Parameter setting of OTDR optical fiber test method

OTDR is the main instrument in the field of optical fiber testing technology. It is widely used in the maintenance and construction of optical cable lines. It can measure optical fiber length, optical fiber transmission attenuation, joint attenuation, and fault location. OTDR has the advantages of short test time, fast test speed, and high test accuracy.

Optical Time Domain Reflectometer (OTDR), using the method of optical time domain measurement, emits a certain pulse width of light into the tested fiber, and detects the Rayleigh scattering (Rayleigh scattering) and Fresnel reflection (Fresnel reflection) optical signal power along the time Axis distribution, draw OTDR curve, to measure various optical cable and joint parameters to locate optical fiber fault points, and understand the distribution of optical cable loss. The following takes OTDR tester as an example to analyze and explain.

1. Test wavelength selection

Since OTDR is for optical fiber communication, select the test wavelength before performing fiber test. Only 1310 nm or 1550 nm is selected for single-mode fiber. Since the 1550nm wavelength has a much more sensitive influence on the bending loss of the fiber than the 1310nm wavelength, it does not matter. Whether it is fiber optic cable line construction or fiber optic cable line maintenance or experimentation and teaching, use OTDR to test the entire fiber backscatter signal curve of a certain optical cable or a certain optical fiber transmission link. Generally, the wavelength of 1 550 nm is used.

The shape of the test curves at 1310nm and 1550nm wavelengths is the same, and the measured optical fiber connector loss values ​​are basically the same. If no problems are found in the 1550 nm wavelength test, then the 1310 nm wavelength test must be no problem.

Choosing the 1550 nm wavelength test, you can easily find whether there is excessive bending of the fiber throughout the entire process. If a large loss step is found somewhere on the curve, repeat the measurement with a wavelength of 1310 nm. If the loss step disappears at a wavelength of 1310 nm, it means that there is indeed an excessive bending situation, which needs to be further searched and eliminated. If the loss step is the same at the 1310 nm wavelength, there may be other problems in the fiber, which need to be found and eliminated. In the single-mode optical fiber line test, the 1550 nm wavelength should be selected as much as possible, so that the test effect will be better.

2. Test range selection

The range of the OTDR refers to the maximum distance that the abscissa of the OTDR can reach. The measurement range should be selected according to the length of the optical fiber under test. It is better for the measurement range to be 1.5 times the length of the optical fiber under test. When the range is selected too small, the display of the optical time domain reflectometer is not comprehensive; when the range is selected too large, the abscissa on the display of the optical time domain reflectometer is compressed and can not be seen clearly.

According to the actual experience of engineers and technicians, when the test range is selected so that the backscatter curve accounts for about 70% of the OTDR display screen, both the length test and the loss test can get a better direct-view effect and accurate test results.

In the optical fiber communication system test, the link length is several hundred to several thousand kilometers, the relay section length is 40-60 km, and the single-reel optical cable length is 2 to 4 km. A reasonable selection of the OTDR range can get good test results.

3. Test pulse width selection

Setting the light pulse width too large will produce strong Fresnel reflection, which will increase the blind area. Although the narrow test light pulse has a small blind area, the light power of the test light pulse is too narrow, and the corresponding backscatter signal is also weak. The backscatter signal curve will be undulating and the test error is large. The set optical pulse width must not only ensure that there is no excessive blind zone effect, but also ensure that the backscattered signal curve has sufficient resolution and can see every point along the optical fiber.

Generally, according to the length of the fiber under test, an appropriate test pulse width is selected first, and an optimal value is determined from the pre-test once or twice. When the distance of the tested fiber is short (less than 5 000 m), the blind area can be less than 10 m; when the distance of the tested fiber is longer (less than 50,000 m), the blind area can be less than 200 m; the distance of the tested fiber is very long (Less than 2 500 000 m), the blind area can be as high as more than 2 000 m.

In single-disk testing, proper selection of the optical pulse width (50 nm) can make the blind zone less than 10 m. By taking the average of two-way test or multiple tests, the impact of the blind zone will be smaller.

Generally speaking, the longer the averaging time, the higher the test accuracy. In order to increase the test speed and shorten the overall test time, the test time can be selected within 0.5 to 3 min.

