Within RF ground segments, antenna testing has always been critical to mitigating RF interference. But is in-field testing with drones providing a better alternative to traditional testing methods? Joakim Espeland, CEO of QuadSAT argues in favour of the former.
RFI has a detrimental impact on antenna performance, with signals and throughput being negatively affected. The financial and reputational implications of RFI are severe and the ramifications are not limited only to the offending antenna, but its effects can also be seen in neighbouring users of spectrum. Poor quality equipment and user error are often to blame of RFI incidents and, therefore, introducing and maintaining a testing regime is crucial when managing ground segment infrastructures.
The longstanding testing routine
For years, the most popular option within testing has been within designated testing facilities. Antennas are transported to the facility and a series of tests are completed to assess its technical capabilities and current calibration. Repeatability is easily achieved, with testing being performed in anechoic chambers, and operators receive detailed results specifying its performance. This type of testing has provided many operators with an insight into antenna performance; however, does it maximise the potential of testing?
Logistically, transporting antennas to and from testing facilities is inconvenient and costly. Beyond the costs associated with transportation, downtime introduces significant financial implications. For some operators, additional capacity on alternative teleports must be sourced, whereas others, such as those in aviation and maritime, are required to cease operations whilst the antennas are being tested. The financial implications of testing can sometimes deter teleport operators from testing as frequently as they would like to; regular testing is the best way to ensure high-quality connectivity, however, if it is not viable within a business strategy, it may be neglected.
Beyond cost, a huge issue surrounding facility testing is the lack of environmental context within the tests. We know that environmental factors can have a large effect on antenna performance and testing an antenna within a facility cannot account for these issues. An antenna may perform perfectly within a facility and have issues due to reflectivity, geographical features, such as trees or hills, or even other teleports. To truly understand antenna performance, it must be tested within its own environment.
In-field testing
Historically, there have been substantial challenges facing in-field testing. Intercepting RF signals to evaluate antenna performance would require substantial infrastructures being built to house testing equipment, and testing is often limited due to the constraints of the static test site. Additionally, there could be a need for the construction of multiple structures to house the testing equipment as it may not be suitable for all testing needs. Once again, these challenges are enough to deter operators from performing regular testing on-site; not only are infrastructure costs high, but the results may be limited due to positioning restraints.
New technologies have been required to overhaul in-field testing. Drones are now being used as a low-cost and flexible method of performing in-depth antenna testing on-site. Testing is performed by the drone which mimics the satellite, obtaining results as it collects data from its flight. Each flight can be calibrated depending on each antennas needs and, as a dynamic solution, it can obtain several measurements, including azimuth, elevation, and raster cuts. The system ensures repeatability, control over the drone during measurements, and data is aggregated through software to deliver results to the operator.
Importantly, environmental factors can be considered within the results; any location-based challenges can be identified, enabling the operators to make changes where necessary. Reflectivity is a huge concern when managing teleport efficacy; it can impact how RF signals are received and negatively affect services being delivered from that antenna. Drones can be utilised to compute a reflectivity map for a test site through retrieving the reflectivity level for multiple azimuth-over-elevation angular pairs. Identifying the source and impact of the reflectivity enables operators to mitigate its effects through changing the orientation of the antenna, installing displacement equipment or through changing the site configuration. This method is not being limited to existing sites; drones are now being used within site qualification exercises. Building ground segment infrastructures is costly and completing on-site tests ahead of large investments is crucial in ensuring effective ground networks.
Drones are also reducing the ongoing cost of testing through removing the logistical costs associated with relocating antennas, as well as the associated downtime. The reduced costs are also being paired with receiving more realistic results, with the aforementioned environmental factors being considered. This accessibility allows for rigorous testing regimes to be instated and thus enabling operators to maximise throughput of the antenna and ultimately improve the services they provide their customers.
Better testing opportunities for the industry
All operators wish to deliver the best user experience possible whilst maximising business opportunities and managing both teleport effectiveness and RFI is imperative to success. As we see networks within the satcom grow, we must instate new technologies to improve in-field testing that are both accurate and cost-effective. With the number of ground segments set to increase sharply, testing regimes are more important than ever, with spectrum becoming crowded and complexity growing within the up/downlinking process. Simultaneously, testing regimes must be feasible within business strategies; with operators having to test multiple antennas, testing methods must be cost-efficient otherwise they become inaccessible, potentially impacting not only that operator, but others around them. Environmental factors impact the ground segment massively and testing on-site is hugely important when establishing antenna performance. Drones improve both accessibility and provide a well-rounded picture of performance, whilst providing the same repeatability as that of tests performed in a testing facility. As growth within the industry continues, drones will play a substantial role in ground segment infrastructures with antenna testing enabling operators to deliver the most effective and reliable services possible.
