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chatyakksp

HG-5 Probe Cannot Transmit Data

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Hi All,

Somewhat new to KSP and playing along in career mode. I wanted to launch a probe into space and send back some science from way out. I read some posts regarding distance for communication and thought mine was ok - clearly something is not right.

I launched a HG5 probe into orbit but it can't transmit anything. My tracking station is level 2. A couple pics below:

https://steamuserimages-a.akamaihd.net/ugc/853844677164383081/155C07EC5C07B14F485DDFDA98B9AD96C6BB7953/

https://steamuserimages-a.akamaihd.net/ugc/853844677164383228/B72B85ECFECC02153705C5EFE6B7A92468825EFC/

If someone could point me to a thread or the right direction that'd be appreciated.

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Welcome to the forums.

The distance between Kerbin and Eve orbits is about 3.6Gm. Yeah, that's just a bit much for an HG5 + T2 tracking station. It's probably maxing out at about .5Gm on your ship is my guess.

This article gives a breakdown of some distances, and has some links that allow you to do more detailed calculations.

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

 

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29 minutes ago, chatyakksp said:

That's 11138M * 1000 = 11,138,000 KM away...

A few things to bear in mind.  The altimeter shows not "how far are you from target" or whatever, but what your altitude is in the SoI of your current celestial body.

In other words:  your altimeter tells you that you're 11,138,000 km away from the Sun, which is not what you're interested in.  You want distance from Kerbin, which this number doesn't tell you.

This picture is from when you're in orbit of the Sun, so all it's telling you is that you're at a solar altitude of about 11.1G meters.  That tells you nothing at all about how far you are from Kerbin.  Kerbin orbits in a perfect circle at an altitude of 13.6G meters, so all you can tell about your distance-from-Kerbin, using your altimeter, is that:

  • you can't possibly be any closer than 13.6G - 11.1G = 2.5G meters (if your probe and Kerbin are both on the same side of the sun)
  • you can't possibly be any farther away than 13.6G + 11.1G = 24.7G meters (if they're on precisely opposite sides of the sun... never mind the sun getting in the way of the signal) :wink:

...i.e. "distance is between 2.5G and 24.7G" is a pretty big range, meaning that your altimeter reading isn't useful for distance-from-Kerbin unless you're in Kerbin's SoI.

The other thing to remember is, the "range" of your antenna depends not just on the antenna's power, but also on the power of whatever it's talking to (the level-2 tracking station on Kerbin, in this case).

As @WanderingKid points out above, to find the actual range, take the two antenna powers (source and destination), multiply them together, and take the square root.  In this case, the HG-5 is 5M, and the level-2 tracking station is 50G.  So the range is sqrt(5M * 50G), which works out to be 500M, i.e. 0.5G.

So, your probe can be controlled at a maximum distance from Kerbin of 0.5G meters, i.e. half a million kilometers.  From your altimeter reading over the Sun, you can't possibly be any closer to Kerbin than 2.5G meters.

So.  Your distance is greater than 2.5G meters, and your range is 0.5G meters... so that's your problem right there.

[EDIT] Ninja'd by WanderingKid.  :)

2 minutes ago, chatyakksp said:

I thought it was height distance from Kerbin in 1000's of meters then millions (times 1000) due to the fact that it shows altitude when launching or going into orbit. Guess I confused myself a lot. Spent a while on tutorials and videos and maybe misunderstood at some point.

You're right, that's exactly what it shows... if you're inside Kerbin's SoI.  As soon as you go to some other body's SoI, it switches to that body.

For example, if you sent a mission to the Mun, it would show you your altitude above Kerbin, until you hit the Mun's SoI, and then it would switch to show your altitude over the Mun.

Or, as in the current case:  when you send an interplanetary probe, then as soon as you leave Kerbin's SoI, it will show you your altitude over the Sun.

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Posted (edited)

Alright... you're down around Eve's orbit, roughly even with Kerbin on the plane rotation, and your orbit is well below the orbital path of Eve. 

Single MG-5: 5M distance.  Tracking 2: 50G distance. 

Range of communication to another body: SqRt( 5,000,000 * 50,000,000,000) 

Range: 500,000,000 meters, or 500,000 km, or 500Mm

Distance between Eve and Kerbin at closest point: 3.668 Mm.  (Edit: Converted the distance wrong)

For more info about CommNet mathematics, check out the wiki here: http://wiki.kerbalspaceprogram.com/wiki/CommNet

For the distances, see @OhioBob's post here:

You should have plenty of range, yet your CommNet indicator says you've got Bupkis.  Either my math is horribly wrong or there's something completely hosing you up... like Mun being in the way (which I doubt, you're way off the solar plane).   You don't have the range, beef up to an RA-2 or RA-15.

So, if it's not the CommNet... That looks like an OKTO core on the probe, but I don't see any solar panels nor batteries.  Is it out of juice?

Edit: One other possibility.  If you're playing without the additional relay stations on Kerbin, the KSP could simply be rotated away from you at this time if you don't have a local relay network up in the Kerbin SOI.

