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No. 11/2017 (March 13, 2017)
Power supply through the air.
Disney Research has converted a room into a space able to charge any home devices and cellular phones. There, it is possible to wirelessly distribute power of ca. 1900 watts. The charging efficiency may range from 40% to 95%, depending on the position of the powered device.The system consists of aluminum panels installed on the ceiling and walls, conductive floor, and a long copper tube with a gap bridged by a set of capacitors, located in the center of the room. The system is powered by a drive coil located in the room and connected to an RF generator with high power amplifier. The frequency of the generator is set to the resonant frequency of the system, 1.32 MHz. The system uses the idea of quasistatic cavity resonance (QSCR) to generate magnetic field circulating around the tube and filling up the whole space inside the room.
Wireless power distribution in the Disney's room
A device (receiver) located in the room is powered/charged when the position of its receiving coil is perpendicular to the magnetic field lines. This condition can be overcome by using an array of three orthogonal coils, so a unit with such an array can be powered regardless of its position. The maximum power levels used in the system should take into consideration the safety margin defined by the allowable Specific Absorption Rates (SAR), being the measure of power absorption by biological tissues. The future will show whether the work of Disney Research is to be reflected in everyday life or to become another fairy-tale vision...
MATV systems for reception of DVB-T in areas with difficult conditions.DVB-T signal regeneration is possible when a single receiver connected directly to the antenna allows a relatively trouble-free reception of digital broadcasts. As the minimum parameters (reception threshold), one can accept the MER of 26 dB and BER of 1E-2. In low-signal areas, it is essential to select a high-gain antenna. However, if the bit error rate (BER) and modulation error rate (MER) are close to the reception threshold, the use of channel amplifiers or frequency converters may be ineffective. In such conditions, the distribution of the DVB-T signal to a great number of users is possible after its regeneration. The regeneration process consists of receiving the DVB-T signal, demodulating it to the transport stream, and then re-modulating RF signals as a new COFDM multiplex (frequency converter function). The regenerated signal can then be distributed to tens or even hundreds of outlets. TERRA TTX-420 R81616 transmodulator is used for reception of DVB-T/T2/C signals and for change of their parameters (regeneration, filtering, retransmission in different RF channels etc.) according to the needs of the project. The device can receive whole sets of channels from two free-to-air DVB-T/T2/C multiplexes, and convert them into two neighboring DVB-T multiplexes with maximum data rate allowed by the DVB-T standard, i.e. 31.68 Mbps. In practice, each multiplex can carry 6 SD channels or 2-3 HD channels. The administrator of the system selects the required channels from the satellite input streams and forms two DVB-T multiplexes. Alternatively, one DVB-T multiplex can be programmed from channels coming from two different DVB-T/T2/C multiplexes. The device can operate in two modes::
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Wiring an Ethernet cable connector.
Twisted-pair (balanced) cables are used to transmit signals in telecommunication systems and computer networks. Currently they are mainly used in analog telephony and Ethernet networks. Twisted-pair cables may consist of one or more pairs. The twisting strongly reduces the influence of external electromagnetic interference and mutual interference between the pairs, called crosstalk.There are two basic termination (pinout) options for 100Base-T networks:
- T568B (more popular)
- T568A
If the two sides of the cable are terminated in the same way, it will be a straight-through cable, often called a patch cable. Otherwise, it will be a crossover cable. Straight-through cables are used to connect computers/peripherals to networking devices such as hubs and switches, while crossover cables are usually used to create a direct connection between two computers.
Green cable - T568A pinout on both ends
Blue cable - T568B pinout on both ends
Red cable - T568B and T568A pinout - crossover cable
Blue cable - T568B pinout on both ends
Red cable - T568B and T568A pinout - crossover cable
Checking the continuity of fiber optic cable using a reflectometer.
The stage of laying cables is always one of the most time-consuming, and thus costly phases of each installation. In the case of fiber optic cables, they can be easily damaged by incorrect transport or storage (microbending), so it is particularly important to check them before installation in cable ducts, jointing chambers, walls, etc.Theoretically, a cable can be checked using a light source and power meter, but usually it is difficult to implement this method because of the lack of access to the other end of the cable wound on the drum. In such a situation the proper technique is to use a reflectometer. It is enough to weld a pigtail to the free end of the cable and connect the reflectometer. Due to the fact that there is a certain event dead zone (the minimum distance after which a reflection can be detected by the reflectometer), the first several or so meters of the cable could not be verified. For this reason one should connect in series an additional cable run with the necessary length.
