CN112379317A - Nuclear magnetic resonance pulse sequence controller - Google Patents

Nuclear magnetic resonance pulse sequence controller Download PDF

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Publication number
CN112379317A
CN112379317A CN202010539845.3A CN202010539845A CN112379317A CN 112379317 A CN112379317 A CN 112379317A CN 202010539845 A CN202010539845 A CN 202010539845A CN 112379317 A CN112379317 A CN 112379317A
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nuclear magnetic
magnetic resonance
pulse sequence
bus
control
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CN112379317B (en
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李正刚
朱天雄
夏明敏
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Wuhan Zhongke Niujin Wave Spectrum Technology Co ltd
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Wuhan Zhongke Niujin Wave Spectrum Technology Co ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
    • G01R33/32—Excitation or detection systems, e.g. using radio frequency signals
    • G01R33/36—Electrical details, e.g. matching or coupling of the coil to the receiver
    • G01R33/3607—RF waveform generators, e.g. frequency generators, amplitude-, frequency- or phase modulators or shifters, pulse programmers, digital to analog converters for the RF signal, means for filtering or attenuating of the RF signal
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
    • G01R33/32—Excitation or detection systems, e.g. using radio frequency signals
    • G01R33/36—Electrical details, e.g. matching or coupling of the coil to the receiver
    • G01R33/3621—NMR receivers or demodulators, e.g. preamplifiers, means for frequency modulation of the MR signal using a digital down converter, means for analog to digital conversion [ADC] or for filtering or processing of the MR signal such as bandpass filtering, resampling, decimation or interpolation
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
    • G01R33/32—Excitation or detection systems, e.g. using radio frequency signals
    • G01R33/36—Electrical details, e.g. matching or coupling of the coil to the receiver
    • G01R33/3692—Electrical details, e.g. matching or coupling of the coil to the receiver involving signal transmission without using electrically conductive connections, e.g. wireless communication or optical communication of the MR signal or an auxiliary signal other than the MR signal
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00—Data switching networks
    • H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
    • H04L12/40—Bus networks
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L67/00—Network arrangements or protocols for supporting network services or applications
    • H04L67/01—Protocols
    • H04L67/12—Protocols specially adapted for proprietary or special-purpose networking environments, e.g. medical networks, sensor networks, networks in vehicles or remote metering networks
    • H04L67/125—Protocols specially adapted for proprietary or special-purpose networking environments, e.g. medical networks, sensor networks, networks in vehicles or remote metering networks involving control of end-device applications over a network
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00—Data switching networks
    • H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
    • H04L12/40—Bus networks
    • H04L2012/40208—Bus networks characterized by the use of a particular bus standard
    • H04L2012/40215—Controller Area Network CAN

Abstract

The invention discloses a nuclear magnetic resonance pulse sequence controller, wherein all nuclear magnetic resonance pulse sequence controller subsystems are electrically connected in sequence, all the nuclear magnetic resonance pulse sequence controller subsystems have the same reference clock, and the nuclear magnetic resonance pulse sequence controller subsystems are arranged in a plug-in box and comprise a plurality of integrated transceivers, a multi-bus computer, a power supply and a back plate; the power supply is electrically connected with the integrated transceiver and the multi-bus computer through the backboard, and each of the power supply, the multi-bus computer and all the integrated transceivers is inserted into each backboard slot of the backboard. The invention can solve the technical problems that the miniaturized nuclear magnetic resonance instrument can only be used as an instrument with specific functions due to the solidified number and functions of the channels, so that the nuclear magnetic resonance imaging instrument or the spectrometer has flexible and complex functions, the expandable number of the channels and the wide-frequency-range working requirement cannot be met.

Description

Nuclear magnetic resonance pulse sequence controller
Technical Field
The invention belongs to the technical field of nuclear magnetic resonance instruments, and particularly relates to a nuclear magnetic resonance pulse sequence controller.
Background
The nuclear magnetic resonance instrument is developed and produced by applying the nuclear magnetic resonance principle, and excites the resonance phenomenon of the atomic nucleus of a measured object by transmitting a high-power pulse signal to the measured object. Nuclear magnetic resonance instruments require the use of two to tens of transmit and receive channels to excite different nuclei or to receive resonance signals of the individual nuclei in parallel. Meanwhile, in order to support the work of the radio frequency function and acquire a good resonance signal, the nuclear magnetic resonance instrument also needs to output a pulse gradient to complete the field locking function, and is provided with various external devices such as a shimming system, a temperature controller, a pneumatic controller, a sample injector, a refrigerator, a medical bed and the like, and the external devices are generally controlled by industrial bus modes such as RS232, RS485, CAN bus and the like.
In order to accomplish these functions, the nmr pulse sequence controller needs to be equipped with different numbers of components such as rf transmitter (transmitter), rf receiver (receiver), gradient controller, lock field system, and external device controller with different numbers of interfaces, and a central controller (generally FPGA or MCU) is provided in each component to control these functional components to work, and an industrial computer capable of performing high-speed real-time communication with the central controller, and a server interacting with a user are also provided. The server interacts with the user, receives the input of the user, interacts with the industrial computer in a non-real-time communication mode such as a network and the like, receives the input control data of the server, controls the service flow of each component in real time through the high-speed bus, and stores the data collected by the receiver.
The nuclear magnetic resonance pulse sequence controller has many functional components, and the prior art designs a transmitter, a receiver, a gradient controller, a field locking system, an external equipment controller and the like respectively, and each component realizes a specific function respectively, and sets the number of the transmitter, the receiver and the gradient controller according to the requirement to realize the function of the system. The transmitter, the receiver, the gradient controller, the lock field system, the external equipment controller and the industrial computer have various design modes, and a common nuclear magnetic resonance pulse sequence controller comprises:
the miniature nuclear magnetic resonance pulse sequence controller comprises: the system is provided with a small number of transmitting, receiving and gradient channels with fixed quantity, one central controller controls all components to work, the central controller can be only a piece of FPGA or the combination of the FPGA and an ARM controller, the central controller simultaneously completes the functions of an industrial computer, directly interacts with a server, and even an instrument with simple function directly completes the tasks of the server in the central controller;
II, a distributed nuclear magnetic resonance pulse sequence controller: each functional unit is provided with a small industrial computer, such as a PCI04 computer, an ARM controller and the like, the small industrial computer is directly connected with a central controller of each functional unit or connected with the central controller through a high-speed interface, each functional unit is synchronized through a backboard bus, and the small industrial computers interact with a server respectively;
thirdly, a centralized nuclear magnetic resonance pulse sequence controller: the system is provided with only one industrial computer, each functional component is connected with one industrial computer through high-speed cables such as USB, PCIe and the like, and the industrial computer interacts with the server and controls all the functional components to work simultaneously.
