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Q&A about Video SFP Transceivers

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1. What is SDI?

SDI, the abbreviation for 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.



2. What are the categories of video transceiver modules?

It can be divided traditionally by operating rate into HD-SDI, 3G-SDI, 6G-SDI, 12G-SDI; by transmission mode into single Tx, single Rx, dual Tx, dual Rx and TR transceivers; by standards into MSA and non-MSA; by operating wavelength into 1310nm, 1490nm, 1550nm and CWDM wave length. It also exists video modules of electrical interfaces that adapting mini BNC port to coordinate with SFP slot-supporting digital matrix. Currently there are also on the market some crossover video transceivers, for example, transfer the encoded SG-SDI to IP protocol conversion module can be used in traditional Ethernet switch, replacing video codec equipment.

3. What are 6G-SDI and 12G-SDI applied in?

Generally in HD digital broadcasting field, such as digital output port of TV station HD professional camera. One-channel 6G-SDI can transmit 36fps 4K resolution zero-compressed video, while one-channel 12G-SDI can transmit 60fps 4K resolution zero-compressed video.


4. What are the main differences between HDMI and SDI?

a. Different transmit mode: Adapting parallel mode, HDMI cables contain up to 19 pairs of wires; while SDI adapts serial mode and contains only one pair of wire.

b. HDMI is applied for consumer products, like DVO from consumer camera, game machine and HD digital Set Top Box; when SDI applied in broadcast market, like TV stations and studio.

c. HDMI interface supports HDCP encryption HD digital copyright protection, but not SDI.


5. What is SDI digital video matrix? What main functions it has?

Digital video matrix arbitrarily exports m channel video signal to the electronic device on n channelmonitor equipment by switching array method, realizes video switch function through digital Cross-point chip, which realized by artificially plugging the copper shaft joint of distribution frame before the digital video matrix appearance. Presently digital matrix has been distinguished by working bandwidth, such as the type supporting 3G-SDI high-speed signal; usually each input-output port supports automatic equilibrium function; and high-end model has CDR clock regeneration function, on port types it has BNC copper shaft joint, also video SFP supportable fiber interface. With module design, it is more flexible to deploy and convenient to use.


6. What long-distance transmission solutions applying 3G-SDI, 6G-SDI and 12G-SDI?

3G-SDI, 6G-SDI and 12G-SDI both are digital baseband signal, thus limited with long-distance transmission on copper cable, for instance, 3G-SDI signal can transmit up to 55 meters on premium copper cables, but that will be much decreased to within 10 meters as for 6G-SDI and 12G-SDI, what’s more, copper cable transmission is susceptible to outside electromagnetic interference. If high-speed baseband signal proceeds optics and electrics conversion, then it can be greatly solved through optic-fiber cables. Currently the generic 3G-SDI video transceivers in marketplace is with transmission distance up to 40km on singlemode optical cables, and it will be easily to solve long-distance transport with 3G-SDI transmitter. Meanwhile there are many optical module options supporting CWDM waveband, which save much fiber resource by carrying WDM(wavelength division multiplexing) on single fiber. Now 6G-SDI and 12G-SDI optical transceivers gradually are commercially available.


7. What’s the difference between MSA and Non-MSA standards of 3G-Video SFP optical transceiver modules? What will be the consequence if they match wrongly to host machine?


The gold finger of 3G-Video SFP transceivers have 20 pins, MSA ans 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.


I2C pins failing to match the host machine can directly lead to SFP module communication connecting error to host machine I2C, it comes out the SFP DDM function is unavailable and EEPROM unreadable by host machine.