SRS Labs SR850 - Manual (Page 235)

7-17
Performance Tests
7. Phase Accuracy
This test measures the phase accuracy of the lock-in. Due to the design of the lock-in, the phase accuracy
can be determined by measuring the phase of the internal oscillator Sine Out.
Setup
Connect the Sine Out to the A input of the lock-in using a 1 meter BNC cable. Do not use any termination.
Procedure
1) {PRESET} (Turn the lock-in off and on with the [
←
] key pressed)
2) Press the keys in the following sequence:
[GAIN/TC]
<Filter db/oct>
Select 24 dB/oct.
[INPUT/FILTERS]
<Coupling>
Select DC coupling.
[DISPLAY/SCALE]
<Type and Trace>
Highlight the trace number.
Use the knob to select trace 3 (R) for the top display.
<Top and Bottom>
Select the Bottom display.
Use the knob to select trace 4 (
θ
) for the bottom display.
3) The value of R should be 1.000 V (±2%) and the value of
θ
should 0° (±1°).
4) Phase accuracy is checked at various frequencies. The test frequencies are listed below.
Test Frequencies
10 Hz
100 Hz
1 kHz
10 kHz
a) Press
[REF/PHASE]
<Ref. Frequency>
Enter the frequency from the table.
b) Wait for the readings to stabilize. Record the value of
θ
.
c) Repeat steps 4a and 4b for all frequencies in the table.
5) This completes the phase accuracy test. Enter the results of this test in the test record at the end of
this section.