In the run up to routine observations with the upcoming generation of radio facilities, the nature of sub-mJy radio population has been hotly debated. Here, we describe multi-frequency data designed to probe the emission mechanism that dominates in these faint radio sources. Our analysis is based on observations of the Lockman Hole using the Giant Metrewave Radio Telescope (GMRT) - the deepest 610-MHz imaging yet reported - together with 1.4-GHz imaging from the Very Large Array (VLA), well matched in resolution and sensitivity to the GMRT data: {sigma}_610_MHz~15uJy/beam, {sigma}_1.4GHz_~6uJy/beam, full width at half-maximum (FWHM) ~5arcsec. The GMRT and VLA data are cross-matched to obtain the radio spectral indices for the faint radio emitters.