The NRK fiber ring Project

With an increasing need for live broadcasting within the metro area of Oslo, Norway it was decided by NRK to build an optical video and data network that could be used for SDI, IP and file transfer access to archives back at the main station. The optical ring would encompass the entire Oslo area and cover 12 key sites.




NRK needed one optical network for news related work and another for event services. NRK wanted both ring networks to pass thought 12 major sites which included a Master Control site and its backup site. All sites had to be ‘On-Air’ and running simultaneously over a single fiber for each network in an East/West backup configuration. They wanted to be able to inject and drop signals at any point within the ring structure while keeping fiber continuity in case of any optical or power outage at any site in the ring. The event service ring would be two portable nodes that could be taken to any site within the 12 nodes and be deployed to provide live services back and forth to the master control. The news ring would have the same protection principles but would have live nodes across the entire ring infrastructure. This means that anyone could connect instantaneously for live reporting of events in the field. Both of these rings would need to be simple to operate, minimal components, simplified serviceability, with a low capital cost of implementation.


The system is built mostly from one highly auto configuring card module called the OC-4B-SDI. The OC-4B-SDI has Norwia’s proprietary AutoSFP™ technology and gives multiple configurations depending on the user’s needs, such as ring structures with redundancy features built-in.




Each node in the NRK metro ring network consists of multiple channels that either act a pass circuit for relaying signals from one point to another. They can also be used to drop signals off at one or many sites in the ring structure or to inject signals at a particular site and return these signals back to the master control. The layering of signals is via optical multiplexing at the wavelength layer on a single fiber.


When a signal is injected, the same card can split this signal in two directions to create the diversity redundancy in case of any fiber failure. While at the receiving end both of these signals are again processed by the OC-4B-SDI on a signal level for redundancy per channel. This means that individual signals are protected as well as having received signal on individual SFP’s, i.e. SFP redundancy.


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TM Broadcast International

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