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No. 18/2009 (May 4, 2009)
Devices of 802.11n standard (so far of its consecutive drafts) utilize MIMO technology - they use multiple antennas at both the transmitter and receiver to improve communication performance. The devices may operate in several channels which multiplies their transmission capacities. Channel Bonding (CB) simultaneously uses two separate non-overlapping channels. Depending on the manufacturer and the equipment, 802.11n devices operate in 2.4 GHz or 5 GHz band.
Another development of MIMO is Spatial Division Multiplexing technology, which - due to the possibility of sending a number of independent data streams using a single radio channel - significantly increases the throughput of data packets.
Another development of MIMO is Spatial Division Multiplexing technology, which - due to the possibility of sending a number of independent data streams using a single radio channel - significantly increases the throughput of data packets.
A reliable multimedia home-networking platform with pre-n devices of TP-Link
In the initial period of development, the "n-like" devices did not ensure mutual compatibility - it was possible to make full use of advantages of that technology only in the product range from one manufacturer.
Draft 2.00 (or "pre-n") moved the increasingly popular wireless networking technology a step further. Manufacturers and customers have been given reassurance that amendments to the final standard won't be essential, and the draft 2.0 gear will mutually cooperate as well as be compliant to the final version. In subsequent years there were released another versions: 2.07, 3.0, 4.0, and finally - on April 4, 2009 - draft 9.0. The anticipated date of ratification of the 802.11n standard is January 2010.
Draft 2.00 (or "pre-n") moved the increasingly popular wireless networking technology a step further. Manufacturers and customers have been given reassurance that amendments to the final standard won't be essential, and the draft 2.0 gear will mutually cooperate as well as be compliant to the final version. In subsequent years there were released another versions: 2.07, 3.0, 4.0, and finally - on April 4, 2009 - draft 9.0. The anticipated date of ratification of the 802.11n standard is January 2010.
Currently the market is still dominated by the devices identified as "pre-n" draft 2.0. They allow to reach real throughput around 90 Mbps (similar to Fast Ethernet). Recently the potential of this standard has been recognized by Apple, implementing 802.11n connectivity in new iPhone devices.
On the Wi-Fi Alliance website there is a list of certified products designed to operate in "pre-n" drafts.
On the Wi-Fi Alliance website there is a list of certified products designed to operate in "pre-n" drafts.
The latest TP-Link devices designed to operate in "n" standard
TV towers lost the distinction of highest buildings. Construction of the Burj Dubai tower in Dubai closed an era in which the world's highest buildings were television towers.
The highest TV towers have been built, as a rule, in countries with large areas, to ensure long-distance reception of television programs. The highest television tower - CN Tower (553 m) - has been built in Canada, the second-highest - Ostankino (540 m) - in Moscow, the third - Oriental Pearl Tower (468 m) in Shanghai, the next - Milad (435 m) in Tehran, and Menara (421 m) in Kuala Lumpur. Now that we see growing importance of satellite transmissions, it is no longer necessary to build expensive high towers.
Photos shown below are snapshots of the city in which already in 1998 the twin skyscrapers were higher than the local TV tower. So the construction of the high-rise towers was not an easy task, since the TV tower had been the fifth of the highest towers in the world.
Where is the twin tower visible in the picture? - Answer at the end of this issue.
The highest TV towers have been built, as a rule, in countries with large areas, to ensure long-distance reception of television programs. The highest television tower - CN Tower (553 m) - has been built in Canada, the second-highest - Ostankino (540 m) - in Moscow, the third - Oriental Pearl Tower (468 m) in Shanghai, the next - Milad (435 m) in Tehran, and Menara (421 m) in Kuala Lumpur. Now that we see growing importance of satellite transmissions, it is no longer necessary to build expensive high towers.
Photos shown below are snapshots of the city in which already in 1998 the twin skyscrapers were higher than the local TV tower. So the construction of the high-rise towers was not an easy task, since the TV tower had been the fifth of the highest towers in the world.
Where is the twin tower visible in the picture? - Answer at the end of this issue.
The high-rise towers seen in the picture were built in this city in 1998.
They are higher than the TV tower shown below - the fifth highest TV transmitter in the world.
The twin towers were the highest construction of the world in the years 1998-2004.
Where are the towers visible in the picture?
(Photo by J. Durych)
They are higher than the TV tower shown below - the fifth highest TV transmitter in the world.
The twin towers were the highest construction of the world in the years 1998-2004.