However, the above-mentioned nuclear magnetic resonance pulse sequence controllers all have some non-negligible drawbacks:
(1) the number and the functions of the channels of the miniaturized nuclear magnetic resonance instrument are solidified, the working frequency range is low, the miniaturized nuclear magnetic resonance instrument can only be used as an instrument with specific functions, and the requirements of flexible and complex functions, expandable channel number and wide frequency range working of a nuclear magnetic resonance imager or a spectrometer cannot be met;
(2) for a distributed or centralized nuclear magnetic resonance instrument, the number of peripheral control interfaces, gradient controller interfaces, a lock field system and the like is fixed because the peripheral control interfaces, the gradient controller interfaces, the lock field system and the like are arranged on a certain daughter board, the expandable peripheral number is limited by the maximum number of interfaces, the number of interfaces cannot be flexibly configured according to the number of the peripheral, and the number of core receivers and transmitters can be reduced by increasing the peripheral interfaces;
(3) for a distributed nuclear magnetic resonance instrument, a server and an industrial computer need to interact for many times due to a distributed structure, control data needs to be sent to all industrial computers usually when one-time scanning is completed, communication time is long, and the whole system is easily stopped due to the fault of a single functional node; meanwhile, industrial computers are expensive, and the unnecessary increase in the number of industrial computers significantly reduces the reliability of the system;
(4) for a centralized nuclear magnetic resonance instrument, high-speed cables such as PCIe and USB are used to connect various components, but the high-speed communication cable significantly reduces the reliability of the system;
(5) for three existing nuclear magnetic resonance instruments, when the nuclear magnetic resonance instruments work within the frequency range of DDS or high-speed DAC (generally below 200 MHz), radio frequency emission directly uses DDS or high-speed DAC to output radio frequency signals, radio frequency reception directly uses high-speed ADC to sample, but the working frequency directly output by DDS or high-speed DAC is low, and the wide-frequency working requirement of several MHz-several GHz of a nuclear magnetic spectrometer cannot be met; moreover, the high-speed ADC with the frequency of more than 100MHz is high in cost and low in resolution, faces the challenge of international trade barrier, and cannot meet the requirements of a nuclear magnetic resonance instrument on high speed and high resolution;
(6) for three existing nuclear magnetic resonance instruments, when the nuclear magnetic resonance instruments work in a frequency range of DDS or high-speed DAC, in order to ensure the wide frequency range and high resolution of the instruments, a transmitter and a receiver generally work on an intermediate frequency signal with lower frequency, a radio frequency part consists of a frequency source, a transmitter and a receiver, the transmitter and the receiver provide local oscillation by the frequency source and output a target frequency after frequency mixing, a mixer is generally arranged in the transmitter and a preamplifier, the frequency source is connected with the transmitter and the preamplifier by a radio frequency cable, and when the number of transmitting and receiving channels needing to be installed is large, the connecting cable becomes very complex; meanwhile, local oscillator leakage, multiple harmonics and the like exist in output signals due to the adoption of a direct frequency mixing scheme for transmission and reception, the signals cause serious nuclear magnetic signal distortion, different band-pass filters are often required to be installed, and the requirements of high bandwidth and automatic and arbitrary switching of working frequency of a nuclear magnetic resonance instrument cannot be met;
(7) for three existing nuclear magnetic resonance instruments, the large step change of the operating frequency of the nuclear magnetic resonance instrument is realized by changing the frequency of the switching frequency source, and the small step frequency switching is realized by changing the frequency of the DDS or the high-speed DAC of the transmitter. But the frequency source is separated from the transmitter and the receiver, the frequency source is controlled in a non-real-time manner through the peripheral controller, the output frequency switching of the frequency source is limited by the switching time consumption of the communication process and the low communication rate of the peripheral controller, the frequency switching speed is between 100us and several ms, the rapid frequency switching can only be realized through the DDS or the high-speed DAC of the transmitter, but the frequency range of the DDS or the high-speed DAC which can be changed is smaller, namely, the rapid frequency switching with small bandwidth can only be carried out, and the requirement that the large stepping frequency switching of the nuclear magnetic resonance instrument over 10MHz is faster than 1us cannot be met;
(8) for three existing nuclear magnetic resonance instruments, in order to reduce cost, a frequency source and an industrial computer are not often used, a field locking system is independently designed into a circuit board block with a frequency conversion function and interacts with the industrial computer in a non-real-time manner, the field locking system can only output signals with narrow bandwidth and cannot meet the field locking requirement that the nuclear magnetic resonance instruments use atomic nuclei with frequency difference of hundreds of MHz, such as D and 19F, and the like, meanwhile, the field locking system does not have the complete functions of a receiver and a transmitter, can only use the nuclei with single frequency to lock fields, cannot use the nuclei with a plurality of spectral peaks to lock fields, and does not have the experimental functions of observation, decoupling and the like of the nuclei used for the field locking.
Disclosure of Invention
In view of the above defects or improvement needs in the prior art, the present invention provides a nmr pulse sequence controller, which aims to solve the above technical problems of the existing miniaturized nmr pulse sequence controller, distributed nmr pulse sequence controller, and centralized nmr pulse sequence controller.
To achieve the above object, according to one aspect of the present invention, there is provided a nmr pulse sequence controller, including a plurality of nmr pulse sequence controller subsystems, a network device, and a server, all the nmr pulse sequence controller subsystems being electrically connected in sequence, all the nmr pulse sequence controller subsystems having the same reference clock;
the nuclear magnetic resonance pulse sequence controller subsystem is arranged in the plug-in box and comprises a plurality of integrated transceivers, a multi-bus computer, a power supply and a back plate;
the power supply is electrically connected with the integrated transceiver and the multi-bus computer through the back plate, and the power supply, the multi-bus computer and each integrated transceiver are respectively inserted into each back plate slot of the back plate;
the multi-bus computer is provided with a plurality of groups of high-speed serial buses, and each group of high-speed serial buses is in communication connection with one integrated transceiver;
the multi-bus computer of the nuclear magnetic resonance pulse sequence controller subsystem is connected with the server through network equipment;
each backboard slot on the backboard is provided with an ID identifier, the integrated transceiver inserted into the backboard slot uses the ID identifier as the identity of the integrated transceiver, and the multi-bus computer is used for allocating tasks to the integrated transceiver according to the identity of each integrated transceiver;
the server is used for receiving an input signal from a user and sending the input signal to the multi-bus computer;
the multi-bus computer is also used for converting the input signal into a control parameter corresponding to the task assigned to each integrated transceiver and sending the control parameter to the corresponding integrated transceiver through the high-speed serial bus.
The unified transceiver is used to process the tasks assigned to the unified transceiver using control parameters from the multi-bus computer.
Preferably, on the backplane, only a plurality of connecting wires for a group of high-speed serial buses are arranged between the backplane slot where the multi-bus computer is located and the backplane slot where each integrated transceiver is located;
the back board is also provided with a synchronous bus for connecting all the integrated transceivers in sequence.
Preferably, the distributed tasks comprise pulse sequence emission, nuclear magnetic signal acquisition, gradient control, peripheral control, lock feedback, gate control IO and the like;
the integrated transceiver is also used for scanning the task by using the control parameters from the multi-bus computer when the distributed task is pulse sequence transmission, nuclear magnetic signal acquisition, gradient control or gate control IO;
the integrated transceiver is also used for performing peripheral control processing on the task by using the control parameters from the multi-bus computer when the distributed task is peripheral control;
the integrated transceiver is also configured to lock the task using the control parameters from the multi-bus computer when the assigned task is lock feedback.
