DIPOL Weekly Review - TV and SAT TV, CCTV, WLAN

The Internet from... a light bulb?

Chinese scientists at the University of Fudan informed of reaching a record speed of wireless data transmission using visible light. A special LED with output power of only 1 W enabled to setup connections with 4 computers at an average speed of 150 Mbps. Such a bandwidth allows for comfortable use of the Internet on several devices. In contrast to the already known and used in commercial applications experimental laser connections - the transmission used "normal" visible light, the intensity of which was modulated at a high frequency. The receivers (photo detectors) installed on the computers detected changes in light intensity, which carried the information. According to the researchers, the devices for data transmission can be very cheap and easily implemented. For example, any light source may become an access point, so even street lamps may be used as public access points. Of course, the changes of the light intensity are carried out at frequencies that are unnoticeable to the human eye.

(source: www.wikipedia.org)

Wireless communication using light as a carrier - Li-Fi (Light Fidelity) - was first presented in 2011 by Professor Harald Haas from the University of Edinburgh. Using one LED, he managed to get a throughput of 10 Mbps, sufficient for streaming an HD video to a computer. This year, a 3 Gbps speed was achieved by the Fraunhofer Heinrich Hertz Institute in Germany, and another research carried out by the Ultra Parallel Visible Light Communications project, a joint venture between the universities of Oxford, Cambridge, Edinburgh, St Andrews and Strathclyde, resulted in transmission speeds of 10 Gbps.
Li-Fi will enable creation of high-speed telecommunications networks with properties similar to Wi-Fi solutions. It can be used in places where radio carriers are prohibited, undesirable, or unreliable, such as in operating rooms, on airplanes, in factories etc. Disadvantages of this technology include the range limited to the area of the room (which may often be an advantage - it can ensure more localized and consistent Internet connectivity) and low uplink speeds.

Where is the tower?

Oriental Pearl TV Tower, with the height of 468 m, had been built for 4 years and opened in 1994. It is now the fifth highest tower of the world. Two large spheres with diameters of 50 and 45 m are connected with tubes with a diameter of 9 m. At the height of 267 m there is a rotating platform with a restaurant.
Where is the tower? - The answer at the end of this issue.

The 468-meter high Oriental Pearl TV Tower
is now the fifth highest tower in the world

Full surge protection!

A server room houses a number of computers and other network devices. The equipment is often a significant asset of the company owning the system. However, the most valuable content is the stored data. Any data loss can be devastating for the company. Aside from standard protection provided by automated backup servers, the best method is to isolate the equipment from environmental threats, including voltage surges.

In many cases, specialists installing computer networks use solutions based on optical media converters, instead of typical protection measures lowering risks of voltage surges between systems with copper cables. Optical fiber is a transmission medium guarantying high bandwidth and being an ideal insulator. In addition, the isolating fiber optic links are much cheaper than solutions dedicated for effective protection of networks with twisted-pair cables.

Protection of the network devices located in a server room from voltage surges that may appear between the internal (LAN) and external (ISP - WAN) parts of the network

Choosing a pair of media converters for this purpose, the installer should take into account the cost effectiveness - the short-distance link can be made of OM3 multimode fiber and affordable multimode media converters. An example: two ULTIMODE M-023G L10025 converters connected with OM3 L3311 patchcord.

Multiswitch system with star topology.

Multiswitches available on the market have up to 32 outputs, so a SMATV system with up to 32 outlets can be based on a single device. The examples are radial Terra multiswitches (M(S)R series), or radial SIGNAL multiswitches (with maximum of 16 outputs). The star/radial networks based on such multiswitches are very simple and usually can be installed "ad hoc" - there is no need for any design.

A multiswitch system with star topology

In the example above, the TERRA MR-516 R70616 multiswitch distributes satellite DVB-S/S2 signals from QUATRO Inverto A98257 LNB and terrestrial DVB-T signals from UHF antenna Dipol 44/21-69 Tri Digit ECO A2660. The signals from the outputs of the TERRA MR-516 R70616 multiswitch are distributed via Triset-113 E1015 cables to eight homes. The users in each home can have two single DVB-S/S2 receivers or one twin PVR receiver allowing for watching one channel and recording another.

Usefulness of WDR function in security cameras.