Where are the towers visible in the picture?
(Photo by J. Durych)
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The fifth highest TV tower of the world, built in 1996
Lossless splitting of cable TV signal. Multi-room reception of cable TV signal, as a rule, requires to use an amplifier to ensure signal levels between 62 and 80 dBuV. Most of antenna amplifiers cannot be used for this purpose, due to unspecified parameters in the special cable channels ("S" channels between VHF and UHF bands).
The void is filled by the RF amplifiers AWS-1145 B117028 and AI-223 R90452. Both amplifiers have been equipped with return channel that allows to use them in cable TV networks with Internet services. Gain adjustment is combined with correction of cable loss.
Maximum output level of these amplifiers is 100 dBuV and 105 dBuV respectively. It allows to feed up to 15 outlets. The condition of good reception is use of quality passive components and cables - we advise to employ Signal distributing devices and TRISET cable.
The void is filled by the RF amplifiers AWS-1145 B117028 and AI-223 R90452. Both amplifiers have been equipped with return channel that allows to use them in cable TV networks with Internet services. Gain adjustment is combined with correction of cable loss.
Maximum output level of these amplifiers is 100 dBuV and 105 dBuV respectively. It allows to feed up to 15 outlets. The condition of good reception is use of quality passive components and cables - we advise to employ Signal distributing devices and TRISET cable.
AI-223 R90452 is used as a signal distribution device, including cable TV networks
Television in Migrand hotel in Szczecin. After the refurbishment of the Migrand hotel, the guests can now use its refreshed interior with modern, bright, clean and cozy rooms.
The investor has also modernized satellite TV installation.
The implementation was done by Elmus company. It used equipment of the world leading manufacturers - TERRA and ALCAD.
The installation employs digital TERRA MMH-3000 headend - dedicated for use in hotels, boardinghouses, and apartment buildings, and ALCAD ZG channel amplifiers. ALCAD high-end amplifiers are designed for distributing terrestrial TV signals in small, medium and large installations.
The installation fully meets the requirements of the investor.
The author has won "Chameleon mug".
How to get "Chameleon mug"?
The investor has also modernized satellite TV installation.
The implementation was done by Elmus company. It used equipment of the world leading manufacturers - TERRA and ALCAD.
The installation employs digital TERRA MMH-3000 headend - dedicated for use in hotels, boardinghouses, and apartment buildings, and ALCAD ZG channel amplifiers. ALCAD high-end amplifiers are designed for distributing terrestrial TV signals in small, medium and large installations.
The installation fully meets the requirements of the investor.
The author has won "Chameleon mug".
How to get "Chameleon mug"?
TERRA headend in Migrand hotel in Szczecin
Residential monitoring - part 2. In the previous issue we described the architecture of residential monitoring based on IP networks. However, the most common solution, especially in single buildings, is use of antenna installation.
In the diagram below, analog CCTV signals drive RF modulators MT-21P R871721 that provide RF signals at desired TV channels. The signals are amplified by ZG channel amplifiers that also eliminate unwanted modulation products and allow to set output levels identical with regular TV programs. Very high amplification coefficient (53 dB) and output levels (up to 2 x 123 dB) are out of the range of any broadband amplifier.
The distribution network shown below uses splitters and taps. The taps in the distribution branches properly isolate the equipment of individual subscribers, lowering interference levels.
In the diagram below, analog CCTV signals drive RF modulators MT-21P R871721 that provide RF signals at desired TV channels. The signals are amplified by ZG channel amplifiers that also eliminate unwanted modulation products and allow to set output levels identical with regular TV programs. Very high amplification coefficient (53 dB) and output levels (up to 2 x 123 dB) are out of the range of any broadband amplifier.
The distribution network shown below uses splitters and taps. The taps in the distribution branches properly isolate the equipment of individual subscribers, lowering interference levels.
Control of PTZ cameras via UTP/FTP cable. In extended CCTV systems there is a necessity of transmitting video signals over long distances (over 200m). The task can be accomplished using coaxial cables and video amplifiers (e.g. M1840). However - in the case of even longer distances (up to 1000 m) and application of PTZ cameras - the best solution is use of UTP/FTP cable as the transmission medium and an appropriate equipment.
