How to calculate the signal period counter - powerbi

Question

I am reading a signal value every few seconds.Plotting the signal results in a clipped fullwave rectified sine wave.I am trying to write a measure, such that everytime the signal completes a period, I should update the counter by 1.How can I do it?
This is how the table looks. This table shows the completion of 1 period.
DeviceID
TesterID
Value
DateTime
1
22
0
01.10.2022 00:00:00
1
22
500
01.10.2022 00:01:00
1
22
500
01.10.2022 00:01:15
1
22
1000
01.10.2022 00:02:00
1
22
1000
01.10.2022 00:02:15
1
22
1000
01.10.2022 00:02:30
1
22
500
01.10.2022 00:02:40
1
22
500
01.10.2022 00:02:42
1
22
0
01.10.2022 00:02:45
This is how the plot of the signal looks like.For the above image, measure should calculate the counter as 3.
I wrote a measure in DAX, to increase the count by 1, if the signal value goes above 500.But this did not work since I am sampling the data quite fast which results in reading the same data again(See the column Value for row number 4,5 and 6).
Counter = CALCULATE (COUNTROWS (tableName), FILTER (tableName, tableName[Value]>500))
Another way would be to determine the slope of the signal i.e to find that the Value column has crossed 500 in upward slope and returned to 500 again in the downward slope.Can I calculate slope like this?

Answer 1

I would identify period start with a column as follows:
Period Start =
VAR cursor = tbl[Value]
VAR val = CALCULATE(SUM(tbl[Value]),OFFSET(1,SUMMARIZE(tbl, tbl[DateTime], tbl[Value]),ORDERBY(tbl[DateTime])), ALLEXCEPT(tbl, tbl[DateTime]))
RETURN
if(cursor ==0 && val>0, 1)
I would then have a running total showing which period each row falls into.
Period =
VAR cursor = tbl[DateTime]
RETURN
CALCULATE(SUM(tbl[Period Start]), tbl[DateTime] <= cursor, REMOVEFILTERS() )

Answer 2

If have a huge table then I'd add 2 calculated column. The reason is that some calculations would be done before data manipulating.
col 1 :
id =
RANKX(
CALCULATETABLE(
tbl
,ALLEXCEPT(tbl,tbl[DeviceID],tbl[TesterID])
)
,[DateTime]
,[DateTime]
,ASC
,Skip
)
col2 :
col =
LOOKUPVALUE(
tbl[Value]
,tbl[id]
,[id]-1
,tbl[TesterID]
,[TesterID]
,tbl[DeviceID]
,[DeviceID]
)
+[Value]
The second column will have 2 values of 1500 for each full wave within DeviceID-TesterID.
So, you can try then following trick:
Sumx(
ADDCOLUMNS(
SUMMARIZE(
tbl
,tbl[TesterID]
,tbl[DeviceID]
)
,"q"
,COUNTROWS(
Calculatetable(
tbl
,tbl[col]=1500
)
)
)
,INT([q]/2)
)
As a result it should be a number of full waves... I believe )