Hitachi, Ltd.

Shuya Hagiwara

Minseok Park

Hideki Tanaka

Kenji Kawasaki

Michiya Okada

Hideta Habara

Yuzo Fukuda

A DDS (direct digital synthesizer) remarkably increased in the number of frequencies which can be output while maintaining the phase coherency, and an NMR instrument using such a DDS are provided. A DDS including phase accumulators and a phase-to-amplitude modulator is provided with a plurality of phase accumulators operating with fixed phase implements which are equal to powers of 2, a controller for outputting each bit of a frequency tuning word as control data, a plurality of switches for outputting an output of an associated one of the phase accumulators when an associated one of the control data supplied from the controller is 1 and outputting 0 when the associated one of the control data is 0, and an adder for adding up outputs of the switches.

Direct digital synthesizer and nuclear magnetic resonance instrument using the same

There is provided a nuclear magnetic resonance probe in which the loss caused by a high frequency cable between a probe coil and a preamplifier is reduced and the sensitivity of an NMR signal is improved. A changeover switch for NMR probe is divided into a switch part including switch elements and a filter part for filtering a switch control signal and an RF transmission signal. The switch part is disposed in a probe body inserted in a magnet of the probe. The filter part is disposed near a measurement apparatus located outside the probe. As for the switch part, a section structure of thickness and width is reduced in conformity with a narrow and slender shape of the probe body. The length of a high frequency cable between the probe coil and the preamplifier is shortened remarkably, and consequently the loss can be reduced.

Nuclear magnetic resonance (NMR) probe

In an NMR measurement method using an NMR apparatus which converts a received signal to digital data using an analog/digital converter and performs a spectral analysis, a folding and aliasing count is decided from a variation in a peak frequency and frequency discrimination is performed. More specifically, a Nyquist frequency is changed to cause a variation of the peak frequency. Since the Nyquist frequency is inversely proportional to an increment of an evolution time twhich is a feature of multi-dimensional NMR, the Nyquist frequency can be changed by changing the increment of the evolution time. Furthermore, the Nyquist frequency is changed in such a way that a ratio between different Nyquist frequencies is not a ratio between natural numbers nand nwhich are greater than 0 and smaller than or equal to the maximum folding and aliasing count.

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Mito, Japan

Shuya Hagiwara