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No. 40/2019 (Dec. 16, 2019)
The tiniest antenna in the world?
When it comes to electronics, bigger is not always better. This is particularly true of a new generation of "wearables", designed to connect people, machines, and other objects in a wireless "Internet of things". Designers need to miniaturize these solutions to guarantee that they are functional and comfortable at the same time. To this end, scientists from the American Chemical Society (ACS) have now made the world's tiniest radio-frequency antenna, with a diameter equal to 1/100 of a human hair.Antennas that receive and transmit radio waves are usually made of metal conductors such as aluminum, copper, and silver. Remarkable as they are for their high electrical conductivity, these materials do not perform well in ultra-thin, lightweight antennas. As a result, most metal antennas are thicker than 30 micrometers in diameter, which limits their application in miniaturized electronic devices. In order to produce even thinner antennas, Keun-Young Shin, Ho Seok Park and their team used exceptionally thin sheets of 2D material, made up of a layer of metallic niobium atoms sandwiched between two thin layers of selenium atoms (NbSe2).
The team made their antenna by spray-coating several layers of NbSe2 onto a plastic substrate. Then they tested the 885 nm-thick antenna and found out that a 10 mm2 patch of the material performed well, with a radiation efficiency of 70.6%. The device transmitted radio waves in all directions. By changing the length of the antenna, the frequencies could be adjusted within the 2.01-2.80 GHz range, as required by Bluetooth and WiFi technologies. Further tests showed that the antenna can also be bent and stretched without any major changes in performance. The researchers claim that apart from wearables, the new antennas could also be used in deep space communication systems, since the material would become a superconductor in the very low temperatures of outer space.
Configuring TERRA'S HDMI-DVB-T COFDM digital modulators.
TERRA's digital modulators, MHD001P R86103 and MHD002P R86104, can be configured via Google Chrome (Android and Windows) or the WebBLE GreenParkSoftware (a paid iOS app). Pairing and establishing connections between devices (such as smartphones, tablets, laptops) and the modulator can be done wirelessly. In order to turn on the wireless communication mode on the modulator, when you plug in the power supply to the 230 VAC socket, press and hold the "+" and "-" buttons simultaneously until the green LED begins to flash. Then open Google Chrome and type in the following address: mhd.mydtv.live.
Simple and intuitive, the configuration allows users to quickly set up all the required parameters
MHD002P R86104 HDMI-1xCOFDM (DVB-T) digital modulator + HDMI Terra bypass
HDMI modulators are perfect for hospitals, stores, shopping malls, supermarkets, and electronics stores where content from one or two sources is delivered to multiple TV receivers. The devices also find important applications in surveillance systems integrated with SMATV networks; they may be used to transmit DVR signals (more than ten camera-captured images) to all the terminal outlets. Digital modulators that do not support the HDCP protocol are employed, for instance, in surveillance systems to introduce the camera signal into the SMATV system.
Reflectometry - a case study.
Reflectometers can provide users with a lot of information on tested fiber-optic lines. The measurement method is also recommended for troubleshooting and fault location in the optical path. A sample reflectogram is shown below. The measurement in question was performed in an actual network designed for the distribution of SMATV signals.
In this particular case, the fiber-optic line consists of:
- a 150 m launch cable (more precisely: 150 m plus two 1.5 m leads, i.e. 153 m in total); the 161 m figure for the first event has to do with the presence of a dead zone: the distance is correctly calculated starting from meter 8,
- an event at the 161th meter, recorded by the reflectometer as a splice, with an attenuation of 0.26 dB. In reality, the event is a connection point between the launch cable and the tested optical path, a high-quality SC/APC connector with very low reflectance. Its attenuation falls in a range typical of connectors, but the reflectance is so low that it is recorded as a splice. More often than not, in order to "improve" the reflectogram in such situations, testers deliberately dirty up the connector to make it more reflectant (reflect light) and show up in the diagram,
- a 172 m optical fiber (between the 161th and 333th m), leading up to a connection point with the attenuation of 0.14 dB and reflectance of 48.36 dB (the event also includes 1 splice),
- a 30 m patchcord (betwwen the 333th and 363th m), leading up to a connection point with the attenuation of 0.32 dB and reflectance of 47.85 dB (the event here includes 1 splice),
- 41 m optical fiber, terminating at the end of the tested fiber-optic line.etrów światłowodu, którego zakończenie stanowi koniec mierzonej linii światłowodowej.
The greatest advantage of the method is the wealth of information it can provide. In order to interpret it properly, however, users need relevant knowledge and experience to prepare for the measurement procedure (set up correct device options, depending on the type and length of the tested line), as well as subsequent results analysis. Unfortunately, automatic measurement machines are practically never the solution in this case.
