[1.1.3] AntennaRange 1.11.4 - Enforce and Encourage Antenna Diversity

[linuxgurugamer]

Does this deal with multiple identical antennas on a single craft?  The idea would be to have two antennas, as far apart as possible, used to gather the signal.  
Theoretically, this should increase the range significantly.  I believe (don't quote me on this) that the effective radius of the combined antennas would be somewhat equal to the total distance between them;  this is how radio-telescope arrays work.  

[Kerbas_ad_astra]

Interferometry and synthetic-aperture radar increase resolution, that is, two adjacent sources can be distinguished from each other at smaller and smaller separations. However, range and sensitivity simply depend on capturing enough signal energy to stand out from background noise, and there's no way to improve that except to increase light-gathering area.

You're correct that a collection of radio dishes can have a very high resolution, equivalent to that of a single dish whose diameter is equal to their separation, but they can't magically collect the energy that falls in between them. 

[linuxgurugamer]

On 1/18/2016 at 6:26 PM, Kerbas_ad_astra said:

Interferometry and synthetic-aperture radar increase resolution, that is, two adjacent sources can be distinguished from each other at smaller and smaller separations. However, range and sensitivity simply depend on capturing enough signal energy to stand out from background noise, and there's no way to improve that except to increase light-gathering area.

You're correct that a collection of radio dishes can have a very high resolution, equivalent to that of a single dish whose diameter is equal to their separation, but they can't magically collect the energy that falls in between them. 

ok, but can adding multiple antennals to a craft increase the range?

[Kerbas_ad_astra]

4 hours ago, linuxgurugamer said:

ok, but can adding multiple antennals to a craft increase the range?

Not by much.  At best, assuming the antennas are perfectly aligned, then N identical antennas will have sqrt(N) times the range of a single antenna, because they can transmit and receive N times as much power, which falls off by the inverse square of the range.  (For dissimilar antennas, the range of the combination would be the square root of the sums of the squares of the antenna's ranges, but this figure is dominated by whichever antenna has the longest range, so the increase is even less.)  This is not a terribly useful improvement -- if an antenna system struggles to close a link from Jupiter (5 AU), then doubling it will not enable it to reach Saturn (1.4 x 5 = 7 < 9 AU).  The antenna would have to be quadrupled, which is quite expensive in terms of spacecraft mass and power.

The way that we increase range in practice has been to shift to higher and higher frequencies (up to optical -- hundreds of THz, effectively -- in current research), which results in narrower and narrower beams (and thus more energy/sensitivity directed at the target) without requiring orders-of-magnitude more antenna mass or transmitter power, and by improving the ground station -- to make bigger, more sensitive receivers on Earth, where mass and power are much cheaper.  This is more or less how AntennaRange works already; the ranges for the level 2 and 3 tracking station are 2-3 orders of magnitude larger than even the Communotron 88-88 dish.

Multiple antennas are sometimes used on spacecraft, but not to improve range.  In CubeSats, for example, multiple monopole antennas are used to ensure that there are antennas with primary gain lobes facing in all directions, so that the satellite can communicate with the ground station even if it is tumbling.  Deep-space missions often include antennas with multiple gains, because a high-gain antenna will only function if the target is within its beam, which becomes narrower as gain increases.  For low-data-rate telemetry and telecommand, it doesn't make sense to go to the trouble (and power expenditure, and possibly fuel expenditure) of pointing a high-gain antenna to within a fraction of a degree when a spacecraft can pack a nearly-omnidirectional monopole along for the ride for just a few grams or kilograms.  Neither of these factors are modeled in AntennaRange (and I don't think they should be).

[linuxgurugamer]

Uhhhhh.  Facepalm!  I haven't yet upgraded the tracking station to level 3, no wonder I'm having problems.

Anyway, thank you for the extremely clear explanation

 

[Waxing_Kibbous]

I have a feature request: It would seem that some bad luck can happen when sending out probes- if you have a capture maneuver that needs to be done, but things line up so that the transmission is blocked you pretty much wasted a trip. I was thinking that high level probe cores could be made to auto execute maneuvers even when out of line of sight, but would that make them too OP? How do people handle this kind of issue?

[Mecripp]

I have never had that problem with this mod but then again I'm a old player of RT so, I always even with this mod build a network as, I go

[godefroi]

13 hours ago, Waxing_Kibbous said:

I have a feature request: It would seem that some bad luck can happen when sending out probes- if you have a capture maneuver that needs to be done, but things line up so that the transmission is blocked you pretty much wasted a trip. I was thinking that high level probe cores could be made to auto execute maneuvers even when out of line of sight, but would that make them too OP? How do people handle this kind of issue?

RemoteTech has that feature. In practice, it was (for me) a bit clunky, so the only time I ever relied on it was to build out the initial ring of satellites for Kerbin. AR doesn't require line-of-sight to KSC, only Kerbin, so it's a non-issue. Like MeCripp, I build out the network as I go.

