Ayscom dataTec’s Project preamble
Last August Ayscom dataTec, leading brand in electronical instrumentation market, was asked to carry through an important and innovative challenge in Spain: the caracterization and RF analysis in HFC facilities (Hybrid Fiber-Coaxial) in one of the biggest worldwide communications company.
Together with our related companuy Ayscom Celular de Servicios S.L. we got down to work to develop an action plan that cover the particular needs of our customer.
The plan was aimed at characterise and analyse different types of RF cables used currently in different locations in Spain.
Before the ejecution of this proyect, the communication company showed the difficulties of not knowing the specifications and efficiency of its cables from a specific level of frecuency.
From Ayscom dataTec we would not only allow our customer to know the behavior of their facilities at high frequencies (until 3Ghz), but we would also carry out measures that allow us to know in detail the physical condition of the lines, in order to be able to carry out preventive maintenance or replacement tasks, in case of obtaining results below certain limits.
In order to build up this analysis, it was agreed to have in mind 6 endpoint of interest:
Once contemplated and configurated the action plan, it was essential to take into account the most sophisticated and robust test equipment. Given the high qualification of the human resources and, adding to the equation, the excelente behaviour and agreement with leading equipment manufacturers, Ayscom dataTec shines for its effectiveness in consulting field and the equipment personalised search,contribuiting the best experience of measure for each need. This business characteristic is what ends up providing the project with the best of guarantees.
From the beginning, in Ayscom dataTec’s mind we were clear about which equipment will be chosen:
1-RF Analyzer FieldFox N9918B Keysight
This powerful RF analyzer with 2 ports, given its versatility from 30kHz to 26,5, allows to make practically all measures required (except for radiation leak measurements). Let us remember the wide range of applications and instruments that this excellent equipment of the American brand Keysight can develop, world leader in all types of measurement instrumentation, of which Ayscom dataTec is a Premium Partner.
Figure 1: Keysight Fieldfox - Portable equipment weighing 3 kg and a similar performance to bench equipment.
As previously mentioned, radiated leaks would remain pending, a task that would be carried out by a measurement team from another of the firms of which Ayscom dataTec is an official partner.
It is the Signal Shark analyzer, from the world’s leading German manufacturer in electromagnetic safety and interference detection Narda STS.
Signal Shark is a sophisticated, portable 40 MHz real-time spectrum analyzer capable of detecting signals with 100% effectiveness of up to 3.125 μs in duration.
Figure 1: Signal Shark by Narda STS
All this aided by specific antennas for each range of working frequencies, up to 8GHz. Although this project would have no a place, thanks to its modern antennas (including one dedicated to drive test), this analyzer is capable of accurately locating and placed all types of sources of interference produced in any environment (both urban outdoor spaces as indoors).
3-Development and explanation of Ayscom dataTec measurements
This project was aimed the measure of 65 cable runs, all of them installed in field and active, distributed in 10 provinces of Spain.
Overall, 17 different types of cables were measured, each with different connections. This feature demonstrates the complex problem of establishing a correct connection between the equipment and the DUTs under test, as there is such a wide range of combinations. However, Ayscom dataTec knew and was able to successfully and effectively solve this difficult task.
Regarding practical measurements, the Keysight FieldFox radio frequency analyzer would rely on its 2 ports and its internal generator / receiver, to perform the following measurements:
Return Loss aims to quantify the relationship between the transmitted energy and the reflected energy, that is, that produced by the reflections of the DUT, which are translated into losses. This measure is represented in a graph in which the vertical axis corresponds to the RL level in dB, while the horizontal axis represents the analysis frequency.
The purpose of the Fault Distance Measurement is to represent the RL losses in space or length (meters). In this case, if there are palpable failures in the cable that affect its performance, we will obtain at a specific distance (for example 80 meters), a reflection peak that would differ from the rest of the points in the graph. This value represented in DTF also has units of dB and in this project, it has additionally helped to know the real length of the cables.
The measurement of Reflections in the Time Domain (TDR), allow to know the nature of the failures found in the DTF measurement. This measurement relates the impedances used in the connection, that is, that of the measurement system and that of the DUT. This relationship is known as the rho index, which depending on the value it reaches, will allow the user to know if the fault is a short circuit, an open circuit or simply the DUT behaves correctly. Furthermore, this measurement determines and represents the value of the real impedance of the DUT, also as a function of distance.
Additionally, our client had the need to know the imaginary impedance of the cable as a function of the working frequency, in order to be able to relate it to RL losses and DTF and TDR failures. In this case we would rely on the Vectorial Network Analyzer and its Smith Chart measurement, which would help us to carry out this measurement, determining the inductive or capacitive nature of the DUT, showing the exact values in Henries or Farads.
Finally, Insertion Loss measurement aims to determine the amount of energy lost, either due to reflections or attenuations, when transmitting a signal from one end and receiving it from the other end of the cable. While DTF measurement allows you to see the most obvious faults, IL shows accumulated losses accurately, especially if done with two ports.
RF FieldFox Analyzer measurements would be already covered.
Next, and finally, it would be necessary to determine the amount of signal that the cable is capable of radiating due to unexpected leaks, either in the connection parts of the end terminals, or in the middle of the route, due to failures in the own shielding of the line.
For this need, the Ayscom dataTec team would use the Signal Shark real-time spectrum analyzer and its 8GHz geolocation antenna.
For the measurement, a small generator would be connected that would act as an active line simulator, providing at one end of the cable the exact signal level in dBm that the teleoperator company regularly uses in its communications. Ayscom dataTec team would cover the line with the Signal Shark, locating any type of leak that the HFC cable might present. All this process, generating and measuring at the different frequencies in which the customer operates.
Ayscom dataTec Successful case
This ambitious project, after a couple of months of rigorous technical study, began to provide the first data in the field in December, with all measurements being concluded at the end of February.
At Ayscom dataTec we have no doubts that these measures have been a great challenge from which, after the magnificent result obtained, there is nothing left to learn from it.
After this project, the solidity and professionalism of our company and its line of business has been consolidated, focused on innovation in processes and support throughout the life cycle of the solution, providing this plus of support and personalized treatment that is so difficult is to achieve with success.
In addition, we are proud to have confirmed, having been the strictest customers of our products, that the chosen equipment have shown to give off in all the measurement days, the characteristic that most represents the firms we represent.
From these lines we want to thank our customer for the trust placed in us, as well as in the human team and our measuring instruments.
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