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Monitor Interference from Walkie Talkie


brett.mayfield

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Hey yall

 

I was operating this weekend and my Transvideo monitor started scrambling while standing by for the shot. It happened again and I quickly realized it was when my AC was receiving a call from the walkie talkie. He was within arms reach. I asked him to change channels, try again, and I again lost my feed but it was up immeditaly after releasing the push-to-talk button. It was both when calling and receiving.

 

I did not have a wireless system on board. Camera was an epic and the path of the signal was camera-breakout-sled-monitor-recorder. There was also a sync box pluggin TC into the breakout.

Sled is a cinelive if that is pertinent. The walkies were standard fare and were open (no surveillance, earpieces, whathaveyou)

 

Does anyone have any specifics as to why this would occur? I read through another post (http://www.steadicamforum.com/index.php?showtopic=18093&hl=%2Bmonitor+%2Binterference) regarding interference from an operators cable to the PA system. Was I experiencing the same in reverse? Is there a way to combat this?

My BNC cables are of the standard lot from the wall at filmtools. Beefy but maybe middle of the road. There were no "unnecessary" breaks (eg barrels etc) in the signal

 

brett.

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Try the same set up but connect hd signal from camera directly to monitor using external bnc (bypassing the sled)

Let us know the result.

Also, pictures of your set up and bnc cables will help.

 

It happened to me before when I used spaghetti size bnc.

Switched to standard size well shielded bnc eliminated the problem.

 

Cheers,

 

Ken Nguyen.

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Go to the back of the 17inch monitor on set and try the same thing. You'll see the same issue.

 

The Transvideo case screening is the best there is out of all the HD monitors on the market. It is nothing to do with the monitor itself but with the screenings on the cables from Epic to Monitor.

 

What sled and post do you have? On some sleds the screening at the junction box's isn't to standard and does drop the picture out. I have had this problem before in the past. Also you say your cables are standard? A lot of standard film industry cables are NOT HD rated cables. I recently swapped all mine out although not for this issue but rather for issues of the HD link sometimes dropping out. Incidently the Epic's signal out the camera isn't the strongest and cleanest so it does need the best cables.

 

I burn tested my Mk-V with HD6 and Cinetronic on the other day with a radio and did not get this problem.

 

This is only really an issue though if its the AD's walkie talkie 5ft away. If you are only getting this problem when your AC is 2 ft away.. tell him not to be 2ft away during a take! Whats he doing so close to you anyway?

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The CineLive should have proper shielding and cabling to not be the problem, assuming you're using the HD lines. Where I'd look would be the "breakout box" or whatever is on the camera. If you can go straight out of the BNC on the camera (no barrels, angles, etc...) directly to the sled's input, and the directly from the output on the base into your monitor, the problem might just go away.

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All day long today my FSI 24" reference monitor was blanking out after the AD yelled "action" into his walkie from a few feet away. Wouldn't have been the end of the world except that I happened to be using it to monitor while operating the Technocrane (courtesy our ol' pal Doc and Active Remote, plug plug). Not easy to operate a remote head shot without a monitor.

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Ill post a few pictures in a bit. but to address a few of the questions-

 

ken-good suggestion, ill try that on the next setup for testing. none of the cables are spaghetti. however the short cable to the breakout box is...

 

thomas-ill look into my cables. these were a quick pick up before set because half of my others got jacked on the last shoot. ill try to find out more about them. How do I go about finding out if they are HD rated? I bought them from FIlmTools, should I talk to them? Regarding my AC, we were between takes and he was cleaning a few things up on the rig. thus the close proximity. the rig is a Pro CineLive with the telescoping post.

 

Tom- I think that you may be right about the breakout box. It was a short spaghetti from camera to the breakout, just covered in a bit of mesh. It was a camera setup from Radiant Images. I would have liked to not have to use it and go straight into sled, but we had a sync box which required the TC-in. I suppose I could have bypassed this and used the split cable that red provides.

 

Eric- im going to go over my short BNCs today and see if theres anything noticeable. The lot I was using were all in good shape and lightly used at this point. However theres a chance I had a cinecoil on there, Ill have to check.

 

Thanks for yalls feedback

 

brett.

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What sled do you have?Ah, i see, It looks like one of your cable's isn't shielded properly, i had my sled re-done by BETZ a while back as a solution. I know of my sled and others with the same issue and i have heard from fellow op's with some other brands dealing with the same issue. After i changed my post cable all was good. But since you have a pro, i can't imagine thats the issue, so then it must be one of your bnc's. The only way to test it out is to wire your monitor directly to your camera and bypassing the sled. If the issue is still there then you know it isn't your sled. If the issue is gone, go talk to the sled builder.

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Ill be going in to Pro on Tuesday for another adjustment, so Ill see if there is anything to note about the sled cable.

I am thinking it had to do with a very short spaghetti from the camera to the breakout, as it only had a little bit of mesh surrounding the cable.

Has anyone see the epic builds from Radiant Images? I didnt snag a photo but I will next time. Hopefully it was the camera build and not my rig. Ill put up images of my BNCs.

How do I know if the BNCs I purchase are properly shielded or good for operating? I tend to pick them up from film tools.

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looks good, ill try to be more scrupulous

any useful tests when comparing all the new cables that will be in my kit? I guess I could do a walkie test, just wondering if anyones got a gauntlet that they put their cables through

 

any brands to definitely avoid?

 

brett.

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