[Crash_00]

Ouch, must be the gamer gene in us. Last August I managed to get just under third degree burns (Doc said 85% of the way between 2nd to third) from that evil yellow orb. With sunscreen.  That was of course a horrible time to find out I'm allergic to Aloe Vera.

And I vowed to never wear shorts in the sun again.

[KarmaInferno]

How do I know this?  Background in wired signaling, if Voice Frequencies weren't part of the electrmagnetic spectrum, your cell phone would have a hard time converting the carrier wave gibberish that it receives into voice with just a few tiny speakers and destructive interference.

Um. Sound waves are mechanical, not electromagnetic. They are vibrations in matter, more or less.

Sound waves can be TURNED into electromagnetic signals via microphones. And back via speakers. Hell, there are child's science kits that will let you build a speaker to understand how it works.

I know you've displayed a considerable amount of tech knowledge in the past, especially about communications, but you're simply wrong here.

For example, sound waves don't propagate across a vacuum. Radio waves do.

Now, sound waves can AFFECT radio waves, in the right circumstances, but they're not part of the same spectrum. They're both longitudinal waves, but again, different spectrum. Kinetic energy vs electromagnetic energy.

Radio waves ARE in the same spectrum as light and heat, though. Which brings up the question as to whether Invisibility spells should affect Radar.




-k

[Onion Man]

None of the low end of the EM spectrum propagates through a vacuum, that threshold is well above the ultrasonic range.

Sound actually wonks up pretty niftily when dealing with vacuums.  In a false vacuum (interstellar medium), sound attenuates and refracts like crazy as it loses potency within the medium (the medium is opaque).  In a lab environment and a true vacuum, sound invariably reflects when it reaches the vacuum (which I suppose would mean that ultrasound would be great for detecting internal vacuums).

ELF range waveforms (also commonly debated, but never as to whether they are part of the scale or not) suffer the same limitations.  With a frequency less than the native frequency of the interstellar medium and cosmic background radiation, ELF waves cannot traverse "natural vacuums" and reflect off of "true vacuums".  To detect ELF, sonic, and ultrasonic waveforms across the interstellar medium a stable carrier wave is needed, and even then you'll only be able to witness the effects of interference (which will be minimal considering the scale of each waveform), similar to how a laser microphone works but over a much, much larger scale.

Edit: A barometric interferometer uses exactly the method I describe to "carry" a low frequency longitudinal wave across a vacuum.  Sexy stuff, interferometry is.

[Shinobi Killfist]

For the purposes of SR the Radar detector specifically gives rules for seeing through materials, if ultrasound could do the same it would be mentioned IMO.  You would be giving one of the primary reasons to get the more expensive radar sensors away for free to the ultrasound sensors. 

[basic]

Yes, they are, although they are generally not created by electromagnetic phenomena.  Voice Frequency is ~300 Hz - ~3kHz, art of a group known as acoustic frequencies (~20Hz - ~20kHz).

Ultrasound varies significantly.  Animal ultrasound (like bats using sonar) are usually in the ~24kHz area, while diagnostic ultrasound (coincidentally made by three magnets) generally operate from 1.5MHz-10MHz with a best practice called ALARA (As Low As Reasonably Achievable).  Why a low as reasonably achievable policy?  Because sending high powered waveforms into objects at these frequencies literally shakes them to the core of their being and causes damage (the purpose of therapeutic ultrasound).

What are you most likely to learn with ultrasound?  The contents of a mixed material container.  What are you unlikely to learn, anything about what's in the air outside that container (or in an entirely air filled compartment within a container, air really wonks up industrial ultrasound).

How do I know this?  Background in wired signaling, if Voice Frequencies weren't part of the electrmagnetic spectrum, your cell phone would have a hard time converting the carrier wave gibberish that it receives into voice with just a few tiny speakers and destructive interference.

http://www.sciencedaily.com/videos/2007/0706-seeing_through_walls.htm

[Onion Man]

Basic, the summary of your link says sound waves while the narrator says radio waves... either someone has discovered a way for sound waves to NOT behave as all other sound waves do, or it's a video of a low spectrum radar in action.

Judging from the fact that the device displays no speakers, and no rod (when you create sound waves via a magnet you generally use a rod to amplify rather than a shitton of power), but does display 4 fractal antenna cases, I'd bet my firstborn on that being a low freq, MIMO radar configuration.

Probably uses cheaper parts than most radar, but still radar and not ultrasonic x-ray vision.

Edit: Put Basic's name where I had mistaken placed another poster's.

[basic]

Well could I build using the level of technology in the shadowrun world to build goggles that can see thought wall. Or Modfi stuff that currently exists to do what I want.

[Onion Man]

Not with ultrasound you couldn't.  Not unless you wanted to be shattering fragile objects somewhat by random as you panned through power settings to get to the right frequency and the right amplitude to see through a wall.

Ultrasound really, really doesn't work well in a gaseous medium.  That's why ultrasound techs smear jelly on the tool and the target, for both diagnostic and therapeutic ultrasound, and industrial ultrasound takes place in empty chambers or underwater.

[Ethan]

You can do this with a Radar sensor. They're in Arsenal or Augmentation and probably SR4A itself these days.

[CanRay]

Great, now I have Radar Rider stuck in my head.

[Charybdis]

Oy, tell me about it.  I'm currently crippled by the number the sun did on my feet.  Blistered and swollen up like foot shaped, pain filled balloons... and this is from me getting along with the sun, just picture how bad it is when we fight... (I'm beginning to think I'm in an abusive relationship with the sun).

I feel your pain...

I get sunburned watching fireworks...

on TV....

[CanRay]

Bah, fireworks...  They seem so lame after where I grew up.   

[Vestax]

So what's the rules for seeing with radar sense?  There's a table which outlines penalties for different conditions in SR4A for low light, normal, therm, and ultrasound but no such reference to radar sense.  So would this just b e unaffected by light, smoke, and flare?

[Shinobi Killfist]

Radar uses the rules for ultrasound but it can penetrate rating(1-4) x 5 of cumulative barrier structure ratings.  It can also be used to detect weapons and cyber on a person like a millimeter wave radar detector.

[Red Canti]

Oy, tell me about it.  I'm currently crippled by the number the sun did on my feet.  Blistered and swollen up like foot shaped, pain filled balloons...

Sounds like a job for Aloe Vera.