Distributing and Synchronizing Signals Between the Worlds of SDI and IP

Abstract

Moving signals between the worlds of serial digital interface (SDI) and Internet Protocol (IP) is not exactly rocket science, but synchronizing these signals may prove to be a challenge. It is these cases that we will discuss in this article and these challenges to which we seek to identify and present a viable and cost-effective solution. We will consider a recent Riedel project with a major U.S. broadcaster. Following the decision to move its operations to ST 2110, this broadcast network experienced synchronization problems between its IP-based flagship station and more than 200 affiliate stations throughout North America relying on SDI. The fact that the remote feed needed to be compressed posed yet another challenge, as it required the decompressed signal to be decoded to ST 2110 before it could be converted to SDI. The Riedel team managed to solve the synchronization issue with a single, powerful device smaller than the size of your thumb: A software-defined processing small form-factor pluggable (SFP) device that enabled the conversion of UHD-1 and ST 2110 signals for bidirectional distribution between the headquarters and the affiliate stations while generating a Precision Time Protocol (PTP) Grand Master clock from the affiliate’s synchronized signal. This greatly reduced both system complexity and the cost of replacing the entire affiliate synchronization system. After a general description of the specific use-case setup, we will present an overview of the various possible solutions and weigh the pros and cons before focusing on the most viable solution. After short explanations of the demarcation switch configuration and the Epoch reference generation at the affiliate sites, we conclude with an outlook on other potential use cases.