CN107026722A - Fourier transform system - Google Patents

Abstract

The present invention relates to a Fourier transform system, comprising: a first signal processor, used for receiving an input signal, and outputting each frequency component of the input signal in the time domain according to the frequency relationship; and analog signal processing A unit, connected to the output end of the first signal processor, to receive the expanded signal output by the first signal processor and perform detection and filtering on the expanded signal to obtain a first Fourier transform result. The above-mentioned Fourier transform system uses the first signal processor to expand each frequency component of the input signal in the time domain, thereby transforming the input signal into a narrowband signal, so that the analog signal processing unit can process the narrowband signal to complete the Fourier transform. Leaf transformation. The above-mentioned Fourier transform system overcomes the shortcoming of narrow working bandwidth of traditional digital signal processing.

Description

Fourier transform system

technical field

The invention relates to the technical field of signal processing, in particular to a Fourier transform system.

Background technique

With the rapid development of computer and information science, digital signal processing (Digital Signal Processing, DSP) technology came into being, forming an independent subject department. Simply put, digital signal processing is the use of computers or special processing equipment to process signals by numerical calculation methods such as acquisition, transformation, synthesis, evaluation and identification, so as to achieve the purpose of extracting information and facilitating applications.

In the field of engineering, engineering signals are complex components composed of multiple frequency signals. The analysis of time-domain signals contains the same amount of information, while the frequency-domain analysis of some concerned quantities will be more intuitive and easy to operate and process. The Fourier transform is the most fundamental tool for transforming time-domain signals into frequency-domain signals. Whether it is digital signal processing or analog signal processing, it is necessary to transform the signal into the frequency domain through Fourier transform for processing. Most of the signals that exist in nature are analog signals, but in the process of digital signal processing, the processing object is digital signals. Therefore, it is necessary to convert the analog signal to the digital signal. The Fourier transform is performed by traditional digital processing technology (DSP), and its working bandwidth is narrow, so it cannot perform Fourier transform on ultra-high-speed and ultra-wideband signals.

Contents of the invention

Based on this, it is necessary to provide a Fourier transform system with a wide working bandwidth.

A Fourier transform system, comprising: a first signal processor, configured to receive an input signal, and expand each frequency component of the input signal in the time domain according to a frequency relationship, and then output it; and an analog signal processing unit, and The output terminal of the first signal processor is connected to receive the expanded signal output by the first signal processor and perform detection and filtering processing on the expanded signal to obtain a first Fourier transform result.

In one of the embodiments, it also includes a digital signal processing unit; the digital signal processing unit is connected to the output end of the first signal processor, and is used to receive the expanded signal output by the first signal processor and convert the Converting the expanded signal from the time domain to the frequency domain signal to complete the Fourier transform, and output the second Fourier transform result.

In one of the embodiments, an oscilloscope is also included; the oscilloscope is respectively connected to the output terminals of the analog signal processing unit and the digital signal processing unit to receive the first Fourier transform result and the second Fourier transform results and display.

In one of the embodiments, a modulator is also included; the output end of the modulator is connected to the input end of the first signal processor; the modulator is used to use the center frequency as the target center frequency mixing signal to the The input signal is modulated so that the input signal is frequency-converted to a band-pass range in which the center frequency is the target center frequency.

In one of the embodiments, the target center frequency is the same as the center frequency of the first signal processor, both of which are microwave frequency bands.

In one of the embodiments, the first signal processor is a dispersive group delay device, and the relationship between the group delay and the frequency of the dispersive group delay device is a linear relationship.

In one of the embodiments, the dispersive group delay device is an all-pass structure.

In one of the embodiments, the analog signal processing unit includes a diode and a low-pass filter connected in series; the diode is used to detect the unfolded signal to obtain envelope information of the unfolded signal; the low-pass filter is used to Filter the unwrapped signal.

