Vzdálené odečítání měřáků přes mobilní síť (ioT) – LTE cat.1, NB-IoT, LTE-M

Dynamický rozvoj komunikačních technologií umožnil automatizaci měřicích procesů v odvětvích energetiky, vodárenství a plynárnictví. Jedním z nejuniverzálnějších řešení je dálkové odečítání měřidel (AMI – Advanced Metering Infrastructure) realizované prostřednictvím mobilní sítě GSM. Tento typ infrastruktury umožňuje spolehlivý přenos dat z mnoha měřicích bodů.
Následující knihovna se zabývá tématem dálkového odečtu energetických měřičů na základě mobilní sítě LTE cat.1/NB-IoT/LTE-M, která zcela eliminuje potřebu ručního odečtu namístě. Díky použití externích antén a profesionálních rozbočovačů je možné připojit více měřičů energie v jedné instalaci a přenášet naměřená data přímo do centrálního operačního systému nebo systému správy budovy. Toto řešení poskytuje větší spolehlivost, efektivitu a úsporu času a usnadňuje správu spotřeby energie v bytových domech nebo budovách s více byty.
Table of contents:
Trocha teorie
The GSM-based remote meter reading system consists of three main layers:
  • Metering layer - includes energy, water or gas meters equipped with communication modules (e.g. GSM, GPRS, LTE-M). These modules enable direct data transmission or cooperation with a local hub.
  • Aggregation layer (GSM splitters) - in areas with a high density of meters, intermediary devices, so-called GSM splitters or concentrators, are used. These collect data from multiple meters (e.g. via RS-485, M-Bus or Modbus) and further transmit them via a single GSM channel to the central system.
  • Communication and central layer - data from the splitters are sent to the system operator's server via the GSM network. They are then stored in a database and made available to billing or energy management systems.
LTE cat.1, NB-IoT and LTE-M are three mobile communication technologies designed for Internet of Things devices, but with different capabilities, bandwidth and applications. LTE cat.1 is the solution offering the highest throughput of the three technologies, allowing data transmission at moderate speeds and supporting more advanced devices such as energy meters, controllers or monitoring systems that require a stable and relatively fast connection. NB-IoT (Narrowband IoT) operates in a narrow bandwidth, consumes very little power and allows devices with low transmission requirements but running for many years on a single battery to communicate - ideal for sensors, utility meters and telemetry systems. LTE-M (LTE cat. M1) provides an intermediate solution, combining low power consumption with greater mobility and the ability to support more complex applications than NB-IoT, making it well suited to tracking systems, wearable devices or building automation components.
In order to reduce costs and improve signal quality, a system is used, in which several meters are connected to a single external antenna with high energy gain using GSM splitters. This solution allows stable communication in areas with poor coverage and minimises the number of service points. The antenna acts as a central transmission point, and the splitters transmit data to it by wire, e.g. via coaxial cables or shielded twisted pair.
Elements of the GSM remote reading infrastructure
The correct design and implementation of the communication infrastructure in remote meter reading systems is crucial to the reliability of data transmission. The basic physical components include antennas, GSM splitters, coaxial cables and antenna connectors. Each of these plays an important role in ensuring a stable connection to the mobile operator's network.
Antennas
The antenna is the basic element of the radio path. Its task is to receive and emit electromagnetic waves in the operating band of the devices - most often 900 MHz, 1800 MHz, 2100 MHz. In remote reading systems, the most frequently used are:
  • omnidirectional antennas - ensuring signal propagation in a 360° radius, used, among others, for free-standing devices, e.g. ATMs, external electrical boxes (WLZ), water meters in manholes
  • directional antennas - used in areas with poor coverage or high signal attenuation, e.g. in basements and transformer stations
  • outdoor antennas (with high gain) - mounted on roofs or masts, connected to several devices using splitters
Key antenna parameters include energy gain (dBi), operating band, polarisation (vertical in Poland) and weather resistance.
Anténa ATK 20/850-960MHz 20-elementová pro GSM
Directional antenna with high gain, usually installed on the roof - ATK-20 A7025
4G/3G/GSM Anténa: TRANS-DATA LTE KYZ 7.5/8/10
Broadband antenna - most universal for one meter - Trans-Data LTE KYZ7.5/8/10 A741031
LTE Antenna: TRANS-DATA LTE KPV 7/10
Panel antenna - ideal where the antenna should not be conspicuous - Trans-Data LTE KPV 7/10 A741021

