Patent ID: 7071691

Claim:
A method for operating a nuclear magnetic resonance (NMR) or a magnetic resonance imaging (MRI) spectrometer using a digital filter which is installed in a low-frequency region of a receiver system, the digital filter having an input which is fed with an NMR signal of time length T A and with an output signal consisting essentially of a rising oscillation B 1 of time length T B , a signal portion [F]′, which consists of a filtered FID or echo signal of time length T A , and a decaying oscillation B 2 of time length T B , wherein this output signal is initially modified using a calculation process RV and subsequently transformed into a desired NMR spectrum through Fourier transformation, the method comprising the steps of: a) initially selecting, during the calculation process RV only the signal portion [F]′; b) subsequently generating at least N copies of the rising oscillation B 1 in positive time shifts T A relative to each other; c) positioning the at least N copies of the rising oscillation B 1 on the signal portion [F]′ in time such that an end of a first rising oscillation is positioned at an end of the signal portion [F]′; d) generating at least N copies of the decaying oscillation B 2 in negative time shifts T A relative to each other; e) positioning the at least N copies of the decaying oscillation B 2 on the signal portion [F]′ in time such that a start of a first decaying oscillation is positioned at a start of the signal portion [F]′; f) adding all N copies of the rising oscillation B 1 , defined in this manner, and all N copies of the decaying oscillation B 2 , defined in this manner, to the signal portion [F]′; and g) selecting, following step f), only portion T A which contains the signal portion [F]″ as a resulting signal F″ of the calculation process RV, wherein the number N is calculated using the formula N=T B /T A and rounded to a next higher integer number.