I. Preparation and Self-Test Before Calibration
Power on the hot runner signal generator and allow it to warm up for at least 30 minutes to allow the internal crystal oscillator and analog circuitry to reach thermal stability, eliminating initial deviations caused by temperature drift.
Enter the device's "System Settings" menu and perform a system self-test to confirm that all channels have no hardware errors and the device is functioning normally.
Disable all AM, FM, PM, and other modulation functions, and uniformly select a standard sine wave/DC signal as the output waveform to avoid interference from additional signals during the calibration process.
Prepare a process signal calibrator with an accuracy class ≥ ±0.01%, a high-precision frequency counter, and a digital oscilloscope with a bandwidth ≥ 100MHz as calibration reference equipment.
II. Frequency Reference Accuracy Calibration
Set the signal generator output frequency to a typical value of 10MHz and use the high-precision frequency counter to measure the actual output frequency.
If the measured value deviation exceeds ±1ppm, enter the "Frequency Calibration" menu and adjust the "Frequency Correction Factor" until the deviation is zero.
Repeat the above steps, covering the full frequency range (1μHz to 200MHz), focusing on calibrating the 10kHz, 1MHz, 10MHz, and 100MHz frequency bands commonly used for hot runner calibration to ensure clock reference accuracy meets standards.
III. Output Amplitude Accuracy Calibration: Set the output amplitude to 1Vpp (peak-to-peak value) and measure the actual output amplitude using an oscilloscope or high-precision multimeter.
If the deviation exceeds ±1%, adjust the "Gain Correction Value" through the "Amplitude Calibration" menu to eliminate amplitude output error.
Repeat the above steps, covering the 10mVpp, 100mVpp, 10Vpp, and 20Vpp amplitude ranges commonly used for hot runner calibration. When calibrating high amplitude, enable the oscilloscope's high-impedance input mode (≥1MΩ) to avoid load effects introducing deviations.
IV. Waveform Distortion Calibration: Output a 1kHz sine wave and use the oscilloscope's THD (Total Harmonic Distortion) measurement function to check the waveform distortion.
If the THD exceeds -60dBc, adjust the signal generator's "waveform optimization" parameters, such as filter bandwidth and waveform smoothing coefficient, to reduce waveform distortion.
If necessary, use an external distortion calibration kit for advanced correction to further optimize waveform quality.
V. Multi-channel Synchronous Calibration
Using the rising edge of the main channel output waveform as a reference, simultaneously acquire the output signals of all slave channels using a multi-channel oscilloscope, and read the phase time difference between each channel and the main channel.
Using an adaptive correction algorithm, adjust the channel transmission characteristic compensation parameters channel by channel to make the transmission characteristics of all channels approach the reference channel, ultimately controlling the synchronization deviation to ≤0.01s.
After calibration, fix the steady-state weight vector of each channel as the correction filter coefficient to ensure long-term stability of the synchronization state.
VI. Thermal Signal Specific Accuracy Calibration
Thermocouple Signal Calibration: Set the signal generator to output millivolt analog signals of commonly used thermocouples such as K-type and J-type. Using the millivolt measurement value of the process calibrator as a reference, adjust the thermocouple output correction coefficient to ensure that the temperature simulation output accuracy matches the calibration requirements of the hot runner temperature control channel.
RTD signal calibration: Set the signal generator to output simulated resistance signals from common RTDs such as Pt100 and Cu50. Using the resistance measurement value from the process calibrator as a benchmark, adjust the RTD output correction coefficient to ensure the simulated resistance output deviation is ≤ ±0.05%FS.
VII. Post-calibration verification and parameter solidification: After all calibrations are completed, randomly select 10 calibration points across the full range and measure the output value one by one using a benchmark device to confirm that the accuracy deviation at all points is within the allowable range.
Run the device continuously for 30 minutes, collecting output accuracy and synchronization deviation data every 5 minutes to confirm no instability due to time-varying drift.
Save all calibrated frequency correction coefficients, gain correction values, and thermal signal correction coefficients to the device's non-volatile memory. These parameters will not be lost after a power outage and restart.
Record all parameter values from this calibration to generate a calibration file, providing a comparison benchmark for subsequent periodic recalibrations.
This detailed calibration procedure is fully adaptable to hot runner industrial field operation and maintenance scenarios. The operation process is clear and practical, enabling rapid, comprehensive, and high-precision calibration of the hot runner signal generator.