Preferably, all the integrated transceivers are used for performing synchronous scanning processing according to a control command from the multi-bus computer under the triggering of the synchronous bus, or each integrated transceiver does not depend on the triggering of the synchronous bus and performs asynchronous scanning processing according to the control command independently;
in the process of synchronous scanning, the synchronous bus is driven by all the integrated transceiver by adopting a line and a mode together, and the driving mode is as follows:
(1) when the integrated transceiver is idle, outputting a high level on the synchronous bus;
(2) when the integrated transceiver needing scanning receives the control parameters and prepares for scanning, outputting a low level on the synchronous bus;
(3) when the integrated transceiver finishes receiving the control parameters and scanning and preparing, outputting a high level on the synchronous bus;
(4) when all the scanned integrated transceivers are ready, the synchronous bus is converted from low level to high level;
(5) the scanning-ready integrated transceiver monitors the change of the synchronous bus, and synchronously starts scanning when the rising edge is monitored.
Preferably, each integrated transceiver comprises a radio frequency signal conversion module, an intermediate frequency transmitter, an intermediate frequency receiver, a gradient controller, a peripheral control interface, a gate control IO, a central controller, and a memory;
in each nuclear magnetic resonance pulse sequence controller, only one of the integrated transceivers also comprises a lock field feedback unit, and the other integrated transceiver also comprises a clock; or only one of the integrated transceivers also comprises a lock field feedback unit and a clock.
Preferably, the central controller is used for receiving control parameters corresponding to different tasks from the multi-bus computer through the high-speed serial bus and respectively storing the control parameters in different areas of the memory;
the central controller is also used for pre-reading a part of control parameters from the memory before scanning is started;
the central controller is also used for analyzing the control parameters which are pre-read one by one during scanning, and controlling the radio frequency signal conversion module, the intermediate frequency emitter, the intermediate frequency receiver, the gradient controller, the lock field feedback unit, the peripheral control interface and the gate control IO to work according to the time sequence appointed by the control parameters, wherein when the pre-read control parameters are executed for a half, the central controller continuously pre-reads a part of the control parameters from the memory; the above process is repeatedly performed until the scanning is completed.
Preferably, the central controller is further configured to control the if transmitter to output the if signal according to a control parameter associated with the if transmitter among the control parameters, the if signal including a frequency, a phase, a shape, and a pulse width;
the intermediate frequency transmitter is used for outputting the intermediate frequency signal to the radio frequency signal conversion module.
The radio frequency signal conversion module is used for converting the frequency of the intermediate frequency signal into a target output frequency in the control parameters, performing power regulation within a range of 90dB on the signal after the frequency conversion by using the variable digital attenuator of the transmitting output end, and finally performing width control of transmitting pulse on the signal after the power regulation by using the radio frequency switch of the transmitting output end so as to obtain an output signal fTX；
The radio frequency signal conversion module is also used for receiving a nuclear magnetic resonance signal fRXThe NMR signal f is adjusted according to the control parametersRXIs converted into an intermediate frequency signal and is converted into an intermediate frequency signal,and outputs the intermediate frequency signal to an intermediate frequency receiver.
Preferably, the radio frequency signal conversion module adopts a high and medium frequency above 1.8GHz, signals such as stray and harmonic waves of an output transmission signal are all beyond the working frequency of the nuclear magnetic resonance system, and the suppression of more than 50dBc can be realized by a low-pass filter or a high-pass filter, so that a nuclear magnetic resonance instrument does not need to be provided with a band-pass filter any more, and the working frequency bandwidth is higher than 5 MHz-2 GHz;
the radio frequency signal conversion module is directly controlled by the central controller, the working frequency of the radio frequency signal conversion module is switched by an internal DDS and a phase-locked loop, the frequency resolution of the DDS is 48 bits, the working bandwidth is larger than 100MHz, and the frequency switching time is smaller than 1 us.
Preferably, the intermediate frequency receiver comprises a radio frequency switch, a variable digital attenuator, a power amplifier and a high-speed high-resolution ADC which are connected in sequence;
the radio frequency switch is used for controlling the width of the intermediate frequency signal output by the radio frequency signal conversion module;
the variable digital attenuator is used for carrying out gain adjustment within the range of 60dB on the signals after width control;
the power amplifier is used for amplifying the signal after the gain adjustment;
the high-speed high-resolution ADC is used for carrying out analog-to-digital conversion on the amplified signal so as to obtain a digitized nuclear magnetic signal.
Preferably, the central controller is further configured to sequentially perform digital down-conversion, digital filtering, digital decimation, and the like on the digitized nuclear magnetic signals according to the control parameters when a radio frequency switch of the if receiver is turned on, so as to form nuclear magnetic data required by the control parameters, and buffer the nuclear magnetic data in the memory.
Preferably, the gradient controller is a medium-speed high-resolution DAC or MLVDS;
when the gradient controller selects the medium-speed high-resolution DAC, the DAC is used for generating an analog gradient waveform according to the control parameters so as to control a gradient power amplifier of the nuclear magnetic resonance instrument to work;
when the gradient controller selects the MLVDS, the MLVDS is used for generating a digital signal according to the control parameters so as to control the gradient power amplifier of the nuclear magnetic resonance instrument to work;
the peripheral control interface is a CAN bus interface and is used for controlling all external equipment connected to the same CAN bus in the nuclear magnetic resonance instrument.
Preferably, the lock field feedback unit, the radio frequency signal conversion module, the intermediate frequency transmitter and the intermediate frequency receiver form a complete lock field system;
the lock field feedback unit is also used for outputting current to drive a Z0 shimming coil of the nuclear magnetic resonance instrument to form a magnetic field so as to adjust the magnetic field intensity of the nuclear magnetic resonance instrument and correct the magnetic field drift of the nuclear magnetic resonance instrument to complete the lock field function.
The lock field system also has a working frequency bandwidth higher than 5 MHz-2 GHz, and can use D, D and GHz which are commonly used in nuclear magnetic resonance instruments,19F and other arbitrary atomic nuclei complete a field locking function, a field locking system can output radio-frequency pulses in any shapes, a complex solvent with a plurality of spectral peaks can be used for field locking, and the field locking system also has a function of observing or decoupling nuclear magnetic resonance signals of the atomic nuclei used for the field locking.
Preferably, the gated IO comprises a plurality of independently controllable IO interfaces, each IO interface is independently controlled by the central controller according to the control parameters, and is used for outputting the switch control signal to the external device of the nuclear magnetic resonance instrument;
the IO interface is also used for receiving a synchronous trigger signal from any external equipment and driving a synchronous bus to start a plurality of integrated transceivers to perform synchronous scanning;
the clock is provided with a constant temperature crystal oscillator and is used for outputting a reference clock to all the integrated transceivers.
