Home >> Hobbies >> Other Hobbies

How to Calculate Signal-to-Noise for an Instrument Amplifier

An instrument amplifier̵7;s signal-to-noise figure is a ratio of a standard output signal level to the noise the amplifier produces with no input signal. Audio noise is an unavoidable part of an amplifier̵7;s electronic circuits; an amplifier designer strives to reduce the noise to very low levels. The signal-to-noise, or SNR, ratio is measured in units of decibels, or dB. To calculate SNR decibels, you divide the standard -10dBV signal, which is .316 volts RMS, by the noise voltage of the amplifier, and then take the common logarithm of the result and multiply by 10.

Things You'll Need

Scientific calculator

Instructions

- 1
  Enter the number ̶0;.316̶1; into your calculator. This is the RMS voltage of a standard output signal. Press the ̶0;Division̶1; key.
- 2
  Enter the RMS voltage of your amplifier̵7;s noise. Usually, this is a very small number, such as .000005 volts. Press the ̶0;Equals̶1; key on your calculator. In this example, the result will be 63,200.
- 3
  Press the ̶0;Common Logarithm̶1; key on the calculator. This key is usually labeled ̶0;Log.̶1; Next, press the ̶0;Multiply̶1; key, enter ̶0;10̶1; and press the ̶0;Equals̶1; key. The result is signal-to-noise in decibels. Continuing the example, the result is 48.

Other Hobbies