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

3D printing with sound.

Researchers at Concordia University in Canada have developed a 3D printing method that enables precise printing using ultrasonic sound waves. The energy transmitted by inaudible high-frequency sound is absorbed by a medium and causes changes in its physical and chemical properties. If the medium in which the waves propagate is a liquid, the phenomenon of so-called acoustic cavitation occurs in it. It means the formation of microscopically small bubbles with extreme properties. The temperature inside them rises to about 15,000 K and the pressure exceeds 1000 bar. Influenced by them, the aggregate state of the medium changes from liquid to solid. It can be said that a kind of reactor is created that drives the process of transformation of a liquid medium into a solid. By controlling the cavitation point, it is possible to create previously designed structures, i.e. the mentioned 3D printing.

The researchers experimented with a popular poly (dimethylsiloxane) polymer used in cosmetics (e.g. for the production of contact lenses) and medical industry. Placed on a moving head, a generator of a tightly focused ultrasonic signal moves along a specific path and turns the liquid substrate into hard, small bubbles. In this way, a pre-programmed structure is created pixel by pixel. The parameters of the resulting structure can be modified by changing the frequency of the wave and by using a different material (viscosity is important).

The research has confirmed the possibility of using polymers and ceramics as a building material. This already offers a wide range of applications, polymer-metal composites are also being tested, and eventually it will be possible to print metal objects. According to the researchers, the aviation industry will benefit from this, as sound waves penetrate the shells of airplanes. This will make it possible to service parts located deep in the fuselage of an aircraft. The method also has medical applications - in a similar way various structures in the human body can be repaired in a non-invasive manner.

TERRA headend.

The owner of one of the hotels decided to upgrade the tv system. The current system, including the headend, allowed to receive terrestrial TV broadcasts in the old DVB-T/H.264 standard, and satellite DVB-S/S2 broadcasts on TVs equipped with DVB-C receivers. The change of digital terrestrial TV broadcasting standard from DVB-T/H.264 to DVB-T2 made it impossible to receive programs in the new HEVC video compression standard. For this purpose, each of the 100 TVs was equipped with Signal T2-MINI A99313 set-top box, which solved the problem of receiving free channels broadcast on DVB-T2 digital terrestrial television in HEVC (H.265/MPEG-H) and H.264/MPEG-4 video coding technology with Dolby E-AC-3 audio. Since the existing headend was converting satellite signal to DVB-C standard, the problem of changing the modulation of satellite programs still remained. For this purpose, the TTX-420 R81616 transmodulator, which allowed to change the DVB-C standard to DVB-T, was used.

Arranging camera points in CCTV systems.

When cameras have to be installed on a pole they have to be powered and their signal has to be delivered to the surveillance center. To do this, the cameras have to be provided with PoE switches that are powered by 230 VAC and connected to the survailance center via fiber optic cable Of course, these elements should be placed in a dedicated cabinet. SIGNAL CCTV 210/230/145 mm sealed box is R90601 designed for mounting on a pole or wall. Inside, there is a mounting plate which can be easily removed, and two DIN rails for easy installation of components such as switches, power supplies, media converters or mini fiber optic distribution frames. Additionally, the box has protective wires which can be connected to active devices.

The design of the box has two main advantages: the possibly small size of the cabinet so that it looks good at camera locations on poles or walls, and convenience of installation of individual components taking into account the power supply cabling, twisted-pair cables, optical fibers, etc.

The box can easily accommodate, among others, an industrial switch, power supply, main switch and mini distribution frame in the case of systems based on fiber optic cabling. In this case we recommend to use ODF-DIN L5312 distribution frame. All these elements can be mounted on DIN rails or aluminum mounting plate. Thanks to adequate number and size of cable gland holes, it is possible to lead in and out the cabling for: power supply, fiber optic cable, twisted pair, for connecting up to 4 surveillance cameras.

The dedicated R90610J bracket allows to mount the cabinet on a mast. The cabinet has six cable gland holes (all are blanked but can be easily punched out, the set includes two PG13.5 glands and four PG9 glands).

Cracking splices? – Perform calibration.

If a splice breaks when removing the fiber from the splicer, this most likely means that the electric arc generated to produce it had too little power (too low temperature). It can also be a result of a very low quality fiber, but this case is rare.

In such a situation it is necessary to calibrate the splicer. Signal Fire AI-8C L5870 and AI-9 L5875 splicers do not have the automatic calibration function which many installers forget. It is necessary to perform a manual calibration always before starting the splicing. Not doing so may result in decreased durability of splices, despite good transmission parameters.

Calibrating a fiber optic splicer involves adjusting the power and temperature of the generated arc to the current environmental conditions. A properly adjusted arc allows for proper splices to be made, both in terms of attenuation and strength. Therefore, calibration should always be performed before the actual splicing – at the beginning of work or in the case of drastically changing conditions, e.g. a sudden drop in temperature resulting from splicing inside a building and further work outside

Batch activation of Hikvision network devices and changing their IP addresses with SADP.

SADP ( Search Active Device Protocol) is free and easy to use software designed to search for Hikvision IP cameras, DVRs and video intercoms on the local network. Using it you can modify their basic network parameters, activate devices and change or restore passwords. SADP is particularly useful when building large CCTV or video intercom systems. Newly purchased devices have to be activated by assigning passwords. In addition to that, the IP addresses of the devices are repeated so there would be a conflict of IP addresses when all of them were connected to the network at the same time. While in the case of a few devices it is possible to connect them one by one, activate and change IP address via a browser (if the device has built-in webserver), for large, e.g. CCTV systems with 32 IP cameras, it would be very laborious and time-consuming. After connecting all devices, SADP running on the local network will detect them as inactive. Selecting them all allows for a quick batch activation of the devices by assigning an administrator password. For DVRs, it is also necessary to enter the password for activating cameras. Upon acceptance, a window will appear confirming the activation of the devices.

When this step is finished, you can proceed to batch addressing of the devices. To do so, select all the devices and complete the network parameters, as shown in the following image. The devices will be addressed one by one starting from the IP address that has been entered. When the password with which the cameras have been activated is entered, a window with information about the changes will appear.

Antenna for LTE over long distances. Wireless Internet access services provided by mobile network operators are an increasingly popular access method chosen by subscribers. Depending on the transmitter and mobile operator, wireless access services can be provided using different data transmission techniques. When selecting an antenna, it is important to obtain information on the location of the nearest transmitters emitting signals in a particular standard. Having obtained information on the location and supported bands, you should measure the distance to the transmitter, check the distribution of connectors of the device (modem/router with built-in modem) and whether the router aggregates bands. Details on band aggregation should be found in the modem or router manual/specification.>>>more