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No. 21/2012 (May 21, 2012)
Since 1989, Russian scientists have faced with the problem of providing adequate amount of energy to the drill head for exploration of Lake Vostok, a sealed water reservoir located in Antarctica below 4-kilometer layer of ice. For this reason, the project continued for over 20 years, until the team reached the upper surface of the water in February 2012.
Considering similar problems with exploration of moons in the Solar System, NASA is interested in laser-powered probes. Low-power laser beams transmitted via fiber optic cables have long been used in telecommunications networks, so the main problem is to increase the power density. Ultimately, the robot is to be powered by a 5000 Wat laser beam, capable of cutting in half e.g. a car.
Considering similar problems with exploration of moons in the Solar System, NASA is interested in laser-powered probes. Low-power laser beams transmitted via fiber optic cables have long been used in telecommunications networks, so the main problem is to increase the power density. Ultimately, the robot is to be powered by a 5000 Wat laser beam, capable of cutting in half e.g. a car.
The first robot powered by a laser was developed in 2003 and was used to research Mexican hydrothermal sources by 2007. Another one explored the bottom of freshwater lakes located under the ice sheet in Antarctica in the years 2008 - 2009. However, none of the robots had ability to use the laser power transmitted by the fiber to remove obstacles on the way.
Research and development of laser technology will revolutionize methods of power supply. Fiber optic cables will be able to transfer energy over distances above 100 kilometers.
Another applications of laser-driven devices include future plans of launching objects into outer space.
Another applications of laser-driven devices include future plans of launching objects into outer space.
The highest television tower.
May 22, will be the day of the official opening of the world's highest television tower - Skytree Tokyo. The tower has a height of 634 m and is 34 meters higher than the previous leader, Canton Tower.The tower has been built by a consortium of six broadcasters, led by NHK, and will be used primarily to broadcast digital television signals. Tokyo Skytree will take over the role from Tokyo Tower (333 m), which, surrounded by tall buildings, does not ensure correct results.
The structure of the Tokyo Skytree tower above 375 m is mounted on special hydraulic shock absorbers, which according to experts are able to absorb about 50% of the earthquake energy. A detailed inspection carried out after the 2011 earthquake did not show any damage to the tower.
Tokyo Skytree - the highest television tower in the world
Power supply in CCTV systems.
The maximum distance at which one can supply power to a CCTV camera is limited by the voltage drop in the cable. Practice shows that most cameras with rated 12 VDC supplying voltage is working correctly also at 11 V. This is the value below which the video becomes distorted.To calculate the maximum possible distance of power transmission over two-wire cable, we need to know the current drawn by the camera (the typical value for cameras without thermostat and heater is 250 mA), the permissible voltage drop (1 V, unless otherwise recommended by the manufacturer), the resistance of the conductor (usually expressed in ohm/km). Knowing these parameters, we may use Ohm's law to calculate the powering range.
In the case of Camset M6100 cable, the maximum distance calculated according to the above-mentioned assumptions is 100 m (1 mm2 intersection, 19.5 ohm/km).
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In the case of cameras consuming more power or when the distances are longer, the solution is provided by the use of power supplies with adjustable output voltage, or a system distributing a much higher voltage and employing local 12 VDC stabilizers at the camera points, e.g. the 40/12 V system .
The problem of voltage drops is negligible in the case of 230 VAC power supply. All devices and cables have to fulfill adequate safety requirements and regulations. The cable suitable for that purpose is e.g. CCTV cable CAMSET 100 M6100.
![CCTV cable: CAMSET 100 75-0.59/3.7+2x1.0 [1m]<br />(92% braid coverage, 2 power wires up to 230V AC)](https://static.dipol.com.pl/images/en/pict/m6100_1_.gif)
More information: Power supplies and accessories
How to combine DVB-T and cable TV signals?
Subscribers of analog cable TV often want to receive also terrestrial DVB-T broadcasts. The main reason is usually the desire to watch selected channels in better quality (HD DVB-T), while having inexpensive access to a wide range of channels from the cable.There are three typical cases:
- DVB-T and cable channels do not overlap nor are adjacent to each other - then the signals can be combined in a passive splitter used as combiner (Signal R2 R60102, band 5-1000 MHz),
- DVB-T and cable channels overlap or are adjacent to each other, the user can manually switch the input signal - the suitable device is DVB-T/CATV switch Signa E2022 which ensures good isolation between inputs,
- DVB-T and cable channels overlap or are adjacent to each other and the user wants to switch the input signal remotely - the ideal choice is DVB-T/CATV switch MST-01, manageable by any IR remote control. Alternate input selection is performed when the user holds down any key on the remote for 3 seconds.
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Note: in the first case (passive combiner) it is necessary to check all signals that can be received from terrestrial antenna (some of them may not have been tuned in on the TV and can interfere with some CATV channels); it also means that this solution cannot be used in transition period (simultaneous operation of analog and digital TV transmitters).
Multimode pigtails - 50 um or 62.5 um?
