CommNet weirdness - am I doing something wrong?

[Mitchz95]

I don't know if it's something I'm doing wrong, but my relay satellites don't seem to be working. Despite having a sat halfway between Minmus and Mun, my Minmus probe refuses to connect to anything except Kerbin itself.

The probe in question:

[KerikBalm]

I don't see any comm device on that probe. No comm 16 or comm 16s. The internal antenna on probes is really really really weak

You also haven't shown the relay that you want to connect to, or specified your tracking station level.

If its halfway between the probe and kerbin, then if the transmitter had the same power as a kerbin ground station, then the signal would be 4x stronger.

If the kerbin ground station network is lvl 3/ 250 G, then a relay halfway between the probe an kerbin will only help if the relay power is greater than 250/4 = 62.5. -> Does the relay have an RA-100 on it? an RA-15 won't cut it in this case - neither will 2 or 3 of them.

As far as I can tell, your problem is that you forgot an antenna on your probe

[Mitchz95]

1 hour ago, KerikBalm said:

I don't see any comm device on that probe. No comm 16 or comm 16s. The internal antenna on probes is really really really weak

You also haven't shown the relay that you want to connect to, or specified your tracking station level.

If its halfway between the probe and kerbin, then if the transmitter had the same power as a kerbin ground station, then the signal would be 4x stronger.

If the kerbin ground station network is lvl 3/ 250 G, then a relay halfway between the probe an kerbin will only help if the relay power is greater than 250/4 = 62.5. -> Does the relay have an RA-100 on it? an RA-15 won't cut it in this case - neither will 2 or 3 of them.

As far as I can tell, your problem is that you forgot an antenna on your probe

Ah, okay. I thought I only needed a comm 16 if I was planning to transmit science. I just want to control the probe at Minmus.

Tracking station is level 3. The relay satellites have two HG-5 antennas, because that's all I have unlocked so far. I'll replace them as soon as I get better ones.

[Streetwind]

On 23.7.2017 at 9:17 AM, Mitchz95 said:

Ah, okay. I thought I only needed a comm 16 if I was planning to transmit science. I just want to control the probe at Minmus.

Tracking station is level 3. The relay satellites have two HG-5 antennas, because that's all I have unlocked so far. I'll replace them as soon as I get better ones.

For reference, the distance formula is:

SQRT(antenna power 1 x antenna power 2) = actual range

Where "antenna power" is 5k for a vessel with no antenna, the antenna's advertised power value for a vessel with one antenna, or the compound value for multiple identical antennas on the same vessel (which has its own special calculation). The simplest possible case is if both sides have the same antenna power, in which case you are taking the square root of a square, and end up with simply the antenna power itself denoting the range. For example, a HG-5 can talk to another HG-5 at a range of 5,000,000 meters, because the HG-5 has an antenna power of 5M(egameters).

But if a pod-internal antenna tries to talk to a pair of HG-5's, you get: SQRT(5,000 * 8,408,964) = 205,048 meters.

Meanwhile, the same pod-internal antenna talking to the level 3 Tracking Station: SQRT(5,000 * 250,000,000,000) = 35,355,339 meters.

With Minmus being over 40 million meters out, the HG-5 satellite has less than 1% of the range it needs even if it already sits halfway between Kerbin and Minmus. Heck, even if your Minmus craft also had a pair of HG-5's, it would still be way short in range. If both craft had three HG-5's, they would still be well out of range. The HG-5 is simply unsuited for relaying anywhere other than the immediate neighborhood of a body; if you want to cover an area the size of Kerbin's SOI, you'll need at least a RA-2.

At the same time, your tracking station is so powerful that it can talk to the pod alone even 35 million meters out (however, it too will eventually lose comms, because Minmus is >40 million meters out). It could reach a lowly Communotron-16 even if it was more than eight times further out than Minmus. So try and ditch the thinking that you must extend your comms signal via satellites. This is never necessary. The ground-based systems have so much power that they can form a direct link to literally anywhere in the system, given a single receiving antenna of appropriate size. The only reason for having relays is getting a comms signal into a planet's comms shadow, and for saving weight and space on smaller craft while a nearby mothership carries the large interplanetary antenna.

