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

301 Tbps in a standard fibre.

An international team of researchers including scientists from Aston University in Birmingham have set a new data speed record of 301 terabits per second. Although their result is much less impressive than rekord broken in 2022 by a team from Sweden and Denmark – 1.84 Petabits per second (Pbitps), it is notable that the Brits conducted the experiment on standard fibre-optic cables used worldwide.

The record speed was achieved by developing a new device using a larger than standard number of optical transmission windows. Data was sent via optical fibre as in a home or office Internet connection, however, as many as four bands were used for transmission simultaneously, which had not been seen before in any solution: the C-band (1530 – 1565 nm) and L-band (1570 – 1610 nm) as well as E-band (1360-1460 nm) and S-band (1460 – 1530 nm).

With the ever-increasing consumer demand for faster Internet connections, the new technology can be used to increase speeds using the existing cable infrastructure.

HDMI-DVB-T signal conversion in small RF systems.

Digital modulators are devices that modulate the input signal supplied to the HDMI connector in DVB-T COFDM or DVB-C QAM standard. The sources of the signal can be, among others: media players, DVRs, Blu-ray players, PCs or STB decoders. DIPOL has introduced a new digital HDMI-DVB-T modulator R86301, dedicated for small systems based on coaxial cables. The R86301 modulator is a single-channel device which can be connected to a single signal source. The RF output generates one carrier in the DVB-T COFDM standard. The devices can be cascaded if several HDMI sources are required.

The diagram below shows distribution of HD signal from any HDMI source and terrestrial DVB-T2 TV in coaxial cable with an example application of Signal R86301 modulator.

Measurements in fiber optic systems. Part 2.2 – measurement with the transmission method – more about the methods of establishing references.

In the previous issue of the Weekly Review the idea and methodology of proceeding with the measurement of attenuation of a fibre optic line with the transmission method was described. The essence of establishing a reference power was also indicated and the methods with 1, 2 or 3 patchcords to reduce the overall measurement uncertainty are described.

As two patchcords are required to connect the light source and the optical power meter to the line to be measured, the most intuitive method of establishing the reference power (calibration of the measurement system) is the one using 2 measurement patchcords (otherwise known as reference patchcords, test patchcords or TRC (Test Reference Cords). It turns out, however, that the most accurate method is the calibration method using 1 patchcord and it is the one recommended as the most appropriate by measurement standards: ISO/IEC 14763-3 and EN 61280-4-2, company standards used by large operators, as well as the instructions of structured cabling system manufacturers.

The figure below shows the measurement range for each of the three methods of setting the reference power. It appears that 1 patchcord method actually allows the measurement of the entire line to be measured: from beginning to end including the start and end connectors. The 2 patchcord method reduces the measurement range by the attenuation of one connector (this is because the attenuation of 1 connector is taken into account in the reference process – see the previous Weekly Review), while the result of a measurement using the 3 patchcord method reference, leaves out the attenuation of 2 connectors. Note that the following figure, although generally accepted by the standards, provides some simplification, since the attenuation of the connector (or connectors) during the establishment of the reference (i.e. the connection of the two reference plugs) is not the same as the attenuation of the connector (or connectors) in the measured line (i.e. the connection of the reference plug to the standards).

///Transmission method measurement when 3 patchcords are used in the reference establishment process (calibration of the measurement system). The green markers indicate the range of measured attenuation – from the start connector to the end connector – without both connectors. This involves taking into account the attenuation of 2 connectors in the calibration process of the measurement system.

At this point, it is worth mentioning the reference patchcords themselves. According to the recommendations of the above-mentioned standards, the "top quality" patchcords, for which the attenuation of the connector does not exceed 0.2 dB (a value of 0.15 dB can also be found), should be used. This is because during the measurement, the start and end connectors of the measured line contain the pins of the above-mentioned reference patchcords (reference connector – standard connector connection). Therefore, the patchcord connectors should introduce as little measurement uncertainty as possible. In fact, during the operation of the line, these connectors will be replaced by standard patchcord connectors – e.g. when connecting active equipment or crossing the distribution frames. Consequently, the lower and more predictable/repeatable the attenuation of the reference connectors, the more accurate the measurement.