In general, compared with the prior art, the above technical solution contemplated by the present invention can achieve the following beneficial effects:
(1) the pulse sequence controller provided by the invention consists of a plurality of pulse sequence subsystems, and each pulse sequence subsystem consists of a plurality of identical integrated transceivers, so that the number of one integrated transceiver and the number of the pulse sequence subsystems can be arbitrarily expanded according to the requirement. Therefore, the technical problems that the number and the function of the channels of the existing miniaturized nuclear magnetic resonance instrument are solidified, the working frequency range is low, the instrument can only be used as an instrument with a specific function, and the requirements of the nuclear magnetic resonance imager or spectrometer for flexible and complex functions, expandable channel number and wide-frequency-range working cannot be met;
(2) in the pulse sequence controller provided by the invention, each integrated transceiver comprises a radio frequency signal conversion module, an intermediate frequency transmitter, an intermediate frequency receiver, a gradient controller, a peripheral control interface and a gate control IO, each integrated transceiver can also be selectively provided with a lock field feedback unit and a clock, and one integrated transceiver has all control functions of a minimum number of complete nuclear magnetic resonance instruments. The number of integrated transceivers can be arbitrarily expanded as required, so that the number of gradient controllers, peripheral control interfaces, lock field systems, and the like can also be arbitrarily expanded. Therefore, the technical problems that the peripheral control interfaces, the gradient controller interfaces, the lock field system and the like of the existing distributed or centralized nuclear magnetic resonance instrument are fixed in number due to the fact that the peripheral control interfaces, the gradient controller interfaces, the lock field system and the like are arranged on a certain daughter board, the number of expandable peripherals is limited by the maximum number of interfaces, the number of the interfaces cannot be flexibly configured according to the number of the peripherals, and the number of core transceivers can be reduced due to the fact that the peripheral interfaces are increased;
(3) because each pulse sequence controller subsystem provided by the invention uses a multi-bus computer to control all integrated transceivers in the subsystem to work, in the process of one-time scanning, the multi-bus computer and a server only interact once, and simultaneously the multi-bus computer only interacts with the integrated transceivers needing to be scanned, and the integrated transceivers in the same pulse sequence controller subsystem have the same functions and form mutual backup; therefore, the invention can solve the technical problems that the server and the industrial computer interact for many times due to the distributed structure of the existing distributed nuclear magnetic resonance instrument, control data is generally required to be sent to all the industrial computers when one-time scanning is completed, the communication time is long, and the whole system stops working easily due to the fault of a single functional node, and the reliability of the system is obviously reduced due to the high cost of the industrial computers and the unnecessary increase of the number of the industrial computers;
(4) because the multi-bus computer in each pulse sequence controller subsystem provided by the invention is provided with a plurality of groups of high-speed serial buses, each group of serial buses is directly connected with each integrated transceiver in the pulse sequence controller subsystem through the backboard, the serial buses are directly connected between the slot where the backboard multi-bus computer is positioned and the slot where each integrated transceiver is positioned by using the PCB connecting wire, the connecting wire is simple in design and has no requirements of high speed, terminal matching and the like; therefore, the invention can solve the technical problem that the high-speed communication cable can obviously reduce the reliability of the system when the conventional centralized nuclear magnetic resonance instrument uses PCIe, USB and other high-speed cables to connect various components;
(5) the integrated transceiver provided by the invention has the functions of transmitting and receiving nuclear magnetic resonance radio frequency signals, wherein the nuclear of the intermediate frequency transmitter is high-resolution DAC, the nuclear of the intermediate frequency receiver is high-resolution ADC, the output frequency of the intermediate frequency transmitter and the input frequency of the intermediate frequency receiver are both intermediate frequency which is only higher than 80MHz, the output frequency of the intermediate frequency transmitter is converted into target frequency specified by a server by the radio frequency signal conversion module, parameters such as phase, power, width and the like of the output signals are controlled at the same time, and the frequency of the input nuclear magnetic resonance signals is converted into the intermediate frequency by the radio frequency signal conversion module and is output to the intermediate frequency receiver. The frequency range of the radio frequency signal conversion module can reach 5 MHz-2 GHz, and meanwhile, a high-resolution DAC and a high-resolution ADC which work at the intermediate frequency of 80MHz are civil products, so that the trade risk can be prevented; therefore, the invention can solve the technical problems that when the three existing nuclear magnetic resonance instruments work within the frequency range of DDS or high-speed DAC (generally below 200 MHz), radio frequency emission directly uses DDS or high-speed DAC to output radio frequency signals, and radio frequency receiving directly uses high-speed ADC to sample, but the direct output working frequency of DDS or high-speed DAC is low, and the wide frequency working requirement of several MHz-several GHz of the nuclear magnetic spectrometer cannot be met, and the high-speed high-resolution ADC with the frequency of more than 100MHz is high in cost and faces the challenge of international trade barrier, so that the implementation is generally difficult, or the resolution of the system is seriously reduced;
(6) because the radio frequency signal conversion module, the intermediate frequency transmitter and the intermediate frequency receiver are directly connected in the integrated transceiver provided by the invention, one integrated transceiver has complete radio frequency transmitting and receiving functions in the full frequency range and is only connected with the output and the input of an external part of a nuclear magnetic resonance instrument; meanwhile, the radio frequency signal conversion module adopts high and medium frequency above 1.8GHz, the output signal is pure in frequency spectrum, and the inherent problems of single frequency mixing technologies such as local oscillator leakage, multiple harmonics and the like do not exist; therefore, the invention can solve the technical problems that the connecting cable becomes very complicated when the number of the transmitting and receiving channels needing to be installed is large in the three existing nuclear magnetic resonance instruments, and the technical problems that local oscillator leakage, multiple harmonics and the like exist in output signals due to the adoption of a direct frequency mixing scheme for transmitting and receiving, the out-of-band signals further cause serious nuclear magnetic signal distortion, different band-pass filters are often needed to be installed, and the requirements of high bandwidth and automatic and arbitrary switching of working frequency of the nuclear magnetic resonance instruments cannot be met.
