ATEM production 4K SDI input problem

I've read 3 or 4 similar topics on the forum but no solution or explanation really match what we experience :

We have 4 Sony cam that output a 1080p50 signal through HDMI. If we use Kramer FC-113 converter (540 euros) to 3G-SDI and connect to one of SDI input of ATEM, no signal. If we use a Decimator MD-HX (320 euros...) , then it works normally...
If we use FC-113 to SDI then FC-331 (total 1080 euros...) back to HDMi then input in HDMI in Atem, then it works...

Crazy no ???

WHY ? Does someone have a clue ?

Thanks for all your help, it's for a school and passionated students.

So, I’ve been around surfing and here is some details of my search :

For 3G HD-SDI, 2 possibilities : Level A or B.

- Level A is used for streaming 1080p50 or 60 in the easy way : one stream on one cable.
It’s used on most of computer screen and a LOT of converter. The cheapest one but also the Kramer.

- Level B is used for the same (1080p50 and 60) but it’s 2 streams on one cable that seem to be used for extra bit depth info (like 4.4.4 or 10bits or both, i’m not sure).

But what I’m sure of is :

- Decimator MD-HX is capable to receive and send at both level A and B
- Kramer plays only with A level as Christie VP does.
- ATEM sdi input seems to only « understand » B level
- ATEM sdi program output is switchable between A and B and it does the trick with a lot of converter or VP.

All my best.

Indeed Level A vs B issue.. And you switch the Whole Atem from Level A to Level B when you switch that setting.. Not just the output.

We run a lot of 4K setups.. But when we run HD we do it 1080P so 3G.. We recently did a test on all our gear to check what standard they are. Put that into a database and put a sticker on each device telling what standard it supports..

We prever Level B as most hardware does do level B. But sometimes we run into issues with hardware from others.. So we always carry a few decimators with us on spare..

Thanks a lot, it confirms all my researches and also the necessity to have some Decimator...

got an issue on my atem
is there any chance of the atem receive an input sdi signal from a 1080i60 pc?

got an issue on my atem
is there any chance of the atem receive an input sdi signal from a 1080i60 pc?

With a Decimator MD-HX or BMD UpDownCross HD converter you will..