Manufacturers of measuring devices for network certification offer such "special" patchcords at multiples of the price of generally available patchcords. These patchcords, in addition to good transmission performance, usually have physical properties (e.g. reinforced design) that allow them to be used for longer periods of time with less risk of deterioration of their characteristics. While for network certification, the use of this type of patchcord makes sense, and may even be a necessity (measurement kits may not accept patchcords other than those recommended by the manufacturer), line attenuation measurements without certification may include the use of standard patchcords, i.e. not identified as TRC. It is important that such patchcords are manufactured in min. class B, according to PN-EN 61300-3-34. This means an average connector attenuation of no more than 0.12 dB and a maximum of no more than 0.25 dB. Ultimately, therefore, the measurement uncertainty involved in using such a connector will not be significantly greater than that of a true reference connector. Certainly, however, these patchcords should be periodically replaced with new ones and cleaned regularly. The length of the measurement patchcord should be no less than 2 m. The use of shorter patchcords involves the risk of an error when establishing the power reference – it may be slightly higher than it should be, and this will result in a distortion of the final measurement result to the detriment of the tester.

Back to the 3 methods for establishing reference power, you already know that the 1 patchcord method is the best one, as the other methods increase the measurement uncertainty by reducing the reference power due to the inclusion of attenuation of one or two reference connections. The 2 patchcord method should be used when the connector of the optical power meter is not compatible with the connector in the switch (e.g. when the meter is equipped with SC connectors and the switch with LC adapters). Then the 1 patchcord method is not feasible and it is necessary to use two measurement patchcords (e.g. SC-LC) and a centering adapter (e.g. LC-LC). The 3 patchcord method can be used when the line to be measured is terminated with connectors. However, as this method excludes the attenuation of the start and end connectors from the measurement (see above figure), it only makes sense to use it when this attenuation is an insignificant part of the attenuation of the whole line.

Information on the interpretation of measurement results obtained using the transmission method will be presented in the next issue of the Weekly Review.

How to limit "live" video viewing privileges in Sunell DVRs?

In surveillance systems, you can create multiple user accounts and assign them various privileges. Among other things, you can allow certain users to view only some of the cameras. What if the user logs out? Sunell DVRs allow you to specify which cameras can be viewed without logging in. The function is useful when automatic logout after a certain period of time is enabled, and surveillance of cameras is to be continuous. Similarly, in case the DVR restarts due to power failure. The next restart of the DVR, despite the failure to log in, can start viewing from the cameras.
This function can be configured via the local interface or web browser under System → Accounts→ Settings.

Types and designations of twisted pair cable.

The description method of twisted-pair cable is provided by ISO/IEC 11801:2002. According to the information provided, the cable description should follow the xx/yyTP syntax where yy-describes a single pair of conductors in the cable, and symbol xx refers to the entire cable.

The xx and yy markings can be as follows:

• U – unshielded
• F – foiled (screened with foil)
• S – shielded (screened with braid)
• SF – shielded and foiled

Common twisted pair cables

• U/UTP – unscreened twisted pair
• F/UTP – foil screened twisted pair
• U/FTP – twisted pair with each pair with a separate foil screen
• F/FTP – twisted pair with each pair with a separate foil screen in addition to foil screened twisted pair
• SF/UTP – overall braid and foil screened cable with unscreened balanced elements
• S/FTP – overall braid screened cable with foil screened balanced elements
• SF/FTP – overall braid and foil screened cable with foil screened balanced elements

Twisted pair cable classes according to European standard EN 50173 and TIA/EIA 568A standard:

Different image parameters for day and night in Sunell cameras. IP Sunell cameras have 4 schemes (operating profiles) related to image settings. For each of them, all image parameters can be independently configured, including those related to exposure: mode and shutter speed, noise reduction, IR illuminator operation (on and power), HLC and BLC function operation, white balance, and color and focus compensation. The schemes can be switched depending on the status of the twilight sensor (then scheme 1 is valid for daytime, scheme 2 for nighttime) or according to the schedule hours. You can also permanently activate any of the 4 profiles...>>>more