CN111756376B - Signal sampling device, system and method - Google Patents
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- CN111756376B CN111756376B CN202010589119.2A CN202010589119A CN111756376B CN 111756376 B CN111756376 B CN 111756376B CN 202010589119 A CN202010589119 A CN 202010589119A CN 111756376 B CN111756376 B CN 111756376B
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Abstract
The application discloses a signal sampling device, a system and a method, wherein the device comprises the following components: a comparison unit configured to compare the received reference signal with an analog signal to be sampled in amplitude and output a corresponding level signal according to a comparison result; a timing unit configured to record and output a time interval from when the amplitude of the received trigger signal reaches a trigger threshold to when the level signal received from the comparing unit generates a corresponding edge transition; a counting unit configured to record the number of times the trigger signal received by the timing unit reaches the trigger threshold; and a processing unit configured to obtain a sampling point by processing the amplitude characteristic of the reference signal, the time interval recorded by the timing unit, and the number of times recorded by the counting unit, wherein the reference signal and the trigger signal are both periodic signals and a phase difference between the reference signal and the trigger signal is kept constant. By utilizing the technical scheme provided by the application, the system cost and the power consumption can be reduced.
Description
Technical Field
The present application relates to the field of signal processing technologies, and in particular, to a signal sampling method, system, and method.
Background
In the conventional art, in order to realize digital sampling of a pulse signal, an Analog-to-Digital Converter (ADC) is generally used to scale the pulse signal in an Analog form into a digital code value. However, the digital sampling of the pulse signal is realized by using the ADC, so that the engineering implementation is difficult and the cost is extremely high.
In the field of radiation detection and imaging, in order to reduce the sampling cost, a Multi-voltage threshold (Multi-Voltage Threshold, MVT) sampling circuit is currently generally used to sample the pulse signal, as shown in fig. 1. For each detection channel, the sampling circuit generally compares the magnitudes between the voltages of the pulse signals and a plurality of voltage thresholds set in advance using a plurality of voltage comparators, and records the times at which the voltages of the pulse signals reach the voltage thresholds using a plurality of TDCs, thereby acquiring sampling points made up of time-voltage threshold pairs.
In the process of implementing the present application, the inventor finds that at least the following problems exist in the prior art:
when sampling an analog signal such as a pulse signal, in order to ensure the recovery precision of a subsequent pulse signal, a plurality of voltage comparators and a plurality of time-to-digital converters are required to obtain enough sampling points, which makes the system have higher cost and higher power consumption.
Disclosure of Invention
The embodiment of the application aims to provide a signal sampling device, a system and a method, so as to reduce the cost and the power consumption of the system.
In order to solve the above technical problems, an embodiment of the present application provides a signal sampling device, which may include:
a comparison unit configured to compare the received reference signal with an analog signal to be sampled in amplitude and output a corresponding level signal according to a comparison result;
a timing unit configured to record and output a time interval from when an amplitude of a received trigger signal reaches a trigger threshold to when the level signal received from the comparing unit generates a corresponding edge transition, wherein the trigger signal is used to trigger the timing unit to perform timing;
a counting unit configured to record the number of times the trigger signal received by the timing unit reaches the trigger threshold;
a processing unit configured to obtain sampling points of the analog signal by processing amplitude characteristics of the reference signal, the time interval recorded by the timing unit, and the number of times recorded by the counting unit,
wherein the reference signal and the trigger signal are periodic signals and a phase difference between the reference signal and the trigger signal remains constant.
Optionally, the comparing unit comprises a voltage comparator or a current comparator.
Optionally, the comparing unit is implemented by an LVDS interface, an SSTL interface, an HSTL interface, an RSDS interface or a TMDS interface in the FPGA chip or a specific chip.
Optionally, the timing unit comprises a time-to-digital converter or a time-to-voltage converter.
Optionally, the timing unit is implemented by an FPGA chip or an ASIC chip.
Optionally, the timing unit is specifically configured to:
starting timing when the amplitude of the trigger signal reaches the trigger threshold;
stopping timing when the level signal generates a specified edge transition, and outputting the recorded time interval to the processing unit;
the timing is maintained when the level signal produces a non-designated edge transition and the recorded time interval is output to the processing unit.
Optionally, the processing unit is configured to calculate a time corresponding to each sampling point according to the time interval recorded by the timing unit and the number of times recorded by the counting unit, and calculate an amplitude corresponding to each sampling point by using the calculated time and combining the amplitude characteristics of the reference signal.
Optionally, the apparatus further comprises:
a signal generation unit configured to generate the reference signal and the trigger signal.
Optionally, the signal generating unit includes:
a first subunit configured to generate the reference signal;
a second subunit configured to process the reference signal to generate the trigger signal.
Optionally, the second subunit comprises a zero-crossing comparator, an inverter, or a delay.
Optionally, the apparatus further comprises:
and a reconstruction unit configured to reconstruct the sampling points obtained by the processing unit to obtain a restored waveform of the analog signal.
