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[WIP][1.2.2] CommSat Transponder

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CommSat Transponder

The purpose of this module is to allow any antenna or combination of antennas on a vessel to act as a relay.

This is an early work in progress and subject to change.

How it works

Place a part containing a ModuleJmCommTransponder on your craft. The transponder will scan the antennas on the vessel and adopt the stronger of the strongest single active antenna, or combined power of combinable active antennas, and present itself to CommNet as a relay antenna.

Each transponder has a maximum power. Multiple transponders may be added to a vessel increase the maximum possible relaying power. The transponders have no transmission capability on their own - the power will never exceed that of your antennas. Bandwidth as a limiting factor would seem to make more sense, but that does not appear to come into play on an unloaded vessel that is acting as a relay.

TODO

It appears to work but needs harsher testing. I'm still waiting for the gottcha.

Parts - a test part using the small radial battery's model is included.

Balance concerns. Non relay antennas are much lighter and cheaper than relay antennas with the same range. A vessel using a Communotron-88 as relay should cost and weigh about the same as one using an RA-100.

Adding the module to a part

MODULE
{
    name = ModuleJmCommTransponder
    maxAntennaPower = 15000000
}

Download

Github

Source code

Github

License

This mod is distributed under the LGPL v3.0

 

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Interesting idea. Perhaps the tradeoff for balance could be reduced range when in relay mode, by minimum of half range, or even an order of magnitude. That would work well to restrict the Communotron-16 to a useful range for, say EVA work, but not to punt a signal home from a Mun base.

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8 hours ago, MaverickSawyer said:

Interesting idea. Perhaps the tradeoff for balance could be reduced range when in relay mode, by minimum of half range, or even an order of magnitude. That would work well to restrict the Communotron-16 to a useful range for, say EVA work, but not to punt a signal home from a Mun base.

I really don't have a problem with a Communotron-16 being able to relay home. As far as I'm concerned if you can make the connection and have the hardware installed to relay it's a go. My motivation here is to provide more choices in antenna selection. There's the obvious gain of being able to relay with any antenna. But also with the relay ability decoupled from the antenna, we're potentially able to de-relay the relay antennas and lower the mass (and cost) accordingly, making them useful for general purposes. With an antenna in the RA-100 class that's worth a half a ton of weight removed from a probe that has no need to provide relay services.

The range limitation (which was admittedly an afterthought) is to maintain balance and there may be a better way of going about it. I'm still pondering some sort of bandwidth limit but I have my doubts that will work. The idea is the mass (and cost) removed from the relay antennas goes into the transponder parts. A small 50kg unit that could enable an HG-5 sized relay would not work on an RA-100. You'd need a half ton of equipment for that.

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2 hours ago, IronCretin said:

There's actually a stock module that does some of this, iirc. Doesn't have the power limiter though.

https://kerbalspaceprogram.com/api/class_comm_net_1_1_module_relay_enabler.html

Yeah, I stumbled into that as I was finishing this up. I couldn't find any stock parts that use it though and haven't had a chance to stick it on something and see if it works. Doing this through that interface would be a simpler but would be an all or nothing approach.

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Updated to 0.2 with an experiment, ModuleJmTweakableTransmitter. This is a drop in replacement for ModuleDataTransmitter that allows adjusting the data rate and transmitter power. Since real probes reduce the rate of transmission as they get farther away rather than lose data to signal quality I thought I'd give this a try.

fStpwkn.png

Adjusting the power works like it really would, 4x the power gives twice the range rating, 1/4 power gives half the range. This could be useful to reduce EC usage with strong connections.

I'm not sure what makes the most sense with data rate, so I went with simply dividing the range by the data rate percentage. 50% data rate gives twice the range, 5% gives 20x the range. The catch here is while the data is moving slower, the EC usage per second is the same, so your EC cost per Mit goes up. You can easily drain a battery transmitting the temperature on Minmus.

Only works while the vessel is loaded. Can not be used to extend the range of a remote relay.

MM to try it:

@PART[longAntenna]
{
	@MODULE[ModuleDataTransmitter]
	{
		@name = ModuleJmTweakableTransmitter
	}
}

 

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