[Andem]

16 hours ago, Waxing_Kibbous said:

I have a feature request: It would seem that some bad luck can happen when sending out probes- if you have a capture maneuver that needs to be done, but things line up so that the transmission is blocked you pretty much wasted a trip. I was thinking that high level probe cores could be made to auto execute maneuvers even when out of line of sight, but would that make them too OP? How do people handle this kind of issue?

This will always be an issue with limited communication systems, because it isn't something you can plan for in KSP. the best solution without breaking the rules is to install kOS and have it run whatever script it needs when it loses line of sight.

[Waxing_Kibbous]

Yeah, thinking of my idea again it would be tough to balance- very careful planning during the initial SOI phase seems to be the best (and probably more fun anyway) solution.

[RocketSquid]

Is it possible to make the ranges partially dependent on the level of the tracking station?

[Kerbas_ad_astra]

1 hour ago, RocketSquid said:

Is it possible to make the ranges partially dependent on the level of the tracking station?

They already are.  Check out the bottom of AntennaRange.cfg -- Kerbin is itself an antenna, just like the antenna parts.

[civilwargeeky]

Hi! So I recently installed this mod with a minimal(ish) set of mods, and I noticed that the antenna range was much greater than what I was expecting. So I went into the config to change the values to match the pictrues shown in the OP. I read the README on github and it said to change the nominal range to what I wanted it to be in meters. At least for the small antenna, this produced a nominal range about 1000x what I wanted, so I figured maybe the nominal range is in km? So I took 3 zeroes off all the ranges. Now they make about 0 sense.

In CFG:

longAntenna
	nomialRange = 1500
mediumDishAntenna
	nomalRange = 30000
commDish
	nominalRange = 80000000

What resulted in my game:

Communotron 16:
	Nominal Range to Kerbin: 32.6Mm
	Maximum Range to Kerbin: 92.1Mm
Comms DTS-M1:
	Nominal Range to Kerbin: 146Mm
	Maximum Range to Kerbin: 346Mm
Communotron 88-88:
	Nominal Range to Kerbin: 7521Mm
	Maximum Range to Kerbin: 25.3Gm

I am very confused as to a) Where these numbers came from and b) What to do to get my desired ranges.

Edit: Also, I am not using RemoteTech and am in a Science game Normal difficulty

Edited January 30, 2016 by civilwargeeky

[DMSP]

Really quick.

This is a great mod. It's really fun to play with.

My one problem is this:

I have spacecraft in Kerbin orbit that have retracted antennas, no electric charge and they're marked as "Debris".

The still are "in contact" with other craft and act as relays.

Is there a way to stop debris or retracted antennas from communicating?

Thanks.

[toadicus]

@civilwargeeky, as suggested in @Kerbas_ad_astra's post just above yours, the ranges are dependent on the tracking station level as well.  They also depend on the other antenna you're connecting to.  Here's a table showing how the antennas relate to each other and to the tracking station using my default numbers:

	From→	Comm. 16	Comms DTS	HG-55	Comm. 88-88	EVA
To↓	[m]	1.80E+04	6.30E+09	1.26E+10	3.70E+10	1.39E+03
Comm. 16	1.80E+04	1.80E+04	1.06E+07	1.50E+07	2.58E+07	5.00E+03
Comms DTS	6.30E+09	1.06E+07	6.30E+09	8.90E+09	1.53E+10	2.96E+06
HG-55	1.26E+10	1.50E+07	8.90E+09	1.26E+10	2.16E+10	4.18E+06
Comm. 88-88	3.70E+10	2.58E+07	1.53E+10	2.16E+10	3.70E+10	7.17E+06
KSC1	8.00E+05	1.20E+05	7.10E+07	1.00E+08	1.72E+08	3.33E+04
KSC2	2.00E+11	6.00E+07	3.55E+10	5.02E+10	8.60E+10	1.67E+07
KSC3	2.00E+12	1.90E+08	1.12E+11	1.59E+11	2.72E+11	5.27E+07

In general this is a fairly realistic simulation, where I've "baked in" concepts like antenna geometry and gain.  For a little more info on the maths behind it, take a look at the README.  EDIT: Note that in non-career games (Science, Sandbox) the tracking station is always considered to be level 3.  I could potentially make the tracking station "level up" based on your science tier in science mode, but that's not in the game at all at this point.

If you want things to use fixed ranges for everything, you need to uncheck the option "Use Additive Ranges" in AntennaRange's options menu in the space center.  Then, all antennas will use a naive fixed radius from themselves based on the simpleRange (not nominalRange) cfg parameter.

All; very sorry for taking January off as well.  Work has just been insane lately.  I'm trying to find a good opportunity to release a few maintenance bits before 1.1.

MOAR EDITS

@DMSP, I'm aware of that issue and intend to fix it in the next release.  Thanks!