A Fourier transform system, comprising: a first signal processor, configured to receive an input signal, and expand each frequency component of the input signal in the time domain according to a frequency relationship, and then output it; and a digital signal processing unit, and The output terminal of the first signal processor is connected to receive the expanded signal output by the first signal processor and convert the expanded signal from the time domain to the frequency domain signal to complete the Fourier transform, and output the Fourier Lie transform result.

In one of the embodiments, the first signal processor is a dispersive group delay device, and the relationship between the group delay and the frequency of the dispersive group delay device is a linear relationship.

The above-mentioned Fourier transform system uses the first signal processor to expand each frequency component of the input signal in the time domain, thereby transforming the input signal into a narrowband signal, so that the analog signal processing unit or digital signal processing unit can process the narrowband signal Processing is performed to complete the Fourier transform. The above-mentioned Fourier transform system overcomes the shortcoming of narrow working bandwidth of traditional digital signal processing.

Description of drawings

Fig. 1 is a structural block diagram of a Fourier transform system in an embodiment;

Fig. 2 is the structural block diagram of the Fourier transform system in another embodiment;

Fig. 3 is the structural block diagram of the Fourier transform system in yet another embodiment;

Fig. 4 is a schematic diagram of the input signal in Fig. 3;

FIG. 5 is a schematic diagram of the expanded signal obtained after being processed by a dispersive group delay device in FIG. 3;

Fig. 6 is the schematic diagram of the first Fourier transform result and the second Fourier transform result in Fig. 3;

Fig. 7 is a structural block diagram of a Fourier transform system in yet another embodiment.

detailed description

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

Fig. 1 is a structural block diagram of a Fourier transform system in an embodiment. The Fourier transform system includes a first signal processor 110 and an analog signal processing unit 120 . An output terminal of the first signal processor 110 is connected to an input terminal of the analog signal processing unit 120 .

The first signal processor 110 is used to receive a signal, and expand each frequency component of the input signal in the time domain according to a frequency relationship to form an expanded signal. The input signal can be an arbitrary waveform signal, either an analog signal or a digital signal. The expanded signal formed by the first signal processor 110 is a narrow-band signal, so that the Fourier transform system can process any input signal such as ultra-high-speed and ultra-wideband signals without being affected by the working bandwidth. The first signal processor 110 has a dispersive group delay characteristic, and its group delay has a linear relationship with frequency, so that the analog signal processing unit 120 can process each frequency component conveniently. Group delay is a quantity used to describe how fast the phase changes with frequency. In this embodiment, the first signal processor 110 is a dispersive group delay device, and its group delay has a positive linear relationship with frequency (ie, the slope of the group delay response is positive). Therefore, among the different frequency components in the input signal, the low-frequency components have a small time delay and appear earlier in the output signal, and the high-frequency components have a large time delay and appear late in the output signal, so that the time delay of each frequency component can be expand on the domain. The larger the linear slope of the group delay and frequency of the dispersive group delay device, the greater the delay corresponding to each frequency component, thus ensuring that each frequency component can be completely separated in the time domain, which is conducive to improving the transformation accuracy of analog signal processing. In other embodiments, the first signal processor 110 can also use a dispersive group delay device whose group delay response slope is a negative linear slope or only has a linear relationship within its operating frequency range, as long as the input signal can be Each frequency component may be expanded in the time domain to form an expanded signal. At the same time, the signal bandwidth of the expanded signal formed after the input signal is expanded in the time domain by the first signal processor 110 is narrowed, so that the subsequent signal processing process is relatively simple.

The expanded signal processed by the first signal processor 110 is sent to the analog signal processing unit 120 for processing. The analog signal processing unit 120 is configured to perform detection and filtering processing on the unfolded signal to complete Fourier transform and obtain a first Fourier transform result. The result of the first Fourier transform is obtained through an analog signal processing technology, and the processing speed is fast, so that real-time Fourier transform can be realized.

