Author: Barbara Schmitz, Chief Marketing Officer MEN Mikro Elektronik
Public video surveillance has become a common safety application in passenger trains, both in the equipment of new and the retrofitting of older vehicles. Video data is characterized by high bandwidth and memory requirements. The technology which has originally been developed for data centers becomes mobile and thus exposed to harsh environmental conditions. Real-time behavior is an additional challenge in live video and audio applications.
The code of practice recently published by the APTA (American Public Transport Association) for video surveillance in trains defines the following standard requiremens as the lowest common denominator:
- All cameras in the train have to be recording constantly
- Recording is done at two different bit rates (12/15 fps (frames per second) and 25/30 fps)
- The bandwidth of the in-train network (“Trainline”) is 100 Mbits/s
- Video data has to be stored for at least 72 hours
In a typical CompactPCI system (PICMG 2.0) SBCs with RAID support are used for such an application. As modern hard disks or solid state disks are nowadays equipped with SATA interfaces, the CompactPCI PlusIO (PICMG 2.30) standard with its four SATA interfaces defined on the backplane is ideally suited for configuring new RAID systems. Such a system e.g. consists of a CPU unit for controlling the recording and two to four hot-plug-capable HDDs or SDDs which are located on shuttles in the CompactPCI Plus peripheral slots. A radio unit controls the transfer of live video images and the download process.
Another advantage of CompactPCI PlusIO is the standardization within the PICMG. A well-developed ecosystem is the best guarantee for the availability of replacement components in "form, fit and function" for a system in use for 10 to 15 years even if some assemblies or system components have finished their life cycle.