Detection of Nuclear Resonance Signals: Modification of the Receiver Operating Characteristics Using Feedback

Blauch, A.J.; Schiano, J.L.; Ginsberg, Mark D.

doi:10.1006/jmre.2000.2074

Cited by 4 publications

(4 citation statements)

References 13 publications

(29 reference statements)

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“…Incrementing of the transmitter frequency requires re-tuning and/or re-configuration of the probe, which can be extremely time consuming. Automated NQR systems capable of scanning a wide range of frequencies have been developed to address this problem [45][46][47][48][49], though they are not widely available. Both manual and automated experiments benefit from broadband excitation pulses, which serve to reduce the number of frequency increments, and may aid in mapping out broad distributions of quadrupolar frequencies.…”

Section: Introductionmentioning

confidence: 99%

The application of frequency swept pulses for the acquisition of nuclear quadrupole resonance spectra

Rossini

Hamaed

Schurko

2010

Journal of Magnetic Resonance

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Section: Introductionmentioning

confidence: 99%

The application of frequency swept pulses for the acquisition of nuclear quadrupole resonance spectra

Rossini

Hamaed

Schurko

2010

Journal of Magnetic Resonance

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“…A proper model should not be too complex and at the same time should enable one to perform the required generalized analysis. Equivalent diagrams with lumped elements have been established as a good choice [10,11,[17][18][19][20][21][22][23][24][25][26][27][28][29]. In the present approach the resonator ~ and coupling structure are modelled asa set of lumped elements: inductors, capacitors and resistors.…”

Section: Equivalent-diagram Analysismentioning

confidence: 99%

“…(EN E~) =E?+R~ : R~ 3 (24) So the overall noise of the receiver system is represented by the contributions resulting from the resonance circuit resistance of the losses, amplifier input voltage noise, amplifier input stage current noise and the feedback noise. With the values from the equivalent diagram in Fig.…”

Section: S/n Performance Analysismentioning

confidence: 99%

“…This probtem was studied both in conjunction with narrow-band MR receivers [10,11,[17][18][19][20][21][22][23][24] and with the general case of communication devices including wide-band receiver architectures [25][26][27][28][29]. As a rule, for the analysis, the ideal voltage amplification section with resistive or capacitive feedback represents an amplifier.…”

Section: Introductionmentioning

confidence: 99%

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Application of the time-variable feedback to the input amplifiers of pulse magnetic resonance spectrometers: Theoretical considerations

Koptioug

2002

Appl. Magn. Reson.

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An analytical model for the optimization of the signal-to-noise (S/N) performance for the receiver with input resonance circuit and variable feedback is developed. It is shown that by varying the feedback type and depth optimization of the receiver the best S/N performance could be achieved. This approach is based upon a resonator-receiver model with lumped elements. These assumptions are retatively general for the model to be applicable for the design of both continuous and pulse receivers in radio-frequency and microwave bands. The overall S/N performance of the receiver upon the noise properties of its elements and ~he feedback settings in the input amplifier is studied for different parameter settings. It is shown that the separate optimization of individual elements does not necessarily lead to the best S/N performance of the receiver, especially when bando width properties and noise cont¡ of the elements are substantially different. It is shown that critical coupling of the amplifier to the resonance structure could be lar from optimum. In some cases the optimum S/N performance could be achieved with coupling settings below the c¡ value. But under the assumptions made the coupling above the critical value does not correspond to the best reeeiver S/N performance. Suggestions on the optimum architecture of magnetic resonance spectrometer receivers with variable feedback are made.

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Application of time-variable feedback to the input amplifier of pulse magnetic resonance spectrometers: Experimental studies

2002

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Experimental research on the improvement of the sensitivity and time resolution of pulsed magnetic resonance spectrometers is discussed. It is shown that application of a time-variable feedback of a signal to the input of the receiver amplifier can decouple the "fixed" relationship between the quality factor Q and the ringdown time of the resonance system. Experiments were performed with low-frequency, radio-frequency and microwave pulse-type magnetic resonance receivers. Modifications of an S/C-band electron spin echo modulation spectrometer carried out to check the "timeva¡ feedback" performance are described. It is demonstrated that the application of a time-variable feedback can significantly reduce the ¡ time and improve the recovery properties of the magnetic resonance receiver system. It is also demonstrated that the time-va¡ feedback can improve the overall receiver sensitivity due to the fact that the working bandwidth of the resonance system can be optimized separately for the transmitting and the receiving mode. Signal values could be increased at least three times and the signal-to-noise ratio about 1.5-2 times. The largest improvement is achieved with the initially overcoupled resonator. Experimental spectra of test samples for different settings of the time-variable feedback are shown.

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Detection of Nuclear Resonance Signals: Modification of the Receiver Operating Characteristics Using Feedback

Cited by 4 publications

References 13 publications

The application of frequency swept pulses for the acquisition of nuclear quadrupole resonance spectra

The application of frequency swept pulses for the acquisition of nuclear quadrupole resonance spectra

Application of the time-variable feedback to the input amplifiers of pulse magnetic resonance spectrometers: Theoretical considerations

Application of time-variable feedback to the input amplifier of pulse magnetic resonance spectrometers: Experimental studies

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