(This is actually how it works in real life, too. 99.9% of our commsats exist solely for letting ground stations talk to each other beyond the horizon. The one satellite network for spacecraft we have, TDRS, exists solely for low Earth orbit communication because there are regions on Earth, like the pacific ocean, where you can't build a ground station. All spacecraft beyond low Earth orbit talk directly to Earth ground stations 100% of the time, with landers using local spacecraft as relays.)

[KerikBalm]

HG-5s aren't good for much more than surface-low orbit relaying. An HG-5 will connect from minmus to a lvl3 ground station, but it can't relay the signal very far

You can use them to get around line of sight problems like relaying to the far side of Mun/Minmus, but that's about it.

RA-2s are good for relaying within kerbin SOI, but even then you'll probably want a comm16 or better on the probe. The RA-2 network can be used when line of sight is broken like when Mun gets between kerbin and minmus - or they can relay to an HG-5 in on the far side of Minmus that otherwise can't connect for KSC.

A network of 3x relays with RA-2s beyond the orbit of mun will give you very good relay coverage of most of Mun if your probe has a comm 16 or better.

RA-15s are good for relaying from Moho, Eve, or Duna to a lvl 3 tracking station-> most of the time, depending on the relative position of the planets. From that RA-15 interplanetary relay, you can have local relays of RA-2 and HG-5 to cover the surface of the worlds.

I also like to set up a simple setwork around kerbin of 3-4x RA-15s orbiting in a triangle/square formation at the SOI edge, beyond minmus. With Kerbin sending the signal, and all destinations inside the triangle/square, a probe with a comm 16 has a connection almost anywhere it goes (depending on occulsion settings, you can lose contact near a pole of minmus when its at its highest/lowest above the plane of the comm relay network- this can be reduced by giving the individual relays a bit of inclination themselves)

RA-100s are good for relays across the entire stock system. If you have a local network of RA-100s, then you don't need comm 16s at all on your probes in kerbin SOI.

 

Iiiiiffffffffffff you really want to extend your comms range, such as playing in a modded system that is much bigger, you can use multiple RA-100s on a single vessel. Even then, its easiest to use ground stations, like so:

But to me it seems a bit ridiculous that this is more powerful than the massive ground stations (though this isn't so small itself).

There is a stacking penalty, so these 25x RA-100s are only 25^0.75 times as powerful as a single one: ie 11.18x as a powerful, or 1,180 G compared to the lvl 3 power of 250 G. This is nearly 4.5x as powerful as the lvl3 tracking station, and thus it extends the range by nearly sqrt(4.5) -> 2.11x as much range.

With this, I can connect to RA-2s at duna... at certain times.

I also played with OPM, with the range buff turned off, which made connecting to Plock (the pluto analogue) at apoapsis quite difficult. I had that thing above as a ground station, and sent this to plock to form the other end of the connection:

This is 7^0.75x as strong as a single RA-100, so its 4.3x as powerful, or 2.07x as much range. So that 25x RA-100 ground station an7 7x relay pair has 2.11*2.07 = 4.387x as much range as a lvl3 tracking station and single RA-100 pairing.

2 HG-5s and a probe with not even a comm-16 aren't going to connect at much range at all.

On my surface base construction craft, I have a single HG-5 on the dropship to relay to a rover with no antenna. The rover doesn't drive more than a couple KM from the dropships.

Like so:

Spoiler

 

if HG-5s aren't really close to the target you want to relay to, they don't work as relays.

Edited July 24, 2017 by KerikBalm

[KerbMav]

Nobody read until Streetwind answers, do not want to spread false knowledge!

1 hour ago, Streetwind said:

SQRT(antenna power 1 x antenna power 2) = actual range

Is it not sqrt(a x b)+min(a,b)? Or is that a RT specific thing?

[Streetwind]

16 minutes ago, KerbMav said:

Nobody read until Streetwind answers, do not want to spread false knowledge!

Is it not sqrt(a x b)+min(a,b)? Or is that a RT specific thing?

My experience has been that there's no extra term like that. Mind you, I have not specifically tested the edge cases, but my probes seem to lose comms in a way that's fairly consistent with just SQRT(a * b).

The one time I played with RemoteTech I used the default model, not the alternative, so I'm afraid I have no experience with how it works.

[Kerbal101]

@Mitchz95 Think about network connection as of chain. Every pair of vehicles builds a chain segment. If antennas of your probe and next closest relay vehicle are too weak to connect, then this chain will be ignored and your probe will try the next relay vehicle, until the chain can be linked down to DSN.  DSN is a relay itself and has the most attractive signal-strength-to-unlock-difficulty factor in career mode, so situations like this are not rare.