The above-mentioned Fourier transform system uses the first signal processor 110 to expand each frequency component of the input signal in the time domain, thereby converting the input signal into a narrowband signal, so that the analog signal processing unit 120 can process the narrowband signal to Complete the Fourier transform process. The above-mentioned Fourier transform system, through the function of the first signal processor 110, can process arbitrary waveform signals, overcomes the shortcoming of traditional digital signal processing with narrow working bandwidth, and uses analog signal processing technology to improve the efficiency of signal processing. speed, implementing real-time Fourier transform (RTFT).

Fig. 2 is a structural block diagram of a Fourier transform system in another embodiment. The Fourier transform system includes a first signal processor 210 , an analog signal processing unit 220 and a digital signal processing unit 230 . Wherein, the output terminals of the first signal processor 210 are respectively connected to the input terminals of the analog signal processing unit 220 and the digital signal processing unit 230 . The parts that have been introduced in the foregoing embodiments will not be repeated here.

The digital signal processing unit 230 performs Fourier transform on the unfolded signal through digital processing technology, and obtains a second Fourier transform result. The digital signal processing unit 230 adopts the traditional fast Fourier transform method for processing to transform the input signal from the time domain to the frequency domain. The second Fourier transform result processed by the digital signal processing unit 230 is slower than the first Fourier transform result processed by the analog signal processing unit 220 , but the accuracy is higher. Therefore, comparing the first Fourier transform result processed by the analog signal processing unit 220 with the second Fourier transform result processed by the digital signal processing unit 230 can ensure the accuracy of the Fourier transform result. Moreover, in this embodiment, through the processing of the first signal processor 210, the input signal can be converted into a narrowband signal, thereby overcoming the shortcoming of narrow bandwidth in the traditional digital signal processing process, and using a simple digital signal processing unit 230, the input signal can be converted from the time domain to the frequency domain to complete the Fourier transform.

The above-mentioned Fourier transform system, through the first signal processor 210, expands each frequency component of the input signal in the time domain, thereby transforming the input signal into a narrowband signal, so that the analog signal processing unit 220 and the digital signal processing unit 230 can This narrowband signal is processed to complete the Fourier transform process. The above-mentioned Fourier transform system overcomes the shortcoming of narrow working bandwidth of traditional digital signal processing. Moreover, the speed of signal processing is improved by using analog signal processing technology, and the shortcoming of narrow working bandwidth of digital signal processing is further overcome, and the conversion precision is improved by using digital signal processing.

Fig. 3 is a structural block diagram of a Fourier transform system in another embodiment. Referring to FIG. 3 , the Fourier transform system includes a modulator 310 , a dispersive group delay device 320 , an analog signal processing unit 330 and a digital signal processing unit 340 .

The output terminal of the modulator 310 is connected to the input terminal of the dispersive group delay device 320 . The modulator 310 is used to modulate the input signal ψ _in (t). In this embodiment, the input signal ψ _in (t) is described by taking a rectangular wave as an example, as shown in FIG. 4 . Modulator 310 utilizes the mixing signal whose center frequency is the target center frequency ω _o The input signal ψ _in (t) is modulated, so that the input signal ψ _in (t) is up-converted to the band-pass range with the center frequency ω _o , and The center frequency of the input signal modulated by the modulator 310 is the same as the center frequency of the dispersive group delay device 320 , both of which are selected from the microwave frequency band.

The signal modulated by the modulator 310 Processing is performed by a dispersive group delay device 320 with a center frequency of ω _o . The group delay of the dispersive group delay device 320 has a positive linear relationship with frequency, as shown in FIG. 3 . The dispersive group delay device 320 processes the modulated signal, and sequentially expands each frequency component in the time domain according to the magnitude relationship of the frequency, so as to obtain the time domain frequency expansion signal ψ _h (t). The time-domain frequency expansion signal ψ _h (t) processed by the dispersive group delay device 320 is shown in FIG. 5 . In Fig. 5, the abscissa is time, and the ordinate is amplitude. It can also be seen from FIG. 5 that each frequency component is sequentially expanded in the time domain. The larger the linear slope of the group delay and frequency of the dispersive group delay device 320, the greater the time delay corresponding to each frequency component, thereby ensuring that each frequency component can be completely separated in the time domain, which is conducive to improving the efficiency of the Fourier transform process. transform precision.

