# Is there a way to quantify the amount of radiofrequency interference?

Is there a way to quantify the amount of radiofrequency interference? Do any units exist that quantifies how much radiofrequency interference is there?

• Isn’t that signal noise ratio or signal rejection? – Solar Mike Mar 30 at 5:18
• dBmV and dBmV/m – Pete W Mar 30 at 15:26

## 1 Answer

The severity of radio frequency interference is described by comparing the power content of the interfering noise to that of the desired signal. The power content is measured in units of decibels and the ratio of signal power to noise power gives the signal to noise ratio.

For a signal to be readable it must be stronger than the underlying noise interference (this is called the noise floor). Decibel math states that for two signals that differ by 3 decibels, the power content of the stronger signal is twice that of the weaker signal. So to lift a signal above the noise floor by +3dB requires the signal to be twice the strength of the noise floor.

• FYI for the OP: +3dB is also a factor of √2 in terms of amplitude units such as mV or mA. And while signal-to-noise ratio (SNR), in dB, is relevant for signal integrity, for radiated interference (EMI), the specification usually references electric field strength (e.g. mV/m, but again expressed in dB, making it dBmV/m). – Pete W Apr 1 at 1:00
• @PeteW, should I delete? – niels nielsen Apr 1 at 4:39