Here is a great video explaining the concept of signal-to-noise ratio.
Signal-to-Noise Ratio
The video “Signal to Noise Explained in plain English. | Ham Radio For Dummies K6UDA Radio – YouTube” explains the concept of signal-to-noise ratio (SNR) in the context of ham radio. The video is presented by K6UDA Radio, which simplifies the technical jargon of SNR for a layperson. SNR refers to the ratio of the desired radio signal to the background noise in the receiving equipment, measured in decibels.
Having a good receiver is important to overcome SNR, especially on certain bands. The noise floor, which is the level of atmospheric noise picked up by the receiver, is an important factor in SNR. Pixie dust is a term used to describe atmospheric noise, which can create heavy noise floors, particularly on 80 meters.
The video provides an example of how digital signal processing can improve SNR by filtering out noise. The video also contains information about a meter giveaway for subscribers. [1]
Signal to Noise Explained in Plain English
- The video is about explaining the concept of signal-to-noise ratio in ham radio.
- The speaker emphasizes that he is not an expert or a scientist but aims to explain the topic in a simple way for non-technical individuals.
- The noise floor is described as the background atmospheric noise present during radio transmission.
- The speaker demonstrates how adjusting preamps and using digital signal processing (DSP) can improve the reception of weak signals amidst the noise.
- The importance of overcoming the signal-to-noise ratio is highlighted as it allows for better communication with weaker signals, which is considered valuable in ham radio.
Does antenna resonance / non-resonance effect S/N ?
Yes, antenna resonance (or non-resonance) does affect the signal-to-noise ratio (SNR), though the relationship is indirect and depends on how resonance impacts the antenna’s efficiency and impedance matching.
A resonant antenna is one where its electrical length matches the wavelength (or a fraction/multiple thereof) of the signal it’s designed to transmit or receive. When an antenna is resonant:
It maximizes energy transfer between the antenna and the transmitter/receiver due to optimal impedance matching.
This efficiency means more of the desired signal power is captured (for receiving) or radiated (for transmitting), which can improve the signal strength relative to noise.
However, resonance itself doesn’t directly reduce noise—noise is typically determined by external factors (e.g., environmental interference, receiver electronics) and remains relatively constant.
A non-resonant antenna, on the other hand:
Has a mismatch in impedance, leading to less efficient energy transfer.
This inefficiency reduces the signal strength because some power is reflected back rather than being transmitted or received.
Since noise power is largely unaffected by resonance, a weaker signal results in a lower SNR.
So, in practical terms:
A resonant antenna improves SNR by boosting the signal strength while noise stays roughly the same.
A non-resonant antenna degrades SNR by lowering the signal strength, making the noise more prominent relative to the signal.
The effect’s magnitude depends on how far the antenna is from resonance and the quality of the matching network (if any) used to compensate. For critical applications, engineers often tune antennas or use matching circuits to optimize SNR at the desired frequency.