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Beware Of Harmonic or Noise Distortion

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radiant

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So last night on our shoot of (Beyond A Reasonable Doubt) starring Michael Douglas.

Problem:
While performing our stunt, the stunt car was performing donuts & 360 creating a constant high pitch noise that created a Harmonic Wave.
Which caused all of our camera's to stop rolling or recording at the same time.

Cause:
We have not encountered this problem, for couple years, since when I use to shoot for NASCAR. It's called Harmonic Distortion.

This is one of the most elusive and problematic of power quality events. Harmonic distortion alters the 60 hertz (Hz) sinusoidal voltage.

Through an additive process, where multiple low voltage signals (harmonics) “ride” on the 120V 60 Hz signal and corrupt its appearance.
Harmonics are multiples of the fundamental frequency – e.g., 300 Hz is the
fifth harmonic of 60 Hz (60x5=300).

In extreme cases, you may see your lights flicker due to harmonics but the obvious symptoms are motors and transformers overheating.

Harmonic distortion is caused by non-linear loads such as induction motors and welding devices.
Noise distortion creates problems with sensitive electronics but rarely destroys equipment.

Computers are the most prone to noise effects, where data can be lost but no physical damage is done.
Interference from radio and TV broadcasts, welders, loose wiring or grounds, appliances.

Solution:
The solution is to minimize the effects of Harmonic Distortion.
(1) Record on CF Cards.
(2) Place space blanket or sound blanket to block the Harmonic Waves.
(3) Place camera at long distance.

See Pictures:
 
I certainly don't know the details of your setup, which looks very complex. But I'd guess that sustained acoustic noise, if it's loud enough and at the right frequency, might resonate the hard drive parts or even other camera parts enough to cause trouble or even shutdown. It might not be electrical at all, just the acoustic noise, the same way a high pitched sound can break a wine glass. In any case I'm sure solid state storage, eg. CF cards are the best choice for any kind of extreme environment.

Breaking a glass with sound waves - physics demo
http://www.youtube.com/watch?v=17tqXgvCN0E
http://www.oberlin.edu/physics/catalog/demonstrations/waves/beakerbreaker.html
 
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jbeale said:
I certainly don't know the details of your setup, which looks very complex. But I'd guess that sustained acoustic noise, if it's loud enough and at the right frequency, might resonate the hard drive parts or even other camera parts enough to cause trouble or even shutdown. It might not be electrical at all, just the acoustic noise, the same way a high pitched sound can break a wine glass. In any case I'm sure solid state storage, eg. CF cards are the best choice for any kind of extreme environment.
Click to expand...

Yes Our setup are very complex. at times we have used 6 RED's at the same time.

You are 100% right, that is why I swear by the CF cards and mostly shoot on them.

Hard Drives are not the most reliable, capture or recording format.
 
Radiant, you guys are hilarious. The way you guys appeared on Reduser, with accompanying clap of thunder and a stack of posts about a bevy of interesting, high-profile projects is pretty darn funny.

Look forward to reading more from you guys. Thanks for posting!

Bruce Allen
www.boacinema.com
 
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Bruce Allen said:
Radiant, you guys are hilarious. The way you guys appeared on Reduser, with accompanying clap of thunder and a stack of posts about a bevy of interesting, high-profile projects is pretty darn funny.

Look forward to reading more from you guys. Thanks for posting!

Bruce Allen
www.boacinema.com
Click to expand...

Hello Bruce,
You are right, we have had our RED #75 for 9 months now.
We did not want to make any statement or posting unless we had enough on field and off field testing and experiences, also we have learned allot by monitoring other users post's.
 
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Hot Swap Battery Power Supply

Hot Swap Battery Power Supply

Thom said:
What dual battery mount are you using? --those look like Red Batteries in tandem. Does the mount connect with a Red Cable and allow hotswap?
Click to expand...

We are using The Switronix GPTS.
Which is a "hot swap" power adapter that mounts directly to your existing V-plate. Batteries are mounted side by side, so you can easily remove the depleted battery while leaving the other battery connected so there is never any down time. The GP-TS is outfitted with a 2-pin power port so that you are not limited to the cameras' own connector.
The GP-TS works with all RED Brick Power and provide up to 260wh continuous battery.

The only problem with all the dual power system, we tested is that you loose the digital display, which informs you on percentage life span.

See Pix's
 
BASSAM MSSALATIE said:
Mike thanks for that Link
Click to expand...

Bassam,

The Hot-Swap is a must on a shoot, you never every have to wait for camera to boot up.

I use it on all our shoots.

Good Luck on yours!
 
I'm completely confused about your post, Michael.

At first you speak of audible noise from a car...and then start talking about 60hz AC...as if the sound energy from the car is somehow causing corruption of the AC line frequency. I'm cornfused.

I certainly have had hard mounted cameras mounted on cars stop working before from mechanical vibrations (and harmonics thereof). Even had an HVX200 that would shut itself off when the engine on an ultralight aircraft would hit a certain RPM...

...but never had mechanical/audible vibrations make their way into power supplies...
 
I think the original post may be confusing acoustically-driven mechanical resonances (definitely has potential to interfere with a hard drive, for example) with a separate electrical power problem.

I have heard of voltage ripple from a high-precision voltage supply being affected slightly by acoustic noise through a "microphonic" component, some capacitors especially can do this. So in that sense it's possible, but it's not the first thing that would come to my mind.
 
jbeale said:
I have heard of voltage ripple from a high-precision voltage supply being affected slightly by acoustic noise through a "microphonic" component, some capacitors especially can do this.
Click to expand...

Right. I can imagine this happening as well, but only if there's a reasonably complex circuit with the right components (transformer windings vibrating?) in the power supply.

But not if powering by batteries.
 
Yeah, that's the same one I believe.

Edit: Oops, missed next page of posts. Ignore my post.
 
Cameras are DC right so no 60 Hz nonsense unless your ac tethered.
So you're saying a rotating/spinning car produced an EMF field at X distance that spiked your internal power enough to throw a safety circuit...
or an acoustical field somehow generated a third order harmonic wave in camera?
Hard to believe either way i must say.
I don't doubt the cameras turned off though but i would think its a purely physical phenomenon, vibration related.
IMHO
 
JDHolloway said:
Cameras are DC right so no 60 Hz nonsense unless your ac tethered.
So you're saying a rotating/spinning car produced an EMF field at X distance that spiked your internal power enough to throw a safety circuit...
or an acoustical field somehow generated a third order harmonic wave in camera?
Hard to believe either way i must say.
I don't doubt the cameras turned off though but i would think its a purely physical phenomenon, vibration related.
IMHO
Click to expand...

Well Holloway,
Our camera's were both attached and they stopped recording about the same time, two to three times.

This has happened to me several times, when I use to shoot for NASCAR.
We shot on Varicam's then special shots we had to use the P2 camera.
 
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