Optionally, the reconstruction unit is specifically configured to:
directly connecting all the obtained sampling points;
performing interpolation processing on the sampling points, and connecting all the sampling points after the interpolation processing; or alternatively
Performing interpolation processing on the sampling points, performing fitting processing on all sampling points after the interpolation processing,
wherein the interpolation processing includes linear interpolation processing and/or spline interpolation processing.
The embodiment of the application also provides a photoelectric detection system which can comprise the signal sampling device and a detector configured to send pulse signals to the signal sampling device.
Optionally, the detector comprises a scintillation crystal and a photoelectric converter coupled to each other.
The embodiment of the application also provides a signal sampling method, which can comprise the following steps:
comparing the received reference signal with an analog signal to be sampled in amplitude by a comparison unit and outputting a corresponding level signal according to a comparison result;
recording and outputting a time interval from when the amplitude of the received trigger signal reaches a trigger threshold to when the level signal received from the comparison unit generates a corresponding edge jump by a timing unit, wherein the trigger signal is used for triggering the timing unit to perform timing;
recording the number of times the trigger signal received by the timing unit reaches the trigger threshold value by a counting unit;
obtaining, by a processing unit, sampling points of the analog signal by processing the amplitude characteristic of the reference signal, the time interval recorded by the timing unit and the number of times recorded by the counting unit,
wherein the reference signal and the trigger signal are both periodic signals and a phase difference between the reference signal and the trigger signal remains constant.
Optionally, the trigger signal is obtained by processing the reference signal, and a phase of the trigger signal is the same as a phase of the reference signal.
Optionally, the periodic signal includes a sine wave signal, a cosine wave signal, a triangle wave signal, a step wave signal, a sawtooth wave signal, or a square wave signal.
Optionally, the trigger threshold includes 0 or an amplitude when the trigger signal generates a rising edge transition or a falling edge transition.
Optionally, the step of recording and outputting the time interval by the timing unit comprises:
starting timing when the amplitude of the trigger signal reaches the trigger threshold;
stopping timing when the level signal generates a specified edge transition, and outputting the recorded time interval to the processing unit;
the timing is maintained when the level signal produces a non-designated edge transition and the recorded time interval is output to the processing unit.
Optionally, the step of obtaining, by the processing unit, the sampling points comprises:
when the designated edge transitions are each edge transition, the processing unit calculates the time and amplitude corresponding to each sampling point by using the following formula:
y i ＝f(t i )
Wherein t is i And y i Respectively representing the time and the amplitude corresponding to the ith sampling point; t is the period of the trigger signal; Δt (delta t) i Representing an i-th time interval recorded by the timing unit; f (t) i ) Representing an amplitude characteristic of the reference signal; i is a positive integer between 1 and n, and n is the number of times recorded by the counting unit.
Optionally, the step of obtaining, by the processing unit, the sampling points comprises:
when the designated edge transitions are odd edge transitions, the processing unit calculates a time corresponding to each sampling point by using the following formula, and calculates an amplitude corresponding to each sampling point by using the calculated time and combining the amplitude characteristics of the reference signal:
t 1 ＝△t 1
wherein t is (·) Representing the time corresponding to the sampling point; Δt (delta t) (·) Representing the time interval recorded by the timing unit; t is the period of the trigger signal; 2i and 2i+1 are positive integers between 2 and n, and n is the number of times recorded by the counting unit.
Optionally, the step of obtaining, by the processing unit, the sampling points comprises:
when the designated edge transitions are even-numbered edge transitions, the processing unit calculates a time corresponding to each sampling point by using the following formula, and calculates an amplitude corresponding to each sampling point by using the calculated time and combining the amplitude characteristics of the reference signal:
Wherein t is (·) Representing the time corresponding to the sampling point; Δt (delta t) (·) Representing the time interval recorded by the timing unit; t is the period of the trigger signal; 2i-1 and 2i are positive integers between 1 and n, n is the number of times recorded by the counting unit.
Optionally, the method further comprises:
and the reconstruction unit performs reconstruction processing on the sampling points obtained by the processing unit to obtain a reduction waveform of the analog signal.
Optionally, the step of reconstructing the sampling points obtained by the processing unit by a reconstruction unit comprises:
directly connecting all the obtained sampling points;
performing interpolation processing on the sampling points, and connecting all the sampling points after the interpolation processing; or alternatively
Performing interpolation processing on the sampling points, performing fitting processing on all sampling points after the interpolation processing,
wherein the interpolation processing includes linear interpolation processing and/or spline interpolation processing.
