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  • Context:

For several reasons regarding the planet, such as its atmosphere density, landscape and its interference on electronic equipment, in this specific planet, people preferred to use land-ships to travel in its surface.

More specifically, the atmosphere is very dense, highly corrosive and interfere a lot with the electromagnetic stuff, the winds reach almost the speed of sound with sand-like crystal colliding and destroying everything that isn't a bunker-like structure, so you can't just take flight and send radio waves through the planet. Seismic vibrations are the most viable (if not the only) way to detect other land vessels.

For some other specific reasons, they decided to also use land-ships to attack and/or defend other civilian land-ships. And thus, the best way of detecting other land-ships is through a seismic radar (or "seidar"?) that detects the vibration these massive machines produces while moving.

Don't worry about physics and other stuff, it is just about the information displacement.

  • The problem:

I couldn't find any kind of seismic radar that could allow for other land-ships detection, like a Sonar or a conventional Radar.

For reference, here is the Sonar screen of an unspecified ship, as you can see, the vision is in a 360 degrees around the vessel, allowing for a better localisation of stuff around it.

enter image description here

In the other hand, the Seismic Radars that exists in real life focus only in the depth and structure of the soil, not on the direction and characteristics of these vibrations (a land-ship of a certain size and structure would produce a specific wave of vibrations). After all, it is a cientific tool for research, not for war.

enter image description here

Anyway, the thing is that, what would be the best way of showing the vibrations on the soil? Exactly like a Sonar screen, or something totally different that already exists?

The other type of seismic radar that I could find was the "Insar" that is remotely made with satellites and aircraft. But it won't do, since these seismic vibrations of other land-ships need to be detected in site by the land-ship itself.

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    $\begingroup$ I'm wondering, do they have something like a high tower on these landships or just some drones and/or planes and/or satellites? I ask because sonars are prefered underwater since visibility gets very bad extremely quickly as you dive down and look far away. These inconveniences rarely happen in fresh air, meaning sight is a very nice and cheap approach (plus, it's passive detection). Well, until it gets stormy and foggy, that is x). $\endgroup$ Jan 24, 2022 at 16:40
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    $\begingroup$ @Tortliena They have towers and bulky land-drones, the atmosphere is very dense, corrosive and interfere a lot with the electromagnetic stuff, the winds reach almost the speed of sound with sand-like crystal colliding with everything, so you can't just take flight or observe around. Seismic vibrations are the most viable way to detect other transport vessels. $\endgroup$
    – Fulano
    Jan 24, 2022 at 16:44
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    $\begingroup$ Are you asking about what the display readout would look like? Or how the seidar (I like that term, by the way, though I can see arguments against it as not fitting standard acronym conventions) would actually function? $\endgroup$
    – Harthag
    Jan 24, 2022 at 18:34
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    $\begingroup$ Can you clarify what a land ship is? $\endgroup$
    – Daniel B
    Jan 24, 2022 at 19:59
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    $\begingroup$ A denser, abrasive, caustic atmosphere moving at nearly the speed of sound? Nothing above ground is going to exist, and certainly, you’re not going to be able to detect anything by vibrations, because every square inch of the surface is going to be experiencing an ongoing load considerably in excess of what your wheels apply. This would be like trying to detect a scuba diver by the sound of their bubbles in the middle of a hurricane. $\endgroup$
    – Daniel B
    Jan 24, 2022 at 20:49

2 Answers 2

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Like this, but with your choice of colors (most submarine monitors use monochromatic green, but I have no idea why)

enter image description here

It's not likely to be circular, as those circular read-outs are generally used for radar and active sonar, but this sonar read-out is for passive sonar.

Here's the simplest way I know to describe the difference:

A) Active sonar is basically "echo-location", the animal (whales, dolphins, bats, etc.) or ship (submarine, destroyer, land-ship, etc.) generates a sound (dolphin clicks, bat chirps, Hollywood submarine PING sound effect) which goes out, bounces off of something, comes back, and the bounce back is detected by the same thing that sent it out.

B) Passive sonar is just "listening". In a best case scenario, the listener (be it animal or ship) makes no noise itself, but simply listens for anything around itself.