Possible improvement directions:
- spread the packs of relays further and further orbit-diameter-wise,
- upgrade the relay antennas,
- carefully plan to limit probe operations to when the signal between DSN and probe is unblocked

In addition, all relay antennas can do direct communication - and there is no equivalent to HG-5 in terms of signal strength in same class within pure direct antennas, so you may want to abandon Commutron-16 as soon as possible.
Here is a handy table with ratings and possibilities.

[Snark]

On 7/22/2017 at 8:40 PM, Mitchz95 said:

I don't know if it's something I'm doing wrong, but my relay satellites don't seem to be working. Despite having a sat halfway between Minmus and Mun, my Minmus probe refuses to connect to anything except Kerbin itself.

Yep.  The thing that's confusing you is that the tracking station on Kerbin is so much stronger than any of the low-end antennas.  It can talk to them when they're way far out, but two low-end antennas talking to each other (rather than to Kerbin) have a much, much smaller range.  Even the base level-1 tracking station is literally four hundred times more powerful than an HG-5.

6 hours ago, KerikBalm said:

HG-5s aren't good for much more than surface-low orbit relaying. An HG-5 will connect from minmus to a lvl3 ground station, but it can't relay the signal very far

You can use them to get around line of sight problems like relaying to the far side of Mun/Minmus, but that's about it.

Not quite.  HG-5 can reach to the Mun, if you stack a few of them.  The Mun orbits 12M meters out.  The HG-5 has a power of 5M; if you stack four of them on a ship, its power will be 4^0.75 * 5M = 14.14M.

So if you have a satellite with four HG-5's on it in a Kerbin orbit under 1400 km or so, it can talk to a ship on (or in low orbit around) the Mun which also has four HG-5's on it.

But HG5-to-HG5 connection going any farther than the Mun (without spamming truly ridiculous numbers of them)?  Yeah, forget it. 

6 hours ago, KerikBalm said:

Iiiiiffffffffffff you really want to extend your comms range, such as playing in a modded system that is much bigger, you can use multiple RA-100s on a single vessel.

Or you could use this. 

5 hours ago, KerbMav said:

Is it not sqrt(a x b)+min(a,b)?

Nope, it's just the sqrt(a * b).  There's no extra term.

 

[suicidejunkie]

8 hours ago, Streetwind said:

(This is actually how it works in real life, too. 99.9% of our commsats exist solely for letting ground stations talk to each other beyond the horizon. The one satellite network for spacecraft we have, TDRS, exists solely for low Earth orbit communication because there are regions on Earth, like the pacific ocean, where you can't build a ground station. All spacecraft beyond low Earth orbit talk directly to Earth ground stations 100% of the time, with landers using local spacecraft as relays.)

Another good place to link to https://eyes.nasa.gov/dsn/dsn.html

The ping time from Madrid/Goldstone/Canberra to Voyager 1 right now is pretty brutal, but it is a direct connection.

Edited July 24, 2017 by suicidejunkie

[Spricigo]

On 24/07/2017 at 6:20 AM, KerikBalm said:

HG-5s aren't good for much more than surface-low orbit relaying. An HG-5 will connect from minmus to a lvl3 ground station, but it can't relay the signal very far

You can use them to get around line of sight problems like relaying to the far side of Mun/Minmus, but that's about it.

Worth noticing that the fact HG-5 are good for surface to low orbit relaying make it such an useful antenna. Put a triangular formation in 1Mm equatorial orbit around a celestial body and this surface is pretty much covered.  Since the poles are blind spots, put a pair of satellites in high elliptical polar orbits with antennas strong enough to reach Kerbin and you will have a loss of communication once in a century and never in a millennium.  Can't say is a bad antenna when 3/5 of my relays are those. 

BTW,  under normal settings a HG-5 in minmus can connect with ground station lvl2. 

[KerikBalm]

yes, I use them often too. They easily connect to the large ground stations from within kerbin SOI - but you don't want to relay the kerbin ground station signal through them much farther than that.

Snark points out that they can reach Mun... 4 on each end apparently can reach Mun. Of course, I wouldn't want to have to put 4x HG5s on every vessel - so the other option is 16x on one end, and 1x on the other ends.