(7) In the integrated transceiver provided by the invention, the radio frequency signal conversion module is directly connected with the central controller through the in-board high-speed communication interface, the central controller directly controls the working frequency of the radio frequency signal conversion module according to the control parameters, the frequency change step can reach 5 MHz-2 GHz, and the switching time is less than 1 us; therefore, the invention can solve the problems that the large step change of the working frequency of three existing nuclear magnetic resonance instruments is realized by changing the frequency of the switching frequency source, and the small step frequency switching is realized by changing the frequency of the DDS or the high-speed DAC of the transmitter. But the frequency source is separated from the transmitter and the receiver, the frequency source is controlled in a non-real-time manner through the peripheral controller, the output frequency switching of the frequency source is limited by the switching time consumption of the communication process and the low communication rate of the peripheral controller, the frequency switching speed is between 100us and several ms, the rapid frequency switching can only be realized through the DDS or the high-speed DAC of the transmitter, but the frequency range of the DDS or the high-speed DAC which can be changed is smaller, namely, only the rapid frequency switching of small stepping can be carried out, and the technical problem that the requirement of the nuclear magnetic resonance instrument for switching the large stepping frequency above 10MHz is faster than 1us cannot be met;
(8) in the integrated transceiver provided by the invention, the lock field feedback unit, the central controller, the radio frequency signal conversion module, the intermediate frequency transmitter and the intermediate frequency receiver form a complete lock field system, the lock field system can have radio frequency transmitting and receiving capacity with any frequency and any shape, the lock field feedback unit is also used for outputting Z0 current, correcting drift of a magnetic field and completing a lock field function, the lock field system has a working frequency bandwidth higher than 5 MHz-2 GHz, and can use D, D and B commonly used by nuclear magnetic resonance instruments,19F and other arbitrary atomic nuclei complete a field locking function, a field locking system can output radio frequency pulses in any shapes, a complex solvent with a plurality of spectral peaks can be used for field locking, and the field locking system also has a nuclear magnetic resonance signal observation or decoupling function for the atomic nuclei used for the field locking; therefore, the invention can solve the technical problems that in order to reduce the cost, three existing nuclear magnetic resonance instruments often do not use a frequency source and an industrial computer, a field locking system of the three existing nuclear magnetic resonance instruments is independently designed into a circuit board block with a frequency conversion function and interacts with the industrial computer in a non-real-time manner, the field locking system can only output signals with narrow bandwidth and cannot meet the field locking requirement that the nuclear magnetic resonance instruments use atomic nuclei with frequency difference of hundreds of MHz, such as D and 19F, and the like, and meanwhile, the field locking system does not have the complete functions of a receiver and a transmitter, can only use the atomic nuclei with single frequency to lock the field, cannot use the atomic nuclei with a plurality of spectral peaks to lock the field, and does not have the experimental functions of observation, decoupling and the like of the atomic nuclei used for locking the field.
Drawings
FIG. 1 is a block diagram of a nuclear magnetic resonance pulse sequence controller according to the present invention;
fig. 2 is a block diagram of an integrated transceiver in an nmr pulse sequence controller according to the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
The nuclear magnetic resonance instrument is developed and produced by applying the nuclear magnetic resonance principle, the nuclear magnetic resonance instrument excites the resonance phenomenon of the atomic nucleus of the object to be measured by transmitting a high-power pulse signal to the object to be measured, and measures a weak signal generated by a macroscopic magnetization vector of the atomic nucleus in a receiving coil of the nuclear magnetic resonance instrument, so the nuclear magnetic resonance instrument necessarily comprises components of communication, transmission, reception and the like, and provides gradient, lock field, shimming and external design control, the configuration of the instrument has different configurations according to the change of a client scene, the nuclear magnetic resonance instrument is objectively required to have the transmission and reception channels which can be expanded, the number of gradient controllers can be expanded, a lock field system can adapt to the lock field work of different nuclei, and can control different types and different quantities of external equipment and the like, and instrument design modes with different purposes at different:
chinese patent No. ZL 200410060985.3 and the patent name "nuclear magnetic resonance console" (hereinafter referred to as "patent 1") disclose a fully distributed nuclear magnetic resonance pulse sequence controller, in which a plurality of transmitters, receivers, gradient controllers, clock systems, etc. are distributed, each functional component is independently controlled by an industrial computer, and the industrial computer is connected to a control computer through ethernet to realize the respective control of each component, which has the following disadvantages: 1) the transmitting and receiving are separated, the gradient controllers are independently arranged, and the expandable quantity of the system is limited; 2) the lock field system needs to be independently arranged and is not directly controlled by an industrial computer, the lock field functions of lock channel decoupling, selective excitation and the like cannot be realized, and the basic requirements of the lock field of the nuclear magnetic instrument can only be met; 3) the broadband radio-frequency signal conversion module is externally arranged, the radio-frequency signal conversion module is connected with the transmitter and the receiver through coaxial lines, and the more channels are, the more complex the connection is; the external radio frequency signal conversion module simultaneously causes the problem that the frequency cannot be rapidly switched, and cannot be applied to occasions where the frequency needs large stepping and rapid switching; 4) the mode of parallel control of each module through the Ethernet leads to the fact that the number of communication interaction times of one-time scanning is multiplied, and the contradiction between the flexibility and the reliability of the system is formed.
The Chinese patent No. ZL 00128170.4 and the patent name 'a digital nuclear magnetic resonance console device' introduce a nuclear magnetic resonance pulse sequence controller with a classic structure controlled by a backboard bus, functional components such as a transmitting controller, a receiving controller, a gradient controller and the like are arranged in the backboard bus, and one controller controls all the functional components through the backboard bus. The scheme is characterized in that functional components are randomly inserted into the back plate, but the scheme has the defects that the back plate is complex, the high-speed buses are all connected through the back plate, the design of the back plate is difficult, and the cost is high. Similar to patent 1, each functional component in the controller only completes a single function, the number of expandable channels in one system is limited, and an external radio frequency signal conversion module is required for frequency conversion in transmitting and receiving, so that the problems of complicated cable connection and too slow frequency switching exist.
The Chinese patent No. ZL 200610025890.7 and the patent name of the integrated nuclear magnetic resonance spectrometer console based on the USB bus, the Chinese invention application No. 201410832609.5 and the invention name of the digital nuclear magnetic resonance console device introduce a miniaturized nuclear magnetic resonance pulse sequence controller formed by combining an ARM controller and an FPGA controller, the miniaturized nuclear magnetic resonance pulse sequence controller comprises a transmitting function and a receiving function, the transmitting function and the receiving function adopt a mode of outputting DDS and then mixing frequency, and the miniaturized nuclear magnetic resonance pulse sequence controller is characterized in that the system has simple functions, and only simple interaction with a server through the USB or no server is needed. However, such systems have significant drawbacks of miniaturized systems: the functions are solidified and can not be expanded, and the essential functions or expansion requirements of nuclear magnetic resonance instruments such as gradient control, a lock field system, peripheral control and the like are not considered.
As shown in fig. 1, the nmr pulse sequence controller of the present invention includes a plurality of nmr pulse sequence controller subsystems 1, a network device 2, and a server 3 electrically connected in sequence. The adjacent nuclear magnetic resonance pulse sequence controller subsystems 1 are connected through a backplane synchronization bus, and all the nuclear magnetic resonance pulse sequence controller subsystems 1 have the same Reference clock (Reference clock). It should be noted that the upper limit of the number of the nmr pulse sequence controller sub-systems 1 is such that the clocks of all the nmr pulse sequence controller sub-systems 1 can be synchronized without an asynchronous situation.
The nmr pulse sequence controller subsystem 1 is disposed in a card cage and includes a plurality of integrated transceivers 11, a multi-bus computer 12, a power supply 13, and a backplane 14. The upper limit of the number of transceivers installed in a pod of a nuclear magnetic resonance pulse sequence controller subsystem 1 is limited by the width of the pod in which the nuclear magnetic resonance pulse sequence controller subsystem is located.
The power supply 13 is electrically connected to the integrated transceiver 11 and the multi-bus computer 12 through the backplane 14, and the power supply 13, the multi-bus computer 12, and the integrated transceivers 11 are all inserted into the backplane slots of the backplane 14.