As can be seen from the technical solutions provided in the embodiments of the present application, the signal sampling device provided by the present application compares the amplitude of the reference signal and the analog signal to be sampled by using the comparing unit, the timing unit records and outputs the time interval from when the amplitude of the received trigger signal reaches the trigger threshold to when the level signal received from the comparing unit generates the corresponding edge jump, the counting unit records the number of times when the trigger signal received by the timing unit reaches the trigger threshold, and the processing unit obtains the sampling point of the analog signal by processing the amplitude characteristic of the reference signal, the time interval recorded by the timing unit, and the number of times recorded by the counting unit, without a plurality of voltage comparators and time-to-digital converters, which can reduce the system cost, the power consumption, and the process complexity.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments described in the present application, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic diagram of a prior art MVT sampling circuit;
FIG. 2 is a schematic diagram of a signal sampling device according to an embodiment of the present application;
FIG. 3 is a schematic diagram of a timing scheme of the timing unit;
FIG. 4 is a schematic diagram of another timing scheme of the timing unit;
FIG. 5 is a schematic diagram of another timing scheme of the timing unit;
FIG. 6 is a schematic diagram of yet another timing scheme of the timing unit;
FIG. 7 is a schematic diagram of a sampling point obtained by sampling a pulse signal by using a signal sampling device according to an embodiment of the present application;
fig. 8 is a schematic structural diagram of a signal sampling device according to another embodiment of the present application;
fig. 9 is a schematic structural diagram of a signal sampling device according to another embodiment of the present application;
FIG. 10 is a schematic diagram of a photoelectric detection system according to an embodiment of the present application;
FIG. 11 is a flow chart of a signal sampling method according to an embodiment of the present application;
fig. 12 is a flowchart of a signal sampling method according to another embodiment of the present application.
Detailed Description
The technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present application, and it is apparent that the described embodiments are only for explaining a part of the embodiments of the present application, not all the embodiments, and are not intended to limit the scope of the present application or the claims. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, shall fall within the scope of the application.
It will be understood that when an element is referred to as being "disposed on" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected/coupled" to another element, it can be directly connected/coupled to the other element or intervening elements may also be present. The term "connected/coupled" as used herein may include electrically and/or mechanically physical connections/couplings. The term "comprising" as used herein refers to the presence of a feature, step or element, but does not exclude the presence or addition of one or more other features, steps or elements. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.
In addition, in the description of the present application, the terms "first," "second," and the like are used merely for descriptive purposes and to distinguish between similar objects, and there is no order of precedence between the two, nor should it be construed as indicating or implying relative importance. Furthermore, in the description of the present application, unless otherwise indicated, the meaning of "a plurality" is two or more.
In an embodiment of the application, the reference signal may be any signal that can be expressed by a time function, i.e. a signal that can determine the amplitude of the signal at any instant in time. That is, the amplitude of the reference signal may vary with time according to a predetermined rule, and the amplitude characteristic thereof may be expressed as y=f (t). Wherein y is the amplitude; t is time; f (t) is a time function, which represents a preset law. The expression is not limited to a certain functional relationship or a lookup table, and only needs to have a certain corresponding relationship. The reference signal may be a periodic signal, for example, a sine wave signal, a cosine wave signal, a triangle wave signal, a step wave signal, a sawtooth wave signal, a square wave signal, or the like, or may be an aperiodic signal including a direct current signal or an arbitrary signal having a fixed amplitude. When the reference signal is a sine wave signal, the amplitude thereof may be expressed as y=a×sin (2×pi×t+Ω)/T) +b, where a is a peak value of the reference signal; t is the period of the reference signal; omega is the phase of the reference signal; b is the baseline value of the reference signal, which can Is any number, including 0. When the reference signal is a cosine wave signal, the amplitude thereof may be expressed as y=a×cos (2×pi×t+Ω)/T) +b. When the reference signal is a triangular wave signal, its amplitude can be expressed asWherein N is the repetition number, T is the period of the reference signal, a 1 B is the rising edge slope of the reference signal 1 C is the slope of the falling edge of the reference signal 1 The baseline value for the reference signal, which may be any number, including 0. The amplitude expression when the reference signal is a step wave, a sawtooth wave signal or a square wave signal can be referred to the expression modes of the signals in the prior art, and will not be described herein.
The amplitude of the trigger signal may also vary with time according to a preset law, which may be a signal obtained by processing a reference signal, for example, the trigger signal may be obtained by processing the reference signal with a zero-crossing comparator. The trigger signal may be kept in a fixed phase relationship with the reference signal, i.e. the phase difference between the two is kept constant, e.g. the phase difference between the two is 0, i.e. the phases are the same.
The analog signal to be sampled may be a pulse signal, for example, a scintillation pulse signal, or may be other signals. The amplitude may refer to an electrical amplitude such as voltage or current, and may also refer to an amplitude of other properties.
The following describes in detail the signal sampling device, system and method provided by the embodiment of the present application with reference to the accompanying drawings.