The diagram below presents such a solution based on Active Video/Audio/Data Transmitter and Receiver M1678 and M16741. The set ("UTP transceiver") allows to transmit video, audio and data (e.g. RS-485 signals controlling PTZ camera) via typical twisted pair cable (UTP/FTP/STP - 4 pairs). The micro switch in the transmitter allows to choose one of three levels - low (L), medium (M) or high (H), depending on the distance (from several meters to 1.2 km). The set is often used in superstores, warehouses etc. where PTZ cameras allow to monitor interesting objects.
The diagram below presents such a solution based on Active Video/Audio/Data Transmitter and Receiver M1678 and M16741. The set ("UTP transceiver") allows to transmit video, audio and data (e.g. RS-485 signals controlling PTZ camera) via typical twisted pair cable (UTP/FTP/STP - 4 pairs). The micro switch in the transmitter allows to choose one of three levels - low (L), medium (M) or high (H), depending on the distance (from several meters to 1.2 km). The set is often used in superstores, warehouses etc. where PTZ cameras allow to monitor interesting objects.
Control of PTZ camera via UTP/FTP cable
Protection of video surveillance system based on IP network. The basic mistake made by some installers or servicemen at the stage of starting up or maintaining IP CCTV system is preservation of the original (default) logins and passwords of the IP CCTV devices, such as IP cameras, video servers, video decoders/transcoders. It allows to sabotage the system by unauthorized access - change of the settings made by an intruder will enable them to control the system or make it dysfunctional. Especially dangerous is unauthorized change of IP addressing, eliminating support of the devices by NVR software, which will effect in loosing video and sound from the cameras.
The installer or serviceman should also protect other network devices, such as routers, access points, manageable switches etc. In the case of using wireless networks (e.g. based on ULTIAIR devices) it is indispensable to configure data encryption (WEP, WPA, WPA-2).
If the IP CCTV network is to be connected with other internal network (the CCTV system uses the internal network), it is recommended to separate them with a router, similarly to data communications via the Internet. It will block unauthorized access to the IP CCTV network from the internal network.
Another step is configuring security options of NVR (if used). Majority of video surveillance programs (ULTISYSTEM, NUUO) have advanced protection procedures accessible via dedicated configuration window. NVR software usually allows to set access rights at the level of elementary system functions (video and audio channels, archives, alarm inputs and outputs, PTZ control, system configuration).
The last important issue is protection of the operating system against any interference. It is possible to block access to the system shell (explorer, shell) from NVR software level. This can also be done from the system console, but this method requires knowledge of more advanced features of the operating system.
The installer or serviceman should also protect other network devices, such as routers, access points, manageable switches etc. In the case of using wireless networks (e.g. based on ULTIAIR devices) it is indispensable to configure data encryption (WEP, WPA, WPA-2).
If the IP CCTV network is to be connected with other internal network (the CCTV system uses the internal network), it is recommended to separate them with a router, similarly to data communications via the Internet. It will block unauthorized access to the IP CCTV network from the internal network.
Another step is configuring security options of NVR (if used). Majority of video surveillance programs (ULTISYSTEM, NUUO) have advanced protection procedures accessible via dedicated configuration window. NVR software usually allows to set access rights at the level of elementary system functions (video and audio channels, archives, alarm inputs and outputs, PTZ control, system configuration).
The last important issue is protection of the operating system against any interference. It is possible to block access to the system shell (explorer, shell) from NVR software level. This can also be done from the system console, but this method requires knowledge of more advanced features of the operating system.
Window for configuring access rights in ULTISYSTEM
Adjustment of AGC level. Automatic Gain Control is implemented in many CCTV cameras but only more advanced models enable the user to adjust its level. This adjustment allows to set optimum sensitivity in difficult light conditions. The user should realize that higher gain increases noise as well. Optimum AGC level is usually determined by trial and error approach. Below we show influence of AGC level on image quality for ACTi ACM5611 camera (K1512). This function has been implemented in all megapixel cameras from ACTi.
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Incorrect AGC level | Optimum AGC level |
An ideal router for ADSL service - TP-Link TD-8840T N2907. ADSL (Asymmetric Digital Subscriber Line) is probably the most common service providing access to the Internet. Router integrated with ADSL modem and connected directly to the telephone line (using R11 connector) allows to share the service among several users.
TP-Link TD-8840T N2907 is designed for sharing ADSL service. It has built-in ADSL/ADSL2/ADSL2+ modem and 4-port switch. The WAN port (RJ11) is prepared for direct connection to telephone line. The device can work as DHCP server which enables the user to easily create internal network. The router can be easily managed via any browser or by using the included TP-Link software. TD-8840T ensures high stability of operation.
