RF INTERFERENCE TRACING, ANALYSING & MITIGATION
RF INTERFERENCE TRACING, ANALYSING & MITIGATION
Your critical comms link suffers from annoying, often unpredictable intermittent degradation?
The reason could be interference!
Potential sources of interference are too numerous to count, from LEDs, solar systems, garage door openers to unlicensed radio signals. Detecting and locating the exact position of these interferers requires a good description of the problem, good knowledge of the subject, can be expensive and time-consuming and is often depending on equipment that can be cumbersome and difficult for one person to operate efficiently.
Professional interference mitigation and elimination requires skills, patience, common sense, equipment and lots of experience.
Mangosat has the knowledge and the equipment to analyse, trace, monitor, mitigate or even fix most of the problems related to terrestrial interference. Please contact Mangosat directly for a free consult.
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What Is Interference
Interference is the presence of disruptive signals affecting radio communications in either the uplink or downlink path, resulting in network issues, service disruptions and dissatisfied customers.
The more urban and/or population dense the area, the higher the likelihood of (unpredictable) interference.
Interference is annoying, frustrating and not always well understood.
Interference impacts network performance and also threatens network quality
Most interference however is unintentional, which can it make extremely difficult to overcome. Unless the problem is very simple, the only really productive approach is an orderly and systematic one that first finds the cause of the specific problem, then applies appropriate corrective action.
Photo credit: Unsplash
The risk of harmful interference from any kind of radiator can usually be reduced through the use of various interference prevention measures, and the risk of sustained interference generally can be eliminated through various interference mitigation techniques. Expertise and experience are key – trial and error as a solution, a waste of time.
A clean, interference free spectrum today is not a guarantee for tomorrow’s situation.
How to Eliminate / Mitigate Interference – Mangosat’s Approach
Mangosat performs a professional and very thorough RF interference (RFI) site inspection and survey.
Before thinking about any solution, we first want to have the problem clearly defined. After-all, understanding the problem is 50% of the solution. Other than trial and error, this is a highly technical operation, and only a few of our field engineers are capable of performing it.
Unfortunately, sources of interference can not always be eliminated or even discussed therefore, positive results can never be guaranteed.
Why a RFI Site Inspection Survey Is Different From Typical Site Surveys
….and therefore organised and charged differently
For such jobs we can only dispatch qualified engineers and the number of qualified engineers is limited. Read More
More About Interference
In short, Radio Frequency Interference (RFI) is a challenge that industries which rely on RF and microwave emissions must tackle head-on. It has the potential to disrupt operations, compromise safety, and erode the efficiency of vital processes. To ensure critical communication links are not affected, RFI mitigation must be prioritised.
Radio Frequency Interference (RFI) is the presence of unwanted signals or electrical energy that detrimentally impact a radio communication system.
Interference issues in wireless networks can result in a higher noise floor on the received channel and a lower carrier-to-noise ratio (C/N) that degrades signal quality. Users suffering from interference will experience lower or intermittent data throughput and if about voice calls: limited range, more dropped calls, or poor voice quality.
The causes of RFI include external, naturally occurring sources like thunderstorms and static electricity, as well as man-made sources created through out-of-band transmissions, radiation from network antennas and cabling, and the proximity of adjacent networks operating on overlapping frequencies.
Badly designed and/or manufactured electronics dramatically contribute to the problem. Think about e.g. solar system inverters.
RFI is a critical issue and a fast growing problem worldwide.
Types of Interference
The wide variety of interference sources and the need for specialised interference test and measurement equipment make it important to distinguish between interference types.
RF signal interference sources fall within the broad sub-categories of intentional and unintentional radiators of RF energy. Both types of RF interference can contribute to the noise floor of a receiver, which makes interference analysis more challenging.
What causes radio frequency interference?
Intentional interference is produced by everyday objects like cell phones and any device intended to function as a transmitter as well as inadequate RF designs or cell tower co-siting practices that impact a receiver’s sensitivity.
