Blackmagic Forum

hello,

I have some questions about sync:

Xtreemtec reported that the constellation was drifting.
« Wed Mar 29, 2023 2:20 pm : As our 8K slips about 1,5 seconds in 12 hours.
Wed Apr 03, 2024 9:08 am : 2 constellations 8K slipping about 3 seconds in 12 hours
Its drift has doubled in a year.» It seems important drift evolution on short time.

- Did someone open the device to identify the time base used? Can the tcxo component be improved?

- Poor man's method. Blackmagic software synchronizes the clock on the computer. With a raspberry as NTP server synchronized on a GPS receiver, can we get a sufficient result?

- Rich man's method. There are dedicated devices (yellowbrik, tascam...). Does anyone have an experience to share?

have a nice day

BMD should just consider to set the Analog inputs to LTC input. LTC is an Analog audio signal. And there is no special hardware required to trigger it. Just decoding it to TC in software. So it would be fairly easy to do. ( This is how it also works on the 4ME Broadcast and 2ME 4K switchers )

Most pro companies that want accurate LTC also use Madi in for there audio since the Analog audio inputs suck anyway as it has a very poor frequency response especially under 100Hz..

LTC lock to external timecode or an NTP server is going to yield the same result. If the Constellation isn't genlocked to the master clock then drift is still the same we're just dropping or adding ~45 TC counting frames per day. When should the course correction happen? Certainly not hourly, maybe at midnite?

Of course if the Constellation is genlocked to the master clock the there's no drift. It's why Master Clocks exist.

Good Luck

thanks friends for sharing experience.

Until now I froze the purchase of constellation due for a large part of old firmware (and cost )
- sound sync:
I have a madi dante converter that I will use for recording sound from FOH and multitrack recording. I wonder how all these devices are going to synchronize.
- video sync
If constellation sync is not good enough, and external genlock source may help.
In this case I should also sync hyperdeck ?
if I set TC to 0 on the atem software, will all connected hyperdeck also be initialized?

have a nice day.