In today's security systems, coaxial cables are still commonly used for short-distance video transmission. However, with the rise of IP-based technologies, TCP/IP network transmission is becoming increasingly popular. Despite these advancements, neither method fully meets the demands of modern security systems. As a result, optical transceivers have become essential components in the transmission chain, serving as critical terminal devices that bridge the gap between data and optical signals.
**Classification and Principles of Optical Transceivers**
An optical transmission system typically consists of three main components: a light source (optical transmitter), a transmission medium (such as fiber optic cable), and a detector (optical receiver). These functions are carried out by optical transceivers. One key device in this system is the optical multiplexer, which converts multiple E1 signals (a standard for digital transmission at 2.048 Mbps, widely used in China and Europe) into optical signals for transmission. Its primary role is to perform electro-optical and optical-electrical conversions.
Optical transceivers can be broadly categorized into two types: analog and digital.
**1. Analog Optical Transceivers**
Analog optical transceivers use PFM (Pulse Frequency Modulation) technology to transmit video signals in real time. At the transmitting end, the analog video signal undergoes PFM modulation—either through frequency, phase, or amplitude modulation—before being converted into an optical signal. Upon reaching the receiver, the optical signal is converted back to electrical form and demodulated to restore the original video signal. This technology allows for transmission distances of up to 30 km, with some models capable of reaching 60 km or even hundreds of kilometers. The image distortion is minimal, with high signal-to-noise ratios and low nonlinear distortion. Additionally, wavelength division multiplexing enables bidirectional transmission of both video and data signals over a single fiber.
**2. Digital Optical Transceivers**
With the growing advantages of digital technology over traditional analog methods, the digitalization of optical transceivers has become inevitable. Two main types of digital optical transceivers are currently available: those using MPEG-II compression and those that transmit uncompressed digital video.
The MPEG-II compression type compresses moving images into N×2 Mbps data streams, allowing them to be transmitted via standard telecommunication interfaces or directly through optical fibers. This reduces bandwidth usage and makes it easier to leverage existing infrastructure. However, image compression introduces delays (typically 1-2 seconds) and may cause some distortion. Moreover, the cost of such equipment tends to be higher.
Uncompressed digital optical transceivers, on the other hand, convert analog video signals to digital format, multiplex various signals (such as audio, data, and voice), and transmit them over fiber. They offer superior image quality, with signal-to-noise ratios exceeding 60 dB and minimal distortion. These transceivers support real-time transmission and are ideal for applications requiring high-quality video, such as broadcast-grade surveillance. Their use of digital technology also enhances reliability and reduces costs through advanced multiplexing techniques.
**Application Fields of Optical Transceivers**
Video optical transceivers have been in the Chinese market for over two decades. Initially, they were mainly used in well-funded sectors such as government, public safety, and industries requiring efficient transmission. As domestic technology improved, their application expanded into various fields.
**Smart Cities**
The Safe City initiative represents one of the largest and most comprehensive urban management systems. It involves public security, traffic control, emergency response, disaster warnings, and more. Video optical transceivers, although not the dominant component, play a crucial role in integrating surveillance with alarm systems, access control, and broadcasting. In large-scale projects, the cost of video optical transceivers can reach millions of yuan.
**Highways**
Long-distance highway projects often require hundreds of kilometers of cabling, making video optical transceivers essential. Although they represent a small portion of overall electromechanical costs, their performance directly affects the entire monitoring system. Due to high technical and service requirements, only a few major brands dominate the market.
**Urban Intelligent Transportation**
With increasing urbanization, cities like Beijing, Shanghai, and Shenzhen have established traffic monitoring networks. While IP-based systems are emerging, many still rely on fiber optics. Video optical transceivers are used for traffic signal control, vehicle detection, and accident monitoring, ensuring smooth city operations.
**Urban Rail Transit**
As urban rail systems expand, the demand for reliable monitoring equipment grows. Optical transceivers, due to their long-distance capabilities and resistance to interference, have become widely adopted. With rising market demand, their costs have decreased, leading to a healthier industry environment.
Currently, smart cities, highways, urban intelligent transportation, and rail transit are the major markets for optical transceivers. According to forecasts, China’s urban rail transit investment will reach 415.9 billion yuan from 2010 to 2015, with a compound annual growth rate of 13.8%. This highlights the continued importance of optical transceivers in modern security and communication systems.
2. Open the shut-off valve to allow water to flow to the sprayer.
3. The method of use for the hand held bidet becomes a personal choice.
4. Lightly squeeze the trigger on the nozzle to start spraying.
5. Check cleanliness with toilet paper.
What is Bidet Sprayer?
A bidet shower is a hand-held triggered nozzle that is placed near the toilet and delivers a spray of water used for anal cleansing and cleaning of the genitals after using the toilet for defecation and urination. The device is similar to that on a kitchen sink sprayer.
Is a bidet sprayer worth it?
Because they are hooked up directly to your plumbing system, they require professional installation, usually as part of a bathroom renovation. Veteran bidet users point out that the money you save on toilet paper means a bidet installation will fairly quickly pay for itself - and yes, they say, bidets are worth it!
How to Use a Hand Held Bidet Sprayer
1. Locate and grab the bidet sprayer next to the toilet.2. Open the shut-off valve to allow water to flow to the sprayer.
3. The method of use for the hand held bidet becomes a personal choice.
4. Lightly squeeze the trigger on the nozzle to start spraying.
5. Check cleanliness with toilet paper.
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