In your scenario, active sonar won't work. If your land-ship sent out a PING through the air, not only would it be heavily distorted or possibly outright blown away by the wind, the return echo would be far worse. If your land-ship sent out a PING through the ground (it would likely be more like a THUMP), the wave would pass under any other landships without bouncing off of them, so there would be no return signal to detect, but any landship listening would definitely hear their PING/THUMP, so they would only succeed in giving away their position. Submarines using active sonar will even get a return sound off of the surface of the water, and this return sound can even vary based on the waves of the surface. In other words, the 'shape' of the surface can affect the return sound. For a land-ship trying to detect another stationary and (relatively) silent landship through active sonar, the best case scenario would be that the sound wave traveling through ground would travel up through the land-ship just like it would through a boulder sitting on the ground, or just like sonar would travel up through a wave on the surface of water. It would cause a change in the return, but with no way to distinguish it from a boulder or hill in the landscape. And that's the "best case". More likely it will pass underneath it completely, registering nothing at all.

That leaves passive sonar as the only option. The display above is a passive sonar display, tracking 9 or 10 different "contacts", the distinct solid green lines (with some few fainter contacts as well, the fainter and intermittent green lines). The horizontal position of the lines indicates the direction of the contact, the vertical center of the screen is direct front. Half way between center and left edge is directly left of the submarine (land-ship). Half way between center and right edge is directly right of the submarine (land-ship). And the extreme edges are directly behind the submarine (land-ship). Top to bottom on the display indicates time. The top is where things are "now", and the farther down you go is where they were farther in the past. So you can see in the image, above, that toward the top are 3 strong green nearly vertical lines indicating 3 contacts nearly directly in front of the submarine, but farther toward the top, those same 3 lines veer to right, all the way to the edge, indicating that either the submarine turned to the left, or the contacts themselves turned to the right, and the submarine passed them on their left (the submarine's right). The best explanation I know of for how to read these types of displays (much better than my attempt here) is in

this video

specifically the part starting at about the 11 minute mark, through to about the 14 minute and 15 second mark.

Now your Land-Ships will not be able to use their ground sonar (seidar) while moving, because the vibrations caused by their own ship will interfere with detection. So the complication of reading those displays will be lessened for your land-ships, when compared to a maneuvering submarine.

It's also important to note that passive sonar (seidar) would be almost useless at determining distance which is another reason why a circular read-out wouldn't be likely, as their distance function isn't relevant for passive detection. Exceptions to that would require in depth knowledge (in advance) of the subsurface ground composition in the direction of the contact, as well as familiarity with the sound signature of the target (meaning you already know, or have a good idea, of what it is you're hearing, and what it normally sounds like), and then take in to consideration how all the changes in soil and stone composition would distort that sound signature (overall, probably a nearly impossible task over any but the shortest of distances).

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Existing seismographs detect all kinds of things.

https://earthquakescanada.nrcan.gc.ca/info-gen/smeters-smetres/interpret-en.php

Other Signal Sources Seismographs are so sensitive that they can detect very small vibrations in the earth. For example, the CNSN station at Watts Point (WPB), north of Squamish, BC, detects trains as they pass by.

The signal from a train is noticeably different from that of an earthquake because it gradually builds up strength as the trains gets closer, reaches its maximum as the train reaches its "closest point of approach", or CPA, and then gradually diminishes as the train moves farther away. You may also see train signals on station BLBC, near Blue River, BC, that is near the rail lines that connect Vancouver with Edmonton.

train

Train Signal Similarly, a large cruise ship generates a lot of vibration in the earth. Our station at Bella Bella (BBB), along the Pacific Coast, receives signals from ships on their way to and from Alaska. The signal has a character that is similar to a train in that it builds gradually to the CPA, then diminishes as it leaves the area. The signal is less steady though so it may have several peaks and valleys throughout. Here is a sample of a ship passing by BBB:

enter image description here Ship Signal

Your land ships must be pretty robust to withstand that planet and they probably have serious ground traction to avoid being blown away. If a seisomgraph can detect a train it can detect your land ships. You would factor out other source of vibrations like the wind, earthquakes, dance parties, explosions, sandworms, goblin cities etc. Correlate readings with known movements of earth ships.

You will need multiple detectors spread over a region. You will compare signal strength and timing between them and triangulate the origin of the detected signal. That is how seismographs determine the epicenter of a quake.

And wolla: your earth ship detector!

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