# What do you mean by noise equivalent temperature?

## What do you mean by noise equivalent temperature?

NEDT (noise equivalent differential temperature) is the key figure of merit which is used to qualify midwave (MWIR) and longwave (LWIR) infrared cameras. It is a signal-to-noise figure which represents the temperature difference which would produce a signal equal to the camera’s temporal noise.

## What is NETD in a thermal camera?

In English, the level of thermal sensitivity is referred to as Noise Equivalent Temperature Difference (NETD). This value indicates the minimum temperature difference that is still resolvable by the IR camera.

How to measure NETD?

The NETD is then calculated from the experimental data as follows: NETD=ΔTSNR NETD = Δ T SNR where ΔT = T target − T bkg, and the SNR is the signal-to-noise ratio of the thermal system. Care must be taken to ensure that the system is operating linearly and that no noise sources are included.

What does mK mean in thermal sensitivity?

One of the most important parameters characterising the quality of a thermal imaging detector/sensor is the Noise Equivalent Temperature Difference (NETD) which describes its thermal sensitivity. This parameter is measured in millikelvin (mK) and denotes when the temperature value signal is equal to the noise signal.

Noise-equivalent temperature (NET) is a measure of the sensitivity of a detector of thermal radiation in the infrared, terahertz or microwave portions of the electromagnetic spectrum. It is the amount of incident signal temperature that would be needed to match the internal noise of the detector such…

### How to calculate the power of a thermal noise source?

Where Pin dBW is the noise power at the output of the thermal noise source, kis Boltzmann’s constant 1.38 x 10-23(J/K), Tis temperature (in Kelvin), and Bis the bandwidth (in Hz). At room temperature (17°C/290K), in a 1 Hz Bandwidth we can calculate the power: P (dBW) = 10 log(1.38 x 10 -23 x 290 x 1) = -204 (dBW) P (dBW) = 10 log(P (W) / 1W)

### Is the signal to noise ratio equal to one?

It is the amount of incident signal temperature that would be needed to match the internal noise of the detector such that the signal-to-noise ratio is equal to one. Often the spectrum of the NET is reported as a temperature per root bandwidth.

How is the noise temperature of a receiving system calculated?

The equivalent noise temperature of the whole receiving system, which is called the system noise temperature TSystem and is defined at the input of LNA, is calculated as follows: where GLNA and GD/C are gains of LNA and D/C amplifiers, respectively, and TLn is a noise temperature generated by a lossy circuit Ln.