In the present embodiment, the multi-bus computer 12 is a computer conforming to the VPX high-speed serial bus standard.
The multi-bus computer 12 has multiple sets of high-speed serial buses, each set of high-speed serial buses being communicatively connected to one of the integrated transceivers 11.
The multi-bus computer 12 of the nuclear magnetic resonance pulse sequence controller subsystem 1 is connected to the server 3 via the network device 2. The network device 2 may be a network-connected or fiber-connected switch or router. When there is only one nmr pulse sequence controller subsystem 1 in the nmr pulse sequence controller, the network device 2 may be omitted, and the multi-bus computer 12 is directly connected to the server 3.
Each backplane slot on backplane 14 is provided with an ID identifier, which is used by all-in-one transceivers 11 inserted into the backplane slot as their Identification (ID), and multi-bus computer 12 is configured to assign tasks to all-in-one transceivers 11 based on the identification of each all-in-one transceiver 11.
Specifically, the assigned tasks include pulse sequence transmission, nuclear magnetic signal acquisition, gradient control, peripheral control, lock feedback, gated IO, and the like.
The server 3 is adapted to receive input signals from a user and to send the input signals to the multi-bus computer 12.
The multi-bus computer 12 is also configured to convert the input signal into a control parameter corresponding to the task to which each integrated transceiver 11 is assigned, and transmit the control parameter to the corresponding integrated transceiver 11 through the high-speed serial bus.
The integrated transceiver 11 is configured to process tasks assigned to the integrated transceiver 11 using control parameters from the multi-bus computer 12, where the processing is a scanning process when the tasks are pulse sequence transmission, nuclear magnetic signal acquisition, gradient control, or gated IO, a peripheral control process when the tasks are peripheral control, and a lock field process when the tasks are lock feedback.
On the backplane 14, only a plurality of connection lines for a set of high-speed serial buses are provided between the backplane slot where the multi-bus computer 12 is located and the backplane slot where each integrated transceiver 11 is located, which is achieved without using a high-speed parallel backplane bus or performing complicated designs such as endpoint matching, thereby reducing design cost and complexity.
The backplane 14 is also provided with a synchronization bus for connecting all the integrated transceivers 11 in sequence.
In one embodiment, all of the integrated transceivers 11 may be used to perform a synchronous scanning process upon control commands from the multi-bus computer upon activation of the synchronous bus.
The synchronous bus is driven by all the integrated transceivers 11 together by adopting a line and a mode, and the driving mode is as follows:
(1) when the integrated transceiver 11 is idle, outputting a high level on the synchronous bus;
(2) when the integrated transceiver 11 to be scanned is ready to scan (i.e., during the process of receiving control parameters from the multi-bus computer 12), a low level is output on the synchronous bus;
(3) when the integrated transceiver 11 is ready for scanning (i.e., when receiving the control parameters from the multi-bus computer 12 is completed), a high level is output on the synchronous bus;
(4) when all the scanned integrated transceivers 11 are ready, the synchronous bus is switched from low level to high level;
(5) the scanning-ready integrated transceiver 11 monitors the change of the synchronous bus and synchronously starts scanning when a rising edge is monitored.
In another embodiment, each transceiver 11 may perform asynchronous scan processing independently of the activation of the synchronous bus, in response to control commands (i.e., scanning is not initiated by the synchronous bus of the backplane).
In both embodiments, the multi-bus computer 12 transmits control commands only to the integrated transceivers 11 that need to be scanned, and does not interact with the integrated transceivers 11 that do not need to be scanned, so as to reduce the number of interactions.
As shown in fig. 2, it shows the internal structure of the integrated transceiver 11 of the present invention.
Integrated transceiver 11 includes rf signal conversion module 111, if transmitter 112, if receiver 113, gradient controller 114, peripheral control interface 115, gated IO116, central controller 118, and memory 119, with one integrated transceiver 11 having all the control functions of a minimum number of complete nmr instruments. In addition, only one of the integrated transceivers 11 of each of the nmr pulse sequence controllers further includes a lock field feedback unit 117 and a clock 120.
In this embodiment, the gradient controller 114 employs a medium-speed high-resolution DAC and a multi-point low-Voltage differential signaling (MLVDS), the field-lock feedback unit 117 includes a high-resolution DAC and a Voltage-current converter (V/I converter), the peripheral control interface 115 employs a CAN transceiver, the central controller 118 employs an FPGA, and the storage 119 employs a DDR memory.
The central controller 118 is used for receiving control parameters corresponding to different tasks from the multi-bus computer 12 through the high-speed serial bus and storing the control parameters in corresponding areas of the memory 119; before starting the scan, the central controller 118 pre-reads a part (specifically 50%) of the control parameters from the memory 119; during scanning, the central controller 118 parses the pre-read control parameters one by one, and controls the rf signal conversion module 111, the if transmitter 112, the if receiver 113, the gradient controller 114, the lock field feedback unit 117, the peripheral control interface 115, and the gate control IO116 to operate according to the timing sequence specified by the control parameters, wherein when the pre-read control parameters are executed by half, the central controller 118 continues to pre-read a part of the control parameters from the memory 119; the above process is repeatedly performed until the scanning is completed.
The invention uses the memory 119 with the storage size of more than 2GB, can continuously store a plurality of pulses with complex shapes of more than 50 ten thousand points in single scanning, eliminates the waiting time of data transmission among a plurality of times of scanning, simultaneously provides more than 100MB of storage space for receiving data by the memory 119, and can carry out nuclear magnetic resonance data operation operations such as a plurality of times of data receiving cache, data receiving superposition and the like in the memory 119.
The if transmitter 112 includes a high-speed Digital-to-analog converter (DAC) and a power amplifier connected in series, the central controller 118 controls the high-speed DAC to output an if signal, which includes frequency, phase, shape and pulse width, according to a control parameter related to the if transmitter 112 among the control parameters, and the if transmitter 112 outputs the if signal to the rf signal conversion module 111.
The rf signal conversion module 111 is a transceiver integrated rf signal conversion module, and has a complete transmission channel and a receiving channel.
The rf signal conversion module 111 is used to convert the frequency of the if signal to a target output frequency specified by the control parameters, and perform power adjustment within 90dB of the frequency-converted signal by using the variable digital attenuator at the transmission output terminal (the power attenuation is determined by the power attenuation amountControl parameter determination), and finally, the rf switch at the transmitting output end is used to perform transmission pulse width control (the width is determined by the control parameter) on the power-adjusted signal, so as to obtain an output signal fTX。
The rf signal conversion module 111 is further configured to receive the nmr signal fRXThe NMR signal f is adjusted according to the control parametersRXConverts to an intermediate frequency signal, and outputs the intermediate frequency signal to intermediate frequency receiver 113.
The radio frequency signal conversion module 111 adopts a high and medium frequency above 1.8GHz, signals such as stray and harmonic waves of the output transmission signals are all outside the working frequency of the nuclear magnetic resonance system, and the suppression of more than 50dBc can be realized by using a low-pass filter or a high-pass filter, so that the nuclear magnetic resonance instrument does not need to be provided with a band-pass filter, and the working frequency bandwidth is higher than 5 MHz-2 GHz (for details, see a signal modulation module and method of CN 2018114990452).
