I. Drift Status Verification and Preparation Prior to Calibration: Use a reference process calibrator to measure the signal generator's full-range output value point by point. To understand the drift distribution pattern, note the actual drift deviation at each calibration point.
To prevent further calibration errors caused by temperature changes, turn on the device and warm it for at least 45 minutes to allow the internal drift analogue circuitry to fully thermally stabilise.
Turn off all modulation functionalities, choose the normal DC/sine wave output mode, and attach an oscilloscope, frequency counter, and reference calibrator with an accuracy class > ±0.01%.
II. Drift Zeroing and Basic Calibration: To directly reset the currently recorded zero-point drift deviation to zero and remove the basic zero-point offset, navigate to the "System Calibration" menu on the device and use the "Drift Zeroing" option.
Recalibrate the frequency reference by setting a typical output frequency of 10MHz, using the frequency counter to measure the actual value, adjusting the frequency correction coefficient, and keeping the frequency drift deviation within ±1ppm.
III. Full-Range Drift Correction Point-by-Point
Using a reference device, determine the actual output value after setting the output amplitude point by point in accordance with the 10%, 25%, 50%, 75%, and 100% range.
To prevent nonlinear drift variations in various range segments, modify the associated channel's gain correction value for each range separately. This will ensure that the full-range output deviation is ≤ ±0.05%FS.
To rectify the temperature analogue signal's drift deviation and meet the hot runner temperature control channel's calibration requirements, calibrate the thermocouple millivolt output and the RTD output point by point.
IV. Verification of Drift Stability
After calibration, operate the apparatus continuously for an hour, taking ten-minute readings of the output values of important calibration points throughout the whole range.
Verify that there is no instability phenomenon with continuous deviation over time, suggesting that the drift has been totally eradicated, and that the drift quantity does not exceed 0.02% of the range during an hour.
Examine the internal crystal oscillator's ageing and the analogue circuit components' deterioration if the drift amount keeps going beyond the limit. Repeat the entire process calibration after replacing the malfunctioning parts.
V. Drift Warning Settings and Parameter Fixation
Create a drift calibration profile that documents the deviation distribution and correction amount for this drift by saving all corrected calibration parameters to the device's non-volatile memory.
Set the drift threshold to 0.1% of the range and activate the device's built-in drift warning feature. When the drift surpasses the limit during future operation, an alarm will be immediately set off, giving early notice of drift recurrence.
