In signal theory, the noise floor is the measure of the signal created from the sum of all the noise sources and unwanted signals within a measurement system. See also Signalling theory, a concept in Evolutionary biology Signal theory is the theory of the Engineering discipline is a one volume manga created by Tsutomu Nihei as a prequel to his ten-volume work Blame!.

In radio communication and electronics, this may include thermal noise, blackbody, and any other interfering signals. Johnson–Nyquist noise ( thermal noise, Johnson noise, or Nyquist noise) is the electronic noise generated by the thermal agitation In Physics, a black body is an object that absorbs all light that falls on it In a measurement system such as a seismograph, it may include nearby foot traffic or a nearby road. Seismometers (from Greek Seism - "the shakes" - and Metro - "I measure" are instruments that measure and record motions of the ground including The noise floor limits the smallest measurement that can be taken with certainty since any measured amplitude can on average be no less than the noise floor.

A common way to lower the noise floor in electronics systems is to cool the system to reduce thermal noise, which is usually the major noise source. In special circumstances, the noise floor can also be artificially lowered with digital signal processing techniques. Digital signal processing ( DSP) is concerned with the representation of the signals by a sequence of numbers or symbols and the processing of these signals