Unintentional interference is generated by devices that produce RF energy as a byproduct of their operation, which allows radiated energy to be “leaked” out to nearby areas. Potential sources of unintentional interference include LED illumination, electrical motors and solar systems. Badly designed equipment which contain a digital timing component (oscillator), including laptop computers and tablets, can also create unintentional interference.
Detecting RF interference begins with recognising the symptoms and analysing the data.
A review of system alarms, KPIs, and logs can often reveal whether a weak signal, elevated receive noise floor, or high bit error rate could be due to a hardware failure or configuration issue, rather than interference.
Locating and diagnosing the wide range of RFI sources quickly and accurately requires a versatile test and measurement tool kit.
RFI hunting practices include the use of a proper real time spectrum analysers at site to determine whether the interference is being generated internally or externally and to:
- Analyse any interference signals within the receiver’s bandwidth that are not filtered out.
- Characterise the noise floor to determine whether intermittent noise is compromising signal quality.
- Use a real time spectrum analyser with continuously overlapping data capture to prevent intermittent or transient signals from being missed.
- Use a persistent spectrum display to allow the rapid data collection of real time spectrum analysis to be presented graphically, using color or brightness to signify the probability of signals appearing at a given frequency.
Once the nature and intensity of the interference has been characterised through a systematic network test and on-site analysis, the physical position of the source must be identified.
A special test device connected to a broadband omni-antenna collects and analyses signal interference data in transit. Software then provides visual prompts to guide investigators to the most probable area of interference origin.
After the geographic area associated with the interference source has been narrowed down, one must perform radial signal analysis and generate intersection vectors to triangulate the precise location of unwanted interference. Working in conjunction with real time spectrum analysis, rogue RF emission sources can be diagnosed, located, and maybe even eliminated but not always quickly.
Measuring interference accurately is the key to correctly diagnosing the type, source, and probable cause.
Each wireless communication technology operates within an expected bandwidth and noise power level, measured in dBm.
Any type of interference can affect the noise level, making it harder for the receiver to maintain a bit error free throughput.
Low-level signal measurement is essential for interference hunting and is directly impacted by the spectrum analyser settings. Utilising a low noise/high gain preamplifier, narrowing the resolution bandwidth (RBW) of the RBW filter, and minimising the input attenuation can improve sensitivity considerably. The dynamic range of the RF signal analyser, specified in dB, is also important for interference hunting applications because the expected and unwanted RF signals are best evaluated side by side.
Each source of interference produces a unique signature that experienced RF engineers use to determine the most probable root cause(s).
Spectrum analysis overlayed with network test data such as throughput or BER can be used to quantify the impact of interference on performance.
What Causes Interference
The broad categories of intentional and unintentional interference frame a growing list of potential interference causes.
Advanced signal duplexing methods and increasingly crowded airwaves have created new RF interference sources requiring innovative test and prevention methods.
Passive Intermodulation (PIM) – Increased traffic within the finite RF spectrum has inevitably led to higher signal density. Multiband operation has helped to alleviate this bottleneck.
The main sources of PIM are usually junctions between different types of passive components such as junction between connector and cable, two different types of cables made from different materials, connection between cable and antenna, corroded hardware, etc.
The resulting passive intermodulation (PIM) causes signals from separate wireless communication sources to be mixed. This can impact networks by lowering the signal-to-noise ratio (SNR), increasing the bit error rate (BER), and decreasing throughput.
The addition of frequency bands and carriers to support the 5G rollout has increased the opportunities for crossband PIM.
Co-Channel Interference – Another interference category that is symptomatic of congestion as individual users and operators share and compete for bandwidth is known as co-channel interference (CCI). As the name implies, this problem occurs when multiple signals are present over the same channel. Overlap in coverage patterns can lead to co-channel or on-channel interference.
Adjacent Channel Interference (ACI) occurs when neighbouring frequencies “bleed” into one another due to improper filtering or tuning. Appropriate guard banding between adjacent channels can mitigate this issue and prevent the loss of bandwidth or noise caused by adjacent interfering signals.