Multimode optical fiber network can be made of 62.5/125 um fibers (OM1, core diameter 62.5 um) or 50/125 um cables (OM2, OM3 and OM4 with core diameter of 50 um). The core diameter influences the attenuation of the fiber. At 1310 nm, the attenuation of OM1 fiber (62.5 um) can reach 11 dB/km, while in the case of OM2 fiber (50 um) it is at the level of 6.3 dB/km. Optical fibers with different core diameter cannot be spliced, so all parts of a transmission line have to use fiber with the same core diameter. |  | |
Shutters used in CCTV cameras.
The shutter in a camera controls the duration of time for which light falls onto the photosensitive elements (pixels) of the image sensor. The sensitivity of a pixel is fixed, so the amount of light necessary to produce a usable image is regulated by the exposure time. There are three popular systems:- CCD with electronic shutter,
- CMOS with rolling shutter,
- CMOS with global shutter.
View of a CCD sensor
CCD sensors, which predominate in analog cameras, provide image data from the same moment (frame transfer). Most CMOS sensors operate with a rolling shutter. The data is read line by line, causing image distortion called skew. The image bends diagonally in one direction or another as the camera or object moves from one side to another, exposing different parts of the image at different times (e.g. the roof of a moving car will be offset from the wheels).
CMOS sensors with global shutter work like CCDs. Thanks to additional transistors, they can store the data to improve the readout process.
CMOS sensors with global shutter work like CCDs. Thanks to additional transistors, they can store the data to improve the readout process.
Best IP camera for video surveillance of public places.
Frequent vandalism, deliberate destruction of cameras in order to prevent monitoring, or even the risk of accidental damages in factories, schools, railway stations etc. - require the use of vandal proof cameras, such as Sunell SN-IPV54/12UDR K1691.
2MP IP vandal-proof dome camera for outdoor / indoor applications - Sunell SN-IPV54/12UDR
In addition to the metal body, the SN-IPV54/12UDR camera employs thick, vandal proof dome, sealed with the chassis to effectively protect the internal parts from adverse weather conditions.
Thanks to Aptina image sensor, mechanical IR filter and IR illuminator, the camera can capture high quality Full HD video both day and night.
Thanks to Aptina image sensor, mechanical IR filter and IR illuminator, the camera can capture high quality Full HD video both day and night.
Which HDMI cable to choose?
An HDMI cable is described by the standard version, length and cable type, including cross section of its wires (AWG). HDMI standard version specifies the parameters of data transmission and other features. HDMI 1.3 cables are now replaced by the version 1.4 enabling 3D video transmission and sharing Internet connection.An important parameter describing wires of HDMI cables is AWG (American Wire Gauge) - a standardized American system used to provide wire diameters. Long HDMI cables should have wires with lower AWG numbers (thicker).
HDMI cables also differ in the kind of the cable used, round, reinforced with steel braid, or flat, easy to place e.g. under the carpet. DIPOL offers a wide range of HDMI cables supporting HDMI 1.4, from 0.5 to 30 meters.
| Reinforced HDMI 1.4 cables: | Flat HDMI 1.4 cables: |
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2m High Speed HDMI cable with Ethernet (v1.4, 28AWG, reinforced) H1022 |
New products offered by DIPOL
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Worth reading:
HUD solutions for U.S. troops. U.S. Department of Defense (DARPA agency) has signed a contract with Innovega company developing ultra-small-form-factor head-up display (HUD).
HUDs use technologies that present data by displaying information on transparent screens. This way, the operator e.g. pilot, is able to access information with the head positioned "up" and looking forward, instead of tilted down looking at lower instruments...
HUDs use technologies that present data by displaying information on transparent screens. This way, the operator e.g. pilot, is able to access information with the head positioned "up" and looking forward, instead of tilted down looking at lower instruments...
The contact lenses that allow the integration of real and virtual world
How does an optical splitter work? ULTIMODE optical splitters can divide the optical power transmitted in an optical fiber into 4/8/16/32 equivalent parts. An optical splitter is a passive element of the network, so every branch gets all the packets sent in the trunk from the optical line terminal (OLT) at the service provider's facility. It is the role of the optical network terminals (ONTs) of the end users to filter the information.
Optical splitters are mainly used in CATV and FTTH passive optical networks (PONs). The diagram below shows the functioning of such a splitter...
Optical splitters are mainly used in CATV and FTTH passive optical networks (PONs). The diagram below shows the functioning of such a splitter...
Optical splitter is a passive component of the network,
so all the packages from the trunk are sent to the branches
so all the packages from the trunk are sent to the branches
How to check the hardware version of a TP-LINK device? When searching for the latest firmware for TP-LINK products at the official manufacturer's site, the user can be asked for the hardware version of their device. It is a very important issue as inappropriate software loaded onto the device may damage the unit. The information on the hardware version of a TP-LINK device can be found on the product label with the rated parameters, usually on the bottom of the device...
Product labels with the rated parameters of two TP-Link devices
