DIPOL Weekly Review - TV and SAT TV, CCTV, WLAN
Quality of CCTV systems.
British Home Office have published a report on the quality of security systems based on CCTV. It says that eight images out of ten supplied to the police from CCTV systems do not help to identify criminals. The main reasons are:
- obsolete equipment,
- inadequate quality of devices,
- faulty deployment of cameras.
Home Office also draws attention to the problems caused by various standards of digital recording, which are great impediments to the police.
Many problems are the result of vague evaluation criteria used in the nineties.
The report has a few dozen pages and is the effect of 18-month work program. Its critical overtones should help to increase effectiveness of monitoring systems. It also provides guidelines for technical and organizational development of video surveillance systems. But at the same time the authors emphasize that CCTV helped to avoid many threats, and there were a large number of cases, including the perpetrators of explosions in London underground, where monitoring systems allowed to apprehend the offenders.
The report also provides statistical data on video monitoring systems in Great Britain. There are about 4.2 million cameras in Britain. In London, it is estimated that - on average - an individual may be recorded daily by over 300 different cameras. Great Britain has been gaining experience in this field since the seventies. Despite the above reservations, the solutions used in this country are recognized as a model.
All underground escalators are watched
The surveillance center at one of the underground stations
Wild imagination - where is the tower?
The owner of this villa, in order to receive TV programs properly, had to put up a mast. Giving free rein to his imagination, he built this miniature of the Eiffel Tower.
However, there is seen certain additional invention, the simple grating has been replaced by geometric designs (the circular elements creating a mosaic).
Will it help to find the whereabouts of the tower?
The answer at the end of this issue.
Miniature of the Eiffel Tower on a villa (picture by W. Kocot)
Ferguson 6600 sat receivers
. The Ferguson family has increased recently. The two receivers, 6600 CK A99235
and 6600 2CK A99236
, are equipped with built-in universal UCAS modules, supporting all systems that not require pairing of the module and the smart card (pairing is necessary e.g. for Polish digital Polsat).
The built-in module allows to decode e.g. Cyfra+ (having the card), the entitlements are transferred.
Ferguson 6600 CK has one UCAS module, the 6600 2CK - two modules. Both receivers have Component Video outputs (very useful for connecting large screen televisions).
Antenna system with distribution of CCTV.
The installation has been built with use of AWS-1030 B11583
amplifier equipped with 4 inputs: BI-FM/BIII/2xUHF. Three inputs are connected with terrestrial FM/TV antennas, the second UHF input takes the signal modulated by video from CCTV camera. Unquestionable advantage of this solution is application of amplifier that eliminates the need of using antenna diplexer, improving C/N parameter. If UHF signals are too low, there may be used additional preamplifier, e.g. AP-103M B4033
. An important feature of SilverLine
, devices (including AWS-1030) is solid metal housing which perfectly shields the internal circuitry from external interferences.
Professional IP monitoring system in MZK Kedzierzyn-Kozle based on PiXORD P400 cameras.
Miejski Zaklad Komunikacji (municipal transportation agency) in Kedzierzyn-Kozle, Poland, have been using professional monitoring system equipped with 16 IP cameras, for several months now. The system has been installed in bus depot and monitors the whole ground and the buildings.
The system consists of 16 IP cameras PiXORD P400 K1131
and dedicated recording computer. The installation uses UTP E1508
cable, 8-port and 5-port switches (TP-Link TL-SF1008D N29918
and TP-Link TL-SF1005D N29915
). The computer is managed by PiXORD P6032 software package. The images from each camera can be watched and recorded with Full D1 resolution at 25 fps, allowing detailed analysis and perfect smoothness.
Designing IP CCTV systems it is important to pay closer attention to compatibility of the cameras and recording software. DIPOL
offers support for installation companies in the fields of equipment selection, system configuration (computer with dedicated software), and pre-installation test of IP-based monitoring systems: PiXORD
Pixord cameras installed in bus depot of MZK in Kedzierzyn-Kozle
The winners choose ACTi.
The winner of 32nd America's Cup sailing regatta - Alinghi crew - used at their yacht water-proof analog cameras and 2-channel video server of ACTi
, to monitor on the screen of the deck computer the current situation below the surface of the see. The software for visualization was prepared by a team of engineers using SDK (Software Development Kit) for ACTi devices.
The winning Alinghi yacht uses ACTi devices
Powering of CCTV systems.
The manufacturer of YAR 75-0.59/3.7+2x0.50 M5995
cable guaranties that the resistance of power wires is not higher than 3.7 ohm/100 m. Typically, the current consumed by a camera is between 150 and 500 mA. Assuming the worst case and permissible voltage drop of 1 V, according to Ohm's law the maximum resistance of the supplying loop can amount to 2 ohm. So the length of the YAR cable providing 0.5 A cannot exceed 27 meters. In the case of using thermostat with 12 V heater, e.g. M5614
, the distance is much shorter.
A solution to this problem can be use of cables with larger cross section, which is expensive, especially in the case of long lines. More elegant and economical solutions are provided by application of adjustable power supplies or special "powering systems" using much higher "input" voltage and additional power regulators at each camera.
Size of an object on monitor screen.
According to EN 50132-7 norm, the size of the representation of an object, e.g. human figure should be strictly connected with the aim of the operator - identification, recognition, detection or general observation. For CCTV systems having resolution better than 400 TVL, the representations of human figures should not be smaller than:
- identification - 120% of screen height;
- recognition - 50% of screen height;
- intrusion detection - 10% of screen height;
- crowd control - 5% of screen height.
The size of human figure on monitor screen as a function of the aim of monitoring system
Installation of cables in winter conditions.
During winter, at temperatures below 0 deg Celsius, one needs to be very careful with laying signal cables. The coaxial, UTP, FTP, telephone, or powering cables should generally be laid above 0 deg C. When the temperature is lower, the cable has to be heat up in a room, and laid as quickly as possible (its temperature during the operation has to be usually above 0 deg C). Otherwise the sheath of the cable looses flexibility and can be easily damaged. It is typical feature of plastics. Warranty terms and conditions do not cover such damages. The cables that are properly installed can be used in sub-zero temperatures without any negative impact.
The limit temperatures at which the cable can be operated/stored are marked as minimum and maximum operating/storage temperature. The minimum temperature at which the cable can be installed is called minimum installation temperature.
Handling a cable we have to know these parameters - e.g. cables designed for equatorial climate are made of different plastics.
Quality RF cables: TRISET
can be stored and operated at temperatures within the range of -40...+70o
C, and installed above -5o
Operation modes of Access Points.
Access Point can be operated in several different modes. Each mode allows for performing specific functions in the network. Before purchasing certain model one should check availability of the modes that are essential for the anticipated application.
Operation mode of AP
Service for wireless clients
Mode of work of cooperating device
Repeater, AP client
The picture of the house with "Eiffel Tower" on the roof has been taken in Amman, the capital of Jordan.
Roman amphitheater in Amman (picture by W. Kocot)
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