  Sub-pulse drifting in pulsar radio emission is considered to be one of the
most promising phenomenon for uncovering the underlying physical processes.
Here we present a detailed study of such a phenomenon in observations of PSR
J1822$-$2256, made using the upgraded Giant Meterwave Radio Telescope (uGMRT).
Observations were made simultaneously using the Band 3 (300-500 MHz) and Band 4
(550-750 MHz) receivers of the uGMRT. The pulsar is known to exhibit subpulse
drifting, mode changing, and nulling. Our observations reveal four distinct
sub-pulse drifting modes of emission (A, B, C, and D) for this pulsar, with the
drift periodicities of 17.9 $P_1$, 5.8 $P_1$, 8 $P_1$, 14.1 $P_1$, respectively
(where $P_1$ is the pulsar rotation period), two of which exhibit some new
features that were not reported in the previous studies. We also investigate
the possible spark configuration, characterised by the number of sparks ($n$)
in the carousel patterns of these four drift modes, and our analysis suggests
two representative solutions for the number of sparks for a carousel rotation
period, $P_4$, which lies in the range of $13$ to $16$. The large frequency
coverage of our data (300-750 MHz) is also leveraged to explore the frequency
dependence of single-pulse characteristics of the pulsar emission, particularly
the frequency-dependent subpulse behaviour and the emission heights for the
observed drift modes. Our analysis suggests a clear modal dependence of
inferred emission heights. We discuss the implications for the pulsar emission
mechanism and its relation to the proposed spark configuration.
