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

Graphene can be used to treat saline water.

Researches from the University of Manchester have developed a new method to clean seawater from salt and contaminants. They designed a filter made of graphene oxide that can separate water molecules from salt and other impurities. The filter is a membrane with microscopic pores (about 1 nanometer in diameter) whose purpose is to block particles other than water (also in the form of vapor). The membrane is made up of many precisely joined graphene-oxide layers (having a thickness of 1 atom), which provides adequate strength. Water, whose molecules are smaller than salt particles, passes through the filter. The breakthrough in the design of the filter was to solve the problem of membrane swelling under the influence of water. It has been solved by placing walls made of epoxy resin on every side of the graphene oxide membrane.

A visualization of the graphene-oxide membrane

The technology used allows for the production of membranes with pores of different sizes. It is possible to design precise filters with scalable membranes with uniform pore size down to atomic scale. This makes it possible to construct filters for a variety of substances, including gases. What's more, the researchers have developed a method for controlling the pore size (up to a few percent) in already made filters.
The filter developed in the UK could solve the problem of fresh water shortage in many parts of the world. By the invention, the researchers want to streamline the filtering process and make it affordable for the poorest countries, where the problem of scarcity of fresh water is most urgent.

What is the accuracy of the estimation of splice loss performed by a fiber splicer?

Nearly all fiber splicers/welders, including EasySplicer L5810, evaluate the attenuation of the splice made using image analysis (the splice is illuminated and suitable software estimates its attenuation). Because this is not a real measurement, the indication should not be put into measurement protocols. In simple installations with point-to-point connections with two 2 splices and without the requirement for a measurement protocol, it is usually permissible (but not recommended) to commission the installation based solely on the indications of splicers.

A simple test was performed to verify the accuracy of the estimation of splice loss made by EasySplicer L5810. The comparative measurements were made at 1550 nm with the use of L5825 optical laser source (power level of -5 dBm, short-term stability of 0.1 dB) and L5821 optical power meter.

The procedure started with welding two pigtails, L3554 and L3551 (the pigtails have connectors compatible with those on the measuring devices). Then, the light source and power meter were connected together through the created FC/PC to SC/PC patchcord. The measured signal power was set as the reference value for the next measurements (0.00 dB). In the next step, the patchcord was cut to make the splice to be measured.

After the reconnection of the patchcord with the use of the EasySplicer L5810 fusion splicer, the splice has been protected by a heat-shrinkable sleeve (because in exceptional cases the protecting operation could cause a change in parameters). The estimated attenuation of the splice was 0.06 dB. The connectors of the pigtails were not pulled out of the measuring equipment and the instruments were continuously switched on so that the reference value was not erased.

The attenuation measurement performed with the light source and optical power meter during splicing operations

After splicing the fibers, the indication of the L5821 meter was -0.07 dB. Due to the previous reference setting operation, this value should be treated directly as the attenuation of the splice. The difference between the splicer's estimate and the actual measurement was only 0.01 dB, so within the measurement uncertainty. The test was repeated several times with similar results.

DVB-T/T2/C transmodulators in shared / MATV antenna systems.

Many multifamily buildings are equipped with old shared antenna systems based on coaxial cables that cannot operate on higher UHF channels. The replacement of the cabling is often possible only in the case of a major overhaul. TERRA company has developed solutions based on TTX-4XX modules that allow for distribution of any television channels regardless of their broadcast frequency, with the use of the old wiring. The TTX-4XX transmodulators can shift the original channels (multiplexes) to lower ones. It is possible to convert channels from the upper part of the UHF band to lower channels, even in the VHF band (above 174 MHz).

TTX-4XX transmodulators can operate in transparent mode - the decoded transport stream is not modified and is directly applied to the COFDM modulator - without PID filtration. This way they can operate as channel converters, changing the input channel(s) to another, usually lower frequency. The output frequency can be set within 174-860 MHz range.

Viewing images from security cameras via a wireless link.

In situations where a DVR and the monitoring post are located at a distance eliminating the possibility of direct wired connection between the DVR and monitor(s), the applicable solution is the use of IP network. A wireless bridge between the installation site and the monitoring post can be based on TP-LINK CPE510 N2352 access points.

In the diagram above, one of the APs is connected with the network card of the Hikvision DS-7208HQHI-F2/N/A M75209 DVR via Netset E1408 UTP cable. The building is monitored by analog cameras N-CAM 760 M7478 and V-CAM 560 M7429 with integrated IR illuminators. They provide high quality 1080p video. The configuration of the DVR and monitoring of the video from the cameras is possible by the application of free iVMS-4200 software installed and run on a PC located on the other side of the wireless link.

New series of hard drives for CCTV systems.

DIPOL has introduced into its offer SkyHawk™ hard drives from Seagate. The HDDs are specially designed for applications in CCTV systems operating in 24/7 mode. They can work non-stop in systems processing and recording audio and video, especially in NVRs and NAS systems. The SkyHawk™ hard drives of capacity from 1 TB to 8 TB with optimized ImagePerfect™ firmware minimize the risk of loss of image frames with heavy load (even 3 times higher than in the case of HDDs in PCs).

The hard drives are compatible with Hikvision DVRs/NVRs. The list of HDDs compatible with Hikvision devices is available here.

Activating Hikvision devices with SADP.

Hikvision cameras and NVRs connected to the network for the first time are detected by the SADP app as "Inactive". To activate a Hikvision device, the user must set a new password for the "admin" account. This can be done via a web browser at the first logon, with iVMS-4200 client software, via the SADP app, or directly from the NVR. To activate a device using SADP, the user should:

A window from the SADP application. The red line shows the password and activation area.

The program automatically checks and displays the strength of the entered password. A strong password must be composed of 8 to 16 characters, among which there should be at least three of the following types: digits, lowercase letters, uppercase letters, special characters.

An application of ROPAM wireless control kit. The RF-4-2K G7060 kit can be used to control an alarm system, gates, ramps, etc. using key fobs. The controller has two relay and two OC outputs. The relay outputs can, for example, control two gates, whereas the two OC outputs can be used for other purposes. After employing the RM85-12V-1P G7055 relay modules, the user can remotely control any 230 VAC appliances with current consumption up to 12 A. In the example below, these are two independent circuits with lamps around a facility... >>>more

The application of the ROPAM wireless control kit and relay modules for remote control of lighting systems