Reading Time: 10 minutes

“How do you read me?” “Loud and clear.”

Every old war movie

Radio frequency interference (RFI) is any interference caused by an external source that affects the normal operation of radio frequency (RF) equipment. This can include interference from other electronic devices, power lines, or even natural sources like lightning. RFI can cause problems such as reduced signal quality, increased noise, and even complete loss of signal. It can also cause equipment malfunction and damage. RFI can be mitigated through the use of shielding, filtering, and other techniques.

RF Signal Level

A low level signal in a wireless communication network can have several impacts, including:

  1. Reduced signal quality: A low level signal may not be strong enough to overcome noise and other types of interference, resulting in a lower signal-to-noise ratio and a degraded signal quality.
  2. Increased error rate: A weak signal can result in more errors in the data transmission, due to the increased likelihood of bit errors caused by fading and other factors.
  3. Reduced coverage area: A low level signal may not be able to reach as far as a stronger signal, resulting in a reduced coverage area for the communication network.
  4. Limited capacity: A low level signal may not be able to support as many simultaneous connections as a stronger signal, limiting the overall capacity of the network.
  5. Difficulty in maintaining network synchronization: in some wireless networks, such as mobile networks, low signal level can make it difficult to maintain network synchronization.
  6. Potential for dropped calls or lost connections: in cellular or mobile networks, low signal level can cause dropped calls or lost connections.
  7. Increased power consumption: In battery-powered devices, low signal levels may result in increased power consumption as the device may have to use more power to try to maintain a connection.

Impulse Noise Interference

Impulse noise interference (INI) in RF is a type of radio frequency interference caused by short-duration, high-energy electrical transients. These transients can be caused by a wide variety of sources such as lightning strikes, electrical power line switching, and equipment malfunctions. INI can cause significant disruptions to RF signals, resulting in errors, loss of data, and even equipment damage. It can be mitigated through the use of filtering, signal processing, and other techniques.

The Noise Floor

The noise floor in the 900 MHz ISM (Industrial, Scientific, and Medical) spectrum can have a significant impact on the performance of wireless communication systems that operate in this frequency band. The noise floor refers to the minimum level of background noise present in a given frequency band, which can be caused by a variety of sources such as electronic devices, atmospheric conditions, and even cosmic radiation.

In the 900 MHz ISM spectrum, the noise floor can limit the sensitivity of wireless receivers, making it more difficult for them to detect and decode signals in the presence of noise. This can lead to increased error rates, reduced signal-to-noise ratios, and decreased overall system performance. It can also make it more difficult to transmit data at low power levels, which can be an important consideration for battery-powered devices, such as smart water meters.

To mitigate the impact of the noise floor, wireless systems may use techniques such as error correction coding, signal processing, and adaptive modulation. Additionally, using techniques such as frequency hopping, beamforming, and spatial multiplexing can help to reduce the overall noise floor.

ANALOGY: You want to hear the song of just one bird. Yet, all of the other birds are happily singing at the same time. So, it is impossible to discriminate the desired bird from the undesired birds. In radio terms, you can not discriminate one signal from the myriad of other signals occupying the same spectrum.

Carrier-to-Interference Ratio

The Carrier-to-Interference ratio (C/I) is a measure of the quality of a radio signal, and it is used to evaluate the performance of wireless communication systems. C/I is the ratio of the power of the desired signal (carrier) to the power of the interfering signals (interference). A higher C/I ratio indicates a better signal quality, while a lower C/I ratio indicates a poorer signal quality.

Radio interference can come from a variety of sources, including other wireless systems, electronic devices, and even natural phenomena such as atmospheric conditions and solar flares. Interference can cause a decrease in the C/I ratio, leading to decreased system performance, increased error rates, and reduced signal-to-noise ratios.

To mitigate the impact of interference, wireless systems may use techniques such as frequency hopping, beamforming, and spatial multiplexing, which can help to reduce the overall interference level and improve the C/I ratio. Additionally, using error correction coding, signal processing, and adaptive modulation can help to improve the system’s ability to detect and decode signals in the presence of interference.

It is important to note that in some cases, the type of service, regulations, and standards may set a minimum C/I level that the wireless system must meet, to ensure a certain level of service quality.

