Abstract: An apparatus for automatically correcting phase shifts in a nuclear magnetic resonance (NMR) spectrum. The apparatus comprises first and second phase correction means. The first phase correction means corrects phase shifts due to measurement delay, phase shifts due to a frequency filter, and phase shifts due to off-resonance effects. The second phase correction means corrects constant terms of the phase shifts. Where the spectrum is a multi-dimensional NMR spectrum, the first phase correction means corrects the phase shifts on the directly observed axis. The first phase correction means corrects the phase shifts due to the measurement delay and the phase shifts due to the off-resonance effects on the indirectly observed axis. The second phase correction means corrects the phase shifts only on the directly observed axis. This construction permits automatic corrections of the phase shifts without relying on spectroscopist's eye, individual intuition or experience.

Abstract: A method for fast Fourier transforming data in large quantities stored in an external storage at a high speed is disclosed. In the method, data stored in the external storage is supposed that the data consists of data elements of N1 rows and N2 columns. And the data is read out from the external storage along the column direction, transferred to the processor, fast Fourier transformed, and returned to the external storage. Then, the data is read out from the external storage along the row direction, transferred to the processor, fast Fourier transformed, and returned to the external storage. Bit reversal of data elements and transposition are done in the appropriate step of the procedure.