As shown in fig. 2, an embodiment of the present application provides a signal sampling apparatus, which includes a comparing unit 110, a timing unit 120, a counting unit 130, and a processing unit 140. Wherein the comparing unit 110 may be configured to compare the received reference signal with an analog signal to be sampled in amplitude and output a corresponding level signal according to the comparison result; the timing unit 120 may be configured to record and output a time interval between when the amplitude of the received trigger signal reaches the trigger threshold and when the level signal received from the comparing unit 110 generates a corresponding edge transition, wherein the trigger signal may be used to trigger the timing unit 120 to perform timing; the counting unit 130 may be configured to record the number of times the trigger signal received by the timing unit 110 reaches the trigger threshold; the processing unit 140 may be configured to obtain sampling points of the analog signal by processing the amplitude characteristic of the reference signal, the time interval recorded by the timing unit 120, and the number of times recorded by the counting unit 130. Wherein, the reference signal and the trigger signal are both periodic signals, and the phase difference between the reference signal and the trigger signal is kept constant.
In at least one embodiment, the comparing unit 110 may be a voltage comparator or a current comparator, and may be implemented through a low voltage differential signal (Low Voltage Differential Signal, LVDS) interface, a stub series termination logic (Stub Series Terminated Logic, SSTL) interface, a high speed transceiving logic (High Speed Transceiver Logic, HSTL) interface, a low swing differential signal (Reduced Swing Differential Signal, RSDS) interface, or a transition minimized differential signal (Time Minimized Differential Signal, TMDS) interface in a Field Programmable Gate Array (FPGA) chip, or may be implemented through a specific chip (e.g., a common chip such as model number ADCMP572BCPZ-R2 or Max9602EUG, but not limited thereto). In addition, the comparison unit 110 may include two inputs (e.g., a forward input and a reverse input) that may be used to receive analog signals from an external device (e.g., a radiation detector such as a PET detector) and reference signals from a signal generation unit (to be described later), respectively.
For the case where the positive input terminal of the comparison unit 110 receives the reference signal and the negative input terminal thereof receives the analog signal, the comparison unit 110 may output a high level signal when the amplitude of the reference signal is greater than or equal to the amplitude of the analog signal, which may be represented by "1", and may output a low level signal when the amplitude of the reference signal is less than the amplitude of the analog signal, which may be represented by "0". For the case where the positive input of the comparison unit 110 receives an analog signal and the negative input thereof receives a reference signal, the comparison unit may output a high level signal when the amplitude of the reference signal is smaller than that of the analog signal, and may output a low level signal when the amplitude of the reference signal is greater than or equal to that of the analog signal.
In at least one embodiment, the timing unit 120 may be implemented by an FPGA chip, for example, logic resources such as delay line units in the FPGA chip, or the timing unit 120 may also be implemented by a dedicated chip (for example, ASIC chip), which may be any unit, module, circuit, or device capable of recording a period of Time, for example, a Time-to-Digital Converter (TDC) or a Time-to-Voltage Converter (TVC). The timing unit 120 may be configured to record a time interval from when the received trigger signal reaches the trigger threshold to when the received level signal generates a corresponding edge transition. Specifically, when the amplitude of the received trigger signal reaches the trigger threshold, the timing unit 120 may start timing after reset, and when the received level signal generates a designated edge transition (e.g., a rising edge transition or a falling edge transition), the timing unit 120 may stop timing and output the recorded time interval to the processing unit 140, and when the received level signal generates a non-designated edge transition, the timing unit 120 keeps timing and outputs the recorded time interval to the processing unit 140 until acquisition of the sampling point is completed. The designated edge transitions may include each edge transition, rising edge transitions, falling edge transitions, etc. For example, when each edge transition is generated by the received level signal, the timing unit 120 stops or keeps timing and outputs the recorded time interval to the processing unit 140. For another example, the timing unit 120 stops timing only when the received level signal generates a rising edge transition, and the timing unit 120 may keep timing when the received level signal generates a falling edge transition. For another example, the timing unit 120 stops timing only when the received level signal generates a falling edge transition, and the timing unit 120 may keep timing when the received level signal generates a rising edge transition.
The trigger threshold may be set according to characteristics of the analog signal to be sampled or historical empirical data, for example, the trigger threshold is 0, which may indicate that the timing unit 120 starts or stops timing as soon as the trigger signal is received, the trigger threshold may also be an amplitude when the trigger signal generates a rising edge or a falling edge transition, which indicates that the timing unit 120 starts or stops timing when the trigger signal generates an edge transition, and may also be other amplitudes.
The time interval may be a difference between a time when the amplitude of the trigger signal reaches the trigger threshold and a time when the level signal generates a corresponding rising edge transition or falling edge transition. For example, the time interval may include a difference between a time when the trigger signal generates a rising edge transition or a falling edge transition and a time when the level signal generates a rising edge transition, and/or a difference between a time when the trigger signal generates a rising edge transition or a falling edge transition and a time when the level signal generates a falling edge transition. For the case of "and", it may mean that the level signal has a rising edge transition and a falling edge transition after the amplitude of the trigger signal rises/falls to the trigger threshold and in the time between falling/rising to the trigger threshold.
