Boston Electronics Corporation, 91 Boylston Street, Brookline MA 02445
(800)347-5445 or (617)566-3821 * fax (617)731-0935 * boselec@boselec.com * www.boselec.com
Bartles Industrial Estate, North Street, Redruth, Cornwall TR15 1HR
Tel. (01209) 314608 E-mail: scitec@scitec.uk.com
Fax. (01209) 314609 Web: http://www.scitec.uk.com
(20) Switch the output select switch (7) to R. The instrument is now correctly set up and
measurements of the signal amplitude can be taken directly from the output display. You
can check that the instrument is correctly set up by rotating either of the phase shift dials
(9)(10). After a short period to allow the X and Y channels to settle, the R output should
return to its original value.
(21) Measurements of the phase of the input signal can be made by turning the phase shift dials
(9)(10) to 0° and then taking readings of both the X and Y channels. The phase relationship
between the input and the reference can then be calculated using the equation
θ
=
−
tan
1
Y
X
.
Please note that it is necessary for the X and Y outputs to be noise free for the calculation of
the R output to be accurate. It is recommended that the time constant control (3) is set to
300mS or higher when taking R measurements. The problem with noise occurs due to the
squaring effect in the R calculation
RXY=+
22
Noise on either the X or Y channels is squared which produces a DC offset which is added to
the R output signal as an error. The solution is to ensure that the X and Y channels are
smoothed before the calculations are made by using a large time constant value.
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