CN104055516A - Multichannel radio-frequency signal control system - Google Patents
Multichannel radio-frequency signal control system Download PDFInfo
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- CN104055516A CN104055516A CN201310089098.8A CN201310089098A CN104055516A CN 104055516 A CN104055516 A CN 104055516A CN 201310089098 A CN201310089098 A CN 201310089098A CN 104055516 A CN104055516 A CN 104055516A
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Abstract
The invention provides a multichannel radio-frequency signal control system. The system comprises a multichannel radio-frequency signal emission unit, a power signal receiving unit and a digital signal processing unit, wherein the multichannel radio-frequency signal emission unit is used for providing first radio-frequency signals of multiple channels; the power signal receiving unit is used for receiving a first power signal fed back by the first radio-frequency signal of any channel in the multichannel radio-frequency signal emission unit; the digital signal processing unit is connected with the multichannel radio-frequency signal emission unit and the power signal receiving unit, is used for processing to-be-emitted radio-frequency signals of the multiple channels and transmitting a first base band signal to the multichannel radio-frequency signal emission unit, receives and processes a second power signal received by the power signal receiving unit and then transmits a third power signal to peripheral equipment. According to the multichannel radio-frequency signal control system, the simulation intermediate frequency process is omitted, the signal performance is improved, the modular design is adopted, the number of the channels can be configured flexibly, and the system can meet requirements of magnetic resonance equipment with various field intensities.
Description
Technical field
The present invention relates to magnetic resonance control technology field, relate in particular to a kind of multichannel radiofrequency signal control system.
Background technology
Emission of radio frequency signals system is the necessary component of NMR (Nuclear Magnetic Resonance)-imaging equipment, radio frequency excitation signal that can fast modulation for generation of frequency, phase place and amplitude, signal transfers to radio-frequency coil through power amplifier, thereby makes the atomic nucleus in magnetostatic field that resonance acquisition magnetic resonance signal occur; Along with magnetic resonance system is day by day to the trend of High-Field development, the parallel transmitting of multichannel radiofrequency signal attracts people's attention day by day.The parallel transmitting of multichannel radiofrequency signal is mainly applicable in high-field magnetic resonance system, for solving the problem such as launching site inhomogeneities and radio-frequency (RF) energy absorption, adopts multi-channel parallel lift-off technology need to produce the adjustable radiofrequency signal that obtains of channelized frequencies, phase place and amplitude.
In prior art, MRI emission of radio frequency signals and transmission are based on radio if digitization principle, radio-frequency transmissions in RF emission system and power detection are selected the mode of analog intermediate frequency, for example, in the patent documentation that publication No. is CN102724162, introduce a kind of transmitter of multichannel nuclear magnetic resonance, NMR, adopt the radiation pattern of analog intermediate frequency, by direct digital synthesiser (DDS), signal is adjusted to intermediate frequency, be then modulated to carrier frequency by analog frequency mixing; Because IF-FRE is lower, the sample rate of mode converter and digital to analog converter is required to reduce, but owing to having adopted analog frequency mixing, can bring the problem such as local oscillator leakage, IQ imbalance, the noise level of simultaneity factor is also higher.
Summary of the invention
The problem that the present invention solves is to provide a kind of multichannel radiofrequency signal control system, in order to solve the local oscillator leakage that in prior art, multi-channel parallel emission system adopts analog frequency mixing mode to cause, the problems such as I/Q imbalance, reduce the magnetic resonance equipment requirement that noise level and mirror image suppress and be applicable to various magnetic field intensities.
In order to address the above problem, the invention provides a kind of multichannel radiofrequency signal control system, comprising:
Multichannel emission of radio frequency signals unit, for providing multichannel the first radiofrequency signal;
Power signal receiving element, for receiving first power signal of the first radio frequency signal feedback of any one passage of described multichannel emission of radio frequency signals unit;
Digital signal processing unit, be connected with described power signal receiving element with described multichannel emission of radio frequency signals unit, for the treatment of the armed radiofrequency signal of multichannel and transmit the first baseband signal to described multichannel emission of radio frequency signals unit, receive, process after the second power signal of described power signal receiving element reception, transmission the 3rd power signal is to external equipment.
Alternatively, described multichannel emission of radio frequency signals unit comprises multichannel emission of radio frequency signals passage, every road emission of radio frequency signals passage comprises D/A conversion unit, re-establishing filter unit and the first variable gain amplifier, and every road radiofrequency signal is emitted to described external equipment by described D/A conversion unit, described re-establishing filter unit and described the first variable gain amplifier successively; Described external equipment comprises power amplifier, directional coupler and radio-frequency coil.
