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Running Sync to multiple edit bays.....

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Alex Frausto
Running Sync to multiple edit bays.....
on Nov 19, 2009 at 7:37:14 pm

Hi all, long time reader first time poster.

I started working at a new facility a few months ago and have been upgrading/tweaking. Lately I've run into some video sync issues that have me a bit confused.

We have 7 FCP edit bays with Kona LHe HD/SD cards that I need to sync up with our master control switcher so I can cleanly switch between the edit bays and our cameras (in case our Dalet/Omneon stops working I can still feed a show out from an edit bay)

Signal flow is as follows:

Evertz 5600MSC (master clock)--->Evertz 5600ACO (Automatic Changeover)--->Evertz 5600ADA (analog distribution amp)--->

I then take one of the outputs of the distribution amplifier and feed that to the edit bays. I'm hooking them up in series (no sync loop-out on Kona cards), T'ing from my coax run to each edit bay (they are all in the same area)

The problem I'm having is that If I hook up more than 3 bays in series, I lose sync to all of them. I originally suspected a bad/shorted coax but they all test fine. Here is where it gets strange. If I hook up my coax tester downstream from the 3 edit bays I have currently hooked up, I get a short. If however, I test them individually, there is no short. Furthermore, If I hook up my tester directly to the output of the DA, It detects a partial short. If you refer to the pic below, PASS light is fully lit and short light glows dimly.




What is proper protocol to follow when running sync from one source to multiple destinations? Can using a combination of 1505a and 1694a coax be causing signal degradation?

This is really beginning to annoy me and there is little to no info online regarding the protocols of sync distribution.

Any advice will be much appreciated. I can offer further technical info if necessary. BTW, our facility is 1080i.

Thanks in advance!





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Bob Zelin
Re: Running Sync to multiple edit bays.....
on Nov 20, 2009 at 2:51:10 am

Hi Alex - reply below -

We have 7 FCP edit bays with Kona LHe HD/SD cards that I need to sync up with our master control switcher so I can cleanly switch between the edit bays and our cameras (in case our Dalet/Omneon stops working I can still feed a show out from an edit bay)

REPLY - before I read any further - master house black generator into a large video DA (like Kramer 1x20 analog video DA). -


Signal flow is as follows:

Evertz 5600MSC (master clock)--->Evertz 5600ACO (Automatic Changeover)--->Evertz 5600ADA (analog distribution amp)--->

REPLY - look how fancy you are with your Evertz automatic changeover in case you lose your output of master black. Throw that piece of crap in the garbage. You are a post house, not a TV station. You need a single black out into a Video DA and one black output goes to each piece of gear.


I then take one of the outputs of the distribution amplifier and feed that to the edit bays. I'm hooking them up in series (no sync loop-out on Kona cards), T'ing from my coax run to each edit bay (they are all in the same area)

REPLY - what is "series". Series means that you are looping. You take one output from the DA out, and feed it into EACH PIECE of equipment (on the Ref Video input, or Reference Input, and you terminate it with a 75 ohm terminator).


The problem I'm having is that If I hook up more than 3 bays in series, I lose sync to all of them.

REPLY -
this is nonsense. What is "in series". You take a SEPERATE OUTPUT and feed EACH piece of equipment with one output of the vidoe DA. If you have SEVEN edit rooms, it means that your company is RICH, and can afford an inexpensive anlaog video DA. TAke your black gen output (your Evertz) into the video DA Input, and feed all the gear in your facility from the DA. What is "in series". In series means that you loop from one piece of gear to another. You probably have the termination set incorrectly.



I originally suspected a bad/shorted coax but they all test fine. Here is where it gets strange. If I hook up my coax tester downstream from the 3 edit bays I have currently hooked up, I get a short. If however, I test them individually, there is no short.

REPLY - I assume that you are double, and tripple and quad terminated. To see this you need a WAVEFORM MONITOR, not a silly Paladin BNC cable tester. BUY A DA. I am not going to sit here and explain how you can properly terminate the signals, because you shoud not be running SEVEN edit rooms in "series" with black reference. You can also get SEVEN cheap Kramer 1x6 video DA's, and take the single black coming into the room, and feed all your gear in each room with the DA OUTPUTS (so you don't have to run a lot of cables from your central rack).


Furthermore, If I hook up my tester directly to the output of the DA, It detects a partial short. If you refer to the pic below, PASS light is fully lit and short light glows dimly.

REPLY - stop it with the stupid Paladin cable tester. This means nothing. Those LED's mean nothing. You want to do a test - GET A WAVEFORM MONITOR. No money, get a 1x20 video DA. Boss says "no money" - tell him to sell his BMW. Seven Edit rooms that require genlock means that your boss is rich, and can afford $800 for a 1x20 video DA.