The obtained time-domain frequency expansion signal ψ _h (t) is divided into two paths, one of which is sent to the analog signal processing unit 330 , and the other is sent to the digital signal processing unit 340 . In this embodiment, the analog signal processing unit 330 includes a diode D1 and a low-pass filter 332 . The diode D1 and the low-pass filter 332 are connected in series. The diode D1 is used to detect the input unfolded signal ψ _h (t), so as to obtain the envelope information of the unfolded signal ψ _h (t). The low-pass filter 332 is used to filter the expanded signal ψ _h (t) to remove clutter in the expanded signal ψ _h (t). That is, the expanded signal ψ _h (t) is detected and filtered by the diode D1 and the low-pass filter 332 to obtain the first Fourier transform result ψ _out1 (t). Realizing the Fourier transform through the analog signal processing unit 330 is fast, and belongs to real-time Fourier transform (RTFT). The first Fourier transform result ψ _out1 (t) is obtained faster, but not accurate enough. In this embodiment, the Fourier transform system further includes an oscilloscope (not shown in the figure). The oscilloscope is used to display the first Fourier transform result ψ _out1 (t), that is, to display the envelope shape of the acquired expanded signal ψ _h (t). The expanded signal ψ _h (t) sent to the digital signal processing unit 340 is subjected to Fourier transform in the digital signal processing unit 340 to obtain a second Fourier transform result ψ _out2 (f). The digital processing unit 340 can be implemented by software, such as MATLAB on a general-purpose computer. The Fourier transform implemented by software takes a certain amount of time and is not a real-time transform, which can be realized by traditional fast Fourier transform (FFT) technology. The second Fourier transform result ψ _out2 (f) is the result of digital processing, and the processing is slower than the first Fourier transform result ψ _out1 (t), but the result is accurate. The oscilloscope will superimpose and display the second Fourier transform result ψ _out2 (f) and the first Fourier transform result ψ _out1 (t), so that the two obtained results can be visually compared to obtain a more accurate The Fourier transform results are shown in Figure 6. In FIG. 6, the bottom abscissa represents time, the top abscissa represents frequency, and the ordinate represents amplitude. In FIG. 6 , the solid line represents the first Fourier transform result ψ _out1 (t), and the dashed line represents the second Fourier transform result ψ _out2 (f). It can be seen that the first Fourier transform result ψ _out1 (t) and the second Fourier transform result ψ _out2 (f) are consistent, but there are slight deviations at some points. This is related to the performance of the dispersive group delay device 320 . The larger the linear slope of the group delay response of the dispersive group delay device 320, the better the real-time Fourier transform effect can be obtained.

The above-mentioned Fourier transform system uses analog signal processing technology to realize real-time Fourier transform, and at the same time uses digital signal processing technology. The speed of signal processing is improved by using analog signal processing technology. At the same time, the first signal processor 310 is used to convert the input signal into a narrowband signal, which overcomes the shortcoming of the narrow working bandwidth of the digital processing technology, so that ultra-high-speed and ultra-wideband signals can be processed. The Liye transform, ie ψ _in (t), can be a signal with a very wide bandwidth. The above-mentioned Fourier transform system does not require complex digital signal processing techniques, because ψ _h (t) is a narrow-band signal, which is easy to digitally process in practice.

FIG. 7 is a structural block diagram of a Fourier transform system in another embodiment, the Fourier transform system includes a first signal processor 710 and a digital signal processing unit 720 .

