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

Glasses that can recognize faces.

Face recognition technology is no longer present only in science fiction movies - it is already used in everyday life. Currently, the user's face can unlock their phone or be the boarding pass for an airplane flying from Boston to Aruba (JetBlue Airways). A novelty is the use of this technology by Chinese policemen who, using a camera attached to glasses, are able to identify people.

In addition to the special glasses, the Chinese system requires the police officer to carry a mobile device with offline database containing a collection of faces of wanted people. In such a configuration, the software could recognize seven wanted people and reveal several passengers who traveled under a false identity only at one municipal station.

A police officer using facial recognition equipment
(source: http://si.wsj.net)

The face recognition software developed for this application uses a two-step process. The first step consists in finding a face in the image, the second is responsible for comparing and matching characteristics of the face to ones contained in the database. The characteristics are numerical data sets obtained as the result of special algorithms. Over the last 10 years, face recognition algorithms have undergone significant development.

Of course, there is a key difference between using face recognition technology on a smartphone, where the user poses for the photo, and for the police, where such a solution should be capable of recognizing faces in a crowd. In the case of police systems, mistakes can cause serious consequences for the suspects. Artificial intelligence systems need a huge amount of data to learn how to correctly perform tasks and minimize mistakes. It seems, however, that there is no turning back from this road.

Maximum transmission range in Turbo HD 4.0 systems.

The newest HD-TVI Turbo HD 4.0 cameras can be connected to CCTV systems via relatively long transmission cables. The video and power can be transmitted by coaxial or twisted-pair cables. Of course, the maximum transmission range depends on the type of the cable. The fourth generation of HD-TVI cameras has transmission parameters identical with the 3rd generation, but much better than previous generations. Compared to the first generation, the maximum transmission distance is on average nearly two times longer. As an example, in the typical case with RG-59 E1041 cable and 1080p image resolution, the range has increased from 500 m to 800 m. A summary of the changes is shown in the chart below.

Comparison of transmission ranges of TurboHD 1.0 and 4.0
for different kinds of cables and image resolutions

As shown above, for TurboHD 4.0, 720p resolution and class A RG-6 cable, the maximum transmission distance is as long as 1200 m. This value is ca. 2.5 times higher than in the case of version 1.0.

Measurements of satellite and terrestrial TV/radio signals.

Signal levels are not the only parameters which must be taken into account in measuring digital TV and radio signals. At least equally important are MER Modulation Error Ratio (MER) and Bit Error Rate (BER). MER can be treated as a measure of the distance of the received signal to the digital cliff. Without knowing this parameter, the antenna installer cannot guarantee stable reception in adverse weather conditions or other situations when the signal can fluctuate (e.g. in DVB-T systems interfered by passing trucks). The confirmation of sufficient values of MER by measurements of this parameter will practically eliminate such risks. The third important parameter that should be taken into account, also when measuring DVB-T signals, is BER. This parameter is well known to all installers of satellite dishes and describes the quality of the received signal. It informs about the proportion of erroneous bits (caused by interference occurring in the transmission channel) in relation to all transmitted bits. All the measurements can be performed with the use of the new DVB-T/T2/C and DVB-S/S2 meter with built-in receiver, Signal WS-6980 R10837.

The WS-6980 R10837 meter measures satellite DVB-S/DVB-S2 (HD), terrestrial DVB-T/DVB-T2 (HD)
and cable DVB-C signals. The functions of the meter are clearly presented on color 7" TFT LCD display.

New Signal IP cameras with H.265+/H.265 video compression.

DIPOL has introduced two new models of Signal IP cameras with 2 MP resolution, HDV-200P K1817 (dome) and HDC-260P K1877 (compact/bullet). Each model is equipped with 2.8-12 mm varifocal lens (viewing angle adjustable within 90° - 26° range) and IR illuminator allowing for effective night operation. The cameras support both the new H.265+/H.265 and older H.264+/H.264 video compression standards. Thanks to the several video coding methods, the camera can be used both in IP CCTV systems based on modern Hikvision NVRs supporting H.265 standard (the DS-76/77NI-I, DS-76/77NI-K series support H.265+, H.265, H.264+, H.264), and those with older models supporting only H.264+/H.264 (DS-76/77NI-E series support H.264+, H.264). Both models of the cameras have IP66-rated housings suitable for outdoor operation and can be powered traditionally with a 12 VDC source or with the use of PoE option (802.3af).

Wireless access to the Internet in a school.

Wireless network in a school should provide access to the Internet throughout the school building and offer bandwidth sufficient for comfortable use of network services by students, teachers and administrative staff. The key factors in choosing the devices is their bandwidth and the maximum number of supported users. The Internet can provide easy and fast access to useful knowledge as well as to content that distracts the student's attention, so the school network should be subject to certain restrictions such as time windows, bandwidth, available content, etc.

The best practice for building this type of wireless network is to create several completely independent SSIDs (Service Set Identifiers) so that individual user groups connect to specific WiFi network. Such networks should be created for:

• students,
• teachers,
• administrative staff,
• guests after classes.

The most important thing is that the wireless networks are to be isolated - devices connected to one network cannot be visible to devices in other networks.

TP-Link EAP access points can be highly recommended for creating reliable and efficient Wi-Fi networks in the demanding school environments. The modern devices can be easily mounted to walls or ceilings. EAP Controller Software enables centralized configuration and management of the wireless network composed of multiple EAP devices. The functions include real-time monitoring, graphical analysis of network traffic and batch firmware updates.

An example of deploying TP-Link EAP EAP225 N2567 units in a building

Calibration of Signal Fire AI-8 fusion splicer.

The calibration of a fiber optic fusion splicer consists in adjusting the power and temperature of the electric arc to the prevailing environmental conditions. Properly adjusted arc parameters guarantee high quality of the splices, both in terms of optical attenuation and mechanical strength. Therefore, the calibration should always be performed before splicing operations - at the beginning of work or in the case of changing the environment (e.g. from indoor to outdoor part of a system, especially when the difference in temperature between the locations is high).

Signal Fire AI-8 L5870 fusion splicer uses popular calibration method - the fibers located in the splicing chamber are subjected to a number of electric arcs. The fibers are melted and the software of the splicer measures and analyzes the distance at which the fiber faces move backward. On the basis of the measurements, the splicer determines the appropriate parameters of the electric arc.

When the fibers (prepared as for normal splicing) are inserted into the splicing chamber and the cover is closed, the calibration process starts automatically. The whole procedure may take several minutes and sometimes should be repeated. When finished, the splicer switches to normal mode, i.e. is prepared for regular splicing operations. This fact is indicated by an icon on the display.

What are the requirements for computers used in Hikvision monitoring systems? An extensive monitoring system, in addition to standard cameras and DVRs/NVRs, may require additional devices such as hardware IP video and audio decoders (e.g. DS-6404HDI-T K2304) used for displaying HD video from IP cameras or encoders on multiple monitors or video walls, dedicated workstations running iVMS-4200 client application, or stream servers - Stream Media Server and Storage Server. The diagram below presents the architecture of such a system... >>>more

TRISET - coaxial cables for modern TV systems