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Systematic errors that changing by a complex law can be
expressed graphically or analytically. If this is difficult, they better
be considered a random errors.
There is no universal method of removal of systematic
errors. Among known methods the most common are:
- removal of sources of errors, especially of errors of
installation;
- preliminary determination of errors and taking them into
account by introducing amendments, found during inspection of
measuring instruments, including adjustments for additional errors.
Special methods of extraction of systematic errors include:
substitution method, method of compensation of error by sign,
method of opposing, method of symmetric observations.
The method of substitution consists in the fact that, initially
at the input of measuring instrument is served measurable value
and then it is replaced with the quantity with known value Х Д, and
measuring device shows previous value. Thus, the unknown value
of the measured quantity x is found by the known value Х Д,
reproduced by measure during replacement.
Method of compensation of error by sign consists in that
quantity is measured twice, but the measurement conditions
change so, that constant systematic error, which is suposed to be
excluded, (known by origin, but unknown by value) is included in
the measurement results with the opposite sign. Then the
arithmetic mean of the results becomes free of this error.
Error compensation method can be used to eliminate error,
sources of which have directed action. However, if the error is
progressive, this method provides only partial removal of it.
Method of opposing consists in the fact that the measured
value is twice compared with the value which is reproduced by
measure, and before the second comparison they are mutually
reversed in measuring circuit. The result of measurement, as an
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