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Browse Prior Art Database

Variable-Power Broadband Decoupler for NMR Spectrometers

IP.com Disclosure Number: IPCOM000041353D
Original Publication Date: 1984-Jan-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 2 page(s) / 50K

Publishing Venue

IBM

Related People

Bleich, HE: AUTHOR

Abstract

In the prior art, as shown in Fig. 1, broadband decoupling is a technique routinely used in NMR spectroscopy. At present the phase of a radio frequency is pseudo-randomly shifted by 180 degrees and this phase shift is kept constant for all decoupling power settings. A continuous, recycled sequence of pulses with phase A (0 degrees, for example) or with phase B (180 degrees, for example) produces effective broadband decoupling. The length of the pulses, however, has to be calibrated for each decoupling radio frequency amplitude H2 . The apparatus shown in Fig. 2 combines a sequence of 1's and 0's stored in memory 1 with a programmable frequency divider 2 to generate the phase pulses for each given decoupling amplitude H2 .

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Variable-Power Broadband Decoupler for NMR Spectrometers

In the prior art, as shown in Fig. 1, broadband decoupling is a technique routinely used in NMR spectroscopy. At present the phase of a radio frequency is pseudo-randomly shifted by 180 degrees and this phase shift is kept constant for all decoupling power settings. A continuous, recycled sequence of pulses with phase A (0 degrees, for example) or with phase B (180 degrees, for example) produces effective broadband decoupling. The length of the pulses, however, has to be calibrated for each decoupling radio frequency amplitude H2 . The apparatus shown in Fig. 2 combines a sequence of 1's and 0's stored in memory 1 with a programmable frequency divider 2 to generate the phase pulses for each given decoupling amplitude H2 . The rate at which the stored 0's and 1's are fed to a phase shifter 3 is kept proportional to the decoupling amplitude H2 and effective decoupling is therefore achieved for each given decoupling amplitude H2 . The programmable frequency divider decodes the power control lines 4 which normally set the radio frequency power level, and it will set the address advance rate proportional to the radio frequency amplitude H2 . In commercial NMR spectrometers the radio frequency output varies from instrument to instrument. This proposes to make the oscillator 5, which controls the rate of phase shifting, adjustable so that it can be optimized at installation or at instrument calibration time. The d...