GE ApexPro TT, Technical Manual

Page: 82 / 192

4-20 ApexPro™ 2001989-351A
Maintenance
11. Set the trace mode to a three cycle average.
a. Press TRACE .
b. Press F1 - TRACE MODE .
c. Select AVERAGE and press ENTER .
d. Type 3 and press ENTER .
12. Set the marker to the peak signal.
a. Press MARKER .
b. Press F3 - SET MARKER .
c. Select Peak and press ENTER .
d. The center maximum peak should be selected.
13. Record the measured frequency of the marker:
Measured frequency: ____________________
14. Subtract the receiver subsystem target frequency ( Determine target frequency on
page 4-15 ) from the measured frequency ( See step 13. ) and record the frequency
difference.
_______________ - _____________ = _____________
Measured frequency - Target frequency = Frequency difference
NOTE
Multiply MHz by 1000000 (one followed by six zeros) to convert to Hz.
15. If the difference is less than or equal to ±10 Hz, no adjustment is required as the
receiver subsystem is within specifications. If the difference is greater, proceed to
Adjust frequency .
Adjust frequency
1. In HyperTerminal , type gvd and press Enter .
2. Record the initial DAC value:
_____________
3. Type svd<space>new value (e.g. svd 162).
NOTE
If the difference calculated above is positive, decrease the DAC value by
one. If the difference is negative, increase the DAC value by one.
CAUTION
Do not move the DAC setting by more than one value at a time to
prevent moving the intended set point/frequency too far, which
could cause signal dropout.