| From: | Adam Getchell <acgetche@****.UCDAVIS.EDU> |
|---|---|
| Subject: | Re: silencers (with Shadowrun stats!) |
| Date: | Tue, 1 Nov 1994 08:26:53 -0800 |
> You still need a fairly large and powerful emitter to generate a 110+dB
> signal that retains the fidelity and nuances of the original signal. While
> the basic waveform is simple, you're dealing with chaos theory with the
> signal permutations: air pressure, density, humidity, temperature all
> subtlely affect the waveform, adding all kinds of little nuances that need
> to be duplicated to obtain full destructive cancelation.
I was thinking of a distributed line of resonating crystals,
perhaps in a sheath outside the gun. This would provide a large working
surface without resorting to tweeters and woofers and such.
But yes, I agree chaos and all the little nuances would prevent
full destructive cancellation. The systems in use now do not cancel
anywhere near the entire signal, but they do reduce the volume quite a bit
(to 1/3 or less of the original levels, if I remember correctly. A loud
air conditioner becomes a muted hum). I think that reducing the sound to
below ambient levels would be the target goal.
> You can't detect it audibly, but there is still energy being emitted. Any
> emitted energy can be detected somehow.
Well, I think if the sound falls below the background noise it
becomes indistinguishable, and essentially undetectable. It is not clear
that the system could get this good, but certainly it would help. I
assign the system ratings in Shadowrun, like anything else with a
geometrically increasing cost for higher ratings.
> The same holds true for the propellant gasses escaping the barrel, which is
> the cause of the "bang!" noise. For the same reasons you can't use
> destructive cancelation to negate the sound of the bullet, you can't use it
> to silence the gasses. That's where the sound suppressor comes in; by
> reducing the velocity of the escaping gasses to subsonic, no sonic boom is
> created.
Agreed. I think this is a very good idea to a truly silent
weapon (I don't mean completely silent, of course but pretty good).
Also, the active sound cancellation could work on the gasses
zipping around in the venturis and gas ports in the sound moderator.
> If you mean to have this system negate the sound of the action, this is
> sufficient (if this is correct, then I think I misinterpreted your original
> comments). Added to a weapon that fires subsonic ammunition from a closed
> bolt and has a good sound suppressor you'll have a weapon that makes about
> as much noise as a longbow, maybe less.
Yes, this system makes a lot of sense. Shadowrun stats:
ASCI: Weight: .5 kg Price: 500Y x Rating ^ 2. Rating cannot be
higher than Sound Suppressor/Silencer rating.
Each rating point adds +1 Target number to Perception rolls
involving Hearing the suppressed weapon. Ratings for silencers are
obtained the usual way, by multiplying cost times rating desired.
Without using subsonic ammo, the maximum modifier is +4. Subsonic
ammunition removes this top limit, but reduces the Power Level of the
Weapon by 1/3 (i.e. a Predator becomes 6M). At GM's option, certain
large caliber rounds may have less reduction (the .45 comes to mind) for
subsonic conversion. The maximum level for a Silencer is 4 (find the
difference on the chart between "unsilenced" weapons and "silenced"
weapons to determine this exactly, but I think it's around a +4 difference).
> Rat <ratinox@***.neu.edu> |Do not use Happy Fun Ball on concrete.
+-------------+---------------------------------------------------------------+
|Adam Getchell|acgetche@****.engr.ucdavis.edu | ez000270@*******.ucdavis.edu |
| acgetchell |"Invincibility is in oneself, vulnerability is in the opponent"|
+-------------+---------------------------------------------------------------+
