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No. 20/2024 (May 13, 2024)
Will laser communication work for future space missions?
NASA tests advanced laser communications technology called Deep Space Optical Communication (DSOC), which encodes data in photons for communication between a probe in deep space and Earth. Currently, the Psyche probe is at a distance of 226 million kilometers from Earth and typically uses antennas operating at radio frequencies between 3 Hz and 3 THz. The operating frequency of the near-infrared laser, on the other hand, reaches 300 THz. As a result, transmission via laser communication can be up to 100 times faster. This is a significant achievement.
However, the operation of this system involves some issues. One must take into account atmospheric phenomena (including space dust), barriers and obstacles in space, such as debris or celestial bodies, which can interfere with signal transmission. In addition, time delays and transmission delays are important, i.e. the time it takes for signals to travel between the spacecraft and ground stations, as well as possible delays related to signal processing or weather conditions. Laser beams require precise alignment with specific receivers over a distance of millions of kilometers, which requires meticulous calculations. Furthermore, both, the Earth and the spacecraft are in constant motion, further complicating the process. Continuous adjustments are needed to ensure precise targeting of the laser beam despite these dynamic movements. The probe uses an 8.6-inch (22 cm) diameter telescope equipped with a photon receiver and a subsystem for autonomous scanning and locking of the high-power near-infrared laser. In contrast, the Hale telescope at Palomar (United States) uses a cryogenically cooled, superconducting single photon detector. Because of the enormous distance the laser must cover, both ends of the system must compensate for the change in position of Earth and Psyche as the signal travels the distance between transmitter and receiver.
The previous record for transmission distance set on December 11, 2023, when the probe was at a distance of 31 million kilometers from Earth, transmitting data at a speed of 267 Megabits per second (Mbps), has now been surpassed. During a test on April 8, 2024, the spacecraft was able to transmit test data at a maximum speed of 25 Mbps from a distance of more than 226 million kilometers, 1.5 times the distance between the Earth and the Sun, far exceeding the project's minimum target of 1 Mbps. Despite the big challenges, the technology is so promising that NASA is seizing the opportunity to test the solutions under development in flight beyond the Earth-Moon system.
On October 13, 2023, NASA sent the Psyche probe to the asteroid of the same name, the study of which may bring new information about the origins of the Solar System and the composition of planetary nuclei. The object belongs to the M-type asteroids – it has high density and is rich in metals, including iron (30 to 60 percent by volume). The asteroid's origin is not clear. In the past, Psyche may have formed the nucleus of a planetozymal, being a potential nucleus of a planet. It is a large object measuring 280 × 232 kilometers.
When to get an antenna for 5G?
One of the primary determinants of whether to install an antenna are the parameters of the signal received by the modem. 5G signal parameters can vary depending on specific environmental conditions, distance from the transmitter, frequencies used and network configuration.Here are some key parameters that should be read from a 5G modem or router if you are considering installing an external antenna:
- Signal Strength Indicator (RSSI): signal strength (Received Signal Strength Indicator) measures the strength of the 5G signal received by the device. The higher the RSSI value, the stronger the signal. RSSI measures the total signal strength received by a device, without distinguishing between the signal coming from the targeted base station (BS) and background signals such as noise and interference. The value can vary depending on specific environmental conditions, but typical limits for RSSI in 5G networks can range from -50 dBm to -120 dBm.
- Signal Power (RSRP): Signal power (Reference Signal Received Power) is a measure of the power of a 5G signal received by a device. It is one of the key indicators that determines the quality of connection. RSRP reflects the strength of the actual signal, which is the signal that is used to synchronize and make measurements on the mobile network. RSRP focuses on the strength of the signal coming directly from the base station, ignoring other interference and noise in the channel. The higher the RSRP value, the stronger the signal. RSRP limits can range from -44 dBm to -140 dBm
- SINR (Signal-to-Interference plus Noise Ratio//): SINR measures the ratio of usable signal to noise in a radio channel. A higher SINR value indicates better signal quality. Typical limits for SINR in 5G networks are from about 0 dB to 25 dB.
- CQI (Channel Quality Indicator///): CQI is an indicator of channel quality and indicates the possible throughput of a channel. The higher the CQI value, the better the channel quality. CQI values typically range from 1 to 15, where higher values indicate better channel quality.
- Throughput: Throughput is the amount of data that can be transmitted over a network per unit of time. In the case of 5G, throughput can be very high and reach gigabit data transfer rates.