Alternatively, described power signal receiving element comprises multichannel power signal receive path, every road power signal receive path comprises the second variable gain amplifier, frequency overlapped-resistable filter and analog-digital converter, and every road power signal transfers to described digital signal processing unit through described the second variable gain amplifier, described frequency overlapped-resistable filter and described analog-digital converter successively.
Alternatively, described digital signal processing unit comprises Master control chip; Described Master control chip is field programmable gate array.
Alternatively, described field programmable gate array also comprises optical fiber interface, for carrying out data communication with the external world.
Alternatively, described D/A conversion unit comprises multilevel interpolation wave filter and digital oscillator, before entering D/A conversion unit, makes the frequency of baseband signal reach the frequency of D/A conversion unit for baseband signal.
Alternatively, described the 3rd power signal exports described external equipment to and/or feeds back to described multichannel emission of radio frequency signals unit, monitors or carries out information interaction processing by described external equipment for the capability correction transmitting, the calculating of radio-frequency (RF) energy field energy.
Alternatively, described system also comprises Clock Managing Unit, for extremely described multichannel emission of radio frequency signals unit, described power signal receiving element and described digital signal processing unit of output multi-channel high accuracy real-time clock.
Alternatively, described Clock Managing Unit comprises reference clock agitator, voltage controlled oscillator and Clock management chip.
Alternatively, the internal system crystal oscillator that is input as of described reference clock agitator produces or external clock input.
Alternatively, the clock source number of described time management unit equals the number sum of number, power signal receive path and the field programmable gate array passage of described emission of radio frequency signals passage.
For solving the problems of the technologies described above, the present invention also provides a kind of method that realizes multichannel radiofrequency signal control system, comprises the following steps:
Described digital signal processing unit completes place states the first Digital Signal Processing of multi-channel rf signal transmission channel data, transmits the first baseband signal of any one transmission channel to described multichannel emission of radio frequency signals unit;
Described multichannel emission of radio frequency signals unit provides multichannel radio frequency transmissions, and any one transmission channel is exported the first emission of radio frequency signals to external equipment;
Described power signal receiving element receives the first power signal of described the first radio frequency signal feedback, carries out Direct Sampling, obtains the second power signal;
Described digital signal processing unit receives the second power signal and carries out the second Digital Signal Processing, obtains the 3rd power signal transmissions to described external equipment.
Alternatively, described the first Digital Signal Processing comprises and adjusts amplitude, the phase attributes of radio frequency transmissions and radio frequency transmissions is carried out to filtering interpolation, digital quadrature up-conversion.
Alternatively, the D/A conversion unit that described the first baseband signal is penetrated by riches all the way arbitrarily in passage carries out one-level quadrature up-conversion or carries out secondary quadrature up-conversion by described digital signal processing unit and described D/A conversion unit.
Alternatively, described secondary quadrature up-conversion comprises the steps:
In described digital signal processing unit, described the first baseband signal is converted to first frequency, obtains first order output radio frequency transmissions and exports in described D/A conversion unit;
In described D/A conversion unit, described first order output radio frequency transmissions is converted to Larmor frequency corresponding to magnetic field intensity, obtains second level output radio frequency transmissions.
Alternatively, described first frequency is the difference of the Larmor frequency that the mid frequency of second level output radio frequency transmissions is corresponding with magnetic field intensity, and described difference is less than 1MHz, and described second level output radio frequency transmissions is described the first radiofrequency signal.
Alternatively, described the first baseband signal enters that riches all the way arbitrarily penetrate the D/A conversion unit in passage before, the frequency of the first baseband signal reaches through multilevel interpolation the frequency that riches all the way arbitrarily penetrates the D/A conversion unit in passage.
Alternatively, described the first radiofrequency signal goes out to export to power amplifier through riches all the way arbitrarily after penetrating the reconstruction filter of passage and the first variable gain amplifier successively.
Alternatively, described the first power signal is the power signal that the first radiofrequency signal of any one transmission channel output is back to any one power signal receive path after radio-frequency coil or directional coupler.
Alternatively, described the first power signal enters analog-digital converter through the second variable gain amplifier and the frequency overlapped-resistable filter of any one receive path successively.
Alternatively, described Direct Sampling method is radio frequency sampling or bandpass sampling, if adopt radio frequency sampling, frequency overlapped-resistable filter is low pass filter; If employing bandpass sampling, frequency overlapped-resistable filter is band filter.