The first signal processor 710 is configured to receive an input signal, and expand each frequency component of the input signal in the time domain according to a frequency relationship, and then output it. The digital signal processing unit 720 is connected to the output end of the first signal processor 710, and is used to receive the expanded signal output by the first signal processor 710 and convert the expanded signal from the time domain to the frequency domain signal to complete the Fourier transform and output Fourier transform result. The functions of the first signal processor 710 and the digital signal processing unit 720 have been described in detail in the foregoing embodiments and will not be repeated here.

The above-mentioned Fourier transform system, through the first signal processor 710, expands each frequency component of the input signal in the time domain, thereby transforming the input signal into a narrowband signal, so that the digital signal processing unit 720 can process the narrowband signal to The Fourier transform process is completed, thereby overcoming the shortcomings of traditional digital signal processing with narrow working bandwidth. Moreover, the above-mentioned Fourier transform system performs Fourier transform through digital signal processing technology, has high transform precision, and can realize fast Fourier transform.

The technical features of the above-mentioned embodiments can be combined arbitrarily. To make the description concise, all possible combinations of the technical features in the above-mentioned embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, should be considered as within the scope of this specification.

The above-mentioned embodiments only express several implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but should not be construed as limiting the patent scope of the invention. It should be pointed out that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent for the present invention should be based on the appended claims.

Claims (10)

1. a kind of Fourier transform system, it is characterised in that including：

First signal processor, is pressed for receiving input signal, and by each frequency component of the input signal Frequency relation is exported after deploying in time domain；And

Analogy signal processing unit, is connected with the output end of first signal processor, to receive described The expansion signal of one signal processor output simultaneously carries out detection and filtering process to obtain the to the expansion signal One Fourier transformation result.

2. Fourier transform system according to claim 1, it is characterised in that also including data signal Processing unit；The digital signal processing unit is connected with the output end of first signal processor, is used for Receive the expansion signal of the first signal processor output and change the expansion signal to frequency domain from time domain Signal exports the second Fourier transformation result to complete Fourier transformation.

3. Fourier transform system according to claim 2, it is characterised in that also including oscillograph； The oscillograph connects with the output end of the analogy signal processing unit, the digital signal processing unit respectively Connect, to receive the first Fourier transformation result and the second Fourier transformation result and show.

4. Fourier transform system according to claim 1, it is characterised in that also including modulator； The output end of the modulator is connected with the input of first signal processor；The modulator is used for profit The input signal is modulated with the mixed frequency signal that centre frequency is target center frequency, it is described to cause Input signal is converted to the bandpass range that centre frequency is target center frequency.

5. Fourier transform system according to claim 4, it is characterised in that target's center's frequency Rate is identical with the centre frequency of first signal processor, is microwave frequency band.

6. Fourier transform system according to claim 1, it is characterised in that at first signal Relation is linear between managing the group delay and frequency that device is dispersion group delay device and the dispersion group delay device Relation.

7. Fourier transform system according to claim 6, it is characterised in that the dispersion group delay Device is all-pass structure.

8. Fourier transform system according to claim 1, it is characterised in that at the analog signal Reason unit includes the diode and low pass filter being serially connected；The diode is used to carry out expansion signal Detection deploys the envelope information of signal to obtain；The low pass filter is used to be filtered place to expansion signal Reason.

9. a kind of Fourier transform system, it is characterised in that including：

First signal processor, is pressed for receiving input signal, and by each frequency component of the input signal Frequency relation is exported after deploying in time domain；And

Digital signal processing unit, is connected with the output end of first signal processor, described for receiving The expansion signal of first signal processor output is simultaneously changed the expansion signal to frequency-region signal with complete from time domain Into Fourier transformation, and export Fourier transformation result.

10. Fourier transform system according to claim 9, it is characterised in that first signal Processor be dispersion group delay device and the dispersion group delay device group delay and frequency between relation be line Sexual intercourse.