The Siren Board

I've noticed with the Whelen Vortex-r siren arround where I live that they are not very tall. It would seem to provide better coverage if they were mounted above surrounding buildings (2 stories or so not skyscrapers) so that the sound would not be deflected. Why are they so short? Money? Material strength? Lazy installers? Some do not even clear second stories on houses!

I guess most of the time it is money and/or supplies availible from the public works department that the sirens are installed in.

Many citys have extra large douglas fir poles from building projects. Rather than spending $xxx on new poles (wheather aluminum, fir, or concrete) , they can just use the surplus.

I guess another attitude (not mine)after spending many thousands of dollars on a new siren or a whole new system, why bother buying more poles, when you can use dinky telephone poles. Might be laziness in some situations, but might be just humble cost-reducing circumstances.

My city, Fond du Lac, although, decided to put the newer added on T128's on super long lasting aluminum poles. I think it was worth the extra $2000 per pole.

Most electronic sirens today produce a sine wave, the simplest wave in its profile, known. The mechanical sirens produce a square wave, a wave composed of much sharper alterations in the vibrational fluctuations of the medium. While the energy of the sound does matter to one's safety of hearing, the type of wave determines the speed of hearing-loss. You'd much rather find a blast of (130) Decibels of sine waves less deteriorating than a blast of (130) Decibels of square or sawtooth waves, because a sine wave spreads its energy out more smoothly than a square or sawtooth wave; square or sawtooth waves have a much straighter and angular scope of particle movement, in the sense of the shape of the wave. It is no wonder that mechanical sirens can be heard through obstacles much easier than some electronic sirens.
I even recall Brent Wilcox stating that Whelens are not that loud, on his site. However, there are plenty of Whelen Vortex series that are on high poles, some poles higher than the ones of some Thunderbolts.
Other than for the acoustical properties of some Whelens today, the only reasons for them being on shorter poles is for economical efficiency.
Those poles are pretty significant.

SirenMadness wrote:Most electronic sirens today produce a sine wave, the most simplest wave in its profile known. The mechanical sirens produce a square wave, a wave composed of much sharper alterations in the vibration fluctuations of the medium. While the energy of the sound does matter to one's safety of hearing, the type of wave determines the speed of hearing-loss. You'd much find a blast of (130) Decibels of sine waves less deteriorating than a blast of (130) Decibels of square or sawtooth waves, because a sine wave spreads its energy out more smoothly than a square or sawtooth wave; square or sawtooth waves have a much straighter and angular scope of particle movement, in the sense of the shape of the wave. It is no wonder that mechanical sirens can be heard through obstacles much easier than some electronic sirens.
I even recall Brent Wilcox stating that Whelens are not that loud, on his site. But there are plenty of Whelen Vortex series that are on high poles, some poles higher than the ones of some Thunderbolts.
Other than for the acoustical properties of some Whelens today, the only reasons for them being on shorter poles is for economical efficiency.
Those poles are pretty significant.

I live a half mile from a Whelen Vortex and I can tell you its loud enough I can hear it in my house with the windows up and the air conitioner going. The Whelen Vortex R-4 can reach lengths of over 2 miles in fact Whelen has told me that they cover 4 square miles. So don't criticize Whelens or any other Electronic siren because of the sine wave they produce. I have been 100 feet from a Vortex and it was so loud I had to cover my ears ( no hearing protection) my ears were ringing for 5 minutes afterwards. We have 7 Vortex R-4s in Tullahoma and they cover the whole city and even up to several miles outside of the city limits. Whelens are the most effective Electronic siren produced today due to integrity when designing and building them they utilize a low tone which is known to carry further. So I personally know that Whelens are just as loud and just as effective as a mechanical siren as I have heard a T-128 tested and I must say our Vortexes are louder!

I am in no way criticizing electronic sirens. I'd prefer a Vortex over a 2001, of any series, or a T-128, in some instances, any day.
But sine waves are easier on most people, though, and do not cause too much wear too quickly on the cells of an electronic siren; that's a major advantage.

There is a chart in the FEMA outdoor warning systems guide that
shows ehe minimum height for siren mounting. The minimum
height depends on the volume of the output of the siren.
Louder sirens have to be at a higher minimum height.
Here is the link to the old version of the guide on my site....
http://www.civildefensemuseum.com/docs/femacpg1-17n.pdf

SirenMadness wrote:I am in no way criticizing electronic sirens. I'd prefer a Vortex over a 2001, of any series, or a T-128, in some instances, any day.
But sine waves are easier on most people, though, and do not cause too much wear too quickly on the cells of an electronic siren; that's a major advantage.

Not that I have anything against Whelen, or "Electronic" in general, but 4 square miles should equate to about a linear mile from the siren. Think of (4) 1 mile x 1 mile squares together forming a 2 mile x 2 mile square ( a circle is more realistic), with the siren in the middle. It's not really more than the ratings for a 2001.

Do not all electronic outdoor counterfeit sirens produce SQUARE waves?
All electronic vehicle sirens produce square waves.

Square waveslam the speaker driver voice coil from onextreme to the other, moving the most air and producing the greatest volume.

I would noterm the sound impulse waves from real sirens as being square waves.

They are whathe rotor/stator just happen to produce.

I assume the [height] (pronounced "hite", not "hi-the") is determined by cost.
Don't have figures here, but a pole not significantly taller is almost exponentially morexpensive.

Elliott wrote:

SirenMadness wrote:I am in no way criticizing electronic sirens. I'd prefer a Vortex over a 2001, of any series, or a T-128, in some instances, any day.
But sine waves are easier on most people, though, and do not cause too much wear too quickly on the cells of an electronic siren; that's a major advantage.

Not that I have anything against Whelen, or "Electronic" in general, but 4 square miles should equate to about a linear mile from the siren. Think of (4) 1 mile x 1 mile squares together forming a 2 mile x 2 mile square ( a circle is more realistic), with the siren in the middle. It's not really more than the ratings for a 2001.

Yes you are right the Vortex covers 4 square miles or a mile at about 70dB. The Vortex R-4 can reach 6,000 feet at 70dB and 12,000 feet at a level of around 60 dB take or give a few dB. The Vortex R-4 is rated at 129 dB @ 100

Robert, the only reason that I can think of for vehicle-sirens producing a square wave is for the fact that their output of sound energy is nowhere near as great as the sound output of an outdoor-warning siren, so even though the waves within the vehicle-siren might be square, the energy within those waves is not great. Two of the factors that determine the speed of reaching a certain fatigue level in a medium are the path of the energy and the amount of it. So even though the small sirens might produce square waves, there is not that much energy within the waves; those sirens might also have a higher pitch, so the fluctuations of the cell(s) would not cause too much damage.
I believe that square waves are more choppy-sounding because they are angular and therefore have pressure points. I also conceive that they seem more energetic, because they are more straight and therefore lose less energy in every oscillation.