Some currently used methods for determining the long-range carbon-proton coupling constants are discussed. We chose the selective heteronuclear 2D J-resolved method because of its good sensitivity and resolution in Fi dimension. We implemented the method on a standard NMR spectrometer with transmitter working at fixed power and no facilities for shaped pulse generation. Selective proton pulse was achieved by using suitable attenuators for the decoupler output power attenuation. The selective proton pulse was calibrated by the indirect method for resonance observation, which allows precise determination of the pulse length. The proposed methodology can be applied to any NMR spectrometer provided that the decoupler output power can be switched by computer at least between two levels in few ,usec. The implementation was tested on a sample of 5-Me-8-OH-quinoline, for which long-range carbon-proton coupling constants have not yet been determined