Alternatively, described the second power signal carries out the second Digital Signal Processing through digital signal processing unit, described the second Digital Signal Processing comprise adjust radio frequency transmissions amplitude, phase attributes, radio frequency transmissions is carried out to digital quadrature down coversion and digital filtering.
Alternatively, described the second power signal obtains the second baseband signal after quadrature frequency conversion and digital filtering, and described the second baseband signal is adjusted amplitude, the phase attributes of radio frequency transmissions by digital signal processing unit, obtains the 3rd power signal.
Alternatively, described digital filter is decimation filter, and described the second power signal, after quadrature frequency conversion, by one or more levels decimation filter, obtains described the second baseband signal.
Alternatively, described the 3rd power signal is exported by optical fiber interface after coding at described digital signal processing unit, and described the 3rd power signal is for the calculating monitoring of transmit power correction or radio-frequency field energy.
Compared with prior art, the present invention has the following advantages: (1) reduces analog intermediate frequency link, effectively improves emitting performance, reduces noise level, and mirror image suppresses, and reduces the problems such as local oscillator leakage, I/Q imbalance; (2) by digital control, can, at wider frequency range internal modulation emitting radio frequency signal and the power signal of reception, meet the requirement of the nuclear magnetic resonance equipment of multiple different magnetic field intensity; (3) adopt modularized design, the number of active lanes of system flexible configuration according to demand, the multi-channel rf signal of generation is isolated mutually, the modulation of energy complete independently frequency, phase place and amplitude.
Brief description of the drawings
Figure 1 shows that the framework schematic diagram of a kind of multichannel radiofrequency signal control system in the present invention;
Figure 2 shows that the configuration diagram of Clock Managing Unit in the present invention;
Figure 3 shows that the method flow schematic diagram of multichannel radiofrequency signal control system in the present invention;
Figure 4 shows that the operation principle schematic diagram of single channel emission of radio frequency signals passage in the present invention;
Figure 5 shows that the operation principle schematic diagram of the first baseband signal one-level conversion method in the present invention;
Figure 6 shows that the operation principle schematic diagram of the first baseband signal secondary conversion method in the present invention;
Figure 7 shows that the data flow schematic diagram of single channel power signal receive path in the present invention.
Detailed description of the invention
A lot of details are set forth in the following description so that fully understand the present invention.But the present invention can implement to be much different from alternate manner described here, and those skilled in the art can do similar popularization without prejudice to intension of the present invention in the situation that, and therefore the present invention is not subject to the restriction of following public concrete enforcement.
Secondly, the present invention utilizes schematic diagram to be described in detail, and in the time that the embodiment of the present invention is described in detail in detail, for ease of explanation, described schematic diagram is example, and it should not limit the scope of protection of the invention at this.
Describe the present invention below in conjunction with accompanying drawing.
In order to solve the problems of the technologies described above, the invention provides a kind of multichannel radiofrequency signal control system, Fig. 1 is the framework schematic diagram of multichannel radiofrequency signal control system, as shown in Figure 1, in the present invention, multichannel radiofrequency signal control system 100 comprises multichannel emission of radio frequency signals unit 110, power signal receiving element 120, digital signal processing unit 130 and Clock Managing Unit 140; Described emission of radio frequency signals unit 110 is for providing multichannel the first radiofrequency signal, and each road emission of radio frequency signals passage comprises D/A conversion unit 111, reconstruction filter 112 and the first variable gain amplifier (VGA) 113.Every road radiofrequency signal is emitted to external equipment by D/A conversion unit 111, reconstruction filter 112 and the first variable gain amplifier 113 successively; Described D/A conversion unit 111 is for carrying out the first baseband signal of digital signal processing unit transmission to be converted to analogue signal after differential filtering, described D/A conversion unit 111 also comprises multilevel interpolation wave filter 21 and digital oscillator 22, as shown in Figure 4, for before the first baseband signal is entered to D/A conversion unit 111, make the frequency of the first baseband signal reach the frequency of D/A conversion unit 111.Described re-establishing filter unit 112 receives the analogue signal that described high-speed digital-analog converting unit 111 is transmitted, leach the image signal except useful frequency range in described analogue signal, and transfer to described the first variable gain amplifier 113, described the first variable gain amplifier 113 is for adjusting amplitude, the phase attributes of the first radiofrequency signal, to meet the requirement of different output power.
