Users' questions

What is the ideal value of noise figure?

What is the ideal value of noise figure?

It is just a ratio of signal power to the noise power. For an ideal conditions, SNR at the input of an amplifier should be equal to SNR at the output of an amplifier because signal power and noise power, both gets amplified.

Is a higher or lower noise figure better?

Noise figure is a number by which the noise performance of a radio receiver, amplifier, mixer or other circuit block can be specified. The lower the value of the noise figure, the better the performance.

How is noise figure calculated?

Example: If the band of interest is 1 MHz, then the effective thermal noise power comes out as: –174 dBm / Hz + 10log10(106) = –114 dBm / 1 MHz. Noise factor of a network is defined as the ratio of signal-to-noise ratio (SNR) at the input to the SNR at the output.

Does preamp reduce noise?

Compared to a “normal” preamp like the ones you’ll find in a decent audio interface, a high quality ultra low noise preamp can improve the noise performance by about 3 to 6 dB – which can make a noticeable difference, if you want to record quiet sources with ribbons or other dynamic microphones.

Which is the correct formula for noise figure?

It is commonly expressed as NF = 10 log F, where, to reiterate, F is the ratio of input to output S/Ns. One reason why noise figure is such a useful measurement in design is that it can be applied to both individual components, such as a transistor amplifier, and to complete systems, such as a receiver.

How is the noise figure of an amplifier related to the signal level?

Noise figure is also independent of the input signal level, at least for as long as the amplifier is working linearly. However, a system’s noise figure is dependent upon the temperature of the source that excites the network, because the noise generated by that source is usually related to its temperature.

How is noise fed to a pre amp?

A signal with noise already on it will arrive at the antenna which is being bombarded with noise from many sources as near and as far as the limits of our imagination and perhaps beyond. The signal and noise is then fed to the pre-amp (and following receiver) via a noisy feeder.

Can a noise meter be used to measure gain?

An engineer can measure the noise figure over a certain frequency range, and the analyzer can display the system gain together with the noise figure to help the measurement. A noise figure meter also has limitations.