Edited by WanderingKid
Bad conversion on min distance to Eve

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20 minutes ago, WanderingKid said:

Distance between Eve and Kerbin at closest point: 3.668 Gm. 

 

Either my math is horribly wrong ...

 

Actually just a mistake with your data. Maybe because OhioBob used kilometer and wiki uses meter.

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13 minutes ago, Spricigo said:

Actually just a mistake with your data. Maybe because OhioBob used kilometer and wiki uses meter.

D'oh!  My bad, missed that.  Knew something seemed horribly wrong when my math DIDN'T have me switch up to the RA-2...

Sooo... Range: 500,000,000 meters, or 500,000 km, or 500Mm

Distance between Eve and Kerbin at closest point: 3,668 Mm.

You need more Powah!... or Antenna in this case.

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Posted (edited)

 

21 minutes ago, chatyakksp said:

That's 11138M * 1000 = 11,138,000 KM away... or 22x the range of the HG-5?

That altitude is 11,138 MegaMeters above the Sun, it's nothing to do with distance to Kerbin.  Your altitude indicator is always distance above sea level (or whatever is used for sea level) above the body you currently are in SOI (Sphere of Influence) of.

Edited by WanderingKid

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Posted (edited)

12 minutes ago, WanderingKid said:

 

That altitude is 11,138 MegaMeters above the Sun, it's nothing to do with distance to Kerbin.

I thought it was height distance from Kerbin in 1000's of meters then millions (times 1000) due to the fact that it shows altitude when launching or going into orbit. Guess I confused myself a lot. Spent a while on tutorials and videos and maybe misunderstood at some point. Is there way no way to see these readings in game other than calculating or using the wiki beforehand?

Edit: Or does the altitude meter switch to whatever body you are orbiting then (yes that makes sense now since I've orbited Mun before) right? - in this case since the probe is orbiting the sun - that's 11M from the sun.

 

Edited by chatyakksp

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6 minutes ago, Snark said:

A few things to bear in mind.  The altimeter shows not "how far are you from target" or whatever, but what your altitude is in the SoI of your current celestial body.

In other words:  your altimeter tells you that you're 11,138,000 km away from the Sun, which is not what you're interested in.  You want distance from Kerbin, which this number doesn't tell you.

This picture is from when you're in orbit of the Sun, so all it's telling you is that you're at a solar altitude of about 11.1G meters.  That tells you nothing at all about how far you are from Kerbin.  Kerbin orbits in a perfect circle at an altitude of 13.6G meters, so all you can tell about your distance-from-Kerbin, using your altimeter, is that:

  • you can't possibly be any closer than 13.6G - 11.1G = 2.5G meters (if your probe and Kerbin are both on the same side of the sun)
  • you can't possibly be any farther away than 13.6G + 11.1G = 24.7G meters (if they're on precisely opposite sides of the sun... never mind the sun getting in the way of the signal) :wink:

...i.e. "distance is between 2.5G and 24.7G" is a pretty big range, meaning that your altimeter reading isn't useful for distance-from-Kerbin unless you're in Kerbin's SoI.

The other thing to remember is, the "range" of your antenna depends not just on the antenna's power, but also on the power of whatever it's talking to (the level-2 tracking station on Kerbin, in this case).

As @WanderingKid points out above, to find the actual range, take the two antenna powers (source and destination), multiply them together, and take the square root.  In this case, the HG-5 is 5M, and the level-2 tracking station is 50G.  So the range is sqrt(5M * 50G), which works out to be 500M, i.e. 0.5G.

So, your probe can be controlled at a maximum distance from Kerbin of 0.5G meters, i.e. half a million kilometers.  From your altimeter reading over the Sun, you can't possibly be any closer to Kerbin than 2.5G meters.

So.  Your distance is greater than 2.5G meters, and your range is 0.5G meters... so that's your problem right there.

[EDIT] Ninja'd by WanderingKid.  :)

You're right, that's exactly what it shows... if you're inside Kerbin's SoI.  As soon as you go to some other body's SoI, it switches to that body.

For example, if you sent a mission to the Mun, it would show you your altitude above Kerbin, until you hit the Mun's SoI, and then it would switch to show your altitude over the Mun.

Or, as in the current case:  when you send an interplanetary probe, then as soon as you leave Kerbin's SoI, it will show you your altitude over the Sun.

Thanks!  Going to read this over a few times :)

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Posted (edited)

Looks like that probe is going to remain on-hold for a while then until I can get more probes up. Send relays to shorten the distance and/or add more probes...

So by using and comparing Ohio Bob's distance charts and the wiki in meters - can do the math on what is required for probes and/or putting them near each other... guess I will setup some networks around earth and the mun/minmus then for now :)

And when a probe has multiple lines on it - does each line point to a "station" back home? ybF1xR2LQzWplQysBGpbng.png

 

I am only aware of the home base where you launch from but does the game automatically place "spots" around kerbin where signals go to?

