cell phone disturbance

smithgallTV

smithgallTV

Active member
I taped a deposition today and i mic'd 3 lawyers with lav sony ecm-55b mics and then i had two table top mics. Al of these were wired to my mixer and then xlr'd into both mics on my camera. Howver apparently during the depo i received a fair anmount of signal distrubance. I could hear it in my headophones and now hear it on the tape. Its a buzzing that I am attributing to either Cellphones or blackberys. The phones werent ringing so i dont know if they were getting calls or text messages. I know they were getting some messages because I saw some attorney showing the messages to others. Is there any way to filter out this signal? Im not sure if blackberrys and cell phones operate on the same type of signal or not. I notice this same type of interference on radio just ahead of the ring of my cell phone.

unfortunately attorneys wont turn off the phones so it up to me to try to solve the problem on my end if i can.
 
I would try to find cabling with better shielding, or possibly fight fire with fire and use wireless. Cable made for permanent installation usually has foil shield, which is more effective than braid, but tends to be less flexible and more sensitive to damage.
 
On film shoots, I always make the same announcement:

All cell phones OFF. Not on silent, not on vibrate, not on stun, OFF.

My guess is the Blackberry's were the culprit. Email devices like that often create bigger problems. If they are not willing to turn them off, have them leave them in the hall, or as far away from the shoot as possible. Also, I have noticed less cell interference now that I use all Canare quad star cables. More expensive, but worth it.

Phil
 
if the buzzing sounds pulsed and sounds like a constant tic with some up and down buzzing...then it is definatly a cellphone issue, pretty much all carriers besides sprint, operate on a lower frequncy, witch will interfere with VHF based wireless mics...and also battery powered wired mics...i know for a fact with all the government employees at my work there is always an issue with thir nextel blackberries and verizon phones....

Use Balanced cables...shorter cable runs, phantom power from a mixer, and UHF wireless mics...

uhf operates at a freq much higher then all cellphone carriers....
 
thanks for the advice. Unfortunately i have to use the wired mics. I cant go with wirless for the depositions. we already have 5 sony ,ics and cant justify the expense of buying new. The more i read responses and recall the day i think the blackberrys were at fault. One lawyer in particular got a few cell calls and other than the ring i dont recall an interference prior to the call, however i got periodic buzzing and i know the lawyers were checking the blackberrys all day. I shouldnt be so hard. they were up from Miami and I know some of them were without power in offices and home.
 
I've had cell phone interference before when shooting depositions and trial testimony; so I kinda use the same announcement as ptalsky just prior to going on the record: 'all cell phones, pagers and PDA's need to be OFF at this time'.

Wired mics can be a pain, but at least you can keep lawyers on a tether when they're hooked up to 'em ;-)
 
Anyway, the kind of cell phone noise i know shows up as a repeating series of impulses which all sound the same, and i would guess with a main frequency which, again, i guess, sounds always the same.

if this is true, you could try a frequency analysis to detect what frequency that is and try to fix with a notch filter. I'm sure there are other frequencies since it doesn't sound like a clear mono frequency sinusoidal sound, but i'm sure there's a dominant, hopefully consistent in time.

Andrea
 
My Nokia GSM phone emits a short, intermittent, multi-frequency 'signature'. It seems to be some sort "here I am!" beacon. I've heard it come over all kinds of equipment including my DVX. It even pops up on my shielded reference monitors if I leave the phone sitting on top. What a pain. I always have to make sure I turn it off before I start shooting.

-Dan
 
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