In at least one embodiment, the counting unit 130 may be any counter capable of recording data, such as a multi-bit counter, and may also operate in synchronization with the timing unit 120. That is, when the timer unit 120 starts the timing, the counting unit 130 starts counting, and when the timer unit 120 stops the timing, it also stops counting, and the recorded data may be transmitted to the processing unit 140.
In at least one embodiment, the processing unit 140 may include a decoder, and the processing unit 140 may be configured to determine the time to be acquired according to the time interval recorded by the timing unit 120 and the number of times recorded by the counting unit 130, and then determine the amplitude to be acquired according to the calculated time in combination with the amplitude characteristic (i.e., y=f (t)) of the reference signal, so as to obtain the sampling point of the analog signal, which is characterized by the time and the amplitude.
For the case where the designated edge transitions are each edge transitions, that is, for the case where the timing unit 120 stops timing when each edge transition is generated by the level signal, as shown in fig. 3, the processing unit 140 may calculate the time and amplitude corresponding to each sampling point according to the following formula (1):
Wherein t is i And y i Respectively representing the time and the amplitude of the ith sampling point; t is the period of the trigger signal; Δt (delta t) i Representing the i-th time interval recorded by the timing unit 120; f (t) i ) Representing the amplitude characteristics of the reference signal; i is a positive integer between 1 and n, n being the number of times recorded by the counting unit 130.
For example, when the amplitude of the analog signal is a voltage, the reference signal is a sinusoidal signal, and the trigger threshold is 0, the voltage of the i-th sampling point calculated by the processing unit 140 may be expressed as follows:
V i ＝A*Sin(2*π*(t i +Ω)/T)+B
when b=0, when the trigger signal triggers the timing unit 120 to start timing, the voltage value of the reference signal is 0, and at this time, the above equation can be simplified as: v (V) i ＝A*Sin(2*π*△t i /T)。
For the case where the timing unit 120 stops timing when the level signal generates an odd number of edge transitions (e.g., a first edge transition, a third edge transition, or a fifth edge transition, etc.) and keeps timing when the level signal generates an even number of edge transitions (e.g., a second edge transition, a fourth edge transition, or a sixth edge transition, etc.), that is, designates an edge transition as an odd number of edge transitions, as shown in fig. 4, the processing unit 140 may calculate a time corresponding to each sampling point according to the following formula (2), and calculate an amplitude corresponding to each sampling point using the calculated time in combination with an amplitude characteristic (y=f (t)) of the reference signal:
Wherein t is (·) Representing the time corresponding to the sampling point; Δt (delta t) (·) Representing the time interval recorded by the timing unit 120; t is the period of the trigger signal; both 2i and 2i+1 are positive integers between 2 and n, n being the number of times recorded by the counting unit 130.
For the case where the timing unit 120 stops timing when the level signal generates even-numbered edge transitions and keeps timing when the level signal generates odd-numbered edge transitions (i.e., specifies edge transitions to even-numbered edge transitions), as shown in fig. 5, the processing unit 140 may calculate a time corresponding to each sampling point according to the following formula (3), and calculate an amplitude corresponding to each sampling point using the calculated time in combination with the amplitude characteristic (y=f (t)) of the reference signal:
wherein t is (·) Representing the time corresponding to the sampling point; Δt (delta t) (·) Representing the time interval recorded by the timing unit 120; t is the period of the trigger signal; 2i-1 and 2i are positive integers between 1 and n, n being the number of times recorded by the counting unit 130.
It should be noted that the odd edge transitions may be rising edge transitions or falling edge transitions, and correspondingly, the even edge transitions may be falling edge transitions or rising edge transitions.
For the case where the timing unit 120 keeps timing only when each edge transition is generated by the level signal, as shown in fig. 6, the processing unit 140 may calculate the time and amplitude corresponding to each sampling point according to the following formula (4):
Fig. 7 shows a schematic diagram of the result of the sampling points obtained after the processing by the processing unit 140, wherein the reference signal a is a sinusoidal signal, and the trigger signal B is in phase with the reference signal a. As can be seen from fig. 7, the signal sampling device of the present application is used to sample the pulse signal, so that more sampling points can be obtained, and the recovery accuracy of the subsequent signal can be ensured.
In another embodiment of the present application, as shown in fig. 8, the signal sampling apparatus may further include a signal generating unit 150, which may be configured to generate a reference signal and a trigger signal, and may include a first subunit 151 for generating the reference signal and a second subunit 152 for processing the reference signal generated by the first subunit to generate the trigger signal. The first subunit 151 may be any device capable of generating a continuous signal, and the second subunit 152 may include a zero-crossing comparator, an inverter, a delay, or the like, but is not limited thereto. For example, when the second subunit 152 is a zero-crossing comparator, the trigger signal obtained by processing the reference signal by the zero-crossing comparator may be in phase with the reference signal. The first subunit 151 and the second subunit 152 may be implemented by an LC oscillating circuit, an RC oscillating circuit, a quartz crystal oscillator, a direct digital frequency synthesizer (DDS) chip, or the like.