In the optical fiber communication connection test, a satisfactory result can be obtained by choosing 1.5 min (90 s).

If Fiber-mart OTDR is used for testing, the recommended duration is 1min (60s).

Only by accurately setting the basic parameters of the test can conditions be created for accurate testing.

Safety instructions before fiber optic testing

Hello everyone, today we will discuss with you the safety instructions before fiber optic testing. Some people may not understand why the safety instructions of the optical fiber should be emphasized. This is because once the operation is improper, it will not only cause irreversible damage to the naked eye, but also affect the service life of the optical fiber inspection equipment, or even directly damage the equipment.

01.How to avoid damage to the eyes

• Under no circumstances should you look directly at the optical fiber.

• The wavelength used is invisible to the naked eye (the light that actually transmits data is invisible to the naked eye).

• If the power of the energized optical fiber is large enough, the light emitted by it will cause permanent damage to eyesight.

• If the equipment currently in use is occasionally exposed to its radiation, it will not cause damage to eyesight.

• If you are told that the optical fiber is not energized, please treat it as if it is energized.

• Never stand in front of an optical fiber patch panel unless all optical fiber connectors are equipped with protective caps.

• Comply with the safety requirements set by your organization.


On the device level of fiber inspection

• The equipment test recommendations are all passive tests, that is, there should be no light in the optical fiber.

• Light on the optical fiber will cause inaccurate testing.

• If there is too much light, it will damage the optical power interface of the test instrument.


Choose the most suitable test instrument

Why is it strictly forbidden for us to directly observe whether the light source has output during the test? Because the wavelengths used in optical communications are all invisible wavelengths, the wavelengths of multimode fiber transmission are 850nm and 1300nm, and the wavelengths of single-mode fiber transmission data are 1310nm and 1550nm, so even if we observe with the naked eye, there is no light output. , But in fact, this kind of light may cause permanent damage to human eyes, so be careful.

Of course, as long as we pay attention to the above two safety issues, it is still very safe to use the fiber tester itself. Of course, in the process of use, even if there is a strong light device at the opposite end, the power meter of Fluke Networks still has a large range. It will be easily damaged. At the same time, the OTDR type instrument will automatically give an alarm, prompting that the opposite end is detected and the test cannot be performed, which has a good protective effect, so there is no need to worry about the instrument being damaged.

Tips for Using and Maintaining Fiber Patch Cables

Fiber patch cables are common assemblies seen in optical communications to link devices and network components. To ensure normal optical transmission and fiber durability, it is necessary to get familiar with the user instructions and precautions. This post will introduce the precaution for taking care of fiber patch cables from the perspectives of connecting, disconnecting, and routine maintaining, which is recommended for you to prevent a series of possible harmful consequences.

Connecting and Disconnecting Fiber Patch Cables

Fiber patch cables can be used with many network devices, such as optical transceiver modules, fiber adapter panels, fiber cassettes, media converters, and other products having fiber optic interfaces. The following part will introduce the general steps for connecting and disconnecting fiber patch cords, taking connecting a fiber patch cable to a transceiver installed in a network switch as an example.

Connecting Fiber Patch Cables

Remove the rubber safety caps covered on the fiber optic connectors at both ends of fiber patch cables and remember to keep these caps well.

Remove the cap from the optical transceiver.

Insert the cable connector into the optical transceiver.

Fix and fasten the fiber patch cables by placing fixing elements on a loop to help cables maintain their shape.

Disconnecting Fiber Patch Cables

Disable the interface in which the optical transceiver is installed by running a command.

Carefully unplug the cable connector from the transceiver.

Cover the transceiver with a rubber safety cap.

Cover the cable connector with a rubber safety cap.

There are some points that should be noted during the connecting and disconnecting process:

The installation personnel needs to be skilled enough with an understanding of the network layout so as to ensure the quality and safety of the installation.

Always wear safety glasses and protective glasses to avoid electric shock or touching fiber shards. Anti static wrist strap band is necessary to reduce static electricity when operating with active devices.

Pay attention to the bending radius of the fiber patch cords. Excessive pulling or squeezing will possibly cause damage to fiber jumpers.

Do not let the jumpers hang free from optical transceivers or run free on the floor randomly. It is very likely to stress the cables at the fastening point or break the cables once pulling the cables accidentally

Never look directly into the end of fiber cables when there is a laser coupled to it for the safety of your eyes.

Avoid frequently inserting or removing fiber patch cables from devices or the fiber end face will produce wear.

Thoroughly clean the working area after the completion of installation.

Maintaining Fiber Patch Cables

The daily maintenance for fiber patch cables matters a lot in the fiber optic system. There are two main aspects to which you should pay attention during routine maintenance.

Keep Fiber Patch Cables Clean

It is often heard that special attention should be given to the fiber optic patch cable cleaning, but are you clear why it is so important? In brief, for reliable and robust fiber optic networks. According to an industry survey by a major telecom company, contamination is the number-one reason for troubleshooting optical networks. Fibers are so fragile that once they are covered by dust or other contaminations, the optical signal can be degraded. What’s more, the metallic particles worn by the bodies and fiber housings of the fiber optic connectors will block a fiber, which will cause signal loss, thus eventually reducing the network performance and causing a great loss for businesses that rely on fiber-optic networks.

Generally, fiber optic cleaning refers to cleaning fiber connectors. How to ensure you clean fiber connectors using correct ways? There are two main cleaning methods: dry cleaning and wet cleaning, each performing different functions. Reel-type fiber cleaners, pen cleaners, fiber cleaning wipes, and foam swabs are the common fiber connector cleaning solutions. More information about these solutions and cleaning steps is available in How Much Do You Know About Fiber Connector Cleaning?

Store Fiber Patch Cables Properly

No matter a fiber cable is in use or out of use, there is one significant point to be considered: Do not bend or stretch your fiber cable too much. It is often the case when working with fiber optic cables, people stretch or bend them. For this reason, the worst case is the fiber may get damaged. Some breakage caused by bending can be visible, but some loss may not, such as microscopic fiber deformations caused by very low temperature, displacement of a few millimeters caused by buffer or jacket imperfections, poor installation practice or other factors. Since such loss can not be seen by the human eyes directly, it will be overlooked and things can get even worse over time. In case of a huge loss when the fiber patch cords must be replaced, the following essential elements need attention:

Design your fiber cable pathway using proper tools or components to protect fibers, such as horizontal cable managers.

Do not bend fiber patch cables beyond their minimum bend radius, especially in those tight spaces of high-density fiber patching areas.

Make sure not to hit the fiber connector against anything! On the one hand, those ends may get abraded or broken. On the other side, broken glass at the fiber end can cut someone’s skin. It is suggested to use protective caps when storing or pulling fibers.

OTDR and optical fiber microscopes are recommended if you need equipment for measuring and identifying any faults such as breaks within the fiber cable or overall attenuation.

How to Build a 10G Home Fiber Network?

With the wide application of the 10GbE technology in the commercial sector and the popularity of FTTH (fiber to the home), the cost of deploying a 10G network has been reduced to some extent. This trend has driven some home users to think about the upgrade of their current 1G fiber optic home network to a 10G network. Worries and hesitation are common, however, as the 10G network is still a new field for most home users. Thus this post brings some useful tips on how to build a 10G home fiber network from 10G home network basics to network assessment, selections for best home network devices, and a typical 10G fiber optic home network cabling.

Why Need to Build a 10G Home Fiber Network?

Starts from Network Assessment

Before the decision on deploying your 10G fiber network, it’s necessary to have an overall network assessment for your home environment so as to ensure the network deployed can handle all your traffic needs. You should probably ask yourself a few questions, such as how many computers, printers, and other peripherals will connect to your network? How much wireless coverage will you need at your location? What type of mobile devices will access to your network? Do you have to supervise all network devices? Are there any special functions that you want for your network devices? Where would you like to have 10G connections and where would you leave it at 1Gbps?

Know What Makes a 10G Home Fiber Network

To have a better assessment, you also need to have a rough idea about the basics of a 10G home network. For a 10G home network, several components are indispensable: 10Gb home switch, home router, and wireless access point for home (AP). According to different needs, some optional devices can be also included in your home networks such as network-attached storage (NAS) devices (like a network server), 10G network cards, PoE switches, and end devices like PC and security camera.

How to Choose Your Best 10G Home Fiber Network Devices?

Once you decide to upgrade to 10G network, choosing the most suitable home fiber network devices is vital to you, among which home network switch, home router, and AP for home are the most essential and important three types. Next, I take the selection of three types as examples to show you how to choose the best home network device.

Home Network Switch

For a 10G home fiber network, you probably need the 10G Ethernet switch and PoE switch. To choose the best home network switch, you can take into account the following three factors:

Features & Performance

Generally speaking, a home Ethernet switch especially the managed switch has many features. However, there is no need to select a home network switch with all features. Besides the basic features such as advanced QoS, VLAN, and security, you’d better take switching capacity, max. power consumption, continuous availability into consideration. PoE support is also a common requirement as users have many security cameras these days and also access points that provides Wi-Fi to the whole family. Moreover, fanless and stack designs are important factors as well. Fanless design helps to reduce power consumption and keep your home quiet and noiseless, which matters a lot for home users. As for the stack design, it can bring great flexibility to your network. When you want to upgrade the network or add more network devices into your network, stacking multiple switches can be the simplest solution to realize your needs without changing your original network infrastructure.


Usually, a home network switch comes with copper ports, optical ports, or hybrid ports. The copper port can connect with an Ethernet cable like Cat6. While a home network switch with SFP/SFP+ port can connect with SFP/SFP+ transceivers and fiber optic cables. Apart from port type, the port number to connect with your devices should also be considered. If you don’t have many network devices to connect, an 8-port or 12-port 10Gb switch is enough to cover all your needs; otherwise, you will need a 24-port or 48-port switch, or even multiple switches. You can choose a suitable one based on your needs.


The cost of an RJ45 port is lower than an optical port. Therefore, a home switch with copper ports will be cheaper than a fiber switch. And a managed switch with high performance is also much expensive than an unmanaged one. When you have already determined the type of home network switch you want, you can compare the price from different vendors and choose the most cost-effective one.

Home Router

Connecting your home network to the Internet, the selection of the best home router is also important but much simpler than a home network switch. First, you should contact your ISP (internet service provider) or look at your account details to get your Internet speed. Your router is required to handle your Internet speed. Considering you are cabling a 10G home fiber network, at least one SFP+ port should be equipped in that network router. Then you need to figure out what type of router you need: wired router or wireless router. Although a wireless router provides both WiFi and Ethernet connections, the coverage of WiFi signals is limited and the price will be more expensive than a wired one. Therefore if the area needs to be covered by the network is large, a wired router, combined with the additional wireless access point(s), is preferred for its cheaper price and more stable connections.

Wireless Access Point for Home

When connecting your wireless devices to an Ethernet network, the wireless access point for home is indispensable. Similar to routers, you also need to figure out the amount of space the wireless network to cover and the number of wireless devices to connect which will help you determine the number of AP you demand. The wireless AP that you are going to buy should be able to handle that figure. And these days Wi-Fi 6 AP seems to be a new trend, if you want to try a fresh wireless network experience, 2×2 MU-MIMO dual-band Wi-Fi 6 AP is definitely enough for your home use.

A Case of 10G Home Fiber Network

After the network assessment for your home and purchasing all network devices needed, it’s time to deploy your 10G fiber optic home network. As you can see in the following diagram, we now have a good number of devices all over the house. Having counted the possible connections, we take the 24-port 10Gb switch as the core switch in the home, which has 24 RJ45 ports to connect with most of the end-devices and 4 10Gb SFP+ ports to connect with a PoE+ switch, router, NVR, and server. As for the PoE devices in the courtyard, garage, and living room, we use an 8-port Gigabit PoE+ switch to cover them all.


Deploying a 10G home fiber network is not so hard and expensive as you might have thought while pretty much similar to a Gigabit fiber network. What you need is a complete network assessment for your house and a smart choice of affordable 10G home network devices. Based on these, you can build your best 10G fiber optic home network.

Who invented the sex doll?

Sex dolls have long been an adjunct brought on stag and hen nights out.

But who invented them and why? Here is everything we all know …

Who invented the sex doll?
The original inventor of the sex doll is unknown.

The earliest sex doll is credited to Dutch sailors within the 17th century who used a doll made from cloth to alleviate sexual tension during long sea voyages.

The first recorded magnify doll appeared in psychiatrists Iwan Bloch’s book, “The Sexual lifetime of Our Time“.

