In small size fiber optic network building, SFP transceiver plays an important role. There are various types of SFP transceivers on the market, such as 1000BASE-SX SFP, 1000BASE-LX/LH SFP, 1000BASE-T copper SFP (For more knowledge about Ethernet SFP module, you can refer to this article: SFP Module: What’s It and How to Choose It?). In addition to these, there exists a kind of SFP transceiver which is mainly used in video transmission. That’s video SFP transceiver which is also known as SDI SFP.
Video SFP transceivers are also referred to as digital video transceivers or SDI (short for Serial Digital Interface) video transceivers. They are small, hot-pluggable transceiver modules, working with fiber optic cables. Why do we need to use SDI video SFP transceiver? As the rapid evolution of the broadcast video transport for high-capacity HD and ultra high-definition (UHD) digital transmission, it is necessary to produce a kind of fiber optic transceiver that can achieve high performance level in video image transmission. With SDI interface, video SFP transceiver is able to support SDI video pathological signal and ensure the quality of video transmission.
Video SFP transceivers can be classified into various types according to different aspects. Divided by operating rate, there are 3G-SDI SFP, 6G-SDI SFP, 12G-SDI SFP; by transceiver type, there are dual transmitters, dual receivers, single transmitter, single receiver, or a transceiver; by compliant standards, there are MSA and non-MSA; by operating wavelength, there are 850nm, 1310nm, 1490nm, 1550nm and CWDM wavelength; by transmission distance, there are 300m, 2km, 10km, 20km, 40km.
Video SFP modules complete optical signal to digital signal conversion or vice versa in the applications. They are usually used for HD camera or monitor system and broadcast video transport application. This part takes 3G-SDI SFP for example.
Usually there are multiple HD end-devices in HD camera or monitor system, so we can use one HD video matrix as one end, which provides multiple video SFP ports, and multiple HD-SDI equipment as the other end. 3G-SDI transceivers are plugged into the equipment respectively, then SDI SFP transceivers on both ends are connected via fiber optic cables. The cabling diagram is shown in the following figure.
Broadcast video transport application needs high-density cabling, so we use HD-SDI equipment with high-density video SFP ports. As the following figure shows, multiple 3G-SDI SFP transceivers are plugged into the HD-SDI equipment on the two sides respectively, then these video SDI SFP transceivers are connected through optical cables.
As video SFP transceiver can be designed with dual transmitters, dual receivers, single transmitter or single receiver, you should be careful when choosing video SFP transceiver. If you need unidirectional transmission, then you can use single SDI SFP transmitter and single SDI SFP receiver for single signal, dual transmitters and dual receivers for dual signals. If bidirectional transmission is required, you can use video SFP transceiver which has transmitter and receiver built in one module. Besides, there are SDI CWDM SFP and SDI BiDi SFP. The SDI CWDM SFP can transmit signals at different wavelengths, and SDI BiDi SFP can mix and transmit multiple wavelengths simultaneously over the same fiber. Both of them are cost-effective solutions. What’s more, the choice of fiber optic cable must be compatible to the type of video SFP transceiver.
SDI (Serial Digital Interface) is a digital video interface standard made by SMPTE organization. This serial interface transmits every bit of data word and corresponding data through single channel. Due to the high data rate of serial digital signal (a kind of digital baseband signal), it must be processed before transmission.
3G-SDI video SFP transceiver supports 3Gbps data rate, while 6G-SDI video SFP transceiver can deliver a payload of 6Gbps. Both of them are specifically designed for robust performance in the presence of SDI pathological pattern for SMPTE 259M, SMPTE 344M, SMPTE 292M and SMPTE 424M serial rates, but 6G-SDI SFP is also designed for SMPTE 2081. For application, 3G-SDI SFP is generally used for security monitoring application and television broadcasting, while 6G-SDI SFP is often used for 4K /HDTV/SDTV service.
Video SFP transmitter converts digital signal into optical signal, while video SFP receiver converts optical signal into digital signal. Therefore, they must be used together in application. What’s more, video SFP transceiver also needs to be used in pair to complete the link.
4. What’s the difference between MSA and Non-MSA standards of 3G-SDI SFP optical transceiver modules? What will be the consequence if they match wrongly to host machine?
3G-SDI SFP transceiver has 20 pins, MSA and Non-MSA differ in I2C pin definition: MSA standard defines I2C definition on the fourth pin (SDA) and the fifth pin (SCL); while Non-MSA standard defines it on the fifth and sixths pins. The I2C pins failing to match the host machine can directly lead to video SFP module communication connecting error to host machine I2C. It comes out the SFP DDM function is unavailable and EEPROM unreadable by host machine.
5. What’s the difference between video SFP transceiver and fiber video converter? How to make choice between them?
Both video SFP transceiver and fiber video converter are used for video transmission, and they can realize optical signal to digital signal conversion. Fiber video converter consists of fiber optic transmitter set and fiber optic receiver set, so when in use, they must work together.
The main difference between them is that video SFP transceiver is not only connected with fiber patch cable to function, but also has to be plugged into HD-SDI equipment video SFP port; while fiber video converter can just work with fiber optic cable. Also, fiber video converter usually supports 20km transmission distance over singlemode fiber; while video SFP transceiver can support short reach and long reach, over multimode fiber and singlemode fiber respectively. For cost, fiber video converter is more expensive than video transceiver. As for which one to choose, it all depends on your specific requirement.
Video transmission becomes more and more common in our daily life. Being able to ensure the high performance level of video digital transmission, video SFP transceiver gains great popularity among network engineers. FS.COM provides different types of 3G-SDI video SFP and 12G-SDI SFP, and custom service is also available. The table below lists some FS.COM 3G-SDI video SFP transceivers.
|FS.COM P/N||Transceiver Type||Wavelength||Max Cable Distance||Video Pathological Patterns Support|
|SFP-3G85ST-3M||Single Transmitter||850 nm||300m, MMF||Yes|
|SFP-3G31DT-2||Dual Transmitters||1310 nm||2km, MMF||Yes|
|SFP-3G31SR-20||Single Receiver||1310 nm||20km, SMF||Yes|
|SFP-3G31DR-40||Dual Receivers||1310 nm||40km, SMF||Yes|
|SFP-3G55-40||Transmitter & Receiver||1550 nm||40km, SMF||Yes|
|BSFP-3G35-10||Transmitter & Receiver||1310nm-TX/1550nm-RX||10km, SMF||Yes|
|CWDM-SFP3G-10||Transmitter & Receiver||1270 nm||10km, SMF||Yes|
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