In another embodiment of the present application, as shown in fig. 9, the signal sampling apparatus may further include a reconstruction unit 160, which may be configured to perform reconstruction processing on the sampling points obtained by the processing unit 140 to obtain a restored waveform of the analog signal. The reconstruction unit 160 may directly connect all the obtained sampling points to obtain a restored waveform of the analog signal without performing any fitting process, which may increase the data processing speed and reduce the memory consumption. The reconstruction unit 160 may perform interpolation processing on the obtained sampling points, and connect all the sampling points after the interpolation processing; the obtained sampling points may also be fitted directly with a priori model or feature function of the analog signal (e.g., y (t) =a x exp (- (t-d)/b) x (1-exp (- (t-d)/c))); it is also possible to perform interpolation processing on the obtained sampling points and perform fitting processing on all the sampling points after the interpolation processing, wherein the interpolation processing includes linear interpolation processing and/or spline interpolation processing. By carrying out interpolation processing and/or fitting processing on the sampling points, the recovery precision of the analog signals can be improved.
For the specific process of interpolation processing and fitting processing on the sampling points, reference may be made to related descriptions in the prior art, and details are not repeated here.
As can be seen from the above description, the signal sampling device provided in the embodiment of the present application mainly uses the comparing unit to compare the amplitude of the reference signal and the analog signal to be sampled, the timing unit records and outputs the time interval from the amplitude of the received trigger signal reaching the trigger threshold to the generation of the corresponding edge jump from the level signal received by the comparing unit, the counting unit records the number of times the trigger signal received by the timing unit reaches the trigger threshold, and the processing unit obtains the sampling point of the analog signal by processing the amplitude characteristic of the reference signal, the time interval recorded by the timing unit, and the number of times recorded by the counting unit, without requiring a plurality of voltage comparators and time-to-digital converters. For example, for 8 sampling points, the MVT sampling circuit in the prior art needs 4 voltage comparators and 8 TDCs, while the present application needs only one voltage comparator and one TDC, which obviously can reduce the cost, power consumption and complexity of the system.
The embodiment of the present application also provides a photoelectric detection system, as shown in fig. 10, which may include the signal sampling device described in the above embodiment and a detector configured to send a pulse signal to the signal sampling device. The detector may be any radiation detector capable of detecting radioactive rays, such as a PET detector, and may include a scintillation crystal and a photoelectric converter coupled to each other.
The embodiment of the application also provides a signal sampling method executed by the signal sampling device, as shown in fig. 11, which may include the following steps:
s1: the received reference signal is amplitude-compared with the analog signal to be sampled by the comparison unit and a corresponding level signal is output according to the comparison result.
After receiving the reference signal and the analog signal to be sampled, the comparison unit may perform amplitude comparison of the received reference signal and the analog signal to be sampled, and output a corresponding level signal according to the comparison result. For example, the comparison unit may output a high level when the amplitude of the analog signal reaches the amplitude of the reference signal, and may output a low level when the amplitude of the analog signal is smaller than the amplitude of the reference signal.
S2: the time interval from the amplitude of the received trigger signal reaching the trigger threshold to the generation of the corresponding edge transition from the level signal received by the comparing unit is recorded and output by the timing unit.
The trigger signal may be a periodic signal with the reference signal and maintain a fixed phase difference with the reference signal, preferably the same phase. In addition, the periodic signal may include a sine wave signal, a cosine wave signal, a triangle wave signal, a step wave signal, a saw tooth wave signal, a square wave signal, or the like. The trigger threshold may include 0 or the magnitude of the trigger signal when it produces a rising edge transition or a falling edge transition.
The timing unit may start timing after receiving the trigger signal and its amplitude reaches a trigger threshold set in advance, and may stop timing and output a time interval recorded at this time after receiving the level signal output by the comparing unit and the level signal generates a designated edge transition, and may keep timing and also output a time interval recorded at this time after the level signal generates a non-designated edge transition.
S3: the counting unit records the number of times the amplitude of the trigger signal received by the timing unit reaches the trigger threshold.
After the timing unit starts timing, the counting unit may also record the number of times the timing unit is triggered, that is, the number of times the amplitude of the trigger signal received by the timing unit reaches the trigger threshold, and send the recorded number of times to the processing unit.
S4: the sampling point of the analog signal is obtained by the processing unit by processing the amplitude characteristic of the reference signal, the time interval recorded by the timing unit, and the number of times recorded by the counting unit.
After the processing unit receives the time interval recorded by the timing unit and the number of times recorded by the counting unit, the processing unit can determine the time corresponding to the sampling point to be acquired according to the time interval recorded by the timing unit and the number of times recorded by the counting unit, and then can calculate the amplitude corresponding to the sampling point according to the calculated time and the amplitude characteristic of the reference signal, so as to obtain the sampling point characterized by the time and the amplitude of the analog signal.
Specifically, the processing unit may calculate the time and amplitude corresponding to each sampling point using the above formulas (1) - (4).