Taking quick snapshots from recorded footage.
Sometimes, to document the event, the recording must be accompanied by snapshots. With Hikvision DVRs, you can use the VSPlayer software for that purpose. Apart from the playback function, the software also comes with several other handy features, such as a snapshot creator.
The Capture window is used for setting the parameters of snapshots taken from video footage
Snapshots can be taken from any recording performed by Hikvision devices. The process of their creation is automated and the user can specify the following parameters:
- format: JPEG or BMP,
- snapshot frequency: intervals can be defined in seconds or image frames.
A Hikvision IP video intercom system for a single-family home.
The picture below shows a Hikvision IP video intercom system designed for a single-family home. The system consists of a single-button DS-KV8102-IM G73631 gate station and two 7” touchscreen monitors (DS-KH6310 G74038). Both the monitors and the gate station are powered by an 8-port PoE switch (DS-KAD606 -P G74814) with the output voltage of 24 VDC. The switch is equipped with 6 PoE ports and 2 extra LAN ports that enable network and cascade connections (the connection can also be established via a regular switch or router with a local power supply for all devices). The system is connected to the Internet network via a TP-Link C6 AC1200 N3255 router. A symmetrical electric door strike (Bira ES1-001 G74210), with the latch adjustment range of up to 4 mm, was mounted by the gate. The device is designed to work at 12 VDC or 12 VAC. In the system below, it is using a M1820 12 VDC power supply unit. The door strike is powered via a relay located inside the gate station.
An IP video intercom system for a single-family home (blue - a twisted pair cable, red - a 2-wire cable for delivering power supply to the electric door strike)
Once the gate station button is pressed, the two panels inside the home will go off at the same time. Accepting the call will establish two-way audio/video communication and allow the resident to release the door strike. If the resident is not at home, the call may be forwarded to a smartphone and the gate may be opened remotely. The touchscreen monitors allow to save photos and alerts, as well as leave a message for the resident. The system can be used on a smartphone via the dedicated Hik-Connect app, while configuration and operation from a PC is performed with the use of the iVMS-4200 client software.
High-performance fiber-optic backbone networks.
When constructing a backbone network, it is worth paying attention to the main bus transmission speed (between the network nodes). The recommended fiber-optic connection speed between the switches should equal 10 Gbps. Use switches that can be configured and work in the second and third network layer. In addition, when hooking up to smaller subnetworks, you can use media converters connected to the main switch via 1 Gbps SFP inserts.
A special switch recommended for this kind of systems is TP-LINK's T2600G-28SQ N29968, equipped with 24 Gigabit SFP slots, 4 x 10/100/1000 Mbps RJ45 ports, and 4 x 10G SFP+ slots, allowing to create a stable network environment and enjoy fast, high-performance connections. The device ensures high operation quality, advanced QoS support, as well as layer 2 and 2+ management (with the option to configure selected layer 3 protocols).
 | TM103N optical power meter L5815 is designed to measure optical power loss in multimode and single-mode fiber-optic networks. The device is calibrated to work with wavelengths of 850 nm, 1300 nm, 1310 nm, 1490 nm, 1550 nm, and 1625 nm. Its wide measurement range (-50...+26 dBm) and high accuracy (+/-3% for -10 dBm) allow to carry out precise measurements in any fiber-optic network. The device has a reference level (dB) and absolute power (mW, dBm) measurement function. | |
 | TM102N-SM optical laser source (SM 1310/1550 nm) L5819 is a tool necessary for measuring optical power loss in fiber-optic networks (FTTx). The source generates laser beams of predetermined wavelengths (1310/1550 nm) and power (-5 dBm) to ensure reliable and accurate measurements.. | |
 | Hikvision DS-1H18S/E HD-TVI video balun M16642 enables the transmission of video signals from one source via a twisted pair cable. For easy installation, the BNC plugs are mounted on cables. The balun matches the impedance of the unbalanced 75 ohm output/input with the 100 ohm impedance of the balanced line (UTP/FTP cat. 5 cable), and vice versa. The device is compatible with Power over Coaxial (PoC) systems. | |
Worth reading
Electrode replacement and lens cleaning in SignalFire fusion splicers. Electrodes in fusion splicers need to be replaced at regular intervals; the actual frequency will depend on the number of splicing and calibration cycles. The estimated electrode life in Signal Fire L5870 and L5875 splicing machines equals roughly 3000 splices. Each device comes with an extra set of electrodes...>>>more
When you replace the electrodes in your fusion splicer, take the opportunity to clean the device, especially the lenses mounted underneath the electrodes.
Signal Fire AI-8 AI-9 / AI-8C fusion splicers
