trade timing signals - using Advance-Decline line tools

[rimshot]

NASARAVI - here is my quick attempt to answer your question shown below .. I am about to head out for an outing, so will continue thinking about the root of your question

"Question

Is it possible to use a ema 2,3,4 discriminator on BB width to find the precise top or at least an impending top with less ambiguity?"

my Answer

if you look at the basic four A-D line charts on Page 1 of my Public List, you will see:

https://stockcharts.com/public/1442871

1. a fast moving average placed on the daily Advance-Decline values of each index
( FYI - the A-D line is a cumulative version of all these daily values beginning at the start date selected in the chart settings )

AND

you will notice these daily Advance-Decline values did NOT
reach the upper positive levels that were printed on the chart in the week ended July 13, 2018...

no ambiguity here because the shouting loudly at you for nearly two full weeks
is the Negative Divergence by the most important internal
which drives all these other Advance-Decline tools ...

there was much less internal Net Advancing going on for all four
indices after July 13th while each index price level attempted
to keep advancing into the July 26, 2018 evening when Amazon reported earnings

2. and you will see the McO

* vs. its Bollinger Band and
* vs. its zero line

for assessing directional shifts which are growing more serious

3. use #1 and #2 above combined with the changing slope AND the degree of slope by the McSum for the newest direction of the McSum

your best odds for being accurate in my opinion are using the data in #1 and #2 above for fine tuning your trade entry timing based on the McSum changing behavior as these #1 and #2 chart elements
begin to worsen, which may occur after a hesitation of one or more days ... in this case where you
are asking how best to time
your trading action as early as possible before the full price damage starts in earnest

further Answer - I will do some research on your question regarding applying a moving average to the BB BandWidth.

And get back to you once I am satisfied I have the full picture of
what is technically accurate. Could be a while before I have this
answered for you.

Good work, NASARAVI. Thanks for your serious efforts to understand how you can benefit from these A-D tools.