Coşul este gol



DIPOL Weekly Review - TV and SAT TV, CCTV, WLAN
No. 38/2008 (Nov. 17, 2008)
Prospects for IPTV. IPTV (Internet Protocol Television) is a technology enabling transmission of television/video signals in IP networks. Its popularity is growing with throughput and transmission capacity of the Internet.
IPTV broadcasts are currently ca. 3% of the overall distribution of pay-TV channels, but the forecasts say that by 2013 this proportion will increase to about 14%. Now, TV via the Web is available to 15.5 million subscribers; by 2013 the figure is expected to rise to 90-120 million.
The highest number of users is in the USA - 2.5 million, in Europe - 1.74 million, in China - 1.55 million (in Poland - 57 thousand).
In terms of popularity, the leader is Hong Kong, with 46.7% of pay-TV broadcasts distributed via the Net (41% via cable TV networks, 12.3% via satellites).
A standard compression scheme in IPTV becomes MPEG-4 (H.264). For transmitting an SDTV channel (with standard PAL resolution) it requires about 1.6 Mbps, in the case of HDTV channel - up to 6 Mbps.
Because a typical household has 2-3 TV sets, as well as the home network has to ensure smooth access to the Internet, voice transmission etc., the recommended throughput (download speed) is 10-25 Mbps.
To service a larger number of customers, IPTV networks should be based on 10 Gigabit Ethernet. It is the driving force behind the development of FTTH technology (Fiber To The Home).
Where is the tower? Oriental Pearl TV Tower, with the height of 468 m, was built in 1994. It is the third highest tower of the world, after the CN Tower in Toronto and Ostankino tower in Moscow. 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. The highest observation deck is at the height of 350 m. Between the two large balls there is the 20-room Space Hotel. Since 1995, the tower broadcasts 9 television and 10 radio channels.
Where is the tower? - The answer at the end of this issue.
The TV tower is not the highest building in this city. Since this year it has been outstripped by the nearly 492-meter-high (101-story) building - Shanghai World Financial Center.
Multiswitch installations - network topologies. The most flexible multiswitch installations in multi-story buildings are based on 9-cable system. On each floor there is a splitter providing signals to multiswitches. It allows to shape the network according to actual requirements - there can be deployed practically unlimited number of outlets. The kind and number of multiswitches depends on the needs of the residents.
Modern satellite PVR receivers are equipped with two RF tuners, one for live viewing and second for providing data for recording. Each RF input has to be connected to independent output of the multiswitch (it is not allowed to use satellite splitters or loop connections). So these receivers require access to two multiswitch outputs.
Another reason for the need of additional outputs is the prospective demand for multiple satellite receivers in one home. The designer of a SMATV system should take into account even the future needs of the residents.

More on topologies of multiswitch installations in the article: "Professional multiswitch systems".
SAT/TV TAP: Terra SS-510SAT/TV TAP: Terra SS-510SAT/TV TAP: Terra SS-510SAT/TV TAP: Terra SS-5109/16 Multiswitch: Terra MSR-916 (active terrestrial path)9/12 Multiswitch: Terra MSR-912 (active terrestrial path)
How to deliver high quality TV reception in difficult areas? The problem of poor reception from terrestrial TV antennas can be solved by using satellite broadcasts that often duplicate terrestrial channels. Distribution of TV channels received via satellite ensures ideal reception without ghosts and/or noise.
The existing small MATV/SMATV systems can also be enriched with additional programs received via cheap, regular satellite receiver/s (instead of considerably more expensive professional headend). Such solutions can be especially attractive for small housing cooperatives. Below we show a diagram of such an installation, with the use of A99055 receivers and ZG channel amplifiers that guarantee high output levels.
In the diagram, two satellite channels are processed by A99055 receivers and converted to PAL (with MT-21p R871721 modulators), then amplified by ZG-401 (R90517) and distributed in the SMATV network. These channels can be received on every TV set, without using a SAT receiver - any subscriber can select one of them similarly to terrestrial programs.
9-input Cascadable Multiswitch: TERRA MS-9519-input Cascadable Multiswitch: TERRA MS-9519-input Cascadable Multiswitch: TERRA MS-9519-input Multiswitch: TERRA MS-952Switched-mode Power Supply for multisw. Terra MS-554, 18V 800mA, F-con.Subscriber Terminal Outlet: ALCAD BS-110 (Sat/TV/FM)Wall Plate EM-202 (for BS-100 outlets) - ALCADSurface Frame SB-003 (for subscriber outlets) - ALCAD3-way SAT / TV / FM Splitter 1>3F SignalDVB-S Receiver: TechniSat DIGIT S2 (built-in Conax SIM)TV Modulator: Terra MT-21P (G,K: ch.21-69, with AC/DC adapter)
A hybrid SMATV system based on multiswitches and regular SAT receivers
(instead of a professional headend)
Cooperation of megapixel IP cameras with DVRs. IP CCTV devices are usually delivered with free network management software. The client software of ULTIMAX DVRs allows to integrate into one video surveillance system not only the DVRs, but also IP cameras and megapixel IP cameras of ULTICAM. The software enables the operator to configure all CCTV devices, monitor and record the video/audio channels. The client program allows to perform digital zoom of images from megapixel cameras, with simultaneous recording of their full content. It also can synchronize the time clocks of the DVRs with external time server. The newest version allows to notify someone about an alarm (by email).
The newest network client software is included with ULTIMAX DVRs, e.g. M75160, ULTICAM cameras, and ULTINET video servers. The software is also available at this address. The ULTIMAX, ULTICAM, and ULTINET devices can be integrated into one system with devices coming from majority of manufacturers - by using ULTISYSTEM software. This software suite integrates modern city surveillance systems with local CCTV installations.