Described power signal receiving element 120 is for receiving first power signal of the first radio frequency signal feedback of any one passages transmitting of described multichannel emission of radio frequency signals unit 110, every road power signal receive path comprises the second variable gain amplifier 121, frequency overlapped-resistable filter 122 and analog-digital converter 123, and every road power signal transfers to digital signal processing unit 130 through the second variable gain amplifier 121, frequency overlapped-resistable filter 122 and analog-digital converter 123 successively.Described variable gain amplifier 121 is for changing the amplitude, the phase attributes that receive the first power signal, to meet the input range requirement of described analog-digital converter 123, described frequency overlapped-resistable filter 122 is according to sampling thheorem, leach interference and noise outside band, described analog-digital converter 123 carries out digitized to filtered analogue signal, obtains the second power signal.
Described digital signal processing unit 130 is connected with described power signal receiving element 120 with described multichannel emission of radio frequency signals unit 110, for the treatment of the armed radiofrequency signal of multichannel and transmit the first baseband signal to described multichannel emission of radio frequency signals unit 110, receive, process after the second power signal that described power signal receiving element 120 receives, transmission the 3rd power signal to external equipment carries out interaction process.Described digital signal processing unit 130 comprises Master control chip; Described Master control chip is field programmable gate array 131, for radio-frequency transmissions and the power interface collection of letters number are processed, described digital signal processing unit also comprises optical fiber interface 132, and the first digital signal when transmitting, optical fiber being received passes the first base band signal transmission obtaining to described multichannel emission of radio frequency signals unit 110 after first digital processings such as interpolation, filtering and quadrature up-conversion; In the power interface time receiving, the second power signal that described analog-digital converter 123 is transmitted carries out quadrature frequency conversion processing, after filtering with interpolation grade in an imperial examination two digital signal process after by optical fiber interface 132 by the 3rd power signal transmissions to external equipment; Described the 3rd power signal exports external equipment to and/or feeds back to described multichannel emission of radio frequency signals unit, monitors and carries out information interaction processing by described external equipment for the capability correction transmitting, the calculating of radio-frequency (RF) energy field energy.
In the present invention, in multichannel emission of radio frequency signals unit 110 signal data on each road adopt described field programmable gate array 131 or adopt described field programmable gate array 131 and described digital to analog converter 111 in numeric field by wave filter 112 and rear output the first radiofrequency signal of variable gain amplifier 113 of undergoing reconstruction after one-level or the orthogonal mixing of two-stage digital, compared with prior art, reduce analog intermediate frequency process, effectively improve as noise level the emitting performances such as mirror image inhibition; Adopt Direct Sampling simultaneously, the power meter signal that multichannel emission of radio frequency signals unit 110 is fed back detects, after described the second variable gain amplifier 121 and frequency overlapped-resistable filter 122, enter analog-digital converter 123 and carry out Direct Sampling, carry out the second Digital Signal Processing processing through described field programmable gate array 131 again, whole process is carried out in numeric field, obtains described the 3rd power signal and can be used for the application such as the calculating monitoring of transmit power correction or SAR.
Described Clock Managing Unit 140 is for output multi-channel high precision clock, comprise reference clock input 141, voltage controlled oscillator 142 and multipath clock outgoing management chip 143, input for high-speed AD converter 123, D/A conversion unit 111 and field programmable gate array 131 provide the clock of high stability.Fig. 2 is the configuration diagram of Clock Managing Unit in the present invention, refer to Fig. 2, Clock Managing Unit 140 is for exporting the high stability clock source of multichannel psec or the femtosecond order of magnitude, for described multichannel emission of radio frequency signals unit 110, described power signal receiving element 120 and described digital signal processing unit 130 provide the clock source of low jitter, high accuracy and high stability.Particularly, by the reference clock source of internal system crystal oscillator or external clock input, voltage controlled oscillator 142 is chosen as voltage controlled filter VCXO (Voltage ControlOscillator), Clock management chip 143 configures frequency and the passage way of output clock by internal register, the clock passage way that multichannel output can need according to system is carried out choose reasonable, and the clock source number of described time management unit 140 is the number sum of the number of described emission of radio frequency signals passage, described power signal receive path and described field programmable gate array passage.
A kind of multichannel radiofrequency signal control system proposed by the invention adopts modularized design, and number of active lanes can be according to system requirements flexible configuration, and the multi-channel rf signal of generation is isolated mutually, the modulation of energy complete independently frequency, phase place and amplitude.
