Over time, these problems can accumulate and prevent a transmission site from going online due to damaged RF components or even cause fires that completely disable the broadcast transmission system.
How can damage of these kinds be prevented?
SPINNER has developed an active early detection system: the Antenna Monitoring System (AMS). It precisely spots possible problems in cables, distributors, and antennas before major damage can occur.
And How Does Fault Detection Work of the SPINNER AMS work?
In the beginning of 2020, we presented our new distance-to-fault feature: a passive solution that locates faults for fast repairs. Customers showed great interest in it and asked a number of questions, including:
- How does the passive distance-to-fault method work?
- What kind of faults can be detected?
- Can it detect minor degradation of system’s performance or only major faults?
When you think about methods to locate faults is TDR (time-domain reflectometry) that first comes to mind. It works similarly to radar, actively sending a signal and observing the reflected waveforms to calculate the distance. However, an external signal is the last thing a broadcaster wants to inject into a line. It adds noise, can interfere with other services, and in a worst-case scenario may even violates the allowed emission spectrum, which can vary from country to country.
The SPINNER Solution for Distance-to-Fault Detection:
Intelligent VSWR Monitoring
At SPINNER we were aware of the need for an innovative solution and knew that it had to be passive. Our engineers came up with the brilliant idea of taking an approach similar to radar, but using the broadcast signal itself instead of injecting a new one. We will then listen for the reflected waves to calculate the distance to the fault. This approach makes it possible to monitor the VSWR at every point of an antenna line.
To find out when and where a fault occurs, the system’s current VSWR is compared with a recorded reference measurement made during normal operation. Every event that causes VSWR degradation is treated as a potential fault. Even a deterioration in performance as small as -45 dB can be detected. This makes it possible to spot and fix faults that are still too minor to cause damage to the system and before they turn into severe failures.
The recorded reference measurement is made with a mouse click at our GUI without the need for hardware calibratiion.
Monitoring of Arcs and Water Ingress
VSWR monitoring is just one of various fault detection methods used by the AMS. It also applies two other measurement methods: water ingress (insulation) monitoring and arc monitoring. The later one being proven extremely important because it can detect matched arcs. These are arcs that don’t significantly degrade the VSWR. They are extremely dangerous because conventional continuous VSWR monitoring is unable to detect them, which means they would persist and continue to heat the surrounding material.