ULTIMAX DVRs honored with Gold Medal of Intertelecom 2008 perfectly cooperate with ULTISYSTEM software designed for city systems.
LAN and WLAN for IP video surveillance - the basic rules. Every stage of designing and implementing IP CCTV system should comply with adequate standards/codes and follow basic recommendations.

Typical results of inadequate LAN wiring and capacity are:
  • low frame rates, lower than those set in cameras,
  • improper decoding of images on computer or transcoder,
  • loss of connection.

One of the basic conditions for optimum performance of the system is stable power supply. Many breakdowns or dysfunctions of the equipment - like loss of connections, hangups of the cameras, lack of control over PTZ devices - are caused by "dirty power" (voltage dropouts, jumps, ringings, surges etc). Before installing IP devices, the available power supply has to be thoroughly tested, e.g. with a voltage recorder (24h). It can save a lot of time and money for servicing the whole system. The recommended solution is use of a professional UPS.
Video compression in CCTV systems. The development of compression methods allows to get satisfactory results (detailed images) with considerably lower data rates.
The first standard worth mentioning is MJPEG (Motion JPEG). This is a fairly simple way of compressing separate successive frames as JPEG images. This compression is used both in simple cameras (because of the simplicity of the compression), as well as in megapixel cameras - IQinVision K1412, K1422, K1433 - due to achieving high image quality.
The second popular standard is MPEG-4. It has several versions: SP (Simple Profile) K1502, SH (Short Header) K1132, ASP (Advanced Simple Profile) K1115. It is interframe compression where most of the output data represents differences among consecutive frames.
The newest and most effective codec is H.264 (MPEG-4 AVC). The main feature of the codec is division of the image into areas of different sizes and compression dependent on the changes within these areas. The devices based on this compression are new products in the market, manufactured by the most technologically advanced manufacturers. All ULTIMAX DVRs and ULTICAM camera K1140 use this kind of compression.
H.264 IP Camera: ULTICAM DS-2CD892PF
ULTICAM K1140 uses H.264 compression
Access point modes (example device: TP-Link TL-WA501G) - part 2. Access Point is a device that connects wireless network to a wired system. So it has to have at least two interfaces: wireless - WLAN - using 802.11 standard, and wired - LAN - using 802.3 standard.
In the last issue we described Access Point mode. Below we outline next modes: Access Point Client and Repeater.
Access Point Client - in this mode the device operates similarly to a wireless card/adapter used by clients. This mode has to be used when there is a need of connecting a number of LAN users in a home, office, building - via wireless link. The Access Point can cooperate with a switch (not showed in the diagram below) providing the adequate number of LAN connections.

Access Point: TP-Link TL-WA501G <br />(AP/APC/WDS 2.4GHz, eXtended Range)
Access Point Client (APC) mode
Repeater (regenerator) - the mode used for extending wireless network. The device receives the desired stream of data and sends it further. This mode is often used in larger buildings for ensuring better coverage. Due to the way of work, the maximum throughput of the AP is decreased by 50%.
The idea of Repeater mode
In the next part we will describe Bridge (Point to Point) and Bridge (Point to Point) with AP modes.
Protection of WLAN - part 1. Installing wireless devices the user has to remember about proper configuration that protects the network against hacking, data spying etc.
There are several ways of protecting the network:
  • SSID hiding
  • MAC address filtering
  • IP address filtering
  • password protection (recommended WPA2 protocol)
The screenshot below shows how to switch off SSID broadcast
(in TP-LINK TL-WR542G N2950).
View of Wireless Settings menu of TP-Link TL-WR542G N2955
In the next issue we will show filtering of MAC addresses
Shanghai. Oriental Pearl TV Tower has been built in Shanghai, the largest city in China in terms of population (about 9 million). The city competes with Hong Kong to be the economic capital of China.
We have written about:

Problems with implementation of LAN? - Let's build WLAN. Internet access is nowadays indispensable functionality of every office block, hotel or warehouse. When the building is not equipped with wired LAN infrastructure, the quick, cheap and effective way of solving the problem is wireless network...
- archive DWR of Sept. 17, 2007

DiSEqC - switching of satellite signals. The need for switching satellite signal from demanded LNB to the receiver is the reason for development of dedicated solutions...
- archive DWR of Aug. 20, 2007

Lossless splitting of cable TV signal for multi-room TV/video installations.
- archive DWR of Oct. 15, 2007

Index of published issues.
ULTISYSTEM - integration of analog cameras and IP devices <br />into one system
George Popescu
Consiliere clienţi
Dacă doriţi să primiţi Săptămânalul Dipol prin email, introduceţi adresa:
Nou în bibliotecă
Regulamentul | Reclamaţii | Download | Cookies | SitemapToate drepturile rezervate © 1996-2016 DIPOL sp.j.