Anténa TRANS-DATA 5G DZ7
Omni-directional antenna - for free-standing installation - Trans-Data 5G DZ7 A741009
Omnidirectional antenna - to be mounted directly on the device/box housing - Trans-Data 5G DZ5 A741011
Splitters and taps
The GSM splitter acts as an intermediary device between the meters and the mobile network. GSM modules from the meters are connected to GSM splitters, which are connected to an external antenna. A typical splitter is characterised by:
  • different number of outputs
  • working band (splitters must operate from 800-2200 MHz)
  • signal attenuation
These units can be mounted in metering cabinets or in power distribution boards. With a larger number of units, they can be combined in a cascade or in parallel, sharing a single antenna and radio path.
Splitters
Dvojitý GSM Separátor
GSM/DCS/3G/LTE TRANS-DATA two-way splitter 800-2500 MHz A6812
Trojitý GSM Separátor
GSM/DCS/3G/LTE TRANS-DATA three-way splitter 800-2500 MHz A6813
Rozbočovač GSM čtyřcestný 1x4
GSM/DCS/3G/LTE TRANS-DATA four-way splitter 800-2500 MHz A6814
GSM/DCS/3G/LTE/5G TRANS-DATA eight-way splitter 670-3800 MHz A6818
Taps
TRANS-DATA GSM/DSC/UMTS/LTE 2.2/5 dB tap A6822
TRANS-DATA GSM/DSC/UMTS/LTE 1.3/8 dB tap A6824
TRANS-DATA GSM/DSC/UMTS/LTE 1/12 dB tap A6826
Cables
The coaxial cable is used to connect the antenna to the splitter or GSM modem. It consists of an inner conductor, a dielectric insulator, a shielding braid and an outer protective sheath. The choice of a cable depends on:
  • length of the path (the longer, the greater the signal attenuation)
  • operating frequency (higher bands require better quality shielding)
  • environmental conditions (UV, humidity, temperature)
It is recommended to use cables of as short a length as possible and with a high quality of shielding to avoid signal loss in the radio path.
Coaxial Cable (50 ohm): Tri-Lan 240 PVC WLL (white) [100m]
Coaxial Cable (50 ohm): Tri-Lan 240 [100m]
Coaxial cable 50 ohm Tri-Lan 240 PE Fca 1.4/3.8/6.1 E1171_100
Coaxial Cable (50 ohm): Tri-Lan 400 WLL PE Fca 2,7/7,2/10,3 [100m]
50 ohm coaxial cable Tri-Lan 400 WLL PE Fca 2.7/7.2/10.3 E1173_100
Connectors

Connectors should be of good quality and corrosion-resistant. Loose or unscrewed connections that cause high signal attenuation and transmission errors are unacceptable.
N-plug for Tri-Lan 240/H-155 cable (6 GHz) E84130
SMA connector crimped on H-155 gold-plated cableE84544
TNC connector up to 6 GHz for Tri-Lan 240/H-155 cable E84140
FME crimp socket up to 6 GHz for Tri-Lan 240/H-155 E84165
Signal meters
The GSM meter is a key diagnostic tool used during the installation and maintenance of the remote meter reading infrastructure. It makes it possible to precisely determine the mobile network signal quality parameters at the place of installation of the antenna or GSM splitter, allowing for optimal selection of system components and ensuring stable data transmission. The primary task of the GSM meter is to measure the strength and quality of the radio signal in the operating band of communication modules (GSM 900, 1800, LTE 800/1800). This device allows the installer to:
  • check the RSSI signal level (Received Signal Strength Indicator)
  • assess transmission quality parameters such as BER (Bit Error Rate) or SINR (Signal to Interference plus Noise Ratio)
  • detect the nearest base stations (BTS) and determine their identifiers (CID, LAC)
  • select optimal antenna location or direction
  • monitor the stability of the connection over time
Dedicated NB-IoT / CAT-M /LTE cat.1 / GSM signal meter N7057 for the installation, measurement and optimisation of IoT networks. The device connects to the operator's network via a SIM card and measures radio parameter levels at the selected location. The results are presented on an easy-to-read display and can be used to assess signal quality where IoT devices are to be installed.