What is proper protocol to follow when running sync from one source to multiple destinations? Can using a combination of 1505a and 1694a coax be causing signal degradation?

REPLY - no no no . 1505a and 1694 are fantastic cables. You have a termination problem. End this conversation now. Buy a big analog DA. Or buy a scope, and I will SHOW you how to terminate properly.


This is really beginning to annoy me and there is little to no info online regarding the protocols of sync distribution.

REPLY - there are PLENTY of protocols on proper sync distribution, but you have no training as a video engineer, and have not studied information from companies like Tektronix and Leitch. You don't understand how to use or read a waveform monitor (or have no access to one), adn you don't understand 75 ohm line termination. You don't have a video DA with enough outputs on it to feed all your gear, and you are trying to do the best you can with limitied knowlege, and your silly Paladin cable tester.



Any advice will be much appreciated. I can offer further technical info if necessary. BTW, our facility is 1080i.

REPLY - once again, if you are a 1080i facility, YOUR BOSS HAS MONEY. Buy the right equipment, adn you will have no issues.

Bob Zelin


Thanks in advance!




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Alex Frausto
Re: Running Sync to multiple edit bays.....
on Nov 20, 2009 at 4:55:00 pm

Look how fancy you are with your Evertz automatic changeover in case you lose your output of master black. Throw that piece of crap in the garbage. You are a post house, not a TV station. You need a single black out into a Video DA and one black output goes to each piece of gear.

Hi Bob, thanks for responding. We are a full production facility...Shooting, editing, inbound and outbound fiber circuits, live show playout to affiliates, live flashcam hits with affiliates, live web streams, etc.....To say I'm required to wear many hats in my facility would be an understatement.


What is "series". Series means that you are looping. You take one output from the DA out, and feed it into EACH PIECE of equipment (on the Ref Video input, or Reference Input, and you terminate it with a 75 ohm terminator).

Oops, I meant to say that the inputs to our sync DA's are wired in series. Allow me to elaborate.


As you see from the drawing (blurry on purpose), the sync output of our Changeover feeds the input of the DA card through a BNC "T" connector. This input gets looped to the next input and the next one. I personally would rather feed a DA and then take an output of the DA into the input of another DA. Seems to me the designers were trying to save an output on each DA card by looping the inputs.

Regarding Termination, the KONA cards only have one sync input so I'm going to assume termination is not necessary.


I assume that you are double, and tripple and quad terminated. To see this you need a WAVEFORM MONITOR, not a silly Paladin BNC cable tester. BUY A DA. I am not going to sit here and explain how you can properly terminate the signals, because you shoud not be running SEVEN edit rooms in "series" with black reference. You can also get SEVEN cheap Kramer 1x6 video DA's, and take the single black coming into the room, and feed all your gear in each room with the DA OUTPUTS (so you don't have to run a lot of cables from your central rack).

The edit bays are not in the same room, they are along a hallway through which I ran a single coax that I'm T'ing to the various bays. Obviously this is not the appropriate way of feeding the bays and I will take your advice to feed each bay from a single DA output.


Buy a big analog DA. Or buy a scope, and I will SHOW you how to terminate properly.

A Tektronix WFM7000 is what I use to monitor video levels. I'll gladly take you up on your offer to SHOW me how to terminate properly.


there are PLENTY of protocols on proper sync distribution, but you have no training as a video engineer, and have not studied information from companies like Tektronix and Leitch. You don't understand how to use or read a waveform monitor (or have no access to one), and you don't understand 75 ohm line termination. You don't have a video DA with enough outputs on it to feed all your gear, and you are trying to do the best you can with limitied knowlege, and your silly Paladin cable tester.

I come from a broadcast audio/TV Truck background and am making the move to video engineering. You are correct that I have a ways to go as far as mastering the intricacies of this particular subject. Good thing I'm a quick learner. I have been reading the manuals but clearly there are some things I'm still in the process of fully understanding.

I await any further info you might be willing to share.

Thanks!




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Gary Hazen
Re: Running Sync to multiple edit bays.....
on Nov 20, 2009 at 8:12:55 pm

"the sync output of our Changeover feeds the input of the DA card through a BNC "T" connector" - A.F.

"I ran a single coax that I'm T'ing to the various bays." - A.F.

T connectors cause more problems than they solve. Get rid of them.


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Alex Frausto
Re: Running Sync to multiple edit bays.....
on Nov 20, 2009 at 8:15:31 pm

T connectors cause more problems than they solve. Get rid of them.

Agreed. Lesson learned.