The present invention also provides a kind of method that realizes multi-channel control system for solving the problems of the technologies described above.Figure 3 shows that the method flow schematic diagram of multichannel radiofrequency signal control system in the present invention.Refer to Fig. 3, the method for a kind of multichannel radiofrequency signal control system work, comprises the following steps:
Execution step S1, described digital signal processing unit 130 completes place states the first Digital Signal Processing of multi-channel rf signal transmission channel data, obtain the first baseband signal, the digital signal processing unit 130 of penetrating by riches all the way arbitrarily in passage carries out being emitted to multichannel emission of radio frequency signals unit 110 after one-level quadrature up-conversion.
Execution step S2, described multichannel emission of radio frequency signals unit provides multichannel radio frequency transmissions, and any one transmission channel is exported the first radiofrequency signal to external equipment; Described the first base band signal transmission to D/A conversion unit 111 carries out after signal imitation and/or secondary quadrature up-conversion, by described reconstruction filter 112 elimination image signals, described the first variable gain amplifier 113 transfers to described external equipment after adjusting the amplitude, phase attributes of output signal, as power amplifier, directional coupler and radio-frequency coil etc.Particularly, the first baseband signal goes out output the first radiofrequency signal through riches all the way arbitrarily to power amplifier after penetrating the reconstruction filter 112 of passage and the first variable gain amplifier 113 successively, is emitted to radio-frequency coil.
Above-mentioned steps S1 and step S2 are radiofrequency signal is emitted to external equipment after data processing unit 130 first Digital Signal Processing process through any emission of radio frequency signals unit, road 110.
Figure 4 shows that the operation principle schematic diagram of single channel emission of radio frequency signals passage in the present invention; Refer to Fig. 4, described the first digital signal at the scene programmable gate array 131 or field programmable gate array 131 and D/A conversion unit 111 inside after the digital signal base-band of adjusting the amplitude that transmits, phase attributes, radio frequency transmissions is carried out to interpolation, filtering and quadrature up-conversion is processed, carry out signal imitation by described D/A conversion unit 111, the multiple of described interpolation is by the frequency (F of base band data
data) and the mid frequency (F of D/A conversion unit 111
dac) determine, the inside center frequency of described D/A conversion unit 121 can arrange by programmable field programmable gate array 131.Described D/A conversion unit 111 comprises interpolation filter 21 and digital oscillator 22.The first baseband signal enter D/A conversion unit 111 simulated before, the first baseband signal is carried out the first Digital Signal Processing through multilevel interpolation wave filter 21 and digital oscillator 22 to baseband signal, makes the frequency of baseband signal reach the frequency (F of D/A conversion unit 111
dac).Described multilevel interpolation wave filter can be for reducing the interface data rate between field programmable gate array and D/A conversion unit 111 in addition.Particularly, for example, for super high field magnetic resonance equipment, 7T, the magnetic resonance equipment of 300MHz, in the time of outputting analog signal, according to sampling thheorem, the inversion frequency of D/A conversion unit 111 is more than 1GHz, and base band data rate is 10MHz left and right, and the interpolation multiple calculating is 100 times of left and right comparatively.Described the first digital signal is to receive by optical fiber the first baseband I/Q data that transfer to described digital processing element.
The D/A conversion unit 111 that described the first baseband signal is penetrated by riches all the way arbitrarily in passage carries out one-level quadrature up-conversion or carries out secondary quadrature up-conversion by described digital signal processing unit 131 and described D/A conversion unit 111, exports the subsequent parts of described the first radiofrequency signal to any one emission of radio frequency signals passage.
Figure 5 shows that the operation principle schematic diagram of the first baseband signal one-level conversion method in the present invention.Refer to Fig. 5:
Programmable gate array internal at the scene, the feature of utilizing its programmability by the first base band data by multilevel interpolation filtering and quadrature up-conversion by required radio frequency mid frequency, described radio frequency mid frequency is Larmor frequency corresponding to magnetic field intensity, and the mid frequency of digital to analog converter inside is now set by field programmable gate array.
The radio frequency central frequency range of described output the first radiofrequency signal is subject to the restriction of D/A conversion unit 111 frequencies, and according to sampling thheorem, when the frequency of D/A conversion unit 111 is 1GHz, exportable radio frequency mid frequency can reach 400MHz.The first baseband signal is before entering analog-digital converter 111, make data transfer rate reach the frequency of digital to analog converter through interpolation filter, described D/A conversion unit 111 inside comprise interpolation filter 21 and voltage controlled oscillator 22, adopt secondary quadrature up-conversion mode, in programmable gate array 131, realize first order mixting circuit at the scene, in D/A conversion unit 111, realize second level mixting circuit, to reduce the processing load of field programmable gate array 131.
