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

Ultra-fast data recording.

Polish scientists from Faculty of Physics, University of Bialystok, in cooperation with Dutch team of physicists from Radboud University, have developed a method of ultra-fast recording of information with a potential use in computer disks. The ultra-fast non-thermal (cold) all-optical photo-magnetic recording has been demonstrated in transparent films of dielectric cobalt-substituted garnet, with the use of single linearly polarized femtosecond laser pulses with different polarizations.

The team has shown that there is a non-conductive material (yttrium iron garnet doped with cobalt ions, YIG:Co), in which the state of magnetization can be changed using the ultra-short light pulses. Moreover, the process is reversible. A laser pulse changing the state of magnetization means rapid switching of the corresponding binary state. This way, information could be recorded on computer disks thousand times faster than today.

(source: naukawpolsce.pap.pl)

SMATV system in an apartment building.

Multiswitch installations in multifamily buildings must be carefully designed. In the calculations, the input parameters include network topology, type and number of the multiswitches, the type of cable used (attenuation) and the lengths of its sections. The designer has to select the system components so that signal levels in all antenna outlets are within the recommended range.

Below we present a design of such a system created with the use of SatNet software. The system in a residential building with 64 apartments situated on four floors in 4 staircases, is based on TERRA multiswitches of MV-9XX series with die-cast housings having increased screening efficiency (class A). The signal lines are split for the subnetwork in each staircase with the use of 9-path SAT/TV splitters splitters and SAT/TV taps with appropriate attenuation levels.

Do not attempt mixing PC and APC connectors.

Despite several reasons why UPC and APC connectors should not be mixed (PC and APC connectors - are they exchangeable?), some installers employing devices with high power budgets do not pay attention to this issue. It may happen, however, that the excessive attenuation will not allow any transmission.

A simple test verifying the approximate value of the attenuation of such incorrect connection has been conducted. For this purpose there have been employed light source Grandway L5825 and optical power meter Grandway L5821. The measuring system was calibrated using two L3213 patch cords and L4211 adapter. Then, another L4211 adapter was added to connect in series the L3211 patch cord terminated on both ends with SC/PC connectors. The steps are shown in the following figures.

Calibration of the measuring system

The L5825 Grandway light source generates laser bream at a constant power level of -5 dBm. The measurements were made at a wavelength of 1310 nm. During calibration, the meter indicated signal level of -5.20 dBm. This value was the reference point for measuring the attenuation of patch cords. After plugging in the SC/PC - SC/PC patch cord with a length of one meter, the meter showed the result of -5.66 dBm. This meant that the measured attenuation of the patch cord was 0.46 dB.

After plugging in the L3222 SC/APC - SC/APC patchcord instead, the level measured by the meter dropped dramatically. The reading of -12.34 dBm meant that the attenuation of the connection was as high as 7.14 dB. In order to confirm the result, the measurement was repeated for another L3222 patch cord - the reading was very similar.
The high attenuation is caused by air gaps between the ferrule end faces of the PC and APC connectors, strongly attenuating the transmitted signal. Due to very high reflectance of the connections, a significant portion of the signal is reflected back to the transmitter, and only a small part of it is transmitted further. With the measurement based on transmission method, the reflected signal returning to the light source does not cause any harm. A high risk of damage to the connections is, however, caused by the mechanical incompatibility of the ferrule end faces.

Updated HD-TVI DVRs can support 3 MP cameras.

The 3.4.80 firmware version of some Hikvision DVRs provides support for a limited number of 3 MP HD-TVI cameras. It applies to models that support 1080p cameras, and the number of the 3 MP cameras is limited according to the number of channels:

A video surveillance system with two 3-megapixel cameras used for monitoring outdoor area,
where the higher resolution is essential

The 3 MP cameras must be connected to low-numbered inputs (1, 2, 3 etc). The maximum frame rate is 12 fps. The 3 MP resolution (1920x1536) increases the quality of the recorded images. Compared with the normally supported 2 MP cameras, the increase in resolution takes place in vertical axis. The Hikvision HD-TVI DVRs also support AHD and HD-CVI cameras with resolutions up to 1080p.

Integration of intelligent functions of IP cameras and PTZ camera.

Hikvision IP cameras from budget series allow for intelligent image analysis in the form of detection of virtual line crossing and area intrusion. The functions can be activated and configured after logging in to the camera with the use of the iVMS-4200 client software or directly from a Hikvision NVR. The virtual line crossing and area intrusion detection can be used to detect people, vehicles and other objects. In response to the crossing of the line in a defined direction or intrusion into a defined area, the system can inform about the event, trigger video recording or alarm output, send an email, etc. These events can also be linked with PTZ camera in order to trigger preset, patrol or route.

The system presented below employs 10 compact IP cameras Hikvision DS-2CD2022WD-I K17638 and one PTZ camera DS-2DE7187-AE K1796. The cameras are connected to the DS-7616NI-E2/A K22161 NVR that allows for video recording and integration of the intelligent functions of the IP cameras and the features of the PTZ camera. The PTZ camera has been mounted in the middle of the housing development, to enable detailed observation of any part of the inner area. The compact IP cameras installed inside the area have been setup so that they use the line crossing or area intrusion detection function. Any of the events triggers a specific preset defined in the PTZ camera, i.e. monitoring of the corresponding part of the area with defined parameters, including zoom. As a result, the PTZ camera can provide additional information with a wealth of detail.

IP video surveillance system using intelligent functions of compact cameras and special features of PTZ camera

In the case of detecting several events in a short period of time, the PTZ camera handles the first one only. Much more advanced analytical tools are available in Hikvision IP cameras from professional series. They include face detection and, in the case of PTZ cameras, object tracking.

Powering IP cameras with the use of 802.3af standard.

Power supplying of IP CCTV cameras becomes frequent task for installers of security systems. With the use of PoE technology (Power over Ethernet), the installation work can be easier. The best PoE solution seems to be the integration of switching and powering functions, i.e. the application of switches with PoE functionality.

N29980 PoE switch can power four IP CCTV cameras. Its fifth port should be connected to an NVR.

The N29980 PoE switch ensures connection to an NVR of four IP cameras,
with video and power transmission over the same cables

LAN in two buildings - distance of 200 m. The best way to create one LAN network in two buildings located at a distance of 200 meters is the application of fiber optic cable. The use of twisted pair cable over such a distance would not comply with applicable standards and would result in a significant reduction of the throughput of the LAN... >>>more

An implementation of optical link in the case of 200-meter distance between buildings

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