Proper operation of surveillance cameras in difficult lighting conditions is one of the most important priorities for equipment manufacturers. The dynamic range of the image sensor is the parameter describing the ability of a camera to capture details both in very bright and very dark parts of the scene. Cameras with high dynamic range (WDR) are better prepared for operation in environments with the high contrasts.

In most of WDR cameras the image is scanned twice with considerably different exposure parameters (slow shutter speed for capturing details in dark areas and quick shutter speed for bright areas). Thus, the resultant imaging is a combination of two fields, performed by proprietary algorithms embedded in the DSP. This imaging method may, however, cause the formation of so-called "ghost effect". This effect is especially noticeable when the camera is observing a wide outdoor area with quickly moving small objects. So, the advantages of WDR cameras can be best used in closer areas, such as for monitoring staircases and rooms with large differences in light intensity in various parts of the scene.

Sunell cameras with WDR function: SN-FXP59/50UDR M10775, SN-BXC59/50CDN M11225.

Visualization of CCTV coverage with E-map.

In the case of extensive video surveillance systems the operator should know exactly the layout of the camera points. It is necessary for quick identification of the monitored areas. IVMS - 4500 and VMS client software supplied with Ultimax/Hikvision DVRs enables the user to import layouts of buildings and field maps as JPEG/bmp files. The plans will be the backgrounds for placing on camera symbols, in compliance with their actual locations.

E-map window in a CCTV system based on Hikvision/Ultimax DVRs

Each camera point can be correlated with specific alarm event, such as motion detection. When the alarm is triggered, a siren symbol by the camera icon informs the operator about the event. Double-click on the camera symbol allows the operator to quickly monitor the area and assess the situation. With a large number of cameras, E-map enables the operator to find out whether the alarms come from neighboring cameras and to follow the intruder. The E-map application is compliant with analog cameras connected to DVRs as well as with IP cameras.

How to recognize the type of antenna connector in a router or modem?

The user of a wireless network device such as access point, wireless adapter, modem etc. who wants to buy an external antenna should know the type of the antenna connector used in the device. A multitude of solutions and slight differences in appearance mean that less experienced users can have great difficulty in choosing the antenna with a matching connector.

The type of the connector depends on the device manufacturer and may differ in the case of devices operating in different frequency bands. Great diversity can be found in devices used for broadband data transmission in mobile networks (modems).

In order to facilitate the identification of the plugs and sockets, we have prepared the Types of connectors in WLAN, GSM, 3G, LTE devices article. After selecting a suitable connector, the user may also order an appropriate antenna.

Oriental Pearl Radio & TV Tower

is located in Pudong Business District in Shanghai. The main attraction for tourists is the central capsule with an observation deck with a transparent floor. Everyone can enjoy 360-degree views around the tower and look 263 meters down.

October 29, 2013 - new functionality in DIPOL e-Store. Currently, each customer after logging into DIPOL service and selecting My Account can additionally view the history of orders placed, repeat any of them, download invoices in electronic form, edit address data, ... more

SatNet app - professionally designed multiswitch system with 240 outlets, for two satellites. SMATV systems based on TERRA multiswitches are the most popular platform for distributing digital terrestrial television (DVB-T) and satellite DVB-S/S2 broadcasts in multi-dwelling units. Each subscriber can decide on the received channels, having or buying suitable television, satellite receiver, or choosing a pay-TV operator... more

A SMATV system in a multi-family building with 240 outlets designed with the use of the SatNet application

Selecting transmission medium in analog CCTV systems. Video and optionally control and audio signals can be transmitted in several ways. The choice of the designer/installer depends on the field of application, size of the system, environment, budget. Below we present the 3 most popular options... more

Transmission of CCTV signals with the use of active baluns and twisted pair cables allows for longer ranges (up to 2400 m) compared with coaxial cables and ensures high resistance to electromagnetic interference (symmetrical transmission lines)

Video surveillance of sites used seasonally. The protection of buildings and other facilities used only at certain times of the year (summer houses, ski slopes, outdoor pools etc.) is often more troublesome than in the case of homes and offices. Because of their remote location from city centers, it is not always possible to use standard Internet connections... more

Cooperation of M72108 DVR with the N2957 router and a 3G modem