Figure 6 shows that the operation principle schematic diagram of the first baseband signal secondary conversion method in the present invention.Refer to Fig. 6: described the first baseband signal at the scene programmable gate array 131 is inner through amplitude, phase attributes adjustment, filtering interpolation and quadrature up-conversion, to first frequency, obtain first order output radio frequency transmissions and export in described D/A conversion unit 111; Multilevel interpolation wave filter 21 in described D/A conversion unit 111 and digital oscillator 22 to Larmor frequency corresponding to magnetic field intensity, obtain output radio frequency transmissions in the second level by described first order output radio frequency transmissions quadrature up-conversion by multilevel interpolation, filtering; Described first frequency is the difference of the Larmor frequency that the mid frequency of second level output radio frequency transmissions is corresponding with magnetic field intensity, described difference is less than 1MHz, described second level output radio frequency transmissions is described the first radiofrequency signal, and described the first radiofrequency signal transfers to subsequent parts after signal imitation.Particularly, be 1.5T for magnetic field intensity, mid frequency is the magnetic resonance system of 64MHz, when the center output frequency of institute's book radiofrequency signal is 64.2MHz, first by first order mixing by the first mixes baseband signals the first output radio frequency transmissions to 0.2MHz, then reach the second level output radio frequency transmissions of 64MHz by second level mixing.Described first order mixting circuit is realized in programmable gate array 131 at the scene, and second level mixting circuit is realized in D/A conversion unit.
Execution step S3, described power signal receiving element receives the first power signal of described the first radio frequency signal feedback, carries out Direct Sampling, obtains the second power signal;
Execution step S4, described digital signal processing unit receives the second power signal and carries out the second Digital Signal Processing, obtains the 3rd power signal transmissions to external equipment.
Above-mentioned steps S3 and step S4 are power signal receiving element 120 the first power signal of radio frequency signal feedback that receives, samples, and after digital processing element 130 carries out the second Digital Signal Processing, obtain the 3rd power signal, transfer to the process of external equipment
The data flow schematic diagram that Figure 7 shows that single channel power signal receive path in the present invention, refers to Fig. 7:
Described the first power signal enters analog-digital converter 123 through the second variable gain amplifier 121 of any one receive path of power signal receiving element 120 and frequency overlapped-resistable filter 122 successively and samples.Described the first power signal is the power signal that the first radiofrequency signal of any one transmission channel output is back to any one power signal receive path after radio-frequency coil or directional coupler.Choosing of high-speed AD converter 123 sampling rate Fs will be according to the highest sampling rate of the analog-digital converter that can obtain, and sampling rate can have influence on the design of front end frequency overlapped-resistable filter, and in principle, sampling rate is higher, and design of filter index request reduces.Front end frequency overlapped-resistable filter 122 can be chosen band according to the relation of sampling rate and radiofrequency signal highest frequency and lead to or low pass filter.If employing bandpass sampling, frequency overlapped-resistable filter is band filter.Particularly, for middle and high magnetic resonance system, for example, for 1.5T, the magnetic resonance system of radio frequency mid frequency 64M left and right, adopts radio frequency Direct Sampling, and now wave filter is chosen as low pass filter; For the magnetic resonance system of High-Field or super high field, for example field intensity is 3.0T, radio frequency mid frequency 128M and more than, adopt band filter.
Obtain from high-speed AD converter the second power signal that sample rate is Fs, described the second power signal carries out the second Digital Signal Processing through digital signal processing unit.Described the second Digital Signal Processing comprises amplitude, the phase attributes of adjusting radio frequency transmissions, radio frequency transmissions is carried out to the Digital Signal Processing such as digital quadrature down coversion and digital filtering.Described the second power signal obtains the second baseband signal after the quadrature frequency conversion of digital oscillator 31 and the filtering of digital filter 32, and amplitude, phase attributes that described the second baseband signal is adjusted radio frequency transmissions by digital signal processing unit obtain the 3rd power signal.Described digital filter 32 is decimation filter, and described the second power signal, after quadrature frequency conversion, by one or more levels decimation filter, obtains described the second baseband signal.Described the second baseband signal is sent into energy meter 33 and calculate, obtain described the 3rd power, for the calculating monitoring of transmit power correction or radio-frequency field energy (SAR, Specific Absorption Rate).Described the 3rd power and base band data be by interface, and as optical fiber or USB interface are transferred to application layer, exporting external equipment to carries out data communication on the one hand, as provide PC to carry out other processing, for monitoring and the capability correction of SAR, transfer on the other hand transmitter unit, for capability correction.Described the 3rd power signal is exported by optical fiber interface after coding at described digital signal processing unit, and described the 3rd power signal is for the calculating monitoring of transmit power correction or radio-frequency field energy.
