Hey so just to add some documentation on this: https://support.ptc.com/appserver/cs/view/solution.jsp?n=CS252792&lang=en_US
If you notice here, you'll see the push value threshold and the push type "VALUE" is meant to reduce noise and to improve performance when using "noisy" measurement instruments. There is no OOTB functionality designed to be used the way you seem to need, but that could be developed custom.
Pai Chung, I don't think you are right about the EMS functionality. Looking at the template.lua file, the start() service, it appears to only check what property value exists on the Edge and compare the new value to that. I think for both the EMS and the SDKs, this is not supported functionality.
Developers would need to take the measurement data retrieved from their instruments and sensors and compare it against the current property on the platform themselves. In the EMS, this would be very, very tricky. In the SDKs, not so much.