Record inserted within a time period

Hi,

I've a table bat_inf as below.

I need to get a record( select ba_id, BA_DTTM   from bot_inf   where     BA_ST_STG_DTTM (starting time )   is within last 15 hrs),

please help with this sql....   thanks ...........                 

Name                                      Null?    Type

----------------------------------------- -------- ----------------------------

BA_ID                                  NOT NULL NUMBER

BA_APP_INFO                            VARCHAR2(50)

BA_DTTM                                   TIMESTAMP(6)

BA_ST_STG_DTTM                    TIMESTAMP(6)

BA_END_STG_DTTM                 TIMESTAMP(6)

BA_END_TGT_DTTM                 TIMESTAMP(6)

BA_ST                                       VARCHAR2(20)