Harmonics

In the context of RF (radio frequency) signals, harmonics are additional frequency components that are present in a signal, but are not part of the original, or “fundamental,” frequency. These additional frequency components are typically integer multiples of the fundamental frequency, hence the name “harmonics.”


For example, if the fundamental frequency of a signal is 10 MHz, the second harmonic will be at 20 MHz, the third harmonic at 30 MHz, and so on. Harmonics can be generated by non-linear devices, like amplifiers, or by other factors such as distortion in transmission lines. Harmonics can cause interference with other signals and can also indicate poor signal quality.

In-Band Interference

In-band interference in RF (radio frequency) refers to any type of interference that occurs within the same frequency band as the signal of interest. In other words, it is interference that occurs at the same frequency range as the desired signal, as opposed to out-of-band interference which occurs outside of the desired frequency range.


In-band interference can be caused by a variety of sources, such as other transmitters operating on the same frequency, internal equipment malfunction, or even reflections of the desired signal. It can cause a reduction in signal quality, increased noise, and errors in communication. In-band interference can be mitigated through the use of filtering, signal processing, and other techniques.

Adjacent Band Interference

Adjacent band interference in RF (radio frequency) refers to any type of interference that occurs in frequency bands immediately adjacent to the band in which the signal of interest is transmitted. This interference can be caused by a variety of sources, such as other transmitters operating on adjacent frequencies, internal equipment malfunction, or even reflections of the desired signal. Adjacent band interference can cause a reduction in signal quality, increased noise, and errors in communication. It can also cause interference with other communication channels. Adjacent band interference can be mitigated through the use of filtering, signal processing, and other techniques. For example, using proper filtering in the receiver, or ensuring that the adjacent band users have proper coordination and licensing to avoid interference.

How Do You Read Me?

RF devices such as radios, base stations, and transceivers, can read RF signals by receiving and decoding the radio waves that are transmitted over the air. They use antennas to capture the RF energy from the air and convert it into electrical signals that can be processed and understood by the device. “Loud and Clear” in this context means that the RF signal is strong and can be easily received and decoded by the device, which indicating a good quality signal and a reliable communication.

The Importance of Signal Receive Threshold

The signal receive threshold (SRT) in RF (radio frequency) refers to the minimum level of signal strength that is required for a receiver to properly detect and decode a signal. This threshold is set by the receiver’s design and can vary depending on the specific equipment and the environment in which it is used.

The importance of SRT in RF communication is that it helps to ensure that the receiver only detects and processes the desired signals, and not noise or other unwanted signals. A higher SRT can help to reduce the impact of noise and interference, but it also means that weaker desired signals may not be detected. On the other hand, a lower SRT can increase the sensitivity of the receiver and allow it to detect weaker signals, but it also increases the risk of false alarms and errors caused by noise.

Properly setting the SRT is important in order to strike a balance between ensuring that desired signals are received while minimizing the impact of noise and interference. This can be done through adjusting the SRT as well as implementing other techniques such as filtering, error correction, and signal processing.

In summary, SRT is a critical parameter in RF communication systems. It helps to ensure that the receiver only detects and processes the desired signals and not noise or other unwanted signals, while striking a balance between the sensitivity of the receiver and the impact of noise and interference.

Transmit Power

The transmit power in an RF (radio frequency) link refers to the amount of power that is transmitted by the transmitter. The importance of transmit power in an RF link is that it determines the strength of the signal that is received by the receiver, and it also determines the range of the communication.

  1. Signal strength: The greater the transmit power, the stronger the signal that is received by the receiver. This can help to overcome noise and interference, resulting in a higher signal-to-noise ratio and a better signal quality.
  2. Range: The greater the transmit power, the greater the range of the communication. This means that the signal can reach farther, allowing for a larger coverage area.
  3. Capacity: Higher transmit power allows to support more simultaneous connections, which increases the overall capacity of the network.
  4. Interference: Properly managing the transmit power can help to avoid or reduce interference with other communication channels.
  5. Power consumption: Transmit power directly affects the power consumption of the transmitter, in battery-powered devices, high power level can result in shorter battery life.

It’s important to note that while transmit power is important, it is not the only factor that determines the performance of an RF link. Other factors such as receiver sensitivity, antenna gain, and the environment can also play a role. Therefore, it’s important to balance the transmit power with other parameters in order to optimize the performance of the RF link.