The radio frequency signal conversion module 111 is directly controlled by the central controller 118, the working frequency of the radio frequency signal conversion module 111 is switched by an internal DDS and a phase-locked loop, the frequency resolution of the DDS is 48 bits, the working bandwidth is larger than 100MHz, and the frequency switching time is less than 1us, so that the nuclear magnetic resonance pulse sequence controller can rapidly switch the frequency within the 100MHz bandwidth of any working frequency point, and the requirement of a special frequency switching nuclear magnetic experiment is met.
The frequency of the transmitting intermediate frequency signal and the receiving intermediate frequency signal is the same and higher than 80 MHz.
The if receiver 113 includes a radio frequency switch, a variable digital attenuator, a power amplifier, and a high-speed high-resolution ADC, which are connected in sequence, the radio frequency switch is configured to perform width control (the width is determined by a control parameter) on the if signal output by the radio frequency signal conversion module 111, the variable digital attenuator is configured to perform gain adjustment (the gain attenuation is determined by the control parameter) in a range of 60dB on the width-controlled signal, the power amplifier is configured to amplify the gain-adjusted signal (the amplification factor is determined by the control parameter), and the high-speed high-resolution ADC is configured to perform analog-to-digital conversion on the amplified signal, so as to obtain a digitized nuclear magnetic signal.
The central controller 118 is further configured to sequentially perform Digital Down Conversion (DDC), Digital filtering, Digital decimation, and other processing on the digitized nuclear magnetic signals according to the control parameters when the rf switch of the if receiver 113 is turned on, so as to form nuclear magnetic data required by the control parameters, and buffer the nuclear magnetic data in the memory 119.
When the gradient controller 114 selects the middle-speed high-resolution DAC, it is used to generate an analog gradient waveform according to the control parameters to control the gradient power amplifier of the nuclear magnetic resonance instrument to work; when the gradient controller 114 selects the MLVDS, it is configured to generate a digital signal according to the control parameter to control the operation of the gradient power amplifier of the nuclear magnetic resonance instrument.
The peripheral control interface 115 is a CAN bus interface, and is used to control all external devices connected to the same CAN bus in the nuclear magnetic resonance instrument.
Only one lock field feedback unit 117 is provided in one nmr pulse sequence controller subsystem 1, which can be mounted on any one of the integrated transceivers 11.
The lock field feedback unit 117 comprises a high-resolution multi-channel DAC 1171 and a V/I conversion circuit 1172 connected in series, and the lock field feedback unit 117, the radio frequency signal conversion module 111, the intermediate frequency transmitter 112 and the intermediate frequency receiver 113 together form a complete lock field system. The lock field feedback unit 117 outputs a current for driving a Z0 shim coil of the nmr instrument to form a magnetic field, so as to adjust the magnetic field strength of the nmr instrument and correct the magnetic field drift of the nmr instrument, thereby performing a lock field function.
Due to the wide frequency range of the radio frequency signal conversion module 111, the field locking system can excite any atomic nucleus, so that the atomic nucleus used for field locking of the nuclear magnetic resonance instrument is not limited to a specific atomic nucleus any more, and has the capability of field locking of any nuclear nucleus. Meanwhile, due to the characteristic that the intermediate frequency transmitter 112 can output pulses of any shape, the target frequency range can be selectively excited, so that one spectrum peak can be selectively selected to complete the lock field under the condition that the lock field solvent has complex frequency spectrums. Meanwhile, the lock field system is a complete transmitting and receiving system, and can complete functions such as decoupling experiments of the lock field core.
The gated IO116 includes a plurality of independently controllable IO interfaces, each IO interface is individually controlled by the central controller 118 according to control parameters, and is used to output a switch control signal to external devices of the nuclear magnetic resonance instrument, such as a transmit switch of a radio frequency power amplifier, a transmit-receive switch of a preamplifier, a switch of a gradient power amplifier, and the like; the IO interface is further configured to receive a synchronization trigger signal from any external device, and is configured to drive the synchronization bus to start the multiple integrated transceivers 11 to perform synchronous scanning.
The clock 120 is provided with a constant temperature crystal oscillator for outputting a reference clock to all the integrated transceivers 11.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims (13)

1. A nuclear magnetic resonance pulse sequence controller comprises a plurality of nuclear magnetic resonance pulse sequence controller subsystems, network equipment and a server, wherein all the nuclear magnetic resonance pulse sequence controller subsystems are electrically connected in sequence, all the nuclear magnetic resonance pulse sequence controller subsystems have the same reference clock, and the nuclear magnetic resonance pulse sequence controller is characterized in that,
the nuclear magnetic resonance pulse sequence controller subsystem is arranged in the plug-in box and comprises a plurality of integrated transceivers, a multi-bus computer, a power supply and a back plate;
the power supply is electrically connected with the integrated transceiver and the multi-bus computer through the back plate, and the power supply, the multi-bus computer and each integrated transceiver are respectively inserted into each back plate slot of the back plate;
the multi-bus computer is provided with a plurality of groups of high-speed serial buses, and each group of high-speed serial buses is in communication connection with one integrated transceiver;
the multi-bus computer of the nuclear magnetic resonance pulse sequence controller subsystem is connected with the server through network equipment;
each backboard slot on the backboard is provided with an ID identifier, the integrated transceiver inserted into the backboard slot uses the ID identifier as the identity of the integrated transceiver, and the multi-bus computer is used for allocating tasks to the integrated transceiver according to the identity of each integrated transceiver;
the server is used for receiving an input signal from a user and sending the input signal to the multi-bus computer;
the multi-bus computer is also used for converting the input signal into a control parameter corresponding to the task assigned to each integrated transceiver and sending the control parameter to the corresponding integrated transceiver through the high-speed serial bus.
The unified transceiver is used to process the tasks assigned to the unified transceiver using control parameters from the multi-bus computer.
2. The NMR pulse sequence controller of claim 1,
on the backboard, only a plurality of connecting wires for a group of high-speed serial buses are arranged between a backboard slot where the multi-bus computer is located and a backboard slot where each integrated transceiver is located;
the back board is also provided with a synchronous bus for connecting all the integrated transceivers in sequence.
3. The NMR pulse sequence controller of claim 1,
the distributed tasks comprise pulse sequence emission, nuclear magnetic signal acquisition, gradient control, peripheral control, lock feedback, gate control IO and the like;
the integrated transceiver is also used for scanning the task by using the control parameters from the multi-bus computer when the distributed task is pulse sequence transmission, nuclear magnetic signal acquisition, gradient control or gate control IO;
the integrated transceiver is also used for performing peripheral control processing on the task by using the control parameters from the multi-bus computer when the distributed task is peripheral control;
the integrated transceiver is also configured to lock the task using the control parameters from the multi-bus computer when the assigned task is lock feedback.
