Optical transceiver uses optical fiber transmission Analog battle digital, who is better?

With the development of the times and the increasing requirements of users for safety precautions, monitoring optical transceivers have been more and more widely used in the field of security, and the technology of monitoring optical transceivers is becoming more and more mature
.
At present, the monitoring optical transceiver can realize the transmission
of multiple signals such as video, audio, data, telephone, Ethernet, and alarm on a core optical fiber.

Monitor the medium transmitted by the optical transceiver and its domain

The medium transmitted by the monitoring optical transceiver is optical fiber, so why choose to transmit through optical fiber? The main component of optical fiber is silicon dioxide (SiO2), a mineral that accounts for a relatively large proportion of the minerals of the entire earth, and is usually extracted
in stones and sand.
Optical fibers composed of silicon dioxide (SiO2) are brittle as glass and as thin as hair
.
From its internal composition, the optical fiber is divided into single-mode fiber and multimode fiber, the core diameter of single-mode fiber is 9μm, and the core diameter of multimode fiber can be divided into 50μm and 62.
5μm
.
Due to the composition of optical fiber, it has the characteristics of long transmission distance, non-conductivity, strong anti-interference ability, good confidentiality, etc.
, in long-distance transmission, it is usually the first choice of the
majority of engineers.

With the increasing requirements of society for safety precautions, monitoring optical transceivers have been widely used in monitoring systems
in various industries such as intelligent communities, factory and mine monitoring, urban security, bank networking, road traffic checkpoints, electronic police and highway tolls.
It ensures the real-time and security of transmission, and has a large transmission capacity, not only transmitting video, but also transmitting audio, data, telephone and Ethernet at the same time, which is highly respected
.

Analog vs.
Digital Who is slightly better?

Speaking of analog and digital, I am afraid that many people will feel that the two are always a little similar
.
Or maybe it's because there is no modern transmission mode of network transmission
.
Especially in the transmission of optical transceivers, analog and digital systems will always give people a sense
of connection.
But are analog and digital visually similar really that technologically similar? And where is the digital optical transceiver that has been praised for a long time stronger than analog equipment? Let's analyze the difference between analog optical transceivers and digital optical transceivers in depth to see how similar they are?

1.
Different signal processing methods

Don't look at it's just a simple little box
.
But whether it is a digital optical transceiver or an analog optical transceiver
.
There is a division
in the work that is unimaginable.
Although the transmission of video surveillance seems to us to only send a front-end video to the backend
.
But the projects involved are far beyond our imagination
.

In the work of optical transceiver, any device needs to perform meticulous processing
of the video, audio and data signals of the system.
For analog amplitude modulation optical transceiver, the processing method is to modulate the amplitude of video, audio and data to a high-frequency carrier signal, so that the amplitude of the high-frequency carrier signal changes with the amplitude change of video, audio and data; For analog FM optical transceiver, the processing method is to modulate the amplitude of video, audio and data to a high-frequency carrier signal, so that the frequency of the high-frequency carrier signal changes with the amplitude change of video, audio and data; For analog phase modulation optical transceiver, the processing method is to modulate the amplitude of video, audio and data to a high-frequency carrier signal, so that the phase of the high-frequency carrier signal changes
with the amplitude of video, audio and data.
It can be said that the role of the analog optical transceiver on the system is more in the way of pressurization and decompression
.

For digital optical transceivers, its working characteristics are much
simpler than analog equipment.
Digital optical transceivers are digital-to-analog conversion of video, audio, and data input to the transmission line at higher resolutions
.
This allows the signal of video surveillance to be
transmitted digitally in transmission.
When the receiving terminal is received, the digital signal is converted into an analog signal
according to standard rules.
In this way, it is ensured that the video signal can have stronger integrity
in transmission than analog devices.

2.
Different "trials and tribulations"

In the work of the analog optical transceiver, because the equipment needs to constantly carry out amplitude modulation, frequency modulation and image
tuning.
Therefore, it is very important
that the changes in the analog signal can be consistent with the changes formed by the modulation of the carrier signal.
This is also an important indicator
to judge the performance of the optical transceiver.

However, due to the current state of the art, it is difficult for analog optical transceivers to achieve true linear modulation
in operation.
Nonlinear adjustments inevitably lead to signal distortion
.
Therefore, this greatly limits the actual effect
that the transmission signal can still maintain a higher quality after being processed by the optical transceiver.
In addition, because the adaptability of the optics to the surrounding environment is very low, and in the transmission, the consumption and attenuation of the optical signal in the cable, the redistortion of the receiving end, and the redistortion of the analog signal back to the analog Just like the test of "9981 difficulty", it also makes the analog optical transceiver almost no capital
to ensure high-quality and high-fidelity video effects.
Therefore, under such a twist and turn, the distortion of the signal is infinitely amplified
.

