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frequency until channel A frequency has an accuracy of 10
-6
. Since channel A frequency and Channel B frequency
use the same fixed reference clock, after channel A frequency is calibrated, channel B applies the same accuracy.
3.14.3 Calibrate the Carrier Frequency
In the frequency modulation mode, the carrier frequency uses a programmable clock as its reference clock.
Although the carrier frequency is the frequency of the channel A, it still needs to be calibrated. Select “Carrier
Freq” option by the corresponding soft key. The carrier frequency value of channel A changes to yellow. The
instrument outputs a sine wave at fixed 2MHz. Use a frequency counter to measure the frequency of channel A
and adjust the calibration code by the rotary knob until the accuracy of channel A frequency is calibrated to 10
-3
.
3.14.4 Calibrate the Frequency Modulation Deviation
Select “FM Deviation” option by the corresponding soft key. The FM deviation value changes to yellow. The
instrument outputs a carrier frequency at fixed 2MHz. The signal of the frequency modulation deviation is 1%.
Use a modulation meter to measure the FM deviation of channel A and adjust the calibration code by the rotary
knob until the accuracy is calibrated to 10
-3
.
Select “CAL Over” option by the corresponding soft key. The characters change to yellow and exit the calibration
mode. The calibration codes are stored into the nonvolatile memory of the instrument, and will not be lost after
power off. The calibration codes will be refreshed after a second calibration is carried out.
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