Data center networks are rapidly adopting fiber optics technology. Multiple fiber optic devices are integrated to build a fiber-based network for data centers. The optical transceivers are of great significance in these high-capacity networks. Today, most modern data center networks demand high-capacity data transmission. Like all other devices, the optical transceivers are subjected to these data transmission challenges. Despite these challenges, optical transceivers continue to be highly popular in networking industries. Many industry studies on optical trends suggest that the demand and significance of optical transceivers are increasing by the day. If you are unaware of challenges for optical transceivers and optical transceiver trends, then this post is for you. This post discusses the challenges for optical transceivers in data centers and few forecasted market trends.
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The optical transceivers are used for transmitting and receiving the optical signals in high-capacity data centers. Generally, the data centers feature a hierarchy type of Ethernet networks. These networks can be copper-based, fiber-based, or hybrid (copper-fiber). In the modern network, upgrading all devices to fiber-based components may not be convenient. The optical transceivers are used in certain cases to convert an electric signal into an optical signal. These signals are further transferred through fiber optic cables. The transceivers consist of pairs of transmitters and receivers which play important role in the electro-optical and reverse conversion of signals.
Since in high-capacity data centers, multiple copper-fiber connections are required, multiple numbers of optical transceivers are used. Each optical transceiver is exposed to a high volume of data packets and therefore, the need for upgradation and performance enhancement of optical transceivers is a constant requirement.
Network engineers for high-capacity data centers often face challenges for optical transceivers due to the increasing demand for performance efficiency.
Let us discuss the challenges.
The challenges for optical transceivers are generally related to the design and deployment of the transceivers in the network. The challenges are discussed below.
Despite all the challenges, the optical transceivers are used in the data center networks by deploying smart, calculated solutions to overcome these challenges. Owing to the same, the demand for optical transceivers remains high. The next section introduces you to some forecasted optical transceiver trends.
The following optical transceiver trends have been reported and forecasted by industry experts.
You need to consider the following operational parameters of these transceivers when choosing them.
The fiber optic transceivers are essential for electrical to optical data conversion and vice-versa. When buying them, you need to consider several factors such as the type of data converted, data speeds, distance to be covered, equipment used for plugging these transceivers, etc. In addition, these transceivers can transmit different wavelengths, and signal attenuation is less in long wavelengths. So, if you consider fiber optical transceivers like SFP transceivers for your high-speed network, ensure to invest in MSA-compliant transceivers, which are compatible with most switches and router platforms. Many transceiver manufacturers also provide switches and routers, which helps reduce your incompatibility issues.
Initial Published: November 21,
Serial Digital Interface(SDI) is a digital video standard for the broadcast industry. This standard is widely used in SDI encoders, SDI converters, and other equipment, including radio and television scenarios and security monitoring. We have witnessed the development of the video standard with ultra-high definition standards, from SD-SDI and HD-SDI to 3G-SDI, 6G-SDI, 12G-SDI, 24G-SDI, and 48G-SDI. This article will focus on this topic and provide a definitive guide.
Table of Contents
Serial Digital Interface (SDI) is a family of digital video interfaces first standardized by SMPTE (Society of Motion Picture and Television Engineers) in . It is a standard for transmitting uncompressed digital video and audio using coaxial or fiber-optic cables.
The SDI interface can not directly transmit the compressed digital signal. Therefore, the system must decompress the compressed signal recorded by digital video recorders, hard disks, and other equipment and then enter the SDI system to travel.
However, repeated decompression and compression will cause image quality degradation and increased latency. Therefore, various formats of digital video recorders and non-linear editing systems have provisions of their own for the direct transmission of the compressed digital signal interface.
The table below shows the history of the evolution of the standards.
The SD-SDI standard supports the 270 Mb/s bit rate. SD-SDI transmits low-resolution PAL-compatible video 720 * 576 @ 25fps and uses a clock rate of 27 MHz.
In , ITU-R (formerly International Radio Consultative Committee) released Recommendation BT.656-2, incorporating the new serial digital interface defined in EBU Tech. and SMPTE 259M.
This interface uses 10-bit transmission and non-zero Reverse (NRZI) encoding. The clock rate was 270 Mb/s when transmitting a 4: 2: 2 level signal from ITU-R BT. 601 (part A), the SD-SDI standard, was defined as today’s serial digital interface.
The HD Serial Digital Interface (HD-SDI) standard is standardized in SMPTE 292M. Although this standard is known as the 1.5 Gb/s interface, it supports bit rates of 1.485 Gb/s and 1.485 / 1.001 Gb/s.
HD-SDI is widely used in high-definition surveillance. It is unique in its ability to provide high-definition video at a resolution of p at a frame rate of 25 or 30 while retaining all the video details with a latency almost equal to that of analog systems.
OPTCORE provides a comprehensive line of HD-SDI SFP transceivers for particular surveillance applications.
Dual Link HD-SDI is a new standard introduced by SMPTE 372M in . It is an enhanced version of HD-SDI, supporting a higher speed of 2.97 Gb/s through dual links. This standard suits high fidelity and resolution applications like digital cinema and HDTV P.