In another embodiment of the present application, as shown in fig. 12, the method may further include:
s5: the reconstruction unit performs reconstruction processing on the sampling points obtained by the processing unit to obtain a restored waveform of the analog signal.
For the detailed description of the above steps S1 to S5, reference may be made to the detailed descriptions of the comparing unit, the timing unit, the counting unit, the processing unit and the reconstructing unit in the above embodiments, which are not described herein again.
As can be seen from the foregoing description, in the signal sampling method provided by the embodiment of the present application, by comparing the amplitude of the reference signal and the analog signal to be sampled by using the comparing unit, the timing unit records and outputs the time interval from when the amplitude of the received trigger signal reaches the trigger threshold to when the level signal received from the comparing unit generates the corresponding edge jump, the counting unit records the number of times when the trigger signal received by the timing unit reaches the trigger threshold, and the processing unit obtains the sampling point of the analog signal by processing the amplitude characteristic of the reference signal, the time interval recorded by the timing unit, and the number of times recorded by the counting unit, instead of comparing the intermittent values, such as a plurality of voltage thresholds, with the amplitude of the pulse signal, so that the number of sampling points collected is relatively large, and thus the sampling precision and accuracy of the analog signal can be improved, and fitting processing of the collected sampling points is unnecessary, which can improve the data processing speed and reduce the system power consumption.
The systems, devices, units, etc. described in the above embodiments may be implemented by a semiconductor chip, a computer chip, and/or an entity, or by a product having a certain function. For convenience of description, the above devices are described as being functionally divided into various units, respectively. Of course, the functions of the units may be implemented in the same chip or chips when implementing the application.
Although the present application provides method operational steps as described in the above embodiments or flowcharts, more or fewer operational steps may be included in the method, either on a routine basis or without inventive labor. In the steps where there is logically no necessary causal relationship, the execution order of the steps is not limited to the execution order provided by the embodiment of the present application.
In this specification, each embodiment is described in a progressive manner, and identical and similar parts of each embodiment are all referred to each other, and each embodiment mainly describes differences from other embodiments.
The embodiments described above are described in order to facilitate the understanding and use of the present application by those of ordinary skill in the art. It will be apparent to those skilled in the art that various modifications can be made to these embodiments and that the general principles described herein may be applied to other embodiments without the need for inventive faculty. Therefore, the present application is not limited to the above-described embodiments, and those skilled in the art, based on the present disclosure, should make improvements and modifications without departing from the scope of the present application.
Claims (24)
1. A signal sampling device, the device comprising:
a comparison unit configured to compare the received reference signal with an analog signal to be sampled in amplitude and output a corresponding level signal according to a comparison result;
a timing unit configured to record and output a time interval from when an amplitude of a received trigger signal reaches a trigger threshold to when the level signal received from the comparing unit generates a corresponding edge transition, wherein the trigger signal is used to trigger the timing unit to perform timing;
a counting unit configured to record the number of times the trigger signal received by the timing unit reaches the trigger threshold;
a processing unit configured to obtain sampling points of the analog signal by processing amplitude characteristics of the reference signal, the time interval recorded by the timing unit, and the number of times recorded by the counting unit,
wherein the reference signal and the trigger signal are periodic signals and a phase difference between the reference signal and the trigger signal remains constant.
2. The apparatus of claim 1, wherein the comparison unit comprises a voltage comparator or a current comparator.
3. The apparatus according to claim 2, wherein the comparing unit is implemented by an LVDS interface, an SSTL interface, an HSTL interface, an RSDS interface or a TMDS interface in an FPGA chip or a specific chip.
4. The apparatus of claim 1, wherein the timing unit comprises a time-to-digital converter or a time-to-voltage converter.
5. The apparatus of claim 4, wherein the timing unit is implemented by an FPGA chip or an ASIC chip.
6. The apparatus according to claim 1, wherein the timing unit is specifically configured to:
starting timing when the amplitude of the trigger signal reaches the trigger threshold;
stopping timing when the level signal generates a specified edge transition, and outputting the recorded time interval to the processing unit;
the timing is maintained when the level signal produces a non-designated edge transition and the recorded time interval is output to the processing unit.
7. The apparatus according to claim 1, wherein the processing unit is configured to calculate a time corresponding to each of the sampling points according to the time interval recorded by the timing unit and the number of times recorded by the counting unit, and calculate an amplitude corresponding to each of the sampling points by using the calculated time in combination with the amplitude characteristic of the reference signal.
8. The apparatus of claim 1, wherein the apparatus further comprises:
a signal generation unit configured to generate the reference signal and the trigger signal.
9. The apparatus of claim 8, wherein the signal generation unit comprises:
a first subunit configured to generate the reference signal;
a second subunit configured to process the reference signal to generate the trigger signal.