The book, published in 1908, described the doll to be used for sexual purposes.

After the sexual revolution of the late sixties, advertisements began to seem in magazines which allowed you to pick dolls with different hair colours and designs to suit the customer’s desires.

Did Hitler create sex dolls?
During war 2, it had been rumoured that Hitler ordered sex dolls to be supplied to German troops fighting on the battlefront .

According to the rumours the Borghild Project aimed toward combating the spread of syphilis among Nazi troops by supplying the lads with sex dolls.

The project was supposedly inspired by Heinrich Himmler’s 1940 memo to Hitler that there was a syphilis problem within the houses of prostitution in Paris.

In the report, he wrote, “The greatest danger in Paris is that the widespread and uncontrolled presence of whores.”

Hitler supposedly approved the project to supply dolls to the soldiers who were to move them in their backpacks to permit them to avoid Parisian brothels.

Hitler allegedly gave his approval to the project, and designers set to figure creating a doll – or “gynoid” – under the supervision of Franz Tschackert at the German Hygiene Museum.
The lack of evidence supporting this theory led it to being deemed a hoax within the early 2000s.

the most supporting evidence for the project were two photographs purportedly rescued from the trash, which were later disproven as a hoax.

Further to the present , no employee at the German Hygiene Museum had recalled the project ever existing when asked.

Do You Know The Development Process Of Sex Dolls?

The sex doll industry is rich in life size love dolls, bigger than ever, and evolving. But how was this development born? Where did the sex dolls originally come from?

According to the story, the history of lifelike love doll dates back more than 2000 years. The Roman poet Ovid, a collection of poetry and myths published in 8 BC, which also contained the Pygmalion’s story. In the story, Pygmarion, the king of Cyprus and the sculptor, carved a statue of a beautiful girl who is known as Galatea, and he fell in love with her and hoped that she could receive a life. When Galatea brought life to Goddess Aphrodite and could sleep together with Pygmarion, his wish came true.

Others have also reported on 17th century Dutch seafarers who are considered the first forerunners of real sex doll. On their long journey they are said to have searched for sexual companions and made their first primitive sex dolls from used clothes and rags. Thus, one can say correctly that dolls have come a long way to date. The other two terms are more general, but this is still the origin of the expression “Dutch Wife”, which is sometimes used instead of sex dolls, or love dolls.

While it is unclear whether historians are whether Ovid’s poem or dutch sailors are the real source of sexual love dolls, one thing is clear: humans have been with men beautiful for centuries to make people social I created a woman.

In 1908, the German psychiatrist Ivan Bloch mentioned for the first time in his book Sex Doll-made of rubber and sold for sale at the turn of the century in Paris. Each of these real dolls should be individually by a doctor.

The German surrealist Hans Belmer was called “the father figure of a modern sex doll” for their sex dolls in the 1930s. Likewise the international art scene has created a sensation. At this time, other manufacturers began using vinyl and latex to make a real doll. However, the production and sale of sex doll has been a secret activity. Not only were advertisements for sex dolls being sold, they were limited to the secret distribution of catalogs, mainly in places where men often visit, such as barber shops, pubs and brothels.

This suddenly changed in 1968 when an American pornographic magazine applied a sex doll for the first time. And it could be ordered by mail order. The use of silicone from the 70’s has then led to a transformation into a very high quality love doll.

More innovative sexual dolls were finally offered in the UK as the government changed the rules on import of sexual articles in the late 1980s. The sex doll industry has set new milestones for innovation in the 1990s. Artist Matt McMullen probably created the first truly modern sex doll.

However, the greatest contribution to the development of the sex doll industry was the invention of the Internet. Suddenly, producers and sex doll buyers from around the world were connected online and they were able to talk about the latest models available on the market-there was a community for sex doll lovers. The Internet has also made the process of buying sex dolls much easier, as the choice was simply much greater.

Today, Real Love Dolls are more real than ever. Luxury real dolls like dolls club have incredibly realistic skin and come in a variety of breeds, hair colors and dresses. In the meantime, customers will even have the opportunity to make their own dolls to suit their ideas and preferences.

ans. In the foreseeable future of playable DS Doll, this technology will become an important part of manufacturing robotics indispensable.