Měřák sítě IoT – NB-IoT, CAT-M, CAT-1, GSM
IoT Network meter - NB-IoT, CAT-M, CAT-1, GSM N7057
Ballast masts
The non-invasive ballast mast is a support structure designed for the installation of outdoor antennas on the roofs of buildings, where the sheathing or structure of the building cannot be interfered with. It is commonly used for remote meter reading systems based on GSM communication, where it is important to obtain a stable signal without permanent installation. Advantages of a non-invasive solution:
  • no interference with the building structure - no drilling, anchoring or disruption to roof insulation required
  • ease of assembly and disassembly - the mast can be installed in a matter of minutes and moved to another location if necessary
  • mobility and flexibility - ideal for temporary installations, range testing or pilot solutions
  • safety of operation - due to the appropriate ballast and low centre of gravity, the structure is resistant to wind and vibration
  • compliance with building regulations - in many cases the installation does not require a permit if it does not exceed the permissible height and load of the roof
Non-intrusive ballast mast ZB-500/38+RAM2/415*265 with mast angle adjustment E8747
Non-invasive ballast mast ZB-1000/38+RAM2/415*265 E8746
Non-invasive ballast mast ZB-1500/38+RAM4/415*265 E8745
DWG element library for GSM system designers
In order to facilitate the design process and standardise technical documentation, we provide a DWG component library for designers of remote meter reading systems and GSM infrastructure. The set of files contains complete 2D models of the most commonly used installation components, developed in a format compatible with AutoCAD, BricsCAD, ZWCAD and other CAD platforms.

Splitters
Two-Way GSM/DCS/3G/LTE TRANS-DATA Splitter 800-2500 MHz A6812

Three-way GSM/DCS/3G/LTE TRANS-DATA
Splitter
800-2500 MHz splitter A6813

Four-way Trans-Data GSM/DCS/3G/LTE splitter 800-2500 MHz A6814
Eight-way Trans-Data GSM/DCS/3G/LTE/5G  splitter 670-3800 MHz A6818
Taps
TRANS-DATA GSM/DSC/UMTS/LTE 2.2/5 dBA6822 tap
Trans-DATA GSM/DSC/UMTS/LTE 1.3/8 dB A6824 tap
Trans-DATA GSM/DSC/UMTS/LTE 1/12 dB A6826 tap 
Accessories
TRANS-DATA GSM/DSC/UMTS/LTE 1,3/8 dB A6824 tap

Installation diagrams
The diagram shows a complete circuit for connecting electricity meters to the LTE network, enabling remote reading of metering data. The external LTE antenna A741031 is responsible for receiving and transmitting the LTE signal and ensuring a stable connection to the mobile network. The signal from the antenna is fed to the A6812 splitter via a coaxial cable. This element acts as an intermediate device - it receives the signal from the antenna and then passes it on to two independent branches of the installation. From A6812, the signal is routed to two splitters A6814. Each of these serves a group of four electricity meters. The whole system forms a coherent communication system, with one LTE antenna providing the link Thanks to this configuration, all the meters can send data remotely and the metering data is reliably transmitted to the operator or energy management system.
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The diagram shows an elaborate system for connecting electricity meters to the LTE network, enabling centralised and remote reading of metering data from multiple points. The external antenna (900 MHz band) of the A7025 is responsible for receiving and transmitting the LTE signal and ensuring a stable connection to the mobile network, even with a large number of connected devices. The signal received by the antenna is transmitted via a coaxial cable to the first tapping unit A6826. From the A6826 taps, the signal is then directed to two further taps A6824 and A6822, which are further distribution points in the installation. Each of these feeds the signal to one A6818 splitter. The A6818 modules play a key role in the system - they distribute the received communication signal to multiple outputs leading directly to the electricity meters. Each A6818 module supports a set of more than a dozen meters, enabling them to operate in parallel within a single transmission network. This allows all the meters to transmit energy consumption information to the operator's system.

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The diagram shows a communication system for two staircases in a multi-family building, enabling remote reading of metering data from electricity meters via the LTE network. Each staircase has its own external LTE directional antenna, type A7025, responsible for receiving and transmitting the LTE signal to the operator's network. With this solution, each staircase
functions as an independent communication segment, which increases the stability and reliability of data transmission. The signal received by the antenna is routed via a coaxial cable to the A6812 splitter located at the base of the installation in each staircase. The A6812 splitter distributes it to further components of the system. From the splitter, the signal is routed to a series of A6814 modules, arranged vertically along the meter strings. Each A6814 module is responsible for distributing the signal to a set of meters and enables them to be connected in parallel within a single communication infrastructure. A multistage array of A6814 splitters is used in each staircase, each of which supports a group of several electricity meters. These modules provide signal distribution to individual meters, allowing each device to communicate independently and stably with the master system. This structure enables the installation to be scaled effectively - each A6814 module is connected to the next, creating a cascaded manifold system that supports all the meters located in one staircase.