutes ago, Plusck said:

Not as far as I understand it - with level 2 you get out to 50Mm (i.e. Minmus) with the HG-5. The HG-5 to communotron-16 is 1500km or so. So one well-placed HG-5 in Mun or Minmus orbit can relay to any craft not in KSC LoS.

Also, these figures are for full reception and all the associated benefits. I've been sending ships to the Mun without any antenna with a level-2 tracking station, and though the signal is very weak it works well enough for control.

Sorry, yes you are right lvl 2 is sufficient.

[Plusck]

34 minutes ago, Long Finger said:

Sorry, yes you are right lvl 2 is sufficient.

I haven't entirely sussed this out yet.

I was wrong in giving that figure of 50Mm range from level 2 to HG-5 - it's actually 500Mm. However, that is the maximum and not 100% signal strength.

There is a google docs spreadsheet here:

And it tells me that 100% signal strength with that combo is only available up to about 20Mm (halfway between the Mun and Minmus), but Minmus still gets a 98% signal. I have not yet understood how you get signal strength.

From that spreadsheet, you get a factor from (1-(your range/max range)). Then the signal strength is (3-2(factor))*factor². I have no clue where that comes from.

Edited October 16, 2016 by Plusck

[Long Finger]

10 minutes ago, Plusck said:

I was wrong in giving that figure of 50Mm range from level 2 to HG-5 - it's actually 500Gm. However, that is the maximum and not 100% signal strength.

You were half right both times! It's 500 Mm with the lvl 2 tracking station and 1.12 Gm at lvl 3.

10 minutes ago, Plusck said:

And it tells me that 100% signal strength with that combo is only available up to about 20Gm (halfway between the Mun and Minmus), but Minmus still gets a 98% signal. I have not yet understood how you get signal strength.

I have just put a single HG-5 in Munar orbit at 2km and it is giving me a 100% signal strength back to KSC. I also get a 100% signal strength from it, to a lander on the surface with a Communotron DTS-M1. I don't currently understand that formula for signal strength but I guess I'll have to look into it at some point!

Edited October 16, 2016 by Long Finger

[Plusck]

9 minutes ago, Long Finger said:

You were half right both times! It's 500 Mm with the lvl 2 tracking station and 1.12 Gm at lvl 3.

I have just put a single HG-5 in Munar orbit at 2km and it is giving me a 100% signal strength back to KSC. I also get a 100% signal strength from it, to a lander on the surface with a Communotron DTS-M1. I don't currently understand that formula for signal strength but I guess I'll have to look into it at some point!

Doh!

I looked at the signal strength calculations again. It boils down to 3x²-2x³, where x is linear from 0 (max range) to 1 (zero range). I assume this is intended to approximate a sine function with less intensive maths, since the curve from 0 to 1 is almost identical. Didn't know that was a thing.

Basically it means you get 100% signal strength if you are less than 4% out to your maximum range, 50% at 50% of max range, 1% at just under 96% of the range, and the standard sine curve inbetween.

[RocketBlam]

So... how many antennas do I need to be able to talk to a ship at Duna? Because I launched a probe there (actually two probes, currently connected), and they have two antennas on  an RA2 and an HG5. I'm out near Duna now but I don't have full control. I have two relay sats orbiting Kerbin, each with an HG5, but apparently that's not enough.

Now I've put a new satellite around Kerbin with two RA-15s on it, but the probe is still out of contact. According to my calculations, the probe should be able to contact that satellite easily. The range between the two vessels can't be more than about 35 million km (the max distance between Duna and Kerbin) and according to my calculations, those two satellites should be able to communicate as long as they're within 6.7 billion km: 

Square Root of ((15 billion * 1.5) * 2 billion) = about 6.7 billion km.

That's not even taking into account the HG5 on the probes.

Do I need a direct antenna in addition to relay antennas on the probe?

I REALLY wish Squad would explain this better.

ETA: Apparently the ranges are in meters, not kilometers, which would explain a lot.

Edited November 5, 2016 by RocketBlam

[Long Finger]

5 hours ago, RocketBlam said:

So... how many antennas do I need to be able to talk to a ship at Duna? Because I launched a probe there (actually two probes, currently connected), and they have two antennas on  an RA2 and an HG5. I'm out near Duna now but I don't have full control. I have two relay sats orbiting Kerbin, each with an HG5, but apparently that's not enough.

Now I've put a new satellite around Kerbin with two RA-15s on it, but the probe is still out of contact. According to my calculations, the probe should be able to contact that satellite easily. The range between the two vessels can't be more than about 35 million km (the max distance between Duna and Kerbin) and according to my calculations, those two satellites should be able to communicate as long as they're within 6.7 billion km: 

Square Root of ((15 billion * 1.5) * 2 billion) = about 6.7 billion km.

That's not even taking into account the HG5 on the probes.

Do I need a direct antenna in addition to relay antennas on the probe?

I REALLY wish Squad would explain this better.

ETA: Apparently the ranges are in meters, not kilometers, which would explain a lot.

The probe only needs a direct antenna but the range of a relay is better. I currently have a rover on Duna that only has a surface mounted direct antenna (because it flipped over and broke its HG-5 off) that can talk to Kerbin via a RA-2 in Duna orbit. Now that Duna is falling behind in its orbit I have 22% signal strength at approaching 20 billion metres.

[Sir_Robert]

The wiki knows all

http://wiki.kerbalspaceprogram.com/wiki/CommNet