This standard is the 3 Gb/s interface, but the actual bit rates are 2.97 Gb/s and 2.97 / 1.001 Gb/s. 3G-SDI supports several mapping levels, as described in the SMPTE ST425-1 standard. These levels are called A, B-DL, and B-DS. Like the HD-SDI standard, the 3G-SDI supports 3G CRC generation, checking, line number insertion, and capture.
The 3G-SDI standard has been widely used in the broadcasting industry, and many manufacturers can provide related products. At the same time, as the security industry continues to develop, the advantages of high-speed, uncompressed digital are gradually being explored.
The suppliers have launched many 3G-SDI series products, including optical transceivers, conversion equipment, digital switching matrix equipment, and splitters. These devices adopt 3G-SDI signals and are also backward compatible with 1.5G signals for long-distance transmission to meet users’ diversified needs.
6G-SDI standard defines a bit-serial data structure, electrical signal, and coaxial cable interface for transporting signals with a total payload of 5.940 Gb/s or 5.940/1.001 Gb/s. This standard also specifies coaxial cables and connectors’ electrical and physical characteristics.
This standard defines several mapping modes for carrying -line and -line image formats and associated ancillary data into a Single-link 6 Gb/s [nominal] SDI bit-serial interface.
The 12G-SDI is a serial digital interface standard developed to support higher resolution, frame rate, and color fidelity. It provides four times the bandwidth of 3G-SDI, carrying 12Gbps, making it ideal for the 4K 60p format.
This is not new. UG has been developed 6G / 12G since but has not been approved by the standard governing body SMPTE (Society of Motion Picture and Television Engineers) under the SMPTE ST- draft name.
Most 4K professional cameras, medical endoscopes, and monitors use four BNC connectors simultaneously transmitting 12G-SDI signals. As technology advances, some cameras, such as the Sony PXW-Z280 handheld all-in-one camera, now include 12G-SDI output connectors; nevertheless, only one SDI cable meets the 12G transmission standard and can directly transport 4K 60p signals.
Some video transceiver suppliers also launched 12G-SDI transceivers to meet the higher resolution television and broadcast market usage.
24G-SDI also known as UHD-2 or 24G UHD-SDI, defined in SMPTE ST-, this standard supports 8k 120p resolution. It is the latest generation of serial digital interfaces for targeted UHDTV real-time streaming media interface applications. 24G-SDI uses eight lines of SMPTE ST , allowing video signals to be transferred at speeds of up to 24 Gbps.
48G-SDI is a new term some industry leaders propose but has not been defined in SMPTE. By mixing four independent 12G-SDI channels, 48G-SDI supports an 8K (48G) signal over fiber cable. It is ideal for transmitting multiple uncompressed SDI streams or 8K broadcast-grade UHD signals.
For more information, please visit 3G-SDI optical transceiver.
In , the former CCIR issued CCIR 601 based on the institutional proposals of the European Broadcasting Union (EBU) and the American Society of Motion Picture and Television Engineers (SMPTE). At a sampling frequency of 13.5 MHz, 8-Bit quantification and 4: 2: 2 chrominance sub-sampling unify the digital parameters of both 525/60 and 625/50 television scanning systems.
In , CCIR became the International Telecommunication Union Radio Telecommunication Sector (ITU-R).
In , CCIR released CCIR 656, based on the EBU Tech. and SMPTE 125 standards, and proposed a parallel interface that transmits CCIR 601 specifications using 11 twisted pairs and 25-pin D-type connectors.
Some early digital devices used this interface. Still, because of the short transmission distance, the connection is complicated and, for other reasons, not suitable for large-scale use.
The CCIR 656 also includes the EBU Tech. serial digital interface standard, which EBU proposed in . This standard uses 8/9 block coding at a bit rate of 243 Mb / s but only supports 8-bit quantization, and it is not easy to design a stable, cheap interface chip.
In , ITU-R released Recommendation BT.656-2, incorporating a new serial digital interface defined in EBU Tech. and SMPTE 259M. This interface uses a 10-bit transmission and NRZI encoding. The clock rate is 270 Mb / s when transmitting a 4: 2: 2 level signal from ITU-R BT—601 (part A), now the famous SDI.
Using a 75-ohm coaxial cable and 75-ohm BNC connector (IEC -8) enabled the reuse of many existing cabling inside the station in a digitized system, and SDI became standard on digital devices. This is based on the final realization of the studio, master, and broadcast control system of digital.
China also formulated the corresponding national standard BG / T concerning the above standards. EBU Tech., SMPTE RP145, and ITU-R BT .799 propose dual-link to meet the demand for high-quality program production for the 4: 4: 4 level image and chroma key of ITU-R BT.601 (Part A) Concept that transmits both the R’G’B ‘/4: 4 image and the other broadband signal over two SDI channels at the same time.