And in this example: DgE7hsjLQ0eCMABjWuIvgw.png

The two HG-5 antennas combined form 10M * 50, sqrt that and that leaves about 700K distance from Kerbin or .7G correct?

Edited by chatyakksp

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12 minutes ago, chatyakksp said:

Looks like that probe is going to remain on-hold for a while then until I can get more probes up. Send relays to shorten the distance and/or add more probes...

So by using and comparing Ohio Bob's distance charts and the wiki in meters - can do the math on what is required for probes and/or putting them near each other... guess I will setup some networks around earth and the mun/minmus then for now :)

More probes won't help, if your best antenna is the HG-5.

Bear in mind that although an HG-5 can talk to the level-2 tracking station from a distance of 500,000 km, that's only because the tracking station's so strong.  Two HG-5's talking to each other can be no more than 5,000 km apart, which means you'd need a chain of thousands of them to get to Eve.  Moral of the story is that the HG-5 is just not powerful enough to go interplanetary unless you have a level-3 tracking station, and even then it's marginal.

Note that you can boost the range somewhat by spamming lots of antennas on one craft.  They combine, though not linearly.  If the power of one antenna is P, and you have N antennas on the ship, then the total power is P * N0.75.  For example, suppose you had 8 HG-5 antennas on a ship.  80.75 = 4.75, so the ship's antenna power would be 5M * 4.75 = 23.75M, which means its max communication distance to Kerbin's level-2 tracking station would be sqrt(23.75M * 50G) = 1G.

Which is still not even vaguely enough to get to Eve.

Really, what you need to do is to unlock the next level of antenna, which is literally 400 times more powerful than the dinky HG-5.  If you can unlock the DTS-M1 and/or the RA-2, each of those has a power of 2G, which means they can talk to Kerbin's level-2 tracking station from a distance of sqrt(2G * 50G) = 10G, which is plenty for going either to Duna or to Eve.

(It won't cover all of Duna's or Eve's orbit.  But it'll cover them when they're on the side of the sun closer to Kerbin, which is good enough to be able to control your probe upon arrival, if you launch it at a good launch window.)

So, what you should do is to focus your efforts on gathering enough science to unlock that next tier of antenna.  Do some more Mun/Minmus missions, grab science, then head interplanetary.

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2 hours ago, chatyakksp said:

And when a probe has multiple lines on it - does each line point to a "station" back home?

Yup. They are over the horizon from KSC when you launch -- but when you are up in orbit you can see more of them. There are enough for continuous coverage if you have line-of-sight to Kerbin.

 

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3 hours ago, chatyakksp said:

And when a probe has multiple lines on it - does each line point to a "station" back home?

As @bewing points out, yes it does.  And by the way-- for a grin, take an airplane sometime and fly to one of those other locations.  There's an actual building there-- big satellite dish, usually perched on a mountaintop or something.  It's cool.  :)  Also, the stations have names.  In the flight view, mouse over the little "cell phone bars" indicator for signal strength, which shows the various "nodes" in the communication network that your signal passes through.  The ground station you're talking to will show up by name.  The names of the stations are kinda cool little easter eggs.

Incidentally, if you ever want to play more "hard core" so that those don't exist, and the only communications endpoint is KSC itself (which forces you to build a comsat network around Kerbin), there's a game difficulty option for that-- look for "enable extra ground stations" check box in the CommNet difficulty settings.

3 hours ago, chatyakksp said:

The two HG-5 antennas combined form 10M * 50, sqrt that and that leaves about 700K distance from Kerbin or .7G correct?

Not quite.  They do combine, but it's not linear.  To find out the multiplication factor, take the number of antennas and raise to the 0.75 power.  So, for example, if you have two of them, 20.75 is 1.68.  So, the power of the ship would be 5M * 1.68 = 8.4M.

Which means the max distance from Kerbin would be sqrt(8.4M * 50G) = 648M, i.e. 648,000 kilometers, or 0.648G.

Note:  Combinability depends on the antenna.  The Communotron-16 does combine linearly (i.e. 10 of them would be 10 times more powerful than 1 of them), and the Communotron-16S isn't combinable at all (i.e. you could have a thousand of them, and they would still have the same power as one of them).  But all the other stock antennas, including the HG-5, use an exponent of 0.75.

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Is there not yet a Comm Range mod that can check your planned mission in the VAB/SPH before you launch?  I haven't come across one and there is a need

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2 hours ago, fourfa said:

Is there not yet a Comm Range mod that can check your planned mission in the VAB/SPH before you launch?  I haven't come across one and there is a need

What can be given for a given craft is antenna power .  Range will depend on antenna power of both involved crafts. 

The  " range to ground station"  in antenna description is sufficient for many applications. And while "range to a given relay"  is useful,  pretty often it is either much longer or much shorter then actual distance (in other words,  exact range is not relevant). 

I already considered to build an extended reference table for range between common antenna power but, given the above factor(and some laziness) ,  still didn't care enough. 

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