  We report a detailed analysis of the emission behaviour of the five
component, core-double cone, pulsar J2006$-$0807 (B2003$-$08). The single
pulses revealed the presence of the three major phenomena of subpulse drifting,
nulling and mode changing. The pulsar switched between four different emission
modes, two of which showed systematic drifting with prominent drift bands, and
were classified as modes A and B respectively. The drifting was seen primarily
in the conal components and exhibited the rare phenomenon of bi-drifting, where
the drift direction in the second component was opposite to the fourth
component. This made PSR J2006$-$0807 the only known example where systematic
drift bands were seen around a central core emission. The emission showed a
gradual decrease in intensity during mode A which stabilised to a relatively
constant level in the subsequent mode B. The presence of a low frequency, weak
and wide structure in the fluctuation spectra was also seen primarily in the
core component during modes A and B. The core component vanished during mode C
and was most prominent during the fourth mode D. Both these modes were
frequently interspersed with null pulses. No detectable drifting was seen
during modes C and D, but the pulsar showed short duration periodic nulling in
the core as well as the conal components. In addition to the four emission
modes the pulsar also nulled for long durations lasting up to hundred rotation
periods.
