Please help me understand this code

[Jerson]

Try this. Changes are in Bold

'---[INT - interrupt handler]------Signal found at RB0, take a reading
SignalFound:
    T1CON.0 = 0                             ; Stop timer1
    i = i + 1                               
    FValue = TMR1H * 256 + TMR1L + fvalue   ; Add 10 readings to FValue
    if i >= 10 then                        ' COMPARISON CHANGED TO >=
        fvalue = fvalue / i                ; get the average of one reading CHANGED HERE
        i = 0                               ; Reset counter
        ReadFlag = 1                        ; FValue is ready to read 
    endif        
    TMR1H = 21                              ; reset timer1 to 60mS
    TMR1L = 167
    T1CON.0 = 1                             ; Start timer1
@ INT_RETURN