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No. 25/2021 (June 21, 2021)
As every year, the Review will not be published during the holiday season.
The next issue will be available on August 30, 2021
We wish all Readers, Customers, and Business Partners
great and safe holiday time!
Laser transmission in space.
This year's landing of the Perseverance rover on Mars, followed by the transmission of excellent-quality images and even video to Earth, has sparked discussion about how to effectively transmit data over such a long distance. Not surprisingly, NASA has long been working on improvements in this area. They have developed a method of communication in which the standard information medium, an appropriately modulated radio wave, will be replaced by laser light. The launch of the LCRD test transmitter (Laser Communications Relay Demonstration) into space and the first tests will begin soon.Laser communications will enable data to be transmitted toward Earth up to 100 times faster than current radio systems do. It would take about nine weeks to transmit a complete map of Mars to Earth with current radio systems. With lasers, it would take about nine days. Importantly, laser communication systems require less space, are lighter, and require less power, meaning less wear and tear on spacecraft power systems.
Radio waves and infrared light are types of electromagnetic waves – they differ in length and range. Radio waves, due to the nature of propagation, are more diffuse. This results in limited and less efficient transmission over long distances. Laser technology makes it possible to transmit a cumulative portion of data in the form of a narrow laser beam so the ground stations receive more information in a single packet. This narrow beam unfortunately requires very exact targeting of the transmitter and receiver. This presents a significant technical challenge in some situations.
Graphical representation of the difference in data rate and beam width between radio and laser communications
The first device equipped with LCRD will be ILLUMA-T (Integrated LCRD Low-Earth Orbit User Modem and Amplifier Terminal), which will be installed on the International Space Station in 2022. It will enable transmission speeds of 1.2 Gbps.
Summer Photo Contest!
Take part in the 20th edition of our “Engagingly about Antennas” contest. Encouraged by the high artistic level of the photos sent to us over the past editions, we have decided for a novelty – extending the formula of the contest with a new category, the video. Once again we encourage photographers, and now filmmakers, to present their works, which will be judged by Pawel Zechenter, by a well-known photographer and filmmaker from Krakow. On the occasion of this anniversary, we have arranged extremely attractive prizes, such as DJi Mini 2 drones and JBL Bluetooth speakers. You can learn more about the contest and the rules here.
Main prizes in the competition - DJI Mini 2 drones
The modern video compression method, AI Coding – how does it work?
Monitoring devices allow recording images with increasingly higher resolutions, which results in increased demand for bandwidth and disk space. In order to ensure high quality of video recording, while generating optimal amount of data, it is necessary to use efficient methods of image compression. One of the best and, most importantly, optimized for monitoring is the AI Coding codec developed by Dahua.
The support for CCTV systems is based on a principle that priority is given to moving objects, which must be very clear, while the background can be compressed more, especially when it is unchanging. The algorithm itself is based on 3 main engines that work together to produce the highest quality image possible while sparing the amount of data.
- Video analysis engine. Used for scene assessment and analysis (e.g. determining the of time of day, weather conditions). Performs real-time video analysis, detects motion in the image, types objects and areas, which it divides into background and targets.
- Data allocation engine. According to the result of the analysis engine, it determines how much data can be allocated to a particular location in the monitored scene. If the analysis engine detects the presence of people or vehicles, the algorithm will allocate more data to them, while the background areas will receive less data. The most common situation is that the background occupies a very large part of the images, while in the monitoring system it is not important.
- Bit stream compression engine. It selects the best configuration of existing encoders to compress the bitstream, according to the data allocation from the allocation engine.
Simple point-to-multipoint KVM.
The Signal-HD HDMI to IP converter enables the user to connect remote (up to 100 m) source of HD content to HD-enabled television/monitor, using one CAT5e/6 cable. The package includes the transmitter and receiver units. It is also possible to extend the USB port e.g. to control the recorder with a mouse and a keyboard.IP signal coming from the transmitter may be applied to an Ethernet switch to split it among multiple receivers. The bit rate of the compressed signal at the transmitter output is approx. 15 Mbps. For proper decoding of the signal with a greater number of devices displaying the image a dedicated H3613R receiver is required, the preview of the image on a PC equipped with network card is not possible.
Application diagram of the HDMI > IP converter (point-to-multipoint connection)
How to receive DVB-T2/HEVC signal in a SMATV system with DVB-T/MPEG-4 receivers?
By 2022, a new standard of terrestrial television broadcasting, called DVB-T2/HEVC, will be introduced throughout the European Union. The introduction of the new broadcasting standard should not require changing the receiving antenna, but one may need to change its direction or upgrade the TV system if the TV sets do not support DVB-T2 standard with HEVC codec (also known as H.265 or MPEG-H part 2) and process audio encoded according to the E-AC-3 standard (also known as Dolby Digital Plus or DD+). While in the case of a small system with one or several TVs there should be no problem (it is enough to buy a DVB-T2/HEVC decoder that is connected via HDMI output), it may be quite an issue for larger number of TVs (especially in boarding houses, hotels and the like). The pictures below show measurements of DVB-T2 signal with the use of ST-5150 Signal R10842 meter and example system with the change of the DVB-T2/HEVC standard to DVB-T/H264 possible. |  |
///The picture above shows the measurement of DVB-T2/HEVC signal performed with the Signal ST-5150 meter using DIPOL 28/5-12/21-60 DVB-T/T2 A2810 antenna. The measurements have been performed on channel 27 (frequency: 522 MHz). The signal has PWR = 72 dBµV and MER = 30.5 dB. Such values allow for trouble-free reception of terrestrial television on any TV set. In addition, the ST-5150 R10842 meter has a built-in tuner allowing to continuously monitor the set channel in the DVB-T2/HEVC standard.
///Diagram of TV system allowing to receive DVB-T2/HEVC signal and convert it to DVB-T/H264 standard. Signal from DIPOL 28/5-12/21-60 DVB-T/T2 A2810 antenna has been distributed via R60106 splitter to 6 DVB-T2/HEVC decoders. Then the signal in Full HD resolution (1920x1080-30p) fed to the HDMI port of the MHD001P R86103 modulator has been modulated to the DVB-T COFDM standard.