- Delay: is the time it takes to transfer data between a device and a server. In 5G, this time can be much lower than in previous generations of networks, which is especially important in applications that require fast response, such as online gaming or remote medical operations.
It can be assumed that with parameters worse than those shown below, an external antenna should be used:
- RSSI below -100 dBm
- RSRP below -110 dBm
- SINR below 10 dB
![Antenna TRANS-DATA 5G KYZ 10/10 + 5 m cable + SMA [698-960, 1710-2700, 3300-3800 MHz]](https://static.dipol.com.pl/images/en/pict/a741027_10.jpg)
TRANS-DATA 5G KYZ 10/10 antenna A741027_5 (2x5 cable), A741027_10 (2x10m cable). The antenna has SMA connectors.
Diagram of video door entry system for one-family house with an additional IP camera.
When building a modern video intercom system you need to take into account that the video intercom can control the gate and entrance. An application installed on a smartphone can be used for this purpose. At the door station installed, the view from the built-in camera focuses on the caller. If the camera has a very wide viewing angle, it is possible to observe the area in front of the gate, but even if the door station covers such an area, it is usually insufficient.An additional IP camera can be connected to the Hikvision IP video intercom system to cover the area of the entrance gate or the entrance gate and wicket. During or after answering the call, you can change the view from the main gate station to the additional IP camera and view the area in front of the gate. Thanks to remote operation via a smartphone, it is possible to open and verify remotely at any time, whether the entrance gate is open or closed.
The diagram of an IP video intercom system for a single-family house is shown below. The system is based on the one-subscriber IP Villa DS-KV8113-WME1(C) G73632 door station with a built-in camera and two relays for control of the gate and wicket. The DS-KH6320-WTE1 G74001 monitor equipped with Wi-Fi interface has been installed inside the building. The area at the gate can be viewed with the Hikvision DS-2CD2043G2-I K03207 IP camera. The Ultipower N299781 switch with 4 PoE ports (802.3af/at) is used to power the gateway station, monitor, and IP camera. The system is connected to the Internet via the Mercusys AC12G N2933 router. The wicket is controlled with the use of the Bira S12U G74220 electric door strike with steel keeper/latch with 4 mm adjustment range, suitable for 12 V AC or DC power supply. It is supplied with the 12 V DC M1820 power supply.
Diagram of video door entry system with an additional IP camera
Do Sunell products work with third-party devices?
IP cameras and DVR from the same manufacturer provide the greatest assurance of performance, as all components are optimized for interoperability and functionality. However, if it is necessary to combine systems from different manufacturers, support for the ONVIF (Open Network Video Interface Forum) protocol makes integration and communication between different devices possible. Sunell is a member of ONVIF, which proves the professional level of integration and meeting industry requirements. The devices support ONVIF-compliant S/T/G/M profiles:- Profile S: specifies requirements for video and audio streaming, ways to control PTZ, metadata, and relay inputs and outputs
- Profile T: focuses on advanced video analysis functions such as motion detection, image analysis, etc.
- Profile G: focuses on recording configuration and DVR search and playback
- Profile M: covers requirements for special applications, including mobile devices.
According to our tests, if you use the ONVIF protocol to connect different manufacturers then:
- it is usually necessary to enable the ONVIF protocol on these devices
- cameras are automatically detected by the NVR, and adding them requires only a password
- The NVR allows configuration of basic camera image parameters such as brightness, contrast and saturation, while more advanced features such as. exposure or WDR, require direct configuration at the camera level
- NVR can configure motion detection and receives events from this function, but advanced functions such as intelligent motion detection or intelligent events (line crossing, zone entry) are not supported
- operates to control PTZ cameras and motozoom lens
Dispersion phenomenon in fiber-optic transmission.
One of the phenomena that has a great impact on the capacity limitation of fiber-optic cables is the dispersion. It deteriorates the signal-to-noise ratio of the transmitted signal and increases transmission errors. There are several types of dispersion:Modal dispersion – occurs only with transmission in multimode fibers. It is due to the fact that each mod traveling a different path in the fiber, arrives at the receiver at a slightly different time, which ultimately results in a blurring of the transmitted pulse. This forces an increase in the spacing between transmitted pulses, which in turn significantly reduces the data bandwidth. Modal dispersion has an adverse effect on the maximum transmission distance.
