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No it is the other way round.
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Your ProStick (orange) graph is much better than ProStick+ (blue) graph. It seems you used an external Filter with ProStick (orange), and no external filter with ProStick+ (blue).
If my assumtion is correct, then insert the external filter between antenna and ProStick+ (blue), and observe. Most likely the gap between noise level and signal level will increase.
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Check intensity of Cell Phone signal by RF Scan described in this thread:
Do I Need A Filter.
Here is RF Scan at my location (Urban) using Option-2 (generic dvb-t dongle plugged into Windows computer, No Filter)