The potential interference between satellite signals and 5G networks operating on nearby C-band (3.7 – 3.98 GHz) frequencies is an example of an ACI risk..and a fast growing problem.
How to Mitigate Interference
You cannot stop RF interference, you can only hope to contain it.
Learning how to stop RFI begins with a realisation that there will always be naturally occurring, unintentional, and unexpected forms of interference.
The most successful RFI interference reduction strategies use a multi-faceted approach that includes:
- Shielding: Employing shielding materials and enclosures can help blocking unwanted RFI from entering sensitive areas. Read More
- Filtering: Installing RFI filters can reduce interference by suppressing unwanted frequencies, improving signal quality. Read More
- Grounding: Very important! – Proper grounding and bonding practices are critical to minimising issues, as they divert unwanted electromagnetic energy safely into the ground. Read More
- Antenna Selection: Choosing the right antennas and optimising their positioning can help maximise signal strength while minimising RFI susceptibility. Read More
- Monitoring and Analysis: Regular monitoring and analysis of RFI sources and interference patterns are vital for early detection and prevention. Read More
Furthermore and equally important – if not more important:
- Isolation and Frequency Planning: In situations where RFI sources cannot be eliminated, isolating sensitive equipment from interference sources is an effective solution. Additionally, careful frequency planning can further help avoiding spectral conflicts.
- Employee Training: A well-trained workforce is the first line of defence against RFI. Educate staff on RFI mitigation practices, proper handling of equipment, and what to do when they encounter interference. By fostering a culture of RFI awareness, you can significantly reduce the risk of disruptions.
- Compliance with Standards: Always adhere to industry-specific standards and regulatory guidelines related to RFI. Compliance ensures that you meet safety requirements and operate within legal boundaries. It also demonstrates commitment to high-quality operations.
Effective testing for RF interference should account for all intentional and unintentional interference sources. Utilise the expertise of experienced RF engineers, and deploy a combination of interference test processes including:
- RFI Site surveys to characterise signal strength and quality at various locations and identify previously undetected interference sources.
- Spectrum analysis to identify sources of interference in the frequency band of interest and baseline system noise.
- Continuous monitoring of network transmissions for instances of ongoing or intermittent interference, increased BER, and other forms of signal degradation that should be addressed in real time.
- Interference hunting to proactively seek out, characterise, and eliminate interference sources before they impact QoS.
Interference hunting is the process of locating, identifying, and eliminating unwanted sources of interference that degrade the quality of wireless reception on the receiving end.
As more devices and users are introduced within the limited RF spectrum, minimising the impact of interference becomes more challenging.
What are the requirements to efficiently trace, analyse and reduce the risk of interference and its associated consequences?
A qualified and reputable partner with a proven track record!
Selecting a RFI solutions partner with the right credentials and capabilities is important and should be considered for at least two reasons:
First: To avoid costly and possibly disappointing “trial and error”.
RFI identifying, analysing, mitigation / elimination is a complex field that demands serious expertise in radio, materials, design, and installation.
Second: The appropriate tools and test equipment represents a significant financial investment, one not being made without reason.
Moreover, the operator must have a very good understanding what can be done, and what to do with the equipment.
Mangosat could be your partner.
Tools and Test Equipment Requirements
Finding RFI sources is an essential part of interference mitigation.
RFI sources can be identified through a variety of methods. But most of all it requires knowledge and skills (1), common sense, eyes and ears (2), and some special tools and test and measurement equipment including:
- Spectrum analyzers geared up for the purpose.
- RF detectors: These are sensors that detect the presence of radio waves and can be used to identify the sources of RFI.
- Direction finding equipment: this involves specialized radio receiver and directional antenna systems.
- Radio propagation modeling tool – using computer models to simulate radio wave propagation and help identify RFI sources.
By using a combination of these methods, it is possible to identify the sources of RFI and take steps to reduce their interference.
Reporting and Recommendations
This section is under development and will be published soon.
This section is under development and will be published soon.
