Teac es8, User Manual

Page: 18 / 69

3.4. Calibration while the Power is ON
Stability of the System
When cold booting, it takes about 10 minutes from the time of power-on to an operating state precise enough to guarantee a stable analog
circuit.
Turning the power on main unit reads calibration values automatically. This action makes settings on each amplifier after reading the
calibration value pre-saved on the back-up SRAM.
This value can be rewritten and updated by doing manual calibration in <Calibration> of <SYSTEM MENU>.
In this calibration process, using internal reference voltage, es8 records internal information as to each input range and sampling
frequency, then calibrates the offset values and gains to update and write the calibration value on the backed up SRAM.
Refer to “Section 11 Manual calibration”
for how to update the calibration value by this calibration process.
Rewriting the calibration value by manual calibration
When much more precision is required in particular or the surrounding temperature is far from the normal one (ie:-10
℃ 、
+50 ), manual
℃
calibration must be done before measuring. Even in other cases, we also recommend you to do periodical manual calibration about once
every 6 months to maintain higher measurement precision.
Block Diagram of Calibration Circuit
Input/Calibration Switcher Range Switcher Amp Gain/Zero Adjustment Amp
From INPUT Electric Volume To A/D converter
D/A converter
Control Logic Circuit
Reference Voltage
Overview of Calibration Action
Offset value adjustment: Output 0V from the reference voltage supply, and adjust zero calibration amplifiers by D/A comparator to make
A/D value zero on each input range.
Gain adjustment: 2V from reference voltage supply, and adjust electrical volume to make A/D value +2V on each input range.
Save the results of these settings on backed-up SRAM.
Page 10