SU754279A1 - Device for obtaining and phase detecting of magnetic resonance signals - Google Patents

Description

The invention relates to radio spectroscopy, can be used for searching and recording magnetic resonance signals by pulsed methods, as well as for the implementation of spin echo phase methods. To ensure high sensitivity when searching for signals of low intensity it is necessary to use phase detection.

A non-coherent spectrometer is known that uses a phase method of observing a signal. In the specified device, the excitation pulses and the detecting voltage are formed from the frequency of the continuously operating reference oscillator ^ ί],

However, due to technical difficulties associated with manufacturing, such a spectrometer was not widely used.

A spectrometer is also known in which the phase shift of the excitation radio pulses relative to the phase of the reference voltage is measured. Computing device based on these measurements

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calculates the phase of the carrier signal of the spin echo and through the phase controller sets the phase of the reference voltage on the detector detector in an optimal way ^ 2 ^.

The phase difference of the exciting radio pulses is a random variable and varies in an arbitrary manner from program to program, as in a conventional incoherent spectrometer. Therefore, such radio spectrometers are unsuitable for the implementation of phase spin echo methods.

The closest in technical essence to the proposed is a device for receiving and recording magnetic resonance signals, comprising a pulse oscillator, a programming unit controlling the operation of the pulse oscillator, and a series-connected receiver and indicator of magnetic resonance signals. In this device, a pulse oscillator generates excitation pulses, the phase of high-frequency filling of which is arbitrary. Generator operation control3

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Xia programming unit. The magnetic resonance signal is fed to the input of the receiver, where further amplification and amplitude detection occurs, from which output the voltage is applied to the indicator of ₅ magnetic resonance signals

The disadvantage of this spectrometer is that it does not allow the realization of phase spin-echo methods due to the impossibility of preserving the phase shift between the exciting radio pulses, as well as the detection of low-intensity signals.

The purpose of the invention is to increase the sensitivity and implementation of phase methods 15 observation of spin echo.

The assigned circuit is achieved in that the device is introduced timebase synchronization unit and a unit delay lines, the inputs of the synchronizing device connected to outputs of the programming unit, the clock input to the output of the reference oscillator, and output to the inputs of the lines unit ₂₅ delays the output of which is connected to the input pulse oscillator, the receiver input is connected to the output of the pulse oscillator, and the output to the magnetic resonance signal indicator.

The drawing shows the block diagram of the device, device.

The device contains a pulse oscillator 1, a receiver 2, an indicator 3 of magnetic resonance signals, a block 4 of delays, a programming block 5, a synchronizing device 6 and a reference oscillator 7.

The device works as follows

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Exciting, radio pulses are formed in a pulsed auto-oscillator 1, whose operation is controlled by the program-. by the block 5 through the synchronizing device 6 and the block 4 of the pitch delays. Since the pulse oscillator in its general form is a generator of shock excitation, the phase of the high-frequency filling is determined by the phase of the triggering pulse from the 4-pinch delay unit. The reference oscillator is tuned to the frequency of the magnetic resonance signal. The signal of the reference generator is fed to the synchronization input of the synchronizing device. The synchronizing device performs the time shift of the pulses produced by the programming unit before bringing them into correspondence with

reference generator. Thus, the phase of the trigger pulse, and consequently, the phase of the high-frequency filling of the exciting radio pulse is determined by the phase of the reference oscillator. When implementing phase methods, a certain phase shift between stimulating radio pulses is required. In this device, the latter is achieved by introducing a block of delay lines, performing time and, therefore, phase shifts of trigger pulses.

The phase of transient magnetic resonance signals (induction or spin zx) is determined by the phases of the exciting radio pulses, so the voltage of the reference oscillator can be used for phase coherent detection in the receiver of signals.

The voltage of the transient magnetic resonance signals arising in the output is -. nominal circuit with a sample pulse generator, is fed to the input of the receiver signals. When using a direct conversion receiver, the reference oscillator is its local oscillator. The receiver transducer performs phase detection of the signal. Further amplification of the signal occurs in a broadband amplifier. In the case of using a direct gain receiver with an amplitude detector at the output, the voltage of the reference generator is introduced into the amplification path.

And in the case of the use of a superheterodyne receiver with an amplitude detector at the output, the voltage of the reference generator is supplied (by leakage of pickups) to the input of the receiver. When using a superheterodyne receiver with a phase detector, the output voltage of the reference oscillator and the local oscillator is applied to the second detector input.

The invention allows to search for unknown spectra of low intensity and carry out phase detection at various resonant frequencies.

Claims (1)

Claim A device for receiving and phase detection of magnetic resonance signals, containing a pulse oscillator, a programming unit that controls the operation of a pulse oscillator * And afterwards, POOLYANOVVMO πητιεΛ.υνιτ 5,747 and an indicator of magnetic resonance signals, characterized in that, in order to increase the sensitivity and implementation of phase methods of spin echo observation, a reference generator 5, a synchronization device and a block of delay lines are entered into it, the inputs of the synchronization device being connected to the outputs of the programming unit, the synchronization input with the output of the reference generator K to the torus, and the output with the inputs of the block of delay lines, the output of which is connected to the input of the pulse oscillator, the input of the receiver 79 6 ka is connected to the output of a pulsed oscillator, and the output is connected to an indicator of magnetic resonance signals.