particular $k$ mode and $T_{\rm sys}$ is the system temperature, the sum of the receiver temperature, $T_{\rm rec}$, and the sky temperature $T_{\rm sky}$. For all telescope configurations considered in this work, we assume drift scanning with a total synthesis time of 6 h per night. While HERA can only operate in drift scan mode, LOFAR and SKA can perform tracked scans. In the future, we will investigate various observing strategies; however, drift scanning suffices here for our like-to-like comparisons.

Of great concern for 21 cm experiments is the estimation and removal of the bright foreground emission. Most notable of these are the chromatic effects due to how the interferometric array’s $uv$ coverage depends on frequency. It has been shown that these effects do not lead to mode-mixing across all frequencies, but instead localize the majority of the foreground noise into a foreground ‘wedge’ within cylindrical 2D $k$-space [@Datta:2010p2792; @Morales:2012p2828; @Parsons:2012p2833; @Trott:2012p2834; @Vedantham:2012p2801; @Thyagarajan:2013p2851; @Liu:2014p3465; @Liu:2014p3466]. This results in a relatively pristine observing window where the cosmological 21 cm signal is dominated only by thermal noise. However, it is still uncertain where to define the transition from the foreground ‘wedge’ to the [EoR]{} observing window.

Moreover, the summation over redundant 