High-resolution measurements of rotational-torsional transitions of ethyl methyl ether (EME) were performed in its vibrational-torsional ground state at frequencies up to 350 GHz [1]. The new results correspond to about 1000 new observed transitions including internal rotation splitting of each transition due to torsion of the two methyl groups. A simultaneous fit to experimental accuracy of these and approximately 100 previously assigned transitions (see [2]) allows reliable prediction of additional transition frequencies up to 400 GHz, based on a newly calculated parameter set. The new data set should enable the astrophysical detection of ethyl methyl ether in the interstellar medium. Ethyl methyl ether was tentatively detected in hot cores which are quiescent high-density sources associated with regions of high-mass star formation by Charnley et al. [3].