Quantum precision in practice.

Researchers at the University of Bristol have developed an innovative laser system inspired by quantum physics that enables distance measurements with sub-millimetre accuracy, even in strong sunlight. Until now, one of the biggest challenges in long-range optical measurement has been so-called 'noise', i.e. interference from sunlight and changing weather conditions. Researchers at the University of Bristol have shown that effects known from quantum sensors can be reproduced in a classical laser system, allowing interference and noise to be suppressed while maintaining a strong signal for distance measurement. They were inspired by the phenomenon of energy-time entanglement, in which two photons are related in terms of energy and time, which in quantum systems allows the true signal to be distinguished from background noise. In a classical system, scientists 'faked' this behaviour by manipulating laser pulses in such a way that they had designed correlations that resembled entanglement. Technically, this was achieved by shaping the pulses and rapidly changing the colour of the light using optical fibres and electronic modulators, allowing the signals to behave similarly to the quantum case, effectively eliminating background noise. Importantly, the signals prepared in this way are millions of times brighter than typical quantum light sources, allowing measurements to be made quickly and under natural conditions, such as bright sunlight, changing weather or open spaces.

Experimental set-up for field trials with distance measurement.
Source: Nie, W., Zhang, P., McMillan, A. et al. Entanglement-inspired frequency-agile rangefinding. Nat Commun 17, 2001 (2026). https:doi.org/10.1038/s41467-026-68589-9 Under CC 4.0 licence: https:creativecommons.org/licenses/by/4.0/

The new technique was tested in practice on the university campus. The system measured the distance between the Queens building and Wills Memorial with an accuracy of less than 0.1 mm over a distance of approximately 155 metres, despite changing sunlight and weather conditions. The measurement was fast, taking only one-tenth of a second, using a laser with a power much lower than a typical laser pointer. Further experiments covered distances of more than 400 metres, including between the Queens Building and the Cabot Tower, also in full daylight. The results confirmed that the system works reliably outside the laboratory, in real field conditions. The technique opens up a wide range of practical applications, including precision surveying, infrastructure monitoring, navigation and positioning systems, obstacle detection for autonomous vehicles and even measurements in space exploration. Co-author Dr Alex Clark adds that testing the technology in the university's historic buildings demonstrates the solution's readiness for the real world, not just the laboratory. The next stages of research include increasing the system's range and miniaturising the fibre-optic technology with integrated photonic devices, which will allow for easier implementation in practical applications.

WDM technology in optical-copper RTV-SAT installations.

The WDM (Wavelength Division Multiplexing) technique allows signals of different wavelengths of light to be transmitted simultaneously over the same optical medium, which significantly increases the capacity of RTV-SAT installations. In practice, this means that satellite, DVB-T2 terrestrial TV and radio signals can be transmitted over a single fibre-optic cable and then distributed to end users via traditional copper lines.

In installations based on optical transmitters and receivers, SIGNAL PROfessional signals from SAT multiswitches are converted to optical form and transmitted via single-mode fibre optic cable, allowing long distances to be covered without loss of quality. At the other end, the signal is converted back into electrical signals and distributed to subscriber outlets. WDM enables the simultaneous transmission of multiple independent optical signals in a single fibre, eliminating the need to lay multiple cables and minimising interference.

By using this technology in SIGNAL PROfessional solutions, installers can create modern, scalable RTV-SAT systems with long range and high signal quality, which can be easily integrated into existing copper networks to ensure stable TV and radio reception throughout a building or estate.

Using the Etrix S-13 PoE stabiliser in a video door entry system combined with access control.

The installation of IP video door entry and access control systems using existing cabling previously made by another company, often involves the problem of its inadequacy to meet current requirements or an insufficient number of cables supplied to the devices. A typical example is a single twisted-pair cable led to an IP door station or access control point, such as a terminal. IP video door stations almost always support PoE power and may have a direct or additional voltage output to power the door opener or the relay itself. Terminals, on the other hand, are most often powered by 12 V DC and do not have a dedicated voltage output with which to drive the electric door strike. The optimum solution would, of course, be to run additional wiring, but often, for economic reasons, it is necessary to use what is already there to run a pre-selected system. One way of solving such a problem without the need for additional wiring is to use the Etrix S-13 M18958 PoE stabiliser, which, when connected to the twisted-pair cable coming out of the PoE switch, enables simultaneous data transmission to the end device and the generation of a stabilised voltage of 12 V with a current capacity of up to 2 A, from which both the end device and the electric door opener can be powered. This is an extremely simple and cost-effective solution compared to the need to run additional cabling.

