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

OOFDM - super-fast network for next to nothing.

British scientists from Bangor University have developed a method to increase the data transfer rates via fiber optic cables. They reached a download speed of 20 Gbps, which is at least 20 times greater than the fastest speeds offered to subscribers by some ISPs. The researches from the Welsh university are convinced that they can achieve even up to twice this data transfer rate. The most important advantage of the new technology is no need to replace the cabling infrastructure or increase the number of fibers.

A visualization of multiplexed signals in an optical fiber

The solution seems rather unexpected. The scientists adopted well-known mechanisms used in ... wireless networks. The secret of their success is based on the use of OFDM modulation for optical signals to get OOFDM (Optical Orthogonal Frequency Division Multiplexing). OFDM modulation is commonly used in DVB-T, ADSL, and Wi-Fi applications. It allows extremely efficient use of the available bandwidth, ensuring high flexibility and robustness. The researchers have succeeded in adapting this modulation scheme to optical signals.

In 2011, the average download speed in the world amounted to 4.6 Mbps. However, more and more services move to the Internet or are gaining increasing popularity, especially IPTV, social networking, online gaming, video sharing, video-on-demand, and various applications running on the cloud. This dramatically increases the demands for higher data rates. The 40 Gbps rate promised by the scientists from Wales would ensure reserves for many years, maybe decades. The project attracted the attention of research institutes and industry, and will be implemented in collaboration with Fujitsu Semiconductors Europe, Finisar Israel, Fraunhofer Heinrich Hertz Institute and VPIsystems GmbH.

How to connect single-mode and multimode fibers?

The task of the installer was to combine optical networks in two buildings. In one of them, the network installed a few years ago was based on multimode fibers, the second building was equipped with single-mode fibers. The both networks operated at 1000 Mbps and the link between the buildings was not to be a "bottleneck" restricting the bandwidth.

ULTIMODE MT-202G L1573 converts optical signals between single-mode and multimode networks

The simplest solution was to use optical media converter (SM - MM) Ultimode MT-202G 1310 L1573 (1310 nm), without a need for any additional switch or other active devices. The throughput of the ULTIMODE MT-202G 1310 media converter is 1000 Mbps. In the case 10/100 Mbps networks, the proper choice would be ULTIMODE MT-202M 1310 L1521.

Amplification of DVB-T signals in MATV/SMATV systems.

Shared antenna systems in multi-dwelling units, hotels, hospitals etc. with tens or hundreds of outlets should not use broadband amplifiers at their inputs i.e. just after the antenna array. It is recommended to use channel amplifiers allowing for equalization of the levels of the received channels (multiplexes).

The main advantages of both paths of the twin channel amplifier Terra at420 R82510 include automatic gain control (AGC) and ultra selective SAW (Surface Acoustic Wave) filters. The diagram above well illustrates the effects of the filters. Thanks to high selectivity, Terra at420 R82510 amplifiers can be used even for distribution of DVB-T multiplexes on neighboring channels.-

Monitoring of UPS.

PowerPanel Business Edition free software has been designed for CyberPower N9705 and N9714 uninterrupted power supplies. The software consists of three modules: Agent, Client, Center.

The logical division of devices running Client, Agent, and Center modules of the PowerPanel software

The Agent module is responsible for monitoring and configuring the UPS, and for the computer's power management system. The computer running this module can be connected to the UPS with the use of a USB or serial port. The application records the status determined by power supply events/changes and, in response, triggers necessary actions (such as turning off the computer, sending notification). The functions of the module include UPS configuration and resetting, setting shutdown schedule, sending information on power failure by e-mail, SMS, etc.

The Client module receives status information from the Agent module or the UPS (via optional NIC). In the event of a power failure it can turn off the computer on which is installed.

The Center module can establish a network connection to any computer running Agent or Client module or directly to UPS. It can also record events and trigger suitable actions.

Wireless IP CCTV system.

The basic requirement for creating effective distributed video monitoring system with recording and supervision points is a reliable video transmission system. A lot of flexibility is provided by IP cameras cooperating with separate access points e.g. N2301, N2311. The access points can be placed on roofs, which is not possible in the case of using cameras with built-in APs. In addition, the application of the access points operating in 5.15-5.75 GHz band eliminates potential interference problems that may occur in the congested 2.4 GHz band.

The architecture of a wireless IP CCTV system based on Sunell cameras and ULTIAIR APs

The above diagram shows a wireless video surveillance system based on K1630 and K1680 Sunell cameras managed by a monitoring center with server running NUUO software. The main functions of the software include:

Image analysis functions implemented in the software greatly facilitate the work of the system operator.

Installing wireless link between locations without line-of-sight.

In many situations it is impossible to achieve a direct link between two locations that should be wirelessly connected. However, the lack of line-of-sight does not eliminate wireless technology. In most cases the solution is to create an intermediate node. The transmission path is a combination of two point-to-point links, where the second begins at the point where the first ends. The devices creating the intermediate node (that are usually located side-by-side) can be connected directly via Ethernet cable.

How to reduce video archiving costs? NAS servers enable data archiving in Windows and Unix systems, using e.g. SAMBA or NFS protocols. The total size of memory allocated for data recording depends on the capacity of the hard drives used, their number and the type of RAID array... more

The architecture of an IP CCTV system based on NAS server

How to combine DVB-S and DVB-T signals? Many owners of one-family homes prefer antenna installations that distribute terrestrial and satellite TV signals via a single cable. The best solution is to combine the signals from the receiving antennas at the input of the RF distribution system which usually feeds several outlets located in different rooms. Despite the fact that these signals are transmitted in different bands, they cannot be combined using simple RF splitters/combiners... more

An example of a small antenna system distributing signals to three outlets

CCTV at a vehicle inspection station. fter nighttime theft, the owner of a vehicle inspection station decided to install a video surveillance system. For this goal, he identified three areas from which the images should be of high quality, both day and night... more

Schematic layout of the cameras in the vehicle inspection station