The whole process of checking the cable on the drum takes a few minutes and allows the installer to avoid the disastrous deployment of a damaged cable. The following figure shows an example of reflectometric measurement of a 500-meter section of optical fiber wound on a drum. This cable was probably damaged at the stage of production.
Verification of fiber optic cable on a drum with the use of Grandway FHO3000-D26 L5828 optical time-domain reflectometer. Visible big damage around 348 meter. The application of the cable in an optical link would probably result in the necessity of its replacement.
Automatic backup of recordings.
Remote backup utility developed for Hikvision devices allows for copying recordings from DVRs/NVRs and cameras to hard drives in computers via LANs. The function can be switched on manually or automatically, according to a schedule.Main features of the program:
- backup of up to 32 channels,
- adjustable data rate (bandwidth),
- built-in player.
The main window of the Remote Backup utility
H.264+ video compression in Hikvision cameras.
Due to the emergence of CCTV cameras with higher and higher resolutions, the generated data streams continually grow and occupy more and more space on hard drives. For example, a 1 TB hard drive can store continuous recordings from 22 days, captured by a 2-megapixel camera with recommended bitrate of 4096 kbps (CBR) and 25 fps refresh rate. In the case of a 5-megapixel camera and the recommended bitrate of 9216 kbps (CBR), the same refresh rate of 25 fps and continuous recording, the storage capacity is reduced to approx. 9 days.Taking into account the fact that the H.264 codec was not created and optimized for video monitoring and the problems connected with the increase of the demand for bandwidth and storage capacity in the case of modern cameras, Hikvision has developed a new way of video encoding, H.264+. The algorithm is based on H.264 compression, but optimized for video surveillance. The results are very good, ensuring reduction of the data streams by 50-70%, while maintaining the same image quality compared with the H.264 codec.
Cameras with H.264+ video compression
Cameras with H.264+ video compression
Comparison of H.264 with H.264+
(source: youtube.com)
(source: youtube.com)
 | DVB-S/S2 (8PSK, QPSK) to 2xDVB-C (QAM) Transmodulator TERRA TDQ-420 R81638 is used for reception of DVB-S/S2 (8PSK/QPSK) signals, selection of desired channels and retransmission of them in QAM format in chosen RF channels in VHF/UHF frequency range. The device allows the user to receive and manage a range of free to air satellite channels. One TDQ-420 R81638 panel can receive channels from two satellite transponders and convert them into two neighboring DVB-C multiplexes with maximum throughput of 53 Mbps (no PID filtering). In practice, each multiplex can carry 8 SD channels or 4-5 HD channels. | |
 | Control Panel PROTECT LED KL-1 M80103 is used as a monitor of the operating status of a PROTECT mobile DVR and as IR remote control extender. | |
 | Wall Bracket DS-1272ZJ-110 (for Hikvision cameras) M5135 has been designed for HIKVISION cameras of DS-2CD21xx series. A large space inside is usually used for placing cable connections. The mount is made of aluminum. | |
The latest
March 3, 2017 - training course in video surveillance for WAT students, based on Hikvision devices. This all-day course was conducted in WAT (Military University of Technology in Warsaw) by engineers from our Technical Department. Students of the Security Systems Engineering specialty at the Electronics and Telecommunications faculty showed great interest in monitoring solutions based on Hikvision HD-TVI and IP systems IP. Practical issues were trained in five groups, with different sets of devices. Most of the students had no contact with newest solutions used in video surveillance, so they were very interested and involved in the subject. The ability to connect and configure a small installation with devices known only from textbooks and catalog cards gave them a lot of satisfaction. We thank the students and university authorities for a warm welcome.
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Voltage surges can come from both the AC power network and the signal transmission lines. The protection against overvoltages in the power network is provided by safety extension cords/strips with surge suppressors (varistors) and fuses. In the event of a voltage increase over a limit (typically 250 VAC), the fuses cut off the power for the connected devices... >>>more
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