4. The NMR pulse sequence controller of claim 3,
all the integrated transceivers are used for carrying out synchronous scanning processing according to control commands from the multi-bus computer under the triggering of the synchronous bus, or each integrated transceiver does not depend on the triggering of the synchronous bus and carries out asynchronous scanning processing according to the control commands;
in the process of synchronous scanning, the synchronous bus is driven by all the integrated transceiver by adopting a line and a mode together, and the driving mode is as follows:
(1) when the integrated transceiver is idle, outputting a high level on the synchronous bus;
(2) when the integrated transceiver needing scanning receives the control parameters and prepares for scanning, outputting a low level on the synchronous bus;
(3) when the integrated transceiver finishes receiving the control parameters and scanning and preparing, outputting a high level on the synchronous bus;
(4) when all the scanned integrated transceivers are ready, the synchronous bus is converted from low level to high level;
(5) the scanning-ready integrated transceiver monitors the change of the synchronous bus, and synchronously starts scanning when the rising edge is monitored.
5. The NMR pulse sequence controller of claim 3,
each integrated transceiver comprises a radio frequency signal conversion module, an intermediate frequency transmitter, an intermediate frequency receiver, a gradient controller, an external control interface, a gate control IO, a central controller and a memory;
in each nuclear magnetic resonance pulse sequence controller, only one of the integrated transceivers also comprises a lock field feedback unit, and the other integrated transceiver also comprises a clock; or only one of the integrated transceivers also comprises a lock field feedback unit and a clock.
6. The NMR pulse sequence controller of claim 5, wherein the central controller is configured to receive control parameters corresponding to different tasks from the multi-bus computer via the high-speed serial bus and store the control parameters in different areas of the memory;
the central controller is also used for pre-reading a part of control parameters from the memory before scanning is started;
the central controller is also used for analyzing the control parameters which are pre-read one by one during scanning, and controlling the radio frequency signal conversion module, the intermediate frequency emitter, the intermediate frequency receiver, the gradient controller, the lock field feedback unit, the peripheral control interface and the gate control IO to work according to the time sequence appointed by the control parameters, wherein when the pre-read control parameters are executed for a half, the central controller continuously pre-reads a part of the control parameters from the memory; the above process is repeatedly performed until the scanning is completed.
7. The NMR pulse sequence controller of claim 6,
the central controller is also used for controlling the intermediate frequency transmitter to output an intermediate frequency signal which comprises frequency, phase, shape and pulse width according to the control parameters related to the intermediate frequency transmitter in the control parameters;
the intermediate frequency transmitter is used for outputting the intermediate frequency signal to the radio frequency signal conversion module.
The radio frequency signal conversion module is used for converting the frequency of the intermediate frequency signal into a target output frequency in the control parameters, performing power regulation within a range of 90dB on the signal after frequency conversion by using the variable digital attenuator of the transmitting output end, and finally performing width control of transmitting pulse on the signal after power regulation by using the radio frequency switch of the transmitting output end, thereby obtaining the outputOutput signal fTX；
The radio frequency signal conversion module is also used for receiving a nuclear magnetic resonance signal fRXThe NMR signal f is adjusted according to the control parametersRXConverts the frequency of the intermediate frequency signal into a frequency of the intermediate frequency signal, and outputs the intermediate frequency signal to the intermediate frequency receiver.
8. The NMR pulse sequence controller of claim 7,
the radio frequency signal conversion module adopts high and medium frequency above 1.8GHz, stray and harmonic signals of the output transmission signals are all out of the working frequency of the nuclear magnetic resonance system, and the suppression of more than 50dBc can be realized by a low-pass filter or a high-pass filter, so that a nuclear magnetic resonance instrument does not need to be provided with a band-pass filter, and the working frequency bandwidth is higher than 5 MHz-2 GHz;
the radio frequency signal conversion module is directly controlled by the central controller, the working frequency of the radio frequency signal conversion module is switched by an internal DDS and a phase-locked loop, the frequency resolution of the DDS is 48 bits, the working bandwidth is larger than 100MHz, and the frequency switching time is smaller than 1 us.
9. The NMR pulse sequence controller of claim 8,
the intermediate frequency receiver comprises a radio frequency switch, a variable digital attenuator, a power amplifier and a high-speed high-resolution ADC which are connected in sequence;
the radio frequency switch is used for controlling the width of the intermediate frequency signal output by the radio frequency signal conversion module;
the variable digital attenuator is used for carrying out gain adjustment within the range of 60dB on the signals after width control;
the power amplifier is used for carrying out power amplification on the signal after the gain adjustment;
the high-speed high-resolution ADC is used for carrying out analog-to-digital conversion on the amplified signal so as to obtain a digitized nuclear magnetic signal.
10. The nmr pulse sequence controller of claim 9, wherein the central controller is further configured to sequentially perform digital down-conversion, digital filtering, digital decimation, etc. on the digitized nuclear magnetic signals according to the control parameters when the rf switch of the if receiver is turned on, so as to form nuclear magnetic data required by the control parameters, and to buffer the nuclear magnetic data in the memory.
11. The NMR pulse sequence controller of claim 5,
the gradient controller is a medium-speed high-resolution DAC or an MLVDS;
when the gradient controller selects the medium-speed high-resolution DAC, the DAC is used for generating an analog gradient waveform according to the control parameters so as to control a gradient power amplifier of the nuclear magnetic resonance instrument to work;
when the gradient controller selects the MLVDS, the MLVDS is used for generating a digital signal according to the control parameters so as to control the gradient power amplifier of the nuclear magnetic resonance instrument to work;
the peripheral control interface is a CAN bus interface and is used for controlling all external equipment connected to the same CAN bus in the nuclear magnetic resonance instrument.
12. The NMR pulse sequence controller of claim 5,
the lock field feedback unit, the central controller, the radio frequency signal conversion module, the intermediate frequency transmitter and the intermediate frequency receiver form a complete lock field system;
the lock field feedback unit is also used for outputting current to drive a Z0 shimming coil of the nuclear magnetic resonance instrument to form a magnetic field so as to adjust the magnetic field intensity of the nuclear magnetic resonance instrument and correct the magnetic field drift of the nuclear magnetic resonance instrument to complete the lock field function.
The lock field system has the working frequency bandwidth higher than 5 MHz-2 GHz, and can use D, D and GHz which are commonly used in nuclear magnetic resonance instruments,19F and other arbitrary atomic nuclei complete the field locking function, the field locking system can output radio frequency pulses in any shapes, a complex solvent with a plurality of spectral peaks can be used for field locking, and the field locking system also has the function of carrying out nuclear magnetic resonance on the atomic nuclei used for field lockingA vibration signal observation or decoupling function.
13. The NMR pulse sequence controller of claim 5,
the gated IO comprises a plurality of independently controllable IO interfaces, each IO interface is independently controlled by the central controller according to control parameters and is used for outputting a switch control signal to external equipment of the nuclear magnetic resonance instrument;
the IO interface is also used for receiving a synchronous trigger signal from any external equipment and driving the synchronous bus to start the plurality of integrated transceivers to perform synchronous scanning.
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