Conclusion

To design a great RF (radio frequency) network connection, several factors should be considered, including:

  1. Frequency selection: Selecting the appropriate frequency band for the network is crucial for avoiding interference and ensuring that the network is able to operate effectively.
  2. Transmit power: Properly managing the transmit power can help to ensure that the signal is strong enough to reach the intended coverage area, while also avoiding interference with other communication channels.
  3. Receiver sensitivity: The receiver sensitivity should be set to a level that allows for the desired signal to be received while minimizing the impact of noise and interference.
  4. Antenna design: Proper antenna design is crucial for ensuring that the signal is transmitted and received effectively. This includes selecting the appropriate type of antenna, as well as optimizing the gain, directivity, and other parameters.
  5. Channelization: To avoid interference and to increase the capacity, it’s important to properly plan the channelization of the network and to avoid overcrowding of the channels.
  6. Error correction: Error correction techniques such as forward error correction (FEC) can help to reduce the impact of errors caused by noise and interference.
  7. Power management: In battery-powered devices, it’s important to minimize the power consumption in order to increase battery life.
  8. Network planning: Network planning is critical to ensure that the network is designed to meet the requirements of the users and the intended coverage area, and that the network is scalable to accommodate future growth.
  9. Quality of Service (QoS): To ensure that the network is able to meet the needs of different types of applications and users, it’s important to implement Quality of Service (QoS) mechanisms to prioritize different types of traffic.
  10. Security: It is important to implement security mechanisms to protect the network from unauthorized access and to ensure the confidentiality, integrity and availability of the data.

The above-mentioned factors are important when designing a RF network. With all wireless connections, there is a lot to go wrong. Wireless connections are valuable when copper or optical connections are not possible or cost effective.

————————–MJM ————————–

Note:

This article was written by the author making use of the OpenAI ChatGPT artificial intelligence platform. So, it is a mass-up of human and machine content creation.

To properly make use of this AI platform, it is essential to know exactly what questions to ask as the AI is not perfected to know the questions but can respond very well with answers to your questions.

These are still early days for content creation AI platforms. It is frightening to image where these machines will be next year, in 5 years, or in 10 to 20 years from now….

Here is a link to the AI platform. You need to make an account to access it properly and it is often overworked with too many requests, so you may get rejected to access it. Keeping trying and it will let you in once the cycles are available. Also, try to access it during non-working hours (Pacific Time) as it will be more readily available.

https://openai.com/blog/chatgpt/

About the Author:

Michael Martin is the Vice President of Technology with Metercor Inc., a Smart Meter, IoT, and Smart City systems integrator based in Canada. He has more than 35 years of experience in systems design for applications that use broadband networks, optical fibre, wireless, and digital communications technologies. He is a business and technology consultant. He was senior executive consultant for 15 years with IBM, where he has worked in the GBS Global Center of Competency for Energy and Utilities and the GTS Global Center of Excellence for Energy and Utilities. He is a founding partner and President of MICAN Communications and before that was President of Comlink Systems Limited and Ensat Broadcast Services, Inc., both divisions of Cygnal Technologies Corporation (CYN: TSX). Martin served on the Board of Directors for TeraGo Inc (TGO: TSX) and on the Board of Directors for Avante Logixx Inc. (XX: TSX.V).  He has served as a Member, SCC ISO-IEC JTC 1/SC-41 – Internet of Things and related technologies, ISO – International Organization for Standardization, and as a member of the NIST SP 500-325 Fog Computing Conceptual Model, National Institute of Standards and Technology. He served on the Board of Governors of the University of Ontario Institute of Technology (UOIT) [now OntarioTech University] and on the Board of Advisers of five different Colleges in Ontario.  For 16 years he served on the Board of the Society of Motion Picture and Television Engineers (SMPTE), Toronto Section.  He holds three master’s degrees, in business (MBA), communication (MA), and education (MEd). As well, he has three undergraduate diplomas and five certifications in business, computer programming, internetworking, project management, media, photography, and communication technology. He has completed over 20 next generation MOOC continuous education in IoT, Cloud, AI and Cognitive systems, Blockchain, Agile, Big Data, Design Thinking, Security, Indigenous Canada awareness, and more.