data = io.StringIO(
    """Values
1992-08-27 07:46:48,28.0  
1992-08-27 08:00:48,28.2  
1992-08-27 08:33:48,28.4  
1992-08-27 08:43:48,28.8  
1992-08-27 08:48:48,29.0  
1992-08-27 08:51:48,29.2  
1992-08-27 08:53:48,29.6  
1992-08-27 08:56:48,29.8  
1992-08-27 09:03:48,30.0
"""
    )
s = pd.read_csv(data, squeeze=True)
s.index = pd.to_datetime(s.index)
res = s.resample('s').interpolate().resample('15T').asfreq().dropna()
print(res)
Python regularise irregular time series with linear interpolation