Although the present invention with preferred embodiment openly as above; but it is not for limiting the present invention; any those skilled in the art without departing from the spirit and scope of the present invention; can utilize method and the technology contents of above-mentioned announcement to make possible variation and amendment to technical solution of the present invention; therefore; every content that does not depart from technical solution of the present invention; any simple modification, equivalent variations and the modification above embodiment done according to technical spirit of the present invention, all belong to the protection domain of technical solution of the present invention.
Claims (25)
1. a multichannel radiofrequency signal control system, is characterized in that, comprising:
Multichannel emission of radio frequency signals unit, for providing multichannel the first radiofrequency signal;
Power signal receiving element, for receiving first power signal of the first radio frequency signal feedback of any one passage of described multichannel emission of radio frequency signals unit;
Digital signal processing unit, is connected with described power signal receiving element with described multichannel emission of radio frequency signals unit, for the treatment of the armed radiofrequency signal of multichannel and transmit the first baseband signal to described multichannel emission of radio frequency signals unit; Receive, process after the second power signal of described power signal receiving element reception, transmission the 3rd power signal is to external equipment.
2. multichannel radiofrequency signal control system as claimed in claim 1, it is characterized in that, described multichannel emission of radio frequency signals unit comprises multichannel emission of radio frequency signals passage, every road emission of radio frequency signals passage comprises D/A conversion unit, re-establishing filter unit and the first variable gain amplifier, and every road radiofrequency signal is emitted to described external equipment by described D/A conversion unit, described re-establishing filter unit and described the first variable gain amplifier successively; Described external equipment comprises power amplifier, directional coupler and radio-frequency coil.
3. multichannel radiofrequency signal control system as claimed in claim 1, it is characterized in that, described power signal receiving element comprises multichannel power signal receive path, every road power signal receive path comprises the second variable gain amplifier, frequency overlapped-resistable filter and analog-digital converter, and every road power signal transfers to described digital signal processing unit through described the second variable gain amplifier, described frequency overlapped-resistable filter and described analog-digital converter successively.
4. multichannel radiofrequency signal control system as claimed in claim 1, is characterized in that, described digital signal processing unit comprises Master control chip; Described Master control chip is field programmable gate array.
5. multichannel radiofrequency signal control system as claimed in claim 4, is characterized in that, described field programmable gate array also comprises optical fiber interface, for carrying out data communication with the external world.
6. multichannel radiofrequency signal control system as claimed in claim 2, it is characterized in that, described D/A conversion unit comprises multilevel interpolation wave filter and digital oscillator, before entering described D/A conversion unit, makes the frequency of baseband signal reach the frequency of D/A conversion unit for baseband signal.
7. multichannel radiofrequency signal control system as claimed in claim 1, it is characterized in that, described the 3rd power signal exports described external equipment to and/or feeds back to described multichannel emission of radio frequency signals unit, monitors or carries out information interaction processing by described external equipment for the capability correction transmitting, the calculating of radio-frequency (RF) energy field energy.
8. multichannel radiofrequency signal control system as claimed in claim 1, it is characterized in that, described system also comprises Clock Managing Unit, for extremely described multichannel emission of radio frequency signals unit, described power signal receiving element and described digital signal processing unit of output multi-channel high accuracy real-time clock.
9. multichannel radiofrequency signal control system as claimed in claim 9, described Clock Managing Unit comprises reference clock agitator, voltage controlled oscillator and Clock management chip.
10. multichannel radiofrequency signal control system as claimed in claim 9, is characterized in that, the internal system crystal oscillator that is input as of described reference clock agitator produces or external clock input.
11. multichannel radiofrequency signal control system as claimed in claim 9, it is characterized in that, the clock source number of described time management unit equals the number sum of number, power signal receive path and the field programmable gate array passage of described emission of radio frequency signals passage.
