Jamming an Alexa with a Zaxcom ERX2TCD

[andstrumental]

I thought since I have taken so much from this forum I should give something back. My ERX2TCD would not jam an Alexa the other day with a custom lemo/5pin xlr split cable I made. The problem turned out to be not enough voltage coming from the ERX2TCD's default timecode output voltage of .062. This was enough voltage to pass the test of jamming my 664, but not enough for the camera. Here's the fix: enter the extended menu by powering down the receiver and power up while holding the menu button, scroll though the options by pressing the menu button until you get to the "TC Output Level" menu. Use the arrows to turn it up to 0.250. Hope this helps someone.

 

cheers,

 

Andy  

[fieldmixer]

Same thing can happen with the C300.

[RadoStefanov]

2v has worked on both alexa and c300 many times. I would check your cables if 2v does not work....

[Michael Miramontes]

I had a bit of trouble jamming the other day however this time with my Nomad. Usually attaching the "timecode cable" jams the camera however on this one I had to go into the TC menu and push "Jam Time" in order to put the Alexa in sync, otherwise it was about a second off. 

[Chris Woodcock]

I had a bit of trouble jamming the other day however this time with my Nomad. Usually attaching the "timecode cable" jams the camera however on this one I had to go into the TC menu and push "Jam Time" in order to put the Alexa in sync, otherwise it was about a second off.

Just checking

You know the Alexa screen is to slow to display correct timecode if its a second off its actually locked correctly

Regards

Chris

[Michael Miramontes]

Just checking

You know the Alexa screen is to slow to display correct timecode if its a second off its actually locked correctly

Regards

Chris

Hmm, I didn't know that. If it is slow then wouldn't it always be a second off? The problem seemed to be immediately fixed after I hit the jam button. 

[glenn]

The ERX2TCD has adjustable level to feed both professional and consumer cameras. All broadcast cameras should get at least 1V of time code output level.

 

Glenn

[Chris Woodcock]

Hmm, I didn't know that. If it is slow then wouldn't it always be a second off? The problem seemed to be immediately fixed after I hit the jam button.

The timecode is correct the problem is the refresh rate of the screen isn't quick enough to display the actually timecode.

If the screen says a second off its actually correct, best way to check is ask the camera op to display tc in the eye piece it will give you an accurate read out.

There is a thread on here somewhere taking about this issue

Regards

Chris

From Alexa website

http://www.arri.com/camera/digital_cameras/learn/alexa_faq.html

"The timecode displayed in the cameras display shows some delay in reference to the actual timecode signal. The display is meant as a reference to check if the timecode values are correct, but is by no means frame accurate. Dont use the display to check Timecode frame accuracy. The recorded timecode is, of course, frame accurate."

[Michael Miramontes]

Ok, good to know. Thanks for that. 

[Cloud Wang]

what i found odd is : after using the ERX jammed the Alexa,my deneckit lockit can't jam the same Alexa anymore...... swap back to ERX then it works. 

[andstrumental]

Thank you Rado and Glenn. As you have suggested I turned up my output to to 2 volts for the rest of the shoot. It did work with .062 output but also worked with the 2 volt output. I listened to playback onset and didn't hear any bleed. 

 

I also saw my timecode off by about .5 to a full second on the Alexa's display for the entire shoot. The AC wasn't into checking timecode on the eyepiece, so i couldn't verify cwsound's claim, though I think he's right.

 

Best,

 

Andy Snyder 

[Jim Gilchrist]

Andy,

The timecode output embedded in the Alexa's SDI output is correct.  The ~1 second delay in the menu screen on the dumb side of the camera is indeed a known issue. one posted about on this board several times.

Best regards,

Jim

[efksound]

Besides the 1 second delay on the Alexa Display, it seems now that between the Nomad (maybe the IFB100 too) and the ERXTCD units there a 1.36 frame offset due to Zaxnet Latency

 

On the facebook freelance sound mixers & recordist for TV group Palmer Taylor posted the following :

 

"I've measured the output with and ERX and Nomad and found it to be around 1.36 frames off, measuring with a GR-2. You can offset this descrepency with the TC Offset option in the extended menu to get it to be within about 1/10 of a frame.The GR-2 has a mode you can put it in where it will measure the incoming timecode and tell you how off it is. I jammed the GR-2 with Nomad, feed Zaxnet timecode into the GR-2 to measure the difference, then plugged GR-2 back into nomad to see if there was any drift for reassurance and it was spot on. So, Zaxnet was off by about 1.3 frames"

 

It seems that Howy is aware and looking for a fix in the software to compensate for this

[Jack Norflus]

It seems that Howy is aware and looking for a fix in the software to compensate for this

 

Yes Howy is looking into this.

[andstrumental]

Andy,

The timecode output embedded in the Alexa's SDI output is correct.  The ~1 second delay in the menu screen on the dumb side of the camera is indeed a known issue. one posted about on this board several times.

Best regards,

Jim

 

Thank you Jim. I'll keep that in mind next time I work with an Alexa and see if I can convince the DP or AC to display the SDI TC to check. Anyone measured the timecode latency with the IFB100 ERX2TCD setup?

[soundslikejustin]

So an ERXTCD has always been off by 1.3 frames if jammed via Zaxnet until this point? Or is this only if used with Nomad?

[PTA]

So an ERXTCD has always been off by 1.3 frames if jammed via Zaxnet until this point? Or is this only if used with Nomad?

I also measured to delay by jamming my TRX ad outputting TC via a QRX. Same delay.

[Boomboom]

Would be curious to see the results of similar testing with Ambient ACN and TCBuddy units since the ''weak link'' seems to be the wireless transmission here and it's the first time it's brought up for any of these new-generation TC systems.

[efksound]

So in the meantime while waiting for a permanent fix what would the best solution?  Set the ERX TC delay option to  +1.5 frames?

[soundslikejustin]

It would be -1.5 frames.

[efksound]

Sorry if I'm missing something, I was just using logical math.
If there's a latency it means there is a delay in the transmission, so if TC is -1.36 frames behind, shouldn't we compensate using +1.5 value ?

-1.36+1.50=0,14 ?

 

Thanks

[soundslikejustin]

Sorry if I'm missing something, I was just using logical math.

If there's a latency it means there is a delay in the transmission, so if TC is -1.36 frames behind, shouldn't we compensate using +1.5 value ?

-1.36+1.50=0,14 ?

Thanks

Well, is the TC delay set to positive adding delay or pushing the frame number forward? In which case a negative delay could be either as well. Menu item should be named TC offset (and positive/negative values would therefore make sense)to remove confusion.

Palmer? Can you tell us which was to set the TC delay page please?

[PTA]

It would be -1.5 frames.

Justin is correct to set it to -1.5. A negative delay would be a positive in this case speeding up the TC by 1.5 frames. So lagging by -1.36 - (-1.5) = +0.14 ish frames. I found this closer then setting it to -1.0 frames which still leaves you at -0.36 frames.

SO... Yes, I have set it to -1.5 frames. And yes, it probably should be called TC offset to avoid confusion.

[efksound]

Thanks Palmer !

[andstrumental]

Hey Palmer, 

 

To be clear, what is actually happening when you use the timecode delay on the ERX2? Does it speed up the timecode being received by a certain value? So -1 frame means it's adding 1 frame to the timecode at the receiver side?

 

thank you, 

 

Andy