Edited February 2, 2016 by toadicus

[DMSP]

11 hours ago, toadicus said:

MOAR EDITS

@DMSP, I'm aware of that issue and intend to fix it in the next release.  Thanks!

Ok, that will be great.

Thanks to you too!

[linuxgurugamer]

Hi,

I'm working on a simulation mod, and would like to be able to disable AntennaRange temporarily during a simulation.

Is there an easy way to do this?

Thanks

[toadicus]

There is not currently an easy way to do that.  What parts, specifically do you want to disable?  You could access the config options to disable things like control limiting and pretty lines to make it look off, but there's no way for you to disable the network resolution under the hood, and no way at this point to enable transmission when it shouldn't be possible.

[Gkirmathal]

@toadicus Sorry to be of burden. Last November I thought I understood after @Kerbas_ad_astra. Now (im late to 1.0.5) am looking at it again.

I think I really need the mathematics more simplified, as I have trouble wrapping my head around it somehow. My math is not good enough anymore to understand the functions explained in the Mechanics part of the ReadMe.

On 4-10-2015 at 5:47 AM, Kerbas_ad_astra said:

if you want a spacecraft to have a nominal range of 40 Gm from Kerbin, you would take that distance, square it, and divide by Kerbin's range to get 800 Mm.

Additive range mode goal is 40Gm nominal range to show in game, from Kerbin (KSC lvl3), so up to about Dres SMA.

The calculation, how Kerbas_ad_astra got to 800Mm, I understand: (4.00E+10)^2 / 2.00E+12 = 800Mm

nominalRange = 800000000
simpleRange = 40000000000 > 40Gm simple mode range (this works when put in simple mode)
maxPowerFactor = 4
maxDataFactor = 6

In game this give these results, from the above cfg:

Nominal range = 23.8Gm > no way near to 40Gm
Maximum Range = ~56Gm

Can you please explain, as (stupendously) simple as still humanly possible , how to calculate nominalRange as shown in game with additive range mode on. Simple mode works perfect btw.

 

Again sorry to be of burden to be asking this again

[Angelo Kerman]

Most definitely not a bug, but ran into something unexpected with a Duna mission: when Duna went behind the sun relative to Kerbin, I lost connectivity to my bases! I have to figure out how to put satellites into solar orbit so they can relay transmissions when planets are behind the sun...

[Scotius]

Trojan relay satellites in Kerbin orbit? It would be hard to place them in ideal orbits, so i'd send at least 3 sats, evenly spaced for continuous transmissions.

[MegaGamer328]

Cool I'll check it out. What is the mod that you are using on the Mun lander pic? Not trying to entirely bring another mod into this but just curious.

[marrioman13]

I'll start by saying I've a heap of mods running, but for some unknown reason, even on Kerbin I can't get connection. I have LoS off and antennas extended on the launchpad, yet no connection.

I've no idea if it's relevant, but the log is spewing constant:

Quote

[Log]: dT is NaN! tA: NaN, E: NaN, M: NaN, T: NaN

 

[Kerbas_ad_astra]

47 minutes ago, marrioman13 said:

[Log]: dT is NaN! tA: NaN, E: NaN, M: NaN, T: NaN

I've seen that happen with an old bug from Kerbal Engineer (I submitted a fix, so make sure you've got the 1.0.19.4 release if you have KER), and also intermittently on other occasions with no clear cause.  It can mean that something is trying to query an orbit in an impossible way (e.g. asking for the time to reach an altitude that the orbit doesn't contain -- which is what the KER bug was), and I've usually found that restarting the game, and maybe recovering the craft in question from the Tracking Station resolves the issue.  Is it a consistent issue, and do you have reproduction steps?

@Gkirmathal, looking at the AntennaRange source code, I just learned that the 2e12 is Kerbin's maximum range (so thank you for asking, or I never would have realized this!).  It has an effective maxPowerFactor of 8, so its "nominalRange" is actually 2e12 / sqrt(8), or about 707 Gm.  So, the nominal range in your case is sqrt(800 Mm * 707 Gm) = 23.8 Gm, and the maximum range is sqrt(800 Mm * sqrt(4 [your maxPowerFactor]) * 2,000 Gm) = 56.6 Gm.  So, to get 40 Gm nominal range, you don't square it and divide by 2e12, but you square and divide by 707e9, to get 2.263 Gm as your antenna's ideal nominalRange.  Sorry for the confusion!

[marrioman13]

On 2/13/2016 at 5:12 PM, Kerbas_ad_astra said:

I've seen that happen with an old bug from Kerbal Engineer

yup, your update's fixed it. I've still got my main issue though, there's no connection to Kerbin, even on the launchpad. I can't think of any mod of mine that's causing it, but it's quite infuriating now.

 

Did a complete reinstall of all my mods, works perfectly well now

Edited February 17, 2016 by marrioman13