Realize the method for multichannel radiofrequency signal control system as claimed in claim 1 for 12. 1 kinds, it is characterized in that, comprise the following steps:
A) described digital signal processing unit completes the first Digital Signal Processing of described multi-channel rf signal transmission channel data, transmits the first baseband signal of any one transmission channel to described multichannel emission of radio frequency signals unit;
B) described multichannel emission of radio frequency signals unit provides multichannel radio frequency transmissions, and any one transmission channel is exported the first emission of radio frequency signals to external equipment;
C) described power signal receiving element receives the first power signal of described the first radio frequency signal feedback, carries out Direct Sampling, obtains the second power signal;
D) described digital signal processing unit receives described the second power signal and carries out the second Digital Signal Processing, obtains the 3rd power signal transmissions to described external equipment.
13. methods that realize multichannel radiofrequency signal control system as claimed in claim 12, it is characterized in that, described the first Digital Signal Processing comprises to be adjusted amplitude, the phase attributes of radio frequency transmissions and radio frequency transmissions is carried out to filtering interpolation, digital quadrature up-conversion.
14. methods that realize multichannel radiofrequency signal control system as claimed in claim 12, it is characterized in that, described the first baseband signal is carried out one-level quadrature up-conversion or is carried out secondary quadrature up-conversion by described digital signal processing unit and described D/A conversion unit by the described arbitrarily D/A conversion unit that riches all the way penetrates in passage.
15. methods that realize multichannel radiofrequency signal control system as claimed in claim 14, is characterized in that, described secondary quadrature up-conversion comprises the steps:
In described digital signal processing unit, described the first baseband signal is converted to first frequency, obtains first order output radio frequency transmissions and exports in described D/A conversion unit;
In described D/A conversion unit, described first order output radio frequency transmissions is converted to Larmor frequency corresponding to magnetic field intensity, obtains second level output radio frequency transmissions.
16. methods that realize multichannel radiofrequency signal control system as claimed in claim 15, it is characterized in that, described first frequency is the difference of the Larmor frequency that the mid frequency of second level output radio frequency transmissions is corresponding with magnetic field intensity, described difference is less than 1MHz, and described second level output radio frequency transmissions is described the first radiofrequency signal.
17. methods that realize multichannel radiofrequency signal control system as claimed in claim 16, it is characterized in that, described the first baseband signal enters that riches all the way arbitrarily penetrate the D/A conversion unit in passage before, the frequency of the first baseband signal reaches through multilevel interpolation the frequency that riches all the way arbitrarily penetrates the D/A conversion unit in passage.
18. methods that realize multichannel radiofrequency signal control system as claimed in claim 12, is characterized in that, described the first radiofrequency signal goes out to export to power amplifier through riches all the way arbitrarily after penetrating the reconstruction filter of passage and the first variable gain amplifier successively.
19. a kind of methods that realize multichannel radiofrequency signal control system as claimed in claim 12, it is characterized in that, described the first power signal is the power signal that the first radiofrequency signal of any one transmission channel output is back to any one power signal receive path after radio-frequency coil or directional coupler.
20. methods that realize multichannel radiofrequency signal control system as claimed in claim 12, is characterized in that, described the first power signal enters analog-digital converter through the second variable gain amplifier and the frequency overlapped-resistable filter of any one receive path successively.
21. methods that realize multichannel radiofrequency signal control system as claimed in claim 12, is characterized in that, described Direct Sampling method is radio frequency sampling or bandpass sampling, if adopt radio frequency sampling, frequency overlapped-resistable filter is low pass filter; If employing bandpass sampling, frequency overlapped-resistable filter is band filter.
22. methods that realize multichannel radiofrequency signal control system as claimed in claim 12, it is characterized in that, described the second power signal carries out the second Digital Signal Processing through digital signal processing unit, described the second Digital Signal Processing comprise adjust radio frequency transmissions amplitude, phase attributes, radio frequency transmissions is carried out to digital quadrature down coversion and digital filtering.
23. methods that realize multichannel radiofrequency signal control system as claimed in claim 22, it is characterized in that, described the second power signal obtains the second baseband signal after quadrature frequency conversion and digital filtering, and amplitude, phase attributes that described the second baseband signal is adjusted radio frequency transmissions by digital signal processing unit obtain the 3rd power signal.
24. methods that realize multichannel radiofrequency signal control system as claimed in claim 23, it is characterized in that, described digital filter is decimation filter, and described the second power signal is after quadrature frequency conversion, by one or more levels decimation filter, obtain described the second baseband signal.
25. methods that realize multichannel radio frequency transmissions control system as claimed in claim 12, it is characterized in that, described the 3rd power signal is exported by optical fiber interface after coding at described digital signal processing unit, and described the 3rd power signal is for the calculating monitoring of transmit power correction or radio-frequency field energy.
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