| 摘要 |
PURPOSE:To correct waveform distortion by providing a gain variable means before or after the Fourier transform of a free induction damping signal obtd. by irradiation of a high frequency pulse and varying the gain according to the predetermined time function in synchronization with sampling. CONSTITUTION:A sample tube 2 is disposed in the static magnetic field generated by a magnet 1. A timing control circuit 18 feeds a timing signal to gates 6, 8 and the high-frequency pulse is supplied to a transmitting and receiving coil 3. The free induction damping signal (FID) is induced in the coil 3 after the irradiation of the high-frequency pulse. The signal FID is taken out via a gate 9 and a demodulator 11 and is fed via an LPF12, a high-speed gain variable circuit 13 and an analog-to-digital converter 14 to a data processing unit 15. The correction function to negate the waveform distortion which the signal FID past the LPF12 is impressed is stored in a memory 16 and a read-out control circuit 17 reads out the correction function from the memory 16 and feeds the same to the circuit 13 in synchronization with the on of the gate 9. The waveform distortion owing to the transient response of the filter is thus corrected. |