TP-Link TD-8840T N2907 is designed for sharing ADSL service. It has built-in ADSL/ADSL2/ADSL2+ modem and 4-port switch. The WAN port (RJ11) is prepared for direct connection to telephone line. The device can work as DHCP server which enables the user to easily create internal network. The router can be easily managed via any browser or by using the included TP-Link software. TD-8840T ensures high stability of operation.
Advantages of TP-Link TD-8840T N2907 ADSL router:
- direct connection to phone line
- simple configuration
- built-in DHCP server
- 4 LAN ports
Home LAN network using ADSL service, based on TP-Link router
IP video surveillance of roadside gas/petrol stations, stores, cafes etc. Such places, distant from cities, are more vulnerable to criminal acts. Parking lots that are indispensable for the customers are often quite large, which makes it difficult to install a wired CCTV system. The problem can be solved by using wireless transmission based on dedicated ULTIAIR devices and IP cameras managed by ULTISYSTEM software.
Below we show the idea of IP video surveillance of such a roadside place:
IP video monitoring of gas/petrol station
Digital video streams from the three K1511 cameras are wirelessly transmitted via ULTIAIR devices (319KC - N2310) to the monitoring center equipped with ULTIAIR 417SB N2330. High transmission speed of ULTIAIR devices allows both seamless live monitoring and recording of the video with ULTISYSTEM software.
The system consists of:
Aesthetic DVD shelf. DS-101 E9660 shelf has been designed for holding home devices like DVD player/recorder, sat receiver, set-top box etc. Maximum capacity is 20 kg. Glass shelves are made of tempered glass of 8 mm thickness. The support has been made of aluminum - it is light and very stable. Cable management system allows to hide connecting cables.
Flat panel wall mounts/arms, projector mounts...
Flat panel wall mounts/arms, projector mounts...
DS-101 E9660 shelf for holding home devices
like DVD player/recorder, sat receiver (click on to enlarge)
like DVD player/recorder, sat receiver (click on to enlarge)
Kuala Lumpur - Malaysia. Kuala Lumpur ("muddy confluence" in Bahasa Melayu language) - capital and largest city of Malaysia, in the central part of the Malaysian Peninsula. Kuala Lumpur has its origins in the 1850s, when the Malay Chief of Klang, Raja Abdullah, hired some Chinese laborers to open new and larger tin mines. They landed at the confluence of Sungai Gombak and Sungai Klang (Klang River) to open mines at Ampang.
The city of an area of 244 km2 has an estimated population of 1.6 million (2006). Greater Kuala Lumpur, also known as the Klang Valley, is an urban agglomeration of 7.2 million. It is the fastest growing metropolitan region in the country, in terms of population as well as economy (yearly growth rate above 10%).
The city of an area of 244 km2 has an estimated population of 1.6 million (2006). Greater Kuala Lumpur, also known as the Klang Valley, is an urban agglomeration of 7.2 million. It is the fastest growing metropolitan region in the country, in terms of population as well as economy (yearly growth rate above 10%).
(Source: Wikipedia)
We have written about:
Connectors for multiswitch systems. The connectors used in multiswitch installations make up a small part of the overall costs, but are very important for signal quality, reliability of the system, and - last but not least - they condition labor consumption during the installation work...
- archive DWR of Jan. 28, 2008
Active video transmitters. Doing a CCTV installation it is often convenient to use thin cables. Sometimes there are needed long cables, over 150 meters...
- archive DWR of Jan. 21, 2008
The significance of connectors in CCTV systems. Every connector, even the best one, causes degradation of the signal. The basic rule is minimizing the number of connections in the transmission channel. Usually manufacturers of connectors give two important parameters describing loss of signal...
- archive DWR of Oct. 6, 2008
Index of published issues
Connectors for multiswitch systems. The connectors used in multiswitch installations make up a small part of the overall costs, but are very important for signal quality, reliability of the system, and - last but not least - they condition labor consumption during the installation work...
- archive DWR of Jan. 28, 2008
Active video transmitters. Doing a CCTV installation it is often convenient to use thin cables. Sometimes there are needed long cables, over 150 meters...
- archive DWR of Jan. 21, 2008
The significance of connectors in CCTV systems. Every connector, even the best one, causes degradation of the signal. The basic rule is minimizing the number of connections in the transmission channel. Usually manufacturers of connectors give two important parameters describing loss of signal...
- archive DWR of Oct. 6, 2008
Index of published issues