The diagram above shows the installation of a Hikvision IP video door entry system consisting of a 4 subscriber DS-KV8413-WME1(C) G73636 door station, which can be powered using PoE but has no dedicated voltage output for controlling the electric door opener, only a relay. Four DS-KH8380-WTE1 G74005 indoor monitors were connected to the door station via a ULTIPOWER PRO0208afat N299851 switch equipped with 8 PoE 802.3af/at ports and a power budget for the entire switch of 120 W. Also connected to the switch was an access control terminal DS-K1T805MBWX G76256, which secures the entrance to the shed, but can only be supplied with 12 V DC and has no dedicated voltage output to control the electric door strike, only a relay. Only one twisted-pair cable was run to both the door station and the terminal during the cabling stage. In the case of both devices, the use of Etrix S-13 M18958 PoE stabilisers allowed the system to start up and power the terminal devices including the locking elements without the need for additional cabling.

DDM function in SFP modules.

DDM, or Digital Diagnostics Monitoring, is a set of functions that allows the monitoring of the operation of fibre SFP modules in network switches. When a DDM-enabled insert is inserted into a switch, it gains access to the following insert performance parameters:

Moreover, depending on the implementation of the protocol in the switch itself, it is possible to display messages on the transmission problems and total loss of signal. DDM in connection with SNMP (Simple Network Management Protocol) allows more efficient network management and monitoring of its parameters at physical layer level. It is possible, among other things, due to possibility of defining alarm levels for individual parameters.

View of the DDM data window in the TP-Link TL-SG3428X switch with Ultimode L1430 SFP+ insert

Basics of IP Addressing - Part 2.

In the previous Guide we discussed the IP address. Another important parameter is the subnet mask. The subnet mask (for IPv4), like the IP address in version 4, is a 32-bit number (for IPv6 it is 128 bits). The mask is used to separate in an IP address the part that is the address of a subnet and the part that is the address of a host in that subnet. The subnet mask has a very distinctive structure - it starts with a sequence of ones and then changes to a sequence of zeros - the part with ones is the network part of the mask, while the sequence of zeros is the so-called host part.

For the IPv4, it is most commonly written in a form of four 8-bit numbers in decimal format and separated by periods (for example 255.255.255.0). The mask value has to be known to all routers and computers in a given subnet. As a result of comparing the address mask (e.g. 255.255.255.0) with a specific IP address (e.g. 192.168.1.122), the router is notified which part of the address identifies the subnet (in this case 192.168.1.), and which refers to the device with that IP address assigned (address ending: .122).

The table below compiles information on the subnet mask size (the number of bits in the network-related part of the address), and the corresponding number of available IP addresses within a given subnet. Note! The number of hosts is lower by 2 than that of the IP addresses allocated to a given subnet (2 addresses are occupied by the so-called network address and the broadcast address for a given network).

Subnet mask	Abbreviated designation	Number of IP addresses
255.0.0.0	/8	16777216
255.128.0.0	/9	8388608
255.192.0.0	/10	4194304
255.224.0.0	/11	2097152
255.240.0.0	/12	1048576
255.248.0.0	/13	524288
255.252.0.0	/14	262144
255.254.0.0	/15	131072
255.255.0.0	/16	65536
255.255.128.0	/17	32768
255.255.192.0	/18	16384
255.255.224.0	/19	8192
255.255.240.0	/20	4096
255.255.248.0	/21	2048
255.255.252.0	/22	1024
255.255.254.0	/23	512
255.255.255.0	/24	256
255.255.255.255.128	/25	128
255.255.255.192	/26	64
255.255.255.224	/27	32
255.255.255.240	/28	16
255.255.255.248	/29	8
255.255.255.252	/30	4
255.255.255.254	/31	2
255.255.255.255	/32	1

Scheme of an IP video intercom installation for a single-family house with a need for floors. This solution can be used in large buildings where the distance between staircases is more than a few dozen metres. Fibre optic cable provides excellent insulation against surges. This means that any surges induced in the vicinity of the antennas will stop at the optical transmitter installed immediately behind them - all other components of the installation are 100% protected. Signal PROfessional uses 1 optical fibre to transmit the entire bundle of TV signals...>>>more

IP video intercom system for a single-family house.

Triset 302 coaxial cables – class A+, triple shielding