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Atlas circuit isolation, noise & crosstalk tests

For the development of our Tentacle Shield for Arduino we analyzed the Atlas Scientific sensor circuits for noise and probe crosstalk.

To be answered:

  • What are normal base values, range of error during normal operation?
  • What is the effect of touching the circuits on these readings?
  • What is the effect of noise on sensor system?
  • Is there cross talk between probes?
  • If so does probe cross talk effect measurements?
  • Is there cross talk between circuits?
  • If so does circuit cross talk effect measurements?



Test Equipment

[feature show_icon=”true” shape=”hex” title=”Controlled environment 1″]thermos with distilled water: temperature approx 25°C[/feature]

[feature show_icon=”true” shape=”hex” title=”Controlled environment 2″]tank with tap water: temperature approx 25°C[/feature]

[feature show_icon=”true” shape=”hex” title=”Noise source”]mains powered florescent tube noise at the Atlas probes at 85mVpp[/feature]

[feature show_icon=”true” shape=”hex” title=”Oscilloscope sensor”]1x 100MHz probes, ground antenna to sense environment noise as a base reading, pigtailed shielded ground connection for accurate noise reading on BNC inputs[/feature]

[feature show_icon=”true” shape=”hex” title=”Atlas Scientific sensor circuits”]circuits calibrated individually on Atlas Scientific Arduino shield[/feature]

[feature show_icon=”true” shape=”hex” title=”Calibration and reading from circuits”]Atlas desktop beta build date: 17/05/2013C[/feature]



Settle times

The time it takes values to converge after a change is made in the environment.

Change media: moving probe from one liquid to another
Touch: making physical contact with the sensor
Change configuration: adding/removing circuits from a ground plane shared with other circuits

[table]Circuit,change media,after touch, change configuration
DO, 5mins, 5sec, 0
ORP, 10mins, >20mins*,10mins[/table]* (10mins after cold restart)


Continue reading: Effects of touch and noise

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