http://www.youtube.com/watch?v=4MQVY-KuXW4
Here is a video of an ATI in which I posted a video response. It's a shame Nashville went with them. Maybe by now they are sorry they did.
I can't think of a better warning for lightning than thunder itself. There is no mistaking it. It can usually be heard from over 5 miles away and can literally shake your entire house from 2 miles. I have heard some thunder from over 10 miles.
There have been a number of patents, German and otherwise, on pneumatic sirens. They are descendants of the steam sirens as used on naval ships during WWII and earlier that are often seen at whistle blows. http://tinyurl.com/3prbxo7 Since pneumatic sirens are totally powered by compressed air, I dou...
Exactly. The output of sirens using a separate blower is independent of the shaft speed of the chopper and does not fall off with the frequency. This is because a constant pressure is supplied to the chopper. The pressure is usually around 7 PSI at a high CFM flow rate. As a result, these sirens hav...
I'm glad you said this. There is a good analogy between the behavior of electromagnetic wave radiation and acoustic wave radiation in that whenever the radiating source is large in comparison to the wavelength, the directivity index increases. In the case of acoustic waves the frequencies are much l...
One good reason that a Whelen WPS2909 may not sound that impressive from up close is that large vertically stacked omni arrays have a rather narrow vertical dispersion. They gain output on the horizontal plane at the expense of narrowing the donut shaped pattern surrounding the radiator into a rathe...
I agree. I was just being facetious about the new math . It helps when you know the actual math involved. Doubling the radius always results in four times the area. Taking a radius of 2 miles (10,560 feet) vs 6000 feet, which is not quite double, the ratio in the increase in radius is 1.76:1. Squari...
http://tinyurl.com/3ozjrcn Compare the 70 dB radii of the sirens below to what I was able to achieve at my toroidal whistle tests held in July, 1982 at the Cincinnati/Northern KY International Airport. http://www.whelen.com/_MASSNOTIFICATION/4000.php http://tinyurl.com/3bagehn Very interesting that ...
http://www.whelen.com/_MASSNOTIFICATION/4000.php http://tinyurl.com/3bagehn Very interesting that Whelen suggests a WPS 4004 as a replacement for a T-135. The WPS 4004 has a 70 dB radius of 6000 feet, whereas the T-135 has a 70 dB radius of 2 miles! By doing the math (A = pi x r squared) you would n...