Siren noise using Computronics sound card

siren-test.lua

local component = require("component")
local soundcard = require("soundcard")
if not component.isAvailable("sound") then
	print("Error: Requires a Computronics Sound Card")
	return
end

local sound = soundcard.wrap(component.sound, 100)

local freq={475,570}
local vol={0.2,0.5}
for i=3,4 do
	freq[i]=freq[i-2]*2
	vol[i]=vol[i-2]/2
end
local unit=10

for i=1, 8 do
	sound.setWave(i, sound.modes.triangle)
end

for i=1, 4 do
	sound.open(i)
	sound.open(i+4)
	sound.setVolume(i, vol[i])
	sound.setVolume(i+4, vol[i])
end

for j=0, 1, 1/3000*unit do
	local j1=(j^0.5)*0.5+0.5
	for i=1, 4 do
		sound.setFrequency(i, freq[i]*j1)
		sound.setFrequency(i+4, math.max(freq[i]*j1-math.random(0, 50), 1))
	end
	sound.delay(unit)
end

while true do
	for i=1, 4 do
		sound.setFrequency(i, freq[i])
	end

	for j=0, 3000, unit do
		for i=1, 4 do
			sound.setFrequency(i+4, freq[i]+math.random(-25, 25))
		end
		sound.delay(unit)
	end

	for j=1, 0, -1/3000*unit do
		local j1=(j^0.75)*0.25+0.75
		for i=1, 4 do
			sound.setFrequency(i, freq[i]*j1)
			sound.setFrequency(i+4, math.min(freq[i]*j1+math.random(0, 50), freq[i]))
		end
		sound.delay(unit)
	end

	for j=0, 1, 1/2000*unit do
		local j1=(j^0.5)*0.25+0.75
		for i=1, 4 do
			sound.setFrequency(i, freq[i]*j1)
			sound.setFrequency(i+4, math.max(freq[i]*j1-math.random(0, 50), freq[i]*0.75))
		end
		sound.delay(unit)
	end
end