  Currently, Fermilab Booster accelerates ~4.5E12 protons per pulse (ppp) in 81
bunches from 400 MeV to 8 GeV at 15 Hz to provide beam to multiple HEP
experiments and is being upgraded to handle higher beam intensity >6.7E12 ppp
at a repetition rate of 20 Hz. In the current mode of operation, we control
longitudinal coupled bunch instabilities (LCBI) using combination of passive
and active dampers. The issues with LCBI are expected to worsen at higher beam
intensities. Here, we would like to investigate at what time in the beam cycle
a particular mode is going to originate and how much it contributes at a
different time of the acceleration cycle using the collected wall current
monitor data from injection to extraction. Also, measure growth rates as a
function of beam intensity for some dominant modes. Finally, this paper
presents results from the observed LCBI analysis for the highest available beam
intensities, unexpected findings, and future plans to mitigate the LCBI at
higher beam intensities
