Synchonization Pattern (RCA)

[tdegroef]

Hello all,

I have a problem interfacing two Optitrack V100R2 cameras.

I need to use a external trigger with the RCA input/output to control the shutter.

I�d like to know :
- what�s the synchonization pattern (RCA)? I analyzed the sync. Signal, and it�s a word of several consecutive bits of a period ~ 130�s, every 10ms (100Hz). But many of the bits change over time� Is an addressing system of cameras ?
- How I can choose the Master ?
- Are all the cameras taking a picture simultaneously ?
- How many slaves can be synchronized with one master ? (98 ?)

RCA Sync. signal:


Thanks
Thibault

[NaturalPoint - Mike]

The best way to handle an external trigger would be to synchronize the cameras with an OptiHub instead of the RCA sync. You can then attach your trigger to the external sync port on the OptiHub. Up to 24 V100R2 cameras can be synchronized by either an RCA sync or OptiHubs, and all synced cameras take their pictures simultaneously.

When synchronizing multiple cameras, the first one in the chain is the master, and slave cameras are assigned in the order that they are connected.

[Birch]

Some additional information :

* The pattern you are seeing on the Wired Sync signal carries information for frame numbering, camera self-numbering, frame exposure triggering, etc. The easiest way to synchronize V100R2 cameras with external devices is to use them with an OptiHub which has numerous sync in/out features.

You can find out more about the OptiHub here :
http://www.naturalpoint.com/optitrack/products/optihub/

* In a Wired Sync setup the master will be the camera (or OptiHub) at the start of the chain. If you are using an OptiSync (sync over USB) setup then the master will be the OptiHub at the start of the hub-to-hub chain.

* Yes, when the cameras are synchronized they will all expose (take a picture) at the same time.

* The maximum number of V100R2 cameras which can be synchronized to a master has more to do with the maximum number of cameras which can be connected via USB, which is typically about 24 *(1). It may be possible to connect more cameras, but you'd want to add in extra USB host controllers and have a fast computer*(2). To scale beyond that we'd recommend moving to our ethernet cameras such as the S250e. (Note - at this time the S250e does not have support for sync in/out or the OptiHub).


There is some additional information in this forum thread :
http://forum.naturalpoint.com/forum/ubb ... #Post28456


1: The technical upper limit would be ~255, however we have not tested with this large of a USB camera count.

2: In theory it may be possible to connect sets of USB cameras in the same sync chain to different computers to allow scaling beyond the typical maximum, however we have not tested this.

[tdegroef]

Hello,

Thanks Mike and Birch for your answers.

I�m a student (Electronics), and I need to use those cameras for a multitouch screen, controlled by a MCU.

Apparently we can�t bought the OPTIHUB, and I would like to use my two cameras without the optihub.

In my case, do you think it�s possible to use two cameras, without the optihub, and have them synchronise ? Is the sync pattern automatic ?


In this case, how to choose the master ? (without optihub)


Thanks,
Thibault De Groef

[NaturalPoint - Mike]

To sync two or more cameras without an OptiHub, plug a breakout cable into each camera and connect the out from one (this will be the master) to the in on the second (this will be the slave). The cameras will know which is which. If you want to add more, just repeat this pattern attaching 3 to 2, et. cetera.

The sync and breakout cables/connectors are included with V100R2 cameras, and sold separately with V120:SLIM cameras. If you need the breakout cables or sync cables, they are available through our web catalog's cables and hubs page, located here:
http://www.naturalpoint.com/optitrack/s ... ables.html

Good luck with your project!

[tdegroef]

Thanks ! It's perfect and easy.

Thibault De Groef

[NPFan]

Hello,

I have the Track IR 5 and another generic camera (120fps in window mode). I would like to know if it's possibile to obtain a software pseudo-synchronization with time-stamps using the camera SDK. I think that a very small time difference between frames could be not critical.

Thanks

[NaturalPoint - Mike]

Theoretically, yes. Keep in mind, however, that while the TrackIR is supported within the SDK, technical support for this use is not guaranteed by Naturalpoint.

[tdegroef]

Hello,

juste for information, the synchronization works fine. (RCA + MCU + Power interface for 140 Leds)

Actually I've some drivers problem ... (TUIO+CCV+V100R2...) => http://forum.naturalpoint.com/forum/ubb ... #Post47841

[NPFan]

Hello,

with the camera sdk is it possibile to obtain the frame timestamp synchronized with the PC time system?

thanks