Modal dispersion in a multimode fiber
Polarization dispersion – occurs in single-mode fibers. It results from the elliptical (rather than perfectly circular) shape of the core, so that the vertical and horizontal polarizations of the mod propagate in it at different speeds. This phenomenon also limits the transmission range.
Polarization mode dispersion in a single-mode fiber
Chromatic dispersion – results from the different time taken by waves of different wavelengths to travel the transmission path, and is a major problem when using CDWM and DWDM techniques based on signal transmission over multiple wavelengths. The components of chromatic dispersion consist of material dispersion (change in refractive index as a function of wavelength) and waveguide dispersion (inhomogeneity of refractive index in the core).
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Chromatic dispersion in a single-mode fiber
Since the components of chromatic dispersion over a range of wavelengths differ in sign, it is possible to determine the wavelength of zero chromatic dispersion (in the example above: 1300 nm). The manufacturers can also change the components in the production process, moving the zero dispersion area to the region used by a given transmission technique.
DIPOL SMART HORIZON DVB-T2 antenna – reception parameters proven by field tests.
An ideal antenna is the one that has high gain, optimal directivity, relatively small size, and will not require additional power supply. SMART series antennas have been optimized for the above requirements.
The DIPOL SMART HORIZON antenna A2230 underwent a number of field tests, including analysis of performance within a range of 10 to 100 km from a 100 kW transmitter. The tests included measurements in locations with different density of buildings, as well as comparative tests with other DVB-T2 antennas available on the market. The tests showed that the antenna is at the forefront in terms of reception capabilities. Without any major problems, it was possible to receive DVB-T signals at a distance of 94 km from the transmitter (100 kW, low UHF band, terrain profile without any obstacles along the route), with signal strength in passive mode of the antenna averaging 50 dBμV for 3 channels, and the MER value averaging 30 dB. These values should be considered sufficient for reception by 1 receiver. In the case of a larger system, the active mode should be used, which increases the signal power by 15-20 dB, and the MER value by 2-3 dB.
 | Hikvision DS-2DE4225IW-DE(T5) IP PTZ Camera (2 MP, 4.8-120 mm, Optical Zoom: x25, IR up to 100 m, AcuSense, PoE) The K17913 is a Hikvision IP PTZ camera that has a 1/2.8" sensor with 2 MP resolution and a maximum frame rate of 25 fps. The camera features AcuSense technology, based on a deep learning algorithm which allows it to filter out human and vehicle objects, resulting in greater operational efficiency and reduced false alarms. Thanks to advanced image analysis functions, 25x optical zoom and IR illuminator with a range of up to 100 m, the camera can be successfully used for monitoring various types of objects, such as roads, parks, rivers, railroad lines, etc. | |
 | Hikvision DS-2DE4215IW-DE(T5) IP PTZ Camera (2 MP, 5-75 mm, Optical Zoom: x15, IR up to 100 m, AcuSense, PoE) The K17912 is a Hikvision IP PTZ camera with 1/2.8" sensor with 2 MP resolution and maximum frame rate of 25 fps. The camera features AcuSense technology, based on a deep learning algorithm which allows it to filter out human and vehicle objects, resulting in greater operational efficiency and reduced false alarms. Thanks to the advanced image analysis functions, 15x optical zoom, IR illuminator with a range of up to 100 m, the camera can be successfully used for monitoring various types of objects such as roads, parks, rivers, railroad lines, etc. | |
 | Single-mode pigtail set 4 pcs. The PG-271A-1 SC/APC G.657.A1 1 m red, green, blue, yellow L34271A enables neat termination of fiber optic lines. Colors can be used for quick identification of individual connections in large distribution frames (no need to use a visual fault locator to identify the fiber that requires repeated splicing) or to identify signals and services in a given fiber (e.g. camera 1, camera 2 etc.). | |
Worth reading
Does a good splice “glow”? Installers who check systems based on fiber optic cabling often use a so-called visual fault locator. This tool allows checking the continuity of the cabling and, among other things, locating areas of excessive fiber bending in couplers, switches, splice boxes, etc. We are often asked about the splice “glowing”. This is encountered relatively often, but light leakage at the splice of the fiber does not always mean a damaged (broken) splice...>>>more
The photo above shows the difference in "glow" on a bad and on a good splice. A cracked splice (as a result of mishandling the sheath immediately after heating) glows intensely and spot-on. A proper splice emits a much less intense and more diffuse light.
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