Clock synchronization frequency modulation continuous terahertz transmit-receive system

Abstract

The invention discloses a clock synchronization frequency modulation continuous terahertz transmitting and receiving system, and relates to the technical field of terahertz in-situ nondestructive testing and imaging. The clock synchronization frequency modulation continuous terahertz transmitting and receiving system provided by the invention has the characteristics of ultra wide band, high resolution and the like, can transmit and receive frequency modulation continuous terahertz waves of which the center frequency is 330GHz and the bandwidth is greater than 90GHz, and can be applied to terahertz in-situ nondestructive testing and imaging. According to the system, a radio frequency reference signal is led out through a coupler between a transmitting source and a local oscillator signal source, an intermediate frequency reference signal is obtained through a frequency mixer and a filter, and a transmitting link and a receiving link adopt the same sweep frequency source after power division, so that the transmitting signal and the receiving signal keep a coherent relationship; the problems of synchronization and phase consistency of different signal sources are solved.

Description

Technical Field

[0001] The present invention relates to the field of terahertz in-situ non-destructive testing and imaging technology, and particularly to a clