TV-SAT, CCTV, WLAN Dipol Weekly Review

DVB-S2X for NGSO satellites – high performance even in MEO orbit.

The DVB Project has confirmed that DVB-S2X and DVB-RCS2 technologies can be used effectively not only in geostationary satellite systems, but also in modern NGSO (Non-Geosynchronous Satellite Orbit) constellations, i.e. satellites in orbits other than geostationary. The latest analysis extends previous research on LEO (Low Earth Orbit) satellites to include MEO (Medium Earth Orbit). In simulations carried out by Magister Solutions, the performance of DVB-S2X and DVB-RCS2 was compared with the 5G NR (New Radio) physical layer in the Ku and Ka bands. For MEO, an orbital altitude of approximately 8,000 km was assumed. The results indicate that, in many applications involving the transmission of large amounts of data, DVB solutions can offer higher spectral efficiency than 5G NR.

A key component of the system is DVB-S2X (Digital Video Broadcasting – Satellite – Second Generation eXtension) – an extension of the DVB-S2 standard designed for data transmission via satellite. This is a downlink transmission technology, i.e. from the satellite to the user’s terminal. DVB-S2X utilises advanced modulation and coding schemes, including QPSK (Quadrature Phase Shift Keying), 8PSK (8 Phase Shift Keying), 16APSK (16 Amplitude and Phase Shift Keying) and 32APSK, as well as efficient LDPC (Low-Density Parity-Check) error correction combined with BCH (Bose–Chaudhuri–Hocquenghem) codes. This enables the system to dynamically select the transmission method based on the current quality of the radio channel. In good conditions, a ‘denser’ modulation is used, allowing more bits to be transmitted per unit of bandwidth, whilst if conditions deteriorate, the transmission can switch to a more robust configuration.

The second component is DVB-RCS2 (Digital Video Broadcasting – Return Channel via Satellite, Second Generation), which is the return channel standard. Whilst DVB-S2X is primarily responsible for transmission from the satellite to the user, DVB-RCS2 enables data to be transmitted in the opposite direction – from the terminal to the satellite. This is of fundamental importance for two-way services, such as internet access, data transmission, VSAT (Very Small Aperture Terminal) or backhaul links – i.e. connections used to link local networks or access stations to the operator’s infrastructure. The combination of DVB-S2X and DVB-RCS2 therefore forms a complete communications system, encompassing both data download and upload channels.

One of the most significant challenges with NGSO satellites is their motion relative to the ground terminal. In LEO systems – that is, in low Earth orbit – the satellite moves relative to the observer at a very high speed. This results in a significant Doppler shift – a change in the observed signal frequency caused by the movement of the transmitter and receiver. For radio systems, this means that changes in channel parameters must be tracked rapidly. In the case of MEO, the Doppler effect is smaller; consequently, the efficient use of available bandwidth and the system’s performance under real-world propagation conditions become more important. It is precisely in this area that simulations carried out by the DVB have demonstrated the superiority of DVB-S2X in scenarios requiring high data rates.

Of particular interest are applications requiring high data rates and efficient use of the spectrum, such as fixed broadband, VSAT links and backhaul. Spectral efficiency determines how many bits of information can be transmitted per unit of bandwidth, most commonly expressed in bits/s/Hz. The higher the value, the more data can be transmitted using the same frequency resource. According to the simulation results for MEO, DVB-S2X consistently delivered higher spectral efficiency compared with the 5G NR physical layer. However, this does not mean that 5G NR is an inferior solution in every scenario. DVB points out that 5G NR may have its advantages in low-traffic connections and in applications that are particularly sensitive to latency.

In summary, the future of such systems may lie in the development of hybrid, multi-orbit satellite networks, in which different technologies and orbits will be selected according to the nature of the service. LEO can provide low latency and high availability thanks to extensive constellations, MEO may offer a compromise between coverage, latency and the number of satellites required, whilst DVB-S2X/DVB-RCS2 may serve as an efficient transmission layer for services requiring high data rates. A key advantage here is the open nature of the DVB standards, which facilitates interoperability between devices from different manufacturers. DVB points out that combining the research results for LEO and MEO confirms the potential for using DVB-S2X and DVB-RCS2 as a complete solution for NGSO systems. In the future, this may lead to ever-greater integration of satellite networks with terrestrial networks, including 5G and subsequent generations of mobile networks, creating a single communications infrastructure that utilises different orbits and radio access technologies simultaneously.

Directional DVB-T2 aerials for receiving VHF and UHF bands.

The DIPOL SMART HORIZON COMBO A2270 and DIPOL SMART CITY COMBO A2050 television aerials are directional broadband aerials designed for receiving DVB-T2 in the VHF and UHF bands. The design of both models allows for the reception of multiplexes broadcast in different polarisations, meaning the antennas can be used in installations requiring simultaneous reception of signals from both frequency ranges.

The main components of the antennas are made of aluminium, which provides a favourable combination of low weight and high mechanical strength. The steel structural components have been protected by electrogalvanising, which enhances the antennas’ resistance to corrosion and long-term exposure to the elements. The components made from black ABS plastic serve a stabilising and protective function, whilst also giving the structure an aesthetic, modern appearance.

A key structural feature is the antenna’s reinforced main profile, which ensures increased rigidity and resistance to mechanical stresses caused, amongst other things, by strong winds, precipitation or birds perching on it. As a result, the antennas maintain the stable geometry of their receiving elements, which is directly important for maintaining the correct signal reception parameters.

The SMART HORIZON COMBO A2270 model, due to its high energy gain, which is achieved even in passive mode, is particularly recommended for installations located at a greater distance from the transmitter and for professional multi-user installations, where a sufficiently high signal level at the installation’s input is essential.

The SMART CITY COMBO A2050, on the other hand, has been designed for locations where compact dimensions and ease of installation are of key importance. Its compact design makes the antenna well-suited to urban environments, including installation on balconies, building facades or near windows.

Both models have also been designed to make installation as straightforward as possible. Their design allows for quick assembly without the need for additional tools, which reduces the time taken to get the antenna ready for use and makes installation easier for both professional installers and domestic users.

Ultimode fibre-optic quick-connectors – Internet connection.

Ultimode fibre-optic connectors allow for direct cable termination, without the need for an intermediate subscriber socket to protect the splice and the spare optical fibre.

This is the solution used when connecting internet services in flats. In the situation presented here, it was necessary to shorten the subscriber cable left in the flat by the operator (location of the modem in another room). Due to the impossibility of using a splicer, it was decided to use an Ultimode L5714 SC/APC quick connector.

A new generation of cameras for challenging lighting conditions.

DarkFighter 2.0 is an advanced image processing technology designed for round-the-clock video surveillance in challenging lighting conditions. Thanks to the use of an AI ISP (Artificial Intelligence Image Signal Processor), the technology optimises image capture parameters in real time, enabling clear, detailed and colourful images to be obtained even in very low light.
DarkFighter 2.0 minimises the trade-off between night-time image brightness and the sharpness of fast-moving objects. In traditional cameras, increasing the exposure time can improve visibility in the dark, but at the same time leads to blurring of moving objects. DarkFighter 2.0 utilises advanced image processing techniques to simultaneously improve scene visibility, minimise noise and reduce motion blur. This makes it possible to capture clearer details, such as the number plate of a fast-moving vehicle, even in very low-light conditions.

Key technologies:

Fresnel zone.

The range of a wireless network depends on many factors. Some of them we can influence, while others are unknown. Fresnel zone is one of the most important concepts appearing in radio subjects you absolutely must be familiar with. It is the area actively involved in the transmission of radio signal energy. The shape of this area in longitudinal section is an ellipse, and in cross-section it is a circle. The radius of this circle varies along the length of the entire radio link and assumes a maximum value in the middle of the distance between the antennas. The first Fresnel zone is the most important, since it is in this zone that almost all the energy of the radio signal is transmitted.

The cross-sectional radius of each Fresnel zone is largest in the center of the zone and decreases to the point of the antenna at each end. The maximum radius of the first Fresnel zone is often useful information. It occurs halfway between the transmitter and receiver.

Objects (hills, trees, buildings, etc.) located in Fresnel zones have a big impact on wave propagation (especially if they are in the first zone). The more of them and the larger they are, the worse the conditions for signal transmission. For links with improved operational reliability, the entire area of the first Fresnel zone should be free of obstructions.

In practice, ensuring the purity of 60% of the 1st Fresnel zone guarantees minimal power loss.

Installation of SIGNAL PRO multiswitches in a telecommunications cabinet. The SIGNAL PRO series multiswitches are devices designed for the distribution of satellite and terrestrial signals in SMATV communal installations. Dedicated brackets are used for their correct installation, one of which is the UCH PRO 1 R69985. This bracket enables the quick, stable and organised mounting of two multiswitches in telecommunications cabinets, as well as on flat surfaces in a two-layer system. Thanks to its design, it ensures an appropriate distance between the device and the surface, improving air circulation and facilitating the routing of coaxial cables. Its rigid construction guarantees stability even with a large number of cables connected to the multiswitches, which reduces the risk of stress on the connectors...>>>more