What is the reason for the anti-signal output of the infrared thermometer?
Under normal circumstances, the inverted signal of the infrared thermometer does not meet the phase conditions of the self-tuning DC amplifier, and there is no vibration or output. However, some transmitters also have output when the reverse signal is added, indicating that the amplifier is activated, that is, a certain harmonic of the added reverse signal just meets the phase condition and amplitude condition, so that the temperature transmitter also has output under the reverse signal.
For the measurement occasion of infrared thermometer with zero point migration, during the temperature rise process of driving, the zero point migration signal is just a reverse signal added to the input terminal of the amplifier. If the anti-signal is output, and there is no other instrument as a reference, it will be mistaken for a temperature rise signal, resulting in operational errors.
The solution is to change the gap of the magnetic box of the frequency selective amplifier, that is, to change the inductance L of the frequency selector of the infrared thermometer. When L changes, the passband of the frequency-selective amplifier also changes, and it is likely not to amplify or the amplification factor of this frequency signal is extremely low, which destroys the amplitude condition of the start-up; in addition, due to the change of L, the frequency signal of the amplifier Liu Phase fir also changes, so that the phenomenon of anti-signal output is overcome. It is also possible to reduce the open-loop magnification of the whole machine (destroying the amplitude condition of the oscillator) to overcome the reverse output.