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maurice jansen
Re: Running Sync to multiple edit bays.....
on Nov 21, 2009 at 10:32:08 am

hi Alex

using T-pieces is in our company called plumbingvideo.
i guess this is enough said now don't do this.
on the blurry photo and your explaination i figure this is also done on the RefDA input's (BRRRR) you don't want a facility wired up like that.
use DA's with passive loopthrough's, loop them through and stop after a few and terminate. I guess the engineer who have made this this way wanted to be redundant so if one DAfails the rest would still work.
but i guess he forgot that it is terminated a few time's now.

greet
Maurice

People saying they don't make mistake's often make nothing at all!


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Bob Zelin
Re: Running Sync to multiple edit bays.....
on Nov 21, 2009 at 6:15:26 pm

replies below -

As you see from the drawing (blurry on purpose), the sync output of our Changeover feeds the input of the DA card through a BNC "T" connector. This input gets looped to the next input and the next one. I personally would rather feed a DA and then take an output of the DA into the input of another DA. Seems to me the designers were trying to save an output on each DA card by looping the inputs.


REPLY - the designers were IDIOTS. I am guessing you have Leitch video DA's. These inputs, with non looping inputs, are TEMINATING - this means that each input has a 75 ohm terminator on the input of the card, and does NOT allow you to loop the input. By putting a T connector on it, you are double terminating, and triple terminating, and quad terminating the input, destroying the input signal (making it smaller and smaller). Use a single Video DA to feed all the inputs to these DAs and GET RID OF THE T Connectors, and find the engineer that designed this, and SUE HIM, becuase he is an idiot, and did not read the installation manual on this product (that has terminating inputs, which is why there is no input loop on the DA).
Where do these people come from ?



Regarding Termination, the KONA cards only have one sync input so I'm going to assume termination is not necessary.

REPLY - Termination IS NECESSARY - AJA Kona cards with with just the breakout cable do not require termination, but if you have an AJA K3 box or LHI box (for example), these have LOOPING REFERENCE INPUTS and it requires a 75 ohm BNC terminator. No excuses - you must do this. (but if you are just using the breakout cable - and who would do this at a major facility - then you don't need it) - if you don't have the K3 boxes, you must have a S#$% load of BNC barrel connectors on the Kona breakout cables !




The edit bays are not in the same room, they are along a hallway through which I ran a single coax that I'm T'ing to the various bays. Obviously this is not the appropriate way of feeding the bays and I will take your advice to feed each bay from a single DA output.

REPLY - stop with the T connectors. You are wrong, adn you are following what you have seen in the past with the original engineer, who was an idiot. Get rid of the T connectors. If you only have one feed per room, get a cheap video DA (Kramer VM80V) and feed each room with one of these under $300 DA's. (one per room, in the room).




A Tektronix WFM7000 is what I use to monitor video levels. I'll gladly take you up on your offer to SHOW me how to terminate properly.

The WFM7000 is a HD-SDI waveform monitor. To see the problem, you need an older analog waveform monitor. This will allow you to see the analog sync (or black) signal properly (you can't see it on a WFM7000). An osciloscope will do as well. You look at the output of your house black gen. You will see on an analog waveform that the sync signal goes from 0 to -40 IRE. Double terminate (use a T connector), and that signal will go to -20IRE (this is shown on the waveform monitor with graticule markings on the display). Double terminate again, and it gets smaller and smaller, and soon, there is no signal. The sync signal (derived from the black reference) is
-300 millivolts. you need this level to properly genlock or reference your equipment. If it gets too small, it can't be detected by the genlock inputs of the equipment (like the Kona cards). You simply run a clean black feed to EACH PIECE OF EQUIPMENT, and there is no issue. The DA takes the single black reference signal, and sends an identical signal to each of it's outputs. If you use LOOPING INPUTS (not T connectors), you can loop DA's together to do this, and terminate the last DA with a single 75 ohm BNC connector. If you don't have looping inputs (and you don't), you use another single DA to feed up to 6 more DA inputs (or 8 if you use the Kramer VM80V).




I come from a broadcast audio/TV Truck background and am making the move to video engineering. You are correct that I have a ways to go as far as mastering the intricacies of this particular subject. Good thing I'm a quick learner. I have been reading the manuals but clearly there are some things I'm still in the process of fully understanding.

REPLY -
the only way to learn is to make mistakes (I am learing IT stuff now, making ALL KINDS of mistakes, and feeling pretty stupid in the process) - so it's good to make mistakes. Read all you can, and keep using forums like Creative Cow, and KEEP ASKING QUESTIONS. You will eventuall "get it". It is so hard to understand these concepts without the proper test gear, so you can actually SEE what is going on, and why these problems happen.

It's like people that say "my colors look all purple - why is that"- without having a Tektronix WFM7000 (for example), it's hard to understand exactly what is happening. It's hard to fix problems without test equipment. I always laugh when I have an AC hum problem, and the electrician shows up, without a voltmeter, and "can't understand" what's wrong, because the lighbulb lights up.
This ain't magic.

Bob Zelin





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