In , with the release of Recommendation ITU-R BT.709, the accelerated development of high-definition television technology, the use of a serial digital interface to transmit high-definition signals has been agreed upon in the industry, for which SMPTE defined in the 292M standard clock frequency up to 1 The serial digital interface of 5 Gb / s level, the corresponding international standard is ITU-R BT. , this is the well-known HD-SDI.
In , the ITU-R specified a 2.97 Gb / s serial interface in BT.-6, which still uses the 75-ohm coaxial cable and the IEC -8 standard connector. In addition, SMPTE 424M also gives a similar definition of a 3 Gb / s level interface. The advent of the 3 Gb / s serial interface solves the previous need for dual-link HD-SDI, such as 4: 4: 4 / 12bit or p50 / 59.94 format programming.
Manufacturers have introduced 3 Gb / s serial interface chip products. However, copper is somewhat powerless in some situations that require long-distance transmission, such as connecting two distant studios.
Currently, optical fiber cable has become a natural substitute for copper. ITU-R BT. and SMPTE 297M are standards for transmitting serial digital signals over optical fiber cables. Take ITU-R BT. as an example. Only single-mode optical fibers and corresponding optical connectors are allowed when transmitting high-definition signals – Electrical, electrical-optical conversion by the appropriate optical receiver and optical transmitter to complete.
The primary electrical specifications of HD-SDI and SD-SDI are the same, but the transmission bit rate is much higher than that of SD-SDI.
Since the ITU-R BT.-2 specifies that the luminance sampling frequency of high-definition video signals is 74.25 MHz and the sampling frequency of two color difference signals is 37.125 MHz respectively, the primary bit rate of HD-SDI reaches 1.485 Gb/s.
The distribution of high-frequency transmission cable parameters affects the transmission of high-definition video signals, so the cable length will be significantly reduced.
The data transmission format of HD-SDI is the same as the transmission format of SD-SDI, and the luminance signal Y and the color difference signals Cb and Cr subjected to time-division multiplexing are handled as 20-bit words. Each 20-bit word corresponds to a color difference sample and a luminance sample. The multiplexing modes are (Cb1Y1), (Cr1Y2), (Cb3Y3), and (Cr3, Y4).
With the advent of high-definition (HD) video standards such as i and 720P, interfaces have been adapted to handle higher 1.485Gbps data rates. The 1.485-Gbps serial interface, commonly called the HD-SDI interface, is defined by the SMPTE292M.
It uses the same 75-ohm coaxial cable. SMPTE approved the new standard, SMPTE424M, which doubles the SDI data rate to 2.97Gbps over the same 75-ohm coaxial cable and supports higher-resolution images such as P and digital cinema.
3G-SDI is an upgraded version of HD-SDI. The system supports SMPTE424M, SMPTE292M, SMPTE259M, SMPTE297M, SMPTE305M, and SMPTE310M standards.
There are many SDI devices for broadcast, post-production, and AV industry applications, but the primary devices include the following.
The SDI converter is one of the most used devices for video and broadcast engineering applications. It usually converts the SDI video signal to the HDMI interface. The user can connect the computer’s HDMI outputs to high-end SDI equipment using this converter.
Generally, we call the SDI to fiber converter an SDI extender. Unlike the standard SDI to HDMI converter, this extender has one or multiple fiber ports to connect with single-mode or multimode fiber cabling systems. Fiber technology provides an extended transmission distance of 2km, 10km, or 40km.
An SDI distributor is a device that takes a single SDI input (SD-, HD-, 3G—or 6G-SDI) with multiple outputs and distributes a single SDI signal to multiple SDI devices simultaneously. The distributor is ideal for Broadcast Studios’ Live Events and Post-Production applications.
A: 8K is a generic name for a video resolution ×. It has a 16:9 aspect ratio and 33,177,600 pixels. The more precise word for broadcast and live event demands is UltraHD2.
A: The main factors are a stable power supply, good impedance matching, the reduced effect of distributed capacitance, suitable connectors, and the cable’s shielding characteristics.
A: No, it doesn’t support HDCP, so converting HDMI to SDI won’t carry HDCP.
A: It depends on your streaming situation. If you run the cable over long distances, it is better to use SDI, but HDMI will be the most economical choice for a very short distance.
A: No, 3G-SDI does not support 4K resolution. Since it only supports p,
You should use 6G- or 12G-SDI for HD video for a 4K signal.
A: SDTI stands for Serial Data Transport Interface. It is a protocol standard for transporting compressed video streams over the SDI (Serial Digital Interface) line. This includes DVCPRO, DVCPRO 50, Betacam SX, Digital-S, DVCAM, and MPEG-2 formats. SDTI was developed to exchange digital audio and video signals in their original compressed formats rather than uncompressed and recompressed formats.
This guide has provided a comprehensive introduction to the SDI terms. Technological advancements have made the serial digital interface ideal for high-resolution broadcast streaming and monitor transmission. Once you understand the differences between SD, HD, 3G, 6G, 12G, and 24G-SDI, you can choose the best solution for your application.
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