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Signal Health
Signal Health is an important advanced
diagnostic feature that is unique to Chemtrac’s DuraTrac 4 sensor. This readout
provides a higher level of confidence in the accuracy of the displayed streaming current reading. The Signal Health feature is
constantly analyzing the generated signal coming from the probe (which is an approximate 5 Hz sine wave) and looking for any
changes in the signal performance that might indicate a problem such as a fouled sensor, worn mechanics, or other
interferences that can cause the reading to be less accurate. A signal health greater than 97% indicates a near perfect signal
is coming from the sensor. If the signal drops below 96%, especially for an extended period, then sensor cleaning is likely
required. If cleaning does not raise the signal health, inspection of the waveform signal is recommended to help determine
the cause of the low signal health. With older units, replacement of worn parts (e.g. probe, piston, yoke & rod end assembly)
will typically help restore signal health.
Waveform Signal
To view the Streaming Current waveform signal, go to Menu> SCM > Options > Diagnostics > Waveform. The waveform view
will update every 5 seconds. The waveform display can aid tremendously with troubleshooting problems with the SCM
response or stability. The Signal Health % of the waveform is only calculated when the signal is greater than 0.050 (peak to
peak) in amplitude. As the signal gets closer to zero volts in amplitude, the Signal Health will no longer be calculated and the
display will show “
---
“ (three dashes).
Negative SC Signal (0.50 V P-P)
Neutral SC Signal (<0.01 V P-P) Slightly Positive SC Signal (0.04 V P-P)
The image to the left shows how the waveform can appear when the sensor
has a worn out Yoke in need of replacement. Hitches start to appear in the
signal’s rising and falling edges as the
sensor drive mechanics, which move
the piston up and down, begin to wear down. This also causes the peak of
the sine wave to shift left or right. These changes in the sine wave cause the
signal health to drop down towards 90%. Note: The Phase readout
measures the location of the sine wave’s peak in relation to the square wave
and should ideally be between 45 to 55%.
Left axis shows amplitude of SC Signal
Right axis shows amplitude of Opto Signal, which should be 10 Volts