10. The apparatus of claim 9, wherein the second subunit comprises a zero-crossing comparator, an inverter, or a delay.
11. The apparatus of claim 1, wherein the apparatus further comprises:
and a reconstruction unit configured to reconstruct the sampling points obtained by the processing unit to obtain a restored waveform of the analog signal.
12. The apparatus according to claim 11, wherein the reconstruction unit is specifically configured to:
directly connecting all the obtained sampling points;
performing interpolation processing on the sampling points, and connecting all the sampling points after the interpolation processing; or alternatively
Performing interpolation processing on the sampling points, performing fitting processing on all sampling points after the interpolation processing,
Wherein the interpolation processing includes linear interpolation processing and/or spline interpolation processing.
13. A photodetection system, characterized in that it comprises a signal sampling device according to any of claims 1-12 and a detector configured to send a pulse signal to the signal sampling device.
14. The photodetection system according to claim 13, wherein the detector comprises a scintillation crystal and a photoelectric converter coupled to each other.
15. A method of signal sampling, the method comprising:
comparing the received reference signal with an analog signal to be sampled in amplitude by a comparison unit and outputting a corresponding level signal according to a comparison result;
recording and outputting a time interval from when the amplitude of the received trigger signal reaches a trigger threshold to when the level signal received from the comparison unit generates a corresponding edge jump by a timing unit, wherein the trigger signal is used for triggering the timing unit to perform timing;
recording the number of times the trigger signal received by the timing unit reaches the trigger threshold value by a counting unit;
obtaining, by a processing unit, sampling points of the analog signal by processing the amplitude characteristic of the reference signal, the time interval recorded by the timing unit and the number of times recorded by the counting unit,
Wherein the reference signal and the trigger signal are both periodic signals and a phase difference between the reference signal and the trigger signal remains constant.
16. The method of claim 15, wherein the trigger signal is obtained by processing the reference signal and the phase of the trigger signal is the same as the phase of the reference signal.
17. The method of claim 15, wherein the periodic signal comprises a sine wave signal, a cosine wave signal, a triangle wave signal, a step wave signal, a sawtooth wave signal, or a square wave signal.
18. The method of claim 15, wherein the trigger threshold comprises 0 or an amplitude at which the trigger signal produces a rising edge transition or a falling edge transition.
19. The method of claim 15, wherein the step of recording and outputting the time interval by the timing unit comprises:
starting timing when the amplitude of the trigger signal reaches the trigger threshold;
stopping timing when the level signal generates a specified edge transition, and outputting the recorded time interval to the processing unit;
The timing is maintained when the level signal produces a non-designated edge transition and the recorded time interval is output to the processing unit.
20. The method of claim 19, wherein the step of obtaining the sampling points by the processing unit comprises:
when the designated edge transitions are each edge transition, the processing unit calculates the time and amplitude corresponding to each sampling point by using the following formula:
y i ＝f(t i )
wherein t is i And y i Respectively representing the time and the amplitude corresponding to the ith sampling point; t is the period of the trigger signal; Δt (delta t) i Representing an i-th time interval recorded by the timing unit; f (t) i ) Representing an amplitude characteristic of the reference signal; i is a positive integer between 1 and n, and n is the number of times recorded by the counting unit.
21. The method of claim 19, wherein the step of obtaining the sampling points by the processing unit comprises:
when the designated edge transitions are odd edge transitions, the processing unit calculates a time corresponding to each sampling point by using the following formula, and calculates an amplitude corresponding to each sampling point by using the calculated time and combining the amplitude characteristics of the reference signal:
t 1 ＝Δt 1
Wherein t is (·) Representing the time corresponding to the sampling point; Δt (delta t) (·) Representing the time interval recorded by the timing unit; t is the period of the trigger signal; 2i and 2i+1 are positive integers between 2 and n, and n is the number of times recorded by the counting unit.
22. The method of claim 19, wherein the step of obtaining the sampling points by the processing unit comprises:
when the designated edge transitions are even-numbered edge transitions, the processing unit calculates a time corresponding to each sampling point by using the following formula, and calculates an amplitude corresponding to each sampling point by using the calculated time and combining the amplitude characteristics of the reference signal:
wherein t is (·) Representing the time corresponding to the sampling point; Δt (delta t) (·) Representing the time interval recorded by the timing unit; t is the period of the trigger signal; 2i-1 and 2i are positive integers between 1 and n, n is the number of times recorded by the counting unit.
23. The method according to any one of claims 15-22, further comprising:
and the reconstruction unit performs reconstruction processing on the sampling points obtained by the processing unit to obtain a reduction waveform of the analog signal.
24. The method according to claim 23, wherein the step of reconstructing the sample points obtained by the processing unit by a reconstruction unit comprises:
directly connecting all the obtained sampling points;
performing interpolation processing on the sampling points, and connecting all the sampling points after the interpolation processing; or alternatively
Performing interpolation processing on the sampling points, performing fitting processing on all sampling points after the interpolation processing,
wherein the interpolation processing includes linear interpolation processing and/or spline interpolation processing.
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