The endpoint shouldn't be far away, but yes if they are connecting to a much more powerful antenna on the other end, they are adequate within kerbin SOI.

You can do the same in Duna/Eve/etc SOI as well if you have one more relay to handle the interplanetary link (like an RA-100).

They can be the last link of a relay network to reach the backside of bodies, or to provide local control to probes which lack any antennate like I showed in one of my screenshots.

I should note that on a similar shuttle/dropship, I forgot the HG-5 and just had a comm16s on it. I couldn't control the rover for deploying the base most of the time - I was handling the connection to the shuttle from a RA-2 connected to the massive grounstation (25x RA-100s). A distant RA-2 connected well to the shuttle, but not to the rover. I had also put an RA-2 in low orbit (this was a modded duna system, and 3x gameplay), which gave me rover control basically 30 minutes on, 30 minutes off. An HG-5 as on my Mun shuttle would have been nice - but due to the atmosphere I removed it and replaced it with a comm16s to provide control during times when an HG-5 would be torn off by aero forces. I should have kept it on to deploy once landed for controlling the rover.

[Spricigo]

7 hours ago, KerikBalm said:

Snark points out that they can reach Mun... 4 on each end apparently can reach Mun. Of course, I wouldn't want to have to put 4x HG5s on every vessel - so the other option is 16x on one end, and 1x on the other ends.

The endpoint shouldn't be far away, but yes if they are connecting to a much more powerful antenna on the other end, they are adequate within kerbin SOI.

Why on every vessel?

2 satellite in high inclined polar orbit around Kerbin, 2 satellite in similar formation around the Mun to stablish a constant link. The other vessels don't need to reach Kerbin, just the relay in polar orbit, which will have a nice 14M antenna power (a craft with a communotron 16 can reach it up to 2.37Mm away, pretty much anywhere in Mun's SoI).

[KerikBalm]

With just 2 in polar orbits at Mun, there will be deadspots near the ground, and the far side of Mun twice per munth.

Also I guess that this is assuming ground stations on Kerbin are turned off (otherwise, its just 1x HG-5 at Mun/Minmus -> done) You'll need at least 3 to relay the signal to a sat on the other side of kerbin. with just 2 one wont be able to talk to the other.

So then you increase it to 3x around Mun, 3x around kerbin, for a total of 12 around kerbin and 12 around Mun. Then if you want to reach minmus as well with the same relay network, its going to mean a whole lot more on the relays for Minmus. I'd rather make the kerbinside relay network stronger.

Its the same reason why to reach Plock I spammed 25x RA-100s on Kerbin, and only sent a 7x RA-100 relay to plock. Closer destinations require less dV to reach, so I load them up with more relay power.

[Spricigo]

55 minutes ago, KerikBalm said:

With just 2 in polar orbits at Mun, there will be deadspots near the ground, and the far side of Mun twice per munth.

Also I guess that this is assuming ground stations on Kerbin are turned off (otherwise, its just 1x HG-5 at Mun/Minmus -> done) You'll need at least 3 to relay the signal to a sat on the other side of kerbin. with just 2 one wont be able to talk to the other.

So then you increase it to 3x around Mun, 3x around kerbin, for a total of 12 around kerbin and 12 around Mun. Then if you want to reach minmus as well with the same relay network, its going to mean a whole lot more on the relays for Minmus. I'd rather make the kerbinside relay network stronger.

Its the same reason why to reach Plock I spammed 25x RA-100s on Kerbin, and only sent a 7x RA-100 relay to plock. Closer destinations require less dV to reach, so I load them up with more relay power.

I think you are missing the point, the "deadspots" are not relevant for the "powerfull" satellites in polar orbit.

The satellite in high elliptical* polar orbit, are  setup one with pe over south pole other with pe over north pole, also they are setup so at the time one is at pe the other is at ap. So one of those will always have LoS to kerbin. While is not the intended purpose, those satellite provide good coverage of the surface polar regions.

In any case since those satellite will be most of the time a fairly high altitude over opposite sides of the celestial body a triangular formation of weaker satellites (1xHG-5 each) around the equator will easily handle the majority of the gaps. Every half of the orbital period of the polar satellites a pole will be incommunicable, but not for very long and an extra pair of weak satellites can close this gap if that is really necessary.

 

*For some reason I brain-farted 'inclined",