Two methods, based on the phase modulation of spin-echo signals due to J-coupling, of selective simplification of coupled homonuclear spectra are described. Both pulse methods employ a 90 Deg-t-180 Deg-t spin-echo sequence to prep. suitable phases of the magnetization in the rotating frame. For t = (4J)-1, all doublet magnetization vectors have opposite phases, parallel to the phase of the initial pulse. The 1st method uses a single 45 Deg pulse, with a phase F alternating between +y and -y and addn. of the decaying half-echoes, to remove doublet magnetization without affecting singlets. The 2nd method employs a pulse sandwich 90 Degf -90 Degx to generate and recall double-quantum coherence. Singlets are suppressed by cycling the phase F through x,y,-x, and -y, while adding and subtracting alternate transients. [on SciFinder (R)]