Precision video & telemetry data sync
The Brief
Our client wanted the ability to set up and control a multi-camera recording system, where the shutters of the cameras were timed to within 1ms of each other.
In conjunction with this, the multiple video streams needed synchronising to a data telemetry system governed by a GPS clock source, to within 1ms.
To meet the client’s needs, we had to identify a global shutter video camera that could support frame rates of over 100fps HD. We also needed to find a suitable encoder and video processing platform that could handle the high data throughput.
Despite the high technical demands, the solution had to be cost-effective.
The Solution
We conducted a thorough assessment of the machine video camera market, taking into account factors such as cost, performance, control capability, physical interface, and video format output. Our choice of camera influenced all other aspects of the video processing system.
To further complicate such choices, technology borrowed from consumer electronics drives constant change in the machine-vision camera market.
The final solution combined FPGA, DSP and embedded processor technologies to synchronously capture, debayer, encode and store the outputs of multiple independently controlled video cameras to within a few hundred microseconds accuracy. The solution was based on an embedded Linux platform which deployed GPS, NTP and PTP daemons to synchronise multiple Linux systems to a common GPS clock source. Additionally, we proposed a technical roadmap that would further improve synchronicity and exceed the original requirements specification by achieving accuracy down to the tens of nanoseconds level.
We not only met but also exceeded the requirements of the project, delivering a solution that was within budget.
We identified, integrated and tested a number of Linux and FPGA libraries to use alongside its bespoke code. This minimised development time and risk whilst exceeding the requirements specification in many areas.
Closely synchronised video data and telemetry can only be achieved by taking a system-level design approach. The video/camera specification is at the heart of the system, but by discussing and agreeing on trade-offs in other elements] with the client, it was possible to achieve a highly specified system within a constrained BOM target cost.
Our extensive knowledge of the fast-moving camera product market enabled an element of future-proofing to be incorporated into the design.