No. 25/2024 (June 17, 2024)

The Chinese have shown how to recycle raw materials from used photovoltaic panels in an eco-friendly way.

Researchers from Wuhan University and Northeastern University in China have developed a new method for safely and environmentally friendly recycling of solar panels. The new approach is more energy efficient and allays concerns about disposing of used photovoltaic cells in the future. In the process of moving away from fossil fuels, there has been a surge in the popularity of solar cells related to meeting energy demand. As gigawatt-scale photovoltaic farms are built all over the world, a concern has arisen that huge amounts of waste will be left behind when their life cycle ends. While technology exists to recycle components such as silicon, silver and aluminum, which are the main components of solar power plants, it requires highly reactive nitric acid and generates toxic waste that is difficult to dispose of.
As a way to separate the high-quality silicon in a solar cell from its silver wires, recycling companies use nitric acid and other chemicals. Researchers in China replaced the acids with a molten mixture of sodium and potassium hydroxide (NaOH/KOH), which is highly reactive with any component it comes into contact with. After experimenting with different treatments, the researchers opted for a two-second immersion followed by a bath of up to two minutes in the 200°C mixture. The short exposures allowed the material layers to separate, leaving them largely intact. The heat breaks down the polyvinyl layer, and the highly reactive hydrogen fluoride gas reacts with sodium hydroxide to form sodium fluoride. Once the silicon is etched, the silver wires also loosen and float. The filtration process can concentrate up to 99% of the silver. The aluminum carrier can also be removed with an alkaline water-based solution, leaving a clean silicon wafer. Elements such as tin, copper and lead used in solder oxidize in air and can be recovered in a sodium hydroxide solution. Lead and tin can be separated by electroplating. Adding water to the NaOH/KOH mixture stops the etching reaction. If necessary, the mixture can be concentrated and reused in the next round of recycling. The waste products from the entire process are sodium silicate and sodium aluminate, which are non-toxic and have wide industrial applications.
A life-cycle assessment conducted by the researchers showed that recycling one kilogram of solar panels according to their approach reduced carbon dioxide emissions by 14 kilograms and energy consumption by 220 times.

Wiring a house for the Internet – part 2 – internal network topology.

In the previous issue of the Weekly Review, we discussed the choice of network cabling in a single-family home. Another important issue is the topology of the network, that is, information on how to run the wires. The optimal solution seems to be to run one cable to each room in the house. It will give you the freedom to choose the location (e.g. of the access point) or to connect two access points without any problems when the range of one device is not sufficient. Note that the WiFi signal must reach devices such as air conditioners, heat pumps (central heating furnaces), recuperators, refrigerators and other devices equipped with WiFi modules. The ability to freely connect a computer or other device to a wired network may also prove important. Keep in mind that some applications may require cable connection for stable operation. This applies, for example, to streaming high-definition video or playing online games. When planning cabling, one should remember that the Internet is used today not only by personal computers. Twisted-pair cables have to be led to the places where TV sets, consoles and home theaters are installed. It is also worth thinking about one socket in the kitchen, bathroom or any other room.
Cabling solution for a home LAN
A twisted-pair cable should be run to each room so that you have the ability to connect a computer, TV or console. On each floor, in key places, it is a good idea to lead a twisted-pair cable to connect access points, so that the entire facility can be covered with a WiFi signal.

Hybrid illuminator in Hikvision TurboHD cameras.

Hikvision analog cameras with hybrid illuminator have the ability to operate in different light modes: with an IR illuminator, white light or in Smart mode. The default setting is Smart mode, in which, in response to a smart event (processed by the DVR), the scene is temporarily illuminated with white light, and after a specified time the camera returns to black and white (IR) mode. For the Smart function to work, the camera must be connected to a Hikvision DVR. Perimeter protection functions such as virtual line crossing detection, entry or exit from a zone with target classification (human/vehicle) must be enabled on the DVR. Thus configured, the device will operate in IR illuminator mode, which is virtually invisible to the environment. When the DVR detects the presence of a person or vehicle, the scene is temporarily illuminated with white light, and after a certain period of time the camera returns to black and white (IR) mode.

If the Smart mode is not suitable, you can also force only the IR illuminator or only the white light to operate at night. These settings are configured directly in the camera menu.
IR illuminator works at night
Object detection turns on white light
IR illuminator turns on
Available Hikvision TurboHD units with illumination working as described:

Fiber optic categories and designations.

When studying fiber optic network design documentation, one will come across many designations for fiber optic cables and fibers. There are several popular styles of fiber naming. Some of them come directly from the designations proposed by standards and recommendations. Others are a confusion of these designations with abbreviated descriptions on the outer sheaths of cables.
The most well-known way of describing fibers comes from a series of recommendations ITU-T (the telecommunications standardization division of the United Nations digital technology agency). This method of naming and categorization (G.65xx) is most often found in catalog data offered by fiber optic cable manufacturers and vendors. On the other hand, designers of telecommunications networks, when describing cabling issues in detail, can use a European standard issued by the IEC to describe fibers – IEC – EN 60793-2-50. According to it, single-mode fibers are category B, while multimode fibers are category A1. Each category, of course, also has subcategories, the equivalents of which can be found in the ITU-T recommendations.
The third and final way is through designations introduced by the company standards of large telecommunications operators. Within their own networks, they may use alternative designations to those proposed by the standards. An example is Orange, which has introduced the "J" category for single-mode fibers, along with the corresponding subcategories.
The designations and characteristics of single-mode fibers used in telecommunications are summarized in the table below:
PN-EN 60793-2-50
Designation Orange


G.652A B1.1 J2A Single-mode optical fibers with non-shifted chromatic dispersion.
G.652B B1.1 J2B Fibers with reduced PMD polarization dispersion compared to G.652A fibers.
G.652C B1.3 J2C Fiber with reduced attenuation compared to A and B fibers in the so-called water peak range (E-band).
G.652D B1.3 J2D Fibers with reduced attenuation in the water peak range as well as reduced PMD polarization dispersion level.
G.653A B2 J3A Fiber with shifted chromatic dispersion. The zero value of chromatic dispersion is near the 1310 nm wavelength.
G.653B B2 J3B PMD polarization dispersion reduced compared to G.653A.
G.655A B4 J5A Fibers with shifted non-zero chromatic dispersion. No requirements for the PMD factor are specified for this category.
G.655B B4 J5B Reduced PMD factor.
G.655C B4_c J5C Reduced PMD factor compared to G.655B.
G.655D B4_d J5D Fibers with shifted non-zero chromatic dispersion and dispersion in the 1530 - 1585 nm range greater than in G.655C fibers, reducing the impact of nonlinear effects on DWDM transmission.
G.655E B4_e J5E Greater chromatic dispersion and with a different spectral response slope than in G.655D.
B6_a1, B6_a2, B6_b3 J7A1, J7A2, J7B3 Fibers with non-shifted chromatic dispersion characterized by increased resistance to macro-bending. Minimum bending radius – A1: 10 mm, A2: 7.5 mm, B3: 5 mm.
For multimode fibers, ITU-T has issued one recommendation – G.651.1, while not proposing a subcategory of these fibers (the recommendation refers to other documents in this regard). The most popular classification of multimode fibers is introduced by the structured cabling standard ISO/IEC 11801. OM1, OM2, OM3, OM4 and OM5 symbols are described in this very document. A much less popularized (but still found) way of marking multimode fibers is included in EN 60793-2-10. These are respectively A1b for OM1 fibers, A1a1 for OM2 fibers, A1a2 for OM3 fibers and A1a3 for OM4 fibers.
Outdoor Cable: DRAKA A-DQ(ZN)B2Y SM (8xG.652D) [1m]
L79508 outdoor cable with single-mode G.652D fibers. Other fiber designation: B1.3 or J2D.

How to bring a DVB-S2X/S2/S satellite signal to a headend mounted in the server room of a hotel?

In the case of fiber-optic cabling, the size of the facility in which the system is implemented is irrelevant. The signal can be transmitted over hundreds of meters or even tens of kilometers without regeneration. For large buildings (hotel, guest houses), this will greatly simplify the backbone of the system. A conventional system, based on copper wires, allows the signal to be transmitted in the trunk line for several tens of meters. This distance can be increased through the use of amplifiers, although this too has some limitations (as well as implementation and operating costs). If you want to transmit a satellite signal over a longer distance (more than 100 meters) from the antenna to the server room where the headend is mounted (as is the case in large hotels or boarding houses), you should use a fiber-optic bus.
The diagram below shows a situation where the signal from the optical converter is transmitted to the server room over a length of 150 meters using a fiber-optic cable.
Example of a fiber optic system using LWO102 4F31 E A3033 optical converter with +4 dBm power to distribute DVB-S2X/S2/S satellite signals in single-mode fiber at 1310 nm wavelength. The use of ORF202 E optical receiver with Wideband A3131 output has made it possible to convert optical signals into electrical signals. A wide range of optical receivers from TERRA allows to implement TV systems, as well as hybrid systems, based on traditional multiswitches, dSCR/Unicable. Application of SRM-522 R80522 multiswitch operating in Wide band technology enables reception of programs from any satellite transponder for each of the four polarization/band pairs for one satellite position. The tdx-481 FTA R81621 transmodulator allows for conversion of DVB-S/S2 signals from eight satellite transponders to eight DVB-T MUXes. Transmodulator tdx420c R81619 with dual CI slot enables conversion of signals from two DVB-S/S2 transponders to two DVB-T MUXes.

New products offered by DIPOL

Hikvision DS-2CE10KF0T-LFS 4-in-1 tube camera (5 Mpix, 2.8 mm, 0.001 lx, ColorVu, IR up to 20 m, white light 20 m)
Hikvision DS-2CE10KF0T-LFS 4-in-1 dome camera (5 MP, 2.8 mm, 0.001 lx, ColorVu, IR up to 20 m, white light 20 m) M74122 can work in HD-TVI, HD-CVI, AHD and analog CVBS systems. The choice of the standard is made by the micro-switch located on the additional cable. The camera generates images with a resolution of 5 MP. A distinguishing feature is the hybrid illuminator with intelligent switching, which consists of an IR illuminator and white light. It is possible to select one of three low-light modes: IR, white light or smart mode. Camera in a tubular housing with IR illuminator up to 20 m.
Hikvision DS-2CE78K0T-LFS 4-in-1 dome camera (5 Mpix, 2.8 mm, 0.01 lx, microphone, IR up to 40 m, white light 20 m)
Hikvision DS-2CE78K0T-LFS 4-in-1 dome camera (5 MP, 2.8 mm, 0.01 lx, microphone, IR up to 40 m, white light 20 m) M74124 can work in HD-TVI, HD-CVI, AHD and analog CVBS systems. The choice of the standard is made by the micro-switch located on the additional cable. The camera generates images with a resolution of 1080p. A distinguishing feature is the hybrid illuminator with intelligent switching, which consists of an IR illuminator and white light. It is possible to select one of three low-light modes: IR, white light or smart mode. Camera in dome housing with powerful IR illuminator up to 40 m.

Worth reading

Wiring a house for the Internet – part 1 – choice of cabling. Given the progressive development of technology, changes in the offerings of service providers, as well as technical innovations appearing on the market, the recommended method of building cabling is very different from that of a few years ago. Facing the task of designing Internet cabling, while planning the installation, you have to take into account several factors that may influence the final layout of the cables. Laying too few cables or choosing wrong type of cable can cause significant limitations in the future. On the other hand, it is important to consider the economic factor and not to plan too many cables that will never be used. So how do you currently wire your home correctly...?>>>more
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