As the screens of broadcast-grade imaging machines on the market are becoming 4K or even 8K Ultra High-Definition (UHD), professional video content providers in the fields of broadcast video and other fields continue to upgrade digital transmission interfaces to support higher resolution and meet the growing digital video bandwidth required.

However, the traditional 4K uncompressed digital baseband signal uses 4 parallel transmissions, and the maximum data rate of each channel is only 3Gb/s, which has two obvious problems in practical applications: a panel with 4 BNC connectors is required, taking up too much valuable equipment space; 4 coax cables must be used for the connection, which takes up too much cable resources and poses cabling challenges.

In order to deal with these problems, in 2015, the Society of Motion Picture and Television Engineers (SMPTE) released the 12G-SDI interface standard for uncompressed digital baseband signal transmission for 4K UHD UHD (2160p60), with data rate of 12Gb/s. It needs only one BNC connector and one high-speed coax cable to transmit the 4K UHD image, saving 75% cable resources and precious equipment panel resources.

The Pain Point of 12G-SDI Copper Transmission: Limited Transmission Distance

At the device end, the 12G-SDI high-speed baseband signal undergoes pre-emphasis and equalization processing, and the transmission distance through the coax cable can reach up to 70 meters. According to the typical transmission distance reference value of 75Ω coax cable provided by professional videoconferencing equipment vendors, the higher the operating speed, the shorter the transmission distance of coax cable. In some special applications, such as large-scale events or giant studios, the transmission distance of copper cables is restricted by physical limits, which cannot meet the needs of professional users for long-distance transmission of 12G-SDI signal baseband.

Gigalight's 12G-SDI Video over Fiber Solution

In order to cope with the special application scenarios of 12G-SDI baseband signals extended transmission, Gigalight has developed 12G-SDI optical modules and 12G-SDI optical extenders. With Gigalight's own passive CWDM Mux DeMux, the 12G-SDI video over fiber solution can realize up to 16 channels of 12G-SDI high-speed signal transmission over a single Single-Mode Fiber (SMF). Under the condition of complete 12G-SDI pathological pattern, the transmission distance is up to 10km; under the condition of 12G-SDI color bar, the transmission distance can reach 20km.

Unlike the 12G-SDI coax cable transmission, 12G-SDI optical transmission must solve the stress test under 12G-SDI pathological pattern conditions, which is very important for the performance of the video over fiber transmission system. The 12G-SDI pathological pattern test is a special stress test whose test pattern contains a lot of low-frequency energy. The original intention of the design is to test the robust characteristics of the entire transmission system and test whether the system can successfully transmit the 12G-SDI baseband signal under the worst conditions of the transmission signal. Gigalight adopts professional 12G-SDI video tester —PHABRIX, which can output and test 12G-SDI pathological patterns, including eight 100% bar patterns. Gigalight's 12G-SDI optical module and 12G-SDI optical extender can all pass the test of these patterns.

Gigalight's 12G-SDI optical module and 12G-SDI optical extender comply with SMPTE ST-297-2015, ST 2081 and ST 2082 standards, and are perfectly backward compatible with 6G-SDI, 3G-SDI, HD-SDI and SD-SDI, at the same time meet the demanding 12G-SDI pathological pattern test. Together with Gigalight's own passive CWDM Mux DeMux, the 12G-SDI optics can provide economical and suitable 4K UHD long-distance optical fiber extension for scenarios where the optical fiber resources are scarce in the broadcast video industry.

12G-SDI Optical Modules

12G-SDI Optical Extenders