Ultrasound can be used to determine the levels in things like fire extinguisers and beer barrels, it's used for non-intrusive testing of most metals and ceramics and it's used for lots of medical purposes.

Due to the differences in frequencies between normal audible sound and ultrasound (hearing range is 20Hz to 20kHz, ultrasound is anything above that), it has very different propagation properties to normal sound. So while you couldn't hear through a wall, plaster board etc should be at least somewhat permable to ultrasound. You probably wouldn't get a good picture, and the resolution would be pants, but you'd still be able to tell if there were a humanoid shape there or not.

Okay. since you've mised this the last time I said it Tarantula, I'm gonna say it again. this was not my run, nor was it my trap. I do not know from a GM's perspective(which is what you seem to be after since I don't think many GM's announce that their traps are taking actions before they're sprung) how this trap works. I know what my GM told me about it. Pure and simple.

Now back to the arguement I can respond to. Here is a website with a very tech lingo heavy, yet still comical version of how diagnostic ultrasound works in the real world. Diagnostic Ultrasound workings

To transpose this into Shadowrun, we have to assume that instead of using low power, high frequency transducers that won't read through air, a more advanced emitter, capable of sending moderate power, medium frequency ultrasound wavelengths has been invented in the early to mid 2040's. Now, like normal sound, the density of any object causes some of the waves to be bounced back to the transducer, which in turn creates a visual picture of whatever reflected them back.

Now, here's where your problem with density comes in. The denser an object is, the more waves get reflected back. The more waves that get reflected back, the fewer there are to give an accurate read of what's beyond it. If you have a transducer putting out 10 ultrasonic waves per second(I know this isn't accurate, it's just an example), but 8 of those 10 waves per second get reflected back from the surface of a table, that leaves 2 waves per second to define anything underneath the table. This is why a plaster wall will allow said ultrasonic or thermographic imager to see through it, while a concrete firewall or other high density wall will block the signal.

As a side note, I did spot your post about full auto shooting and enhanced hearing. If I really wanted to keep your ears out of my conversation, I would just form a wall with a reinforced section, followed by a completely airless section behind it, then another reinforced section. The wall is supported by the reinforced sections, but the vacuum between the sections prevents any and all molecular vibrations from passing through, making everything from X-ray to radio signals completely inert as well as normal hearing.

Radio signals trasmit through vaccum just fine. How else do we communicate with all our long range probes we send out?

"Therapeutic ultrasound (like that in a physical therapist's office) utilizes high power levels and low frequencies to heat up tissue to encourage healing of an injured part of the body." From your website link.

Therefor, a moderate power, medium frequency ultrasound would have a worse picture than low power high freq, and also heat up slightly whatever it hit.

As far as density, all you need to do is put the emitter/receiver up against the object, and said object now becomes the point of origin, rather than a place to reflect from.

For example, if I'm in rowboat on a lake, and see with ultrasound, the lake looks mostly like a big flat thing to me. The second I stick the emitter/detector underwater, I now can see a good distance underwater (perspectives distorted though) with a very faint echo of where the top of the lake is.

Why? Because now instead of the sound originating in air, and encountering the water, it originates in the water.

Put your emitter against the wall, and now there is no echo from the wall to block your sight.

Also, you said you were using thermo to see through walls? How exactly does this work? The wall is cold, you would see a cold wall. The end.

Not entirely Tarantula.

If there had been someone leaning against the wall you could pick them up, depending on the sensitivity of your thermal array - exactly what dT can you detect and in what increments.

Now, let's say you had an active turret inside the wall. Unless it moves around a lot, and thus never has time to leave a thermal impression on the material of the wall, it'll have a heat signature which is detectable through the wall. You'd need to have some form of cooling in order to prevent this, basically in order to make a stationay object inside another invisible to thermographic imaging they have to be in thermal equilibrium.

With a strong enough heat source, you could see it through the wall and also the air beyond it. Most metahumans probably wouldn't be radiating that much heat (symbiotes and suprathyroid not-withstanding) but a turret or drone probably could.

The propagation properties of IR radiation is different to normal visible light - some materials don't block one but block the other, and most materials act in different levels for each - though granted mainly that's the material heating up. So, while you'd get really crappy resolution, you'd probably be able to detect a presence.

I allow this in my own campaign, since I take the view if you can do it now why not in 206X, but I only ever allow vague impressions and a 'something might be there, but you can't tell what' kinda stuff. 1 success is all my players should ever expect, but it can be enough and it is reasonably realistic, when you extrapolate.

Oh boy. Tarantula, I give up. I was willing to dig up a weblink to try and show you, but I'm not willing to go to college for four years and graduate with a BA in Computer and Electrical Egnineering so I can show you the mathematical and scientific theories behind it. If you want to think that Ultrasonic and Thermographic scanners in Shadowrun can't see through certain materails and not others, go ahead.

You're right, in Shadowrun, they can't see through certain materials, and they also can't see through any others either. No where in the books is there any justification for it.

Ahh, thermographic vision... Probably one of the most controversial topics in gaming. I remember when Predator came out and people would try to explain thermographic in SR or infravision in that other game as... "Dude, you can see just like the Predator..." A generation of visual effects later, seeing like the "Predator" has become way better than the first movie. Personally, I've come to take my cues from what is possible with thermo from Splinter Cell. But that's just me I guess.

Anyway. You want to hurt your PCs? Two words. Toxic Wave. Even if they manage to survive being hit with it, you'll be able to turn much of their armor into melting goo. If you plan it right, they'll be scraping by with little or no armor for at least one adventure.


I've never seen Toxic Wave not mess people up. (Sometimes this has included the caster!)

personally, if i get in that type of a situation I know I've been doing something stupid. I tend to have a nice big weapon or drugged up implement to quiet people rather than relying on too much armor. Secure long coat and clothing does it form me...

Also, I tend to be freaky fast so I move in and wack em from the back when they not lookin'
hehehe

Bah. Arguement got taken down.

Anyway, I agree with Spark on the issue. Mainly because I mostly play magicians.

Last resorts, have someone driving a truck/car hit them with it. Fire is always good. Toxic wave them.