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

New 3D printing technique allows better robot parts to be printed.

3D printing is a domain that has been growing extremely fast recently. The family of materials used for 3D printing continues to expand. While the technology had previously been limited to fast-curing plastics, it has now also been adapted to slow-curing plastics, which have improved elastic properties and are more durable and robust. The use of such polymers is made possible by a new technology developed by researchers at ETH Zurich and an American start-up. As a result, the researchers can now 3D print complex, more durable robot parts from a variety of high-quality materials in a single process.

Using the new technology, researchers at ETH Zurich have succeeded for the first time in one go, in printing a robotic hand containing bones, ligaments and tendons made of various slow-curing thiolene polymers. These polymers have very good elastic properties and, when bent, return to their original state much faster than polyacrylates, making them ideal for making flexible ligaments of the robotic hand. Moreover, the rigidity of thiolenes can be very easily adjusted to meet the requirements of soft robots, which, compared to robots made of metal, reduce the risk of injury when working with humans and handle delicate goods better.

3D printers typically produce objects layer by layer. Nozzles deposit the material in question in a viscous form at each point, and then a UV lamp immediately cures each layer. Previous methods used a device that scraped off surface irregularities after each curing step. This only works for fast-curing polyacrylates. Slow-curing polymers such as thiolenes and epoxies could cause the mechanism that scrapes off excess material to stick. To accommodate the use of slow-curing polymers, the researchers improved 3D printing by adding a 3D laser scanner that immediately checks each printed layer for any surface irregularities. A feedback mechanism compensates for these irregularities when the next layer is printed, calculating in real time and with remarkable accuracy any necessary adjustments to the amount of material printed. This means that instead of smoothing out irregularities, the new technology simply takes irregularities into account when printing the next layer. Inkbit, an MIT spin-off, was responsible for developing the new printing technology. Researchers at ETH Zurich developed several robotic applications and helped optimize the printing technology for use with slow-curing polymers. The Swiss and U.S. researchers jointly published the technology and its example applications in the journal Nature.

User management in Sunell IP DVRs.

Surveillance system operators should have limited permissions, appropriate to the function they perform. In IP Sunell systems, a user can be assigned to 3 access groups with predefined permissions that can be set for each camera:

If the administrator decides to create a user account, he/she can force a password change every specified time interval or specify a password expiration date (this way access can be given for a specified period of time, such as one day to view the recordings). Moreover, if access to the recordings is to be particularly protected then each playback may require the administrator's password.

Vandal-proof door station in Hikvision IP video door entry system.

Dipol has introduced a single-subscriber door station for the Villa DS-KB8113-IME1 G73619 IP system in a vandal-proof design with IK09 protection rating. This station will be perfect for use in outdoor conditions exposed to mechanical damage. Built-in color camera with a resolution of 2 MP with wide viewing angles (88° (H)/45° (V)) and an IR illuminator with the range of 3 m, , ensures proper area observation round the clock. The panel has a 1 alarm input and 1 relay output (not expandable), dedicated to opening the wicket. The built-in speaker and microphone with echo and noise cancellation function allow for good quality voice connections. The door station is equipped with an Ethernet port for power supply and network connection. The configuration of the IP video door system can be performed with the use of the iVMS 4200 client software or a web browser using an embedded webserver. Remote monitoring and operation are controlled by the Hik-Connect application without the need for port forwarding. The door station can be supplied with 12 VDC or PoE (802.3af).

Problem with OTDR measurement? - Check the connector.

OTD measurements are used whenever there is a need to provide complete information on the condition of an optical link. This includes the attenuation of the entire link and its individual components: connectors, splitters, splices and the fiber itself. The OTDR also provides information on reflectance values for reflective events (e.g. connectors, mechanical splices).

Proper measurements depend not only on the OTDR configuration, but also on the cleanliness of the measuring connector. The OTDR connector as well as the connector of the run-up fiber put into it should be cleaned. Failure to do so may prevent correct measurements from being made.

The picture below shows the connector of a OTDR that was used incorrectly – the connector was not cleaned regularly or was cleaned in an unprofessional way. This has resulted in accumulation of dirt and pitting on the front of the connector. The result was an incorrect pulse at the output of the OTDR. The damaged connector caused a large reflection of the pulse already at the beginning of the fiber, followed by several secondary reflections. This is shown in the reflectogram below.

Installers performing such measurements should definitely get a tool for cleaning fiber optic connectors. The best, and the most universal solution here will be the use of so called "pens", for example NTT Nanoclean-E3 L59161. They can clean both device sockets (or e.g. ferrules of connectors plugged into adapters in switches) and plugs, after applying an appropriate tip.

Basics of IP addressing – part 3: network address and host address.

The subnet mask is discussed in the previous Guide. In the third part, details on the calculation of the network and host address (IPv4) based on the network mask will be discussed. The mask determines how many subsequent bits in the IP address form the network address. The remaining bits, however, specify the addresses of a particular host in the network (end device address). Where the bit in the mask is set to 1, the corresponding bit of the IP address belongs to the network address, and when it equals 0, the corresponding bit of the IP address belongs to the host address.

The subnet mask bits are always set to 1, starting with the most significant bit (commonly the oldest), for example:

As seen in this case, the network address is:

While calculating a network address, and when the device IP address and mask, are available, the AND function should be applied (the result contains one when there is one in both strings):

The result of the AND function is the network address which, after conversion to decimal, has the form: 192.168.11.128.

Knowing the subnet address, the broadcast address can be easily calculated. To this end, the mask bit negation is used, and the resulting number is added to the network address:

Every octet has to be added to its corresponding octet of the network address. Since the first 3 octets are 0, just the last one is added: 128+127=255. The broadcast address sought in this network is therefore: 192.168.11.255.

The ability to calculate addresses is useful, for example, when the provider assigns a pool of IP addresses to the user. The provider rarely provides a list with the specified host, network or broadcast addresses. Only the network address and mask is specified in the provider documentation. For example, a user is notified of being given the 62.121.130.32/29 addressing (the /29 means the mask 255.255.255.248). The user has to calculate that the network address is 62.121.130.32, the host addresses are from 62.121.130.33 to 62.121.130.38 and the broadcast address is 62.121.130.39.

SMATV system in a multi-family building. TERRA products, dedicated to use SMATV systems, are primarily top-class equipment covered by a four-year warranty. TV systems based on those components guarantee proper signal reception for long. The distinguishing features of the TERRA multiswitch system include primarily:...>>>more