What does the doppler parameter mean ? 

> show system parameter | grep -i doppler
Doppler: ENABLED

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Instructions

Doppler --- is an internal framework to instrument user data. It’s a javascript basedframework which collects data from the application and stores at CIS servers. The data is collected from the browsers by the CIS scripts and sent to the servers every 15 seconds.
Doppler on CIS has been deprecated, so there is no Back-end support to the Doppler feature on ADC now. Hence disabling or enabling Doppler on ADC will not make any difference and this feature is not in use.