Latvian Patent No. 14764. “The method for evaluation of random errors of precise meters” Inventor: V.Bespaļko, J.Buls, A.Ribakovs, A.Skaģeris. Owner: Institute of Electronics and Computer Science. Published: 20.11.2013.

The invention concerns the area of measuring hardware metrology, particular estimation of random error of meters. The method supposes multiple measuring of permanent test signal and statistical measuring results processing and includes the following operations:

– in every i-th measuring cycle the test generator signal is being measured simultaneously by two meters

A and B, and the obtained results Ai and Bi are being saved;

– the measuring cycles are repeated multiply (n times), as a result arrays {AI}n i=1 , {Bi} n i=1 ; of measuring results are accumulated;

– for the measuring results the arrays the covariance cov ( A, B ) and variances D[A] and D[B] ere calculated;

– variances D[a] and D[b] of random errors components of each meter are estimated according to the relationships:

D[a] = D[A]- cov (A,B),

D[b] = D[B]- cov (A,B).

The offered method just as well known „three-cornered hat” method is useful for precise instrumentation testing. The offered method implementation is easier since the known method is based on excluding of test generator signal instability influence (that requires for applying three measuring channels), but the offered method is based on the evaluation of this instability (it’s enough with two measuring channels).