Skobeltsyn Institute of Nuclear Physics
Lomonosov Moscow State University

The influence of sensitivity, speed and noise of the receiver on amount of the
information registered by it is considered in the paper. As a basis for the analysis the generalized function block-diagram of the recording instrument. It is shown, that insufficiency of speed derivates so-called threshold information restriction where a threshold of registration is the size of action. The border of trimming of classical thermal noise because of presence of an information threshold is found.