the rms of the off-pulse flux and square root of number of on-pulse bins ($\mathrm{S/N} = \frac{\mathrm{I_{on}}}{\sqrt{\mathrm{nbin}}\,\mathrm{I_{off}}}$). For the fully upgraded instrument, we expect $S_\mathrm{min} = 1.6$ Jyms for a 10$\sigma$ 1-ms wide pulse, 3.5 K Jy$^{-1}$ gain, 100 K system temperature and 31.25 MHz bandwidth. The system bandwidth is however only about half of the initially anticipated 31.25 MHz bandwidth, as the ring antennas have a significant roll-off in sensitivity away from 843 MHz. This has been measured using integrated pulses from the pulsar J1644$-$4559. We find that on average $\sim 86$ percent of the total S/N is concentrated in the upper half of the band ($\sim836 - 850$) as the antennas are tuned to maximum sensitivity at 843 MHz. We adopt a bandwidth of 16 MHz for the sensitivity calculations in the paper, to be conservative.

During the upgrade, we characterise the system sensitivity by a fraction of the final expected gain $\upepsilon$. This factor encompasses systemic losses due to (1) pointing errors (from physical misalignment in the modules N-S, and phasing errors in the antenna system E-W), (2) self-generated radio frequency interference (RFI) mainly due to improperly shielded electronics in the receiver boxes near the telescope, (3) 