Periodic disturbances in machine direction can be detected on site by means of a mobile transmission sensor. Measurement of paper transmission takes place online and without contact.
With contactless online measurement of paper transmission, a transmission sensorin the paper web scans the paper using IR radiation.
This high-frequency signal is recorded, and a frequency analysis of the measured data shows any periodic disturbances in the paper web between 3 Hz and 3000 Hz. Since there is a correlation between the transmission and the basis weight, conclusions about the stability of the basis weight can be drawn from the transmission data. However, optical distortions in the paper, such as gloss variations, can lead to false results.
The analysis is used for checking the basis weight stability in the paper web. A sensor measures the periodic disturbances in the paper so they can be attributed to a cause.