For the digital optical transceiver, because it is only a more complete character transmission during the transmission process, the quantization error in the conversion process is also controlled
within a small range.
As a result, the tested signal of the analog signal is more protected
on the digital transmission side.

3.
More distinct transmission lines

Today, optical fiber is recognized as the most efficient transmission medium
.
Therefore, this also promotes the over-"popularity"
of various signals in transmission.
As mentioned above, in the monitoring information transmission of analog equipment, a variety of signals are transmitted together like a "swarm", which is undoubtedly a major feature
of this type of transmission application.
Theoretically, different signals have different transmission channels will undoubtedly greatly improve the transmission quality of
data.
However, if the three types of signals of analog data are precipitated one by one, and the corresponding optical transceiver is configured, its cost is undoubtedly amazing
.
Therefore, this also promotes the "mixing"
in optical fiber transmission.

However, for FM, amplitude modulation, phase modulation optical transceiver, it is difficult to transmit 10/100M Ethernet signals or multi-channel telephone and other high-speed signals, and mixing multiple video or audio signals with frequency modulation, amplitude modulation, and phase modulation on a certain carrier will inevitably cause various mirror and intermodulation interference
.
And this is also a long-standing defect
of analog equipment.
Therefore, in order to reduce interference, the analog optical transceiver greatly limits the number of simultaneous interpretation of the signal, which is also a great reduction
in efficiency.

For digital optical transceivers, because they are transmitted through more independent digital signals, conflicts between different signals are completely avoided during transmission, thus releasing space to avoid conflicts
.
Therefore, while eliminating interference, it also improves the transmission efficiency
of the system.

4.
Differences in stability and efficiency

As mentioned earlier, the carrier and bald head of the analog optical transceiver are greatly
affected by the environment.
Therefore, in the work of equipment, how to achieve better maintenance in different environments is also one of
the things that make users very headache.
In some engineering applications, in order to ensure the efficient operation of equipment, it is even necessary to configure a very comfortable machine room to achieve control
.
This undoubtedly increases the operating costs
of the equipment.
In addition, due to the high efficiency of digital optical transceivers, analog equipment also has a more economical embodiment
in multiplexing.

After the above comparison, it is not difficult to find that although there may not be much difference
in structure.
However, from a technical point of view, digital devices obviously cleverly avoid the insurmountable obstacles
of many analog devices under the role of digital technology.
During the transmission process, the overall efficiency
of the system work is improved.
This is also one of the
factors why optical transceiver equipment is so popular.

With the continuous development of digital technology, we have enjoyed the convenience
brought to us by many digital devices.
It is believed that with the promotion of this efficient working mode, video surveillance will continue to shorten the distance we monitor and bring us more real experience
.

HD optical transceiver market trends

The development direction of optical transceivers is still tirelessly pursuing single-fiber large-capacity, multi-service, network-managed integrated platforms
.
Let's take a look at the development direction of
the optical transceiver market.

1.
Reuse technology will remain the mainstream

The high-speed digital optical fiber transmission technology, uncompressed high-definition digital video technology, and high-definition video and audio coding technology adopted by the high-definition optical transceiver are all the embodiment of the advanced nature of the
high-definition optical transceiver 。 No matter how many times the HD video signal is transmitted, how many times it is converted, the quality remains unchanged, which is the talent of digital signals, but the HD video signal rate is high, occupying a large bandwidth, HD-SDI signal rate is 1.
485Gb/s, 3G-SDI signal rate is 2.
97Gb/s, HDMI supports 4.
95Gb/s, 10.
2Gb/s, how to transmit multiple high-definition videos on a single optical fiber is the most concerned technical hotspot
of high-definition optical transceivers.
It can be said that the technical level of single-fiber single-band multiplexing can basically represent the R&D capabilities and technical level
of one optical transceiver manufacturer.

2.
Multi-service is indispensable to realize high-definition video transmission at the same time, realize the transmission of asynchronous data, audio, switch, Ethernet and other comprehensive services, which is also one of the hot spots of high-definition optical transceiver that has attracted much attention, and currently there are mainly two ways to achieve
wavelength division multiplexing and time division multiplexing.
Time division multiplexing technology is difficult, combining multiple signals such as video, audio, data, and Ethernet into a single higher-rate data stream, and correctly decomposing each data stream at the receiving end
.
Therefore, it is necessary to deal with high-definition video, clock synchronization between interface services, and clock timing and frame structure relationship
between each other.

3.
The technical difficulties that single-fiber multi-channel high-definition video multi-service optical transceivers must overcome

☉ The clock system is complex and difficult
.
For example, the input HD video stream is locked and the clock is restored
.
There are various high-definition formats, and the user does not know the actual video format, so the video input must be adapted, so that the lock state machine for the reference clock system becomes very complicated
.
Of course, there are other clock synchronization, locking, debounce, etc.

processing.

☉ Under the conditions of existing devices and cost, it is difficult to transmit multi-channel high-definition video, and the bandwidth of 1-channel HDSDI has reached 1.
485G, which is the main reason why
there is only a single high-definition video optical transceiver in the market.
To disassemble, embed, and assemble the video in the 1.
485G code stream without affecting the video quality, you must have a very deep understanding
of the HD video standard system.

☉ GENERAL HD VIDEO TRANSMISSION ADOPTS YCBCR422 FORMAT, WHICH REQUIRES 20BIT TRANSMISSION, SO AT LEAST 10BITSERDERS CHANNELS MUST BE REQUIRED TO ENSURE THAT THERE IS NO LACK OF BITS AND NO LOSS DURING OPTICAL FIBER TRANSMISSION (THAT IS, NO MOISTURE IS ADDED DURING TRANSMISSION, SUCH AS 8BIT), SO AS TO ENSURE THE ENCODING ACCURACY AND ORIGINAL TASTE OF HIGH-DEFINITION VIDEO
.
In order to ensure that the video encoding is not missing or lost in the process of optical fiber transmission, it is necessary to have a relatively deep understanding of optical fiber transmission technology (for example, scrambling and descrambling, ALIGN byte alignment, etc.
, which must be efficient and not mismissed).

☉ In addition, because each high-definition video is asynchronous, the clock frequency and phase are not consistent, and multiple high-definition video streams cannot be directly multiplexed, and the frame synchronization
of multiple asynchronous high-definition videos must be realized.
Due to the high rate and large amount of storage, it is impossible to use a time domain adjustment method similar to FIFO and RAM, and because the high-definition video stream is full real-time, the code stream contains various clocks, synchronization and other information, and each byte can neither be added nor deducted, so the code rate adjustment scheme
cannot be adopted.
This is also the main reason
why the market urgently needs and there is no multi-channel high-definition video optical transceiver.

☉ In order to reduce the transmission capacity and ensure the original taste of high-definition video, only the effective data of the video is
transmitted.
Due to the transmission process, various embedded synchronization signals, clock signals, auxiliary data such as TRS, DE, HS, VS, XYZ, VIP, etc.
have disappeared
.
At the receiving end, various synchronization signals must be regenerated and assembled to generate a video stream
of the same standard as the input.
The high-definition video format has standard, non-standard, 861-compatible with progressive, interlaced, frequency 50, 60HZ, etc.
, and the format generation state machine will become very complex and workload
.

☉ Due to business complexity, it is necessary to deal with the frame structure, number rate, and clock
of various interfaces.
It can directly output various high-definition video systems according to business requirements, (such as SDI, HDSDI, HDMI, and audio embedding, de-embedding, etc.
), avoiding the addition of various expensive converters
.
In addition, network, data, telephone, audio and other interfaces
can be provided.

4.
Intelligent, network management and platform are the inevitable development directions

Intelligence is also another technology and function hotspot of high-definition optical transceiver, through the powerful network management function, to achieve self-diagnosis of equipment, users can intuitively understand the operating status of the equipment through management software, greatly facilitate the maintenance and management
of the equipment.

About the optical transceiver

The optical transceiver is the terminal equipment
for optical signal transmission.
Due to the improvement of current technology, the reduction of optical fiber prices has made it well used in various fields, so the manufacturers of optical transceivers are like mushrooms
.
However, most of the technologies of manufacturers here are not fully mature, and the development of new technologies requires cost, manpower, material resources, etc.
, which produces manufacturers are mostly small and medium-sized enterprises, and various brands have also appeared
.
But the quality is still similar, foreign optical transceivers are good but expensive, therefore, domestic manufacturers have transformed the production of optical transceivers to meet domestic needs
.