We present the Terragraph Sounder platform, developed to promote and enable research in mmWave propagation, systems, and networks, and is actively employed in research studies in over 13 institutions. Recent advancements to the platform include a suite of tools for performing interference measurements and developing interference mitigation techniques through phased-array-based beamforming. The tool provides 6-bits of phase control for 36 individual antenna elements (azimuth plane), allowing users to synthesize custom beam patterns. Researchers can deploy multiple 802.11ad/ay links and quantify the cross-leakage interference as a function of TX/RX beam configurations, measure degradation in SNR due to interference (SINR), study co-existence between mmWave links in the same frequency, and assess signal quality as a function of beam pattern design. Four software packages were developed that can run on the same hardware, enabling a wide array of research activities, ranging from RF propagation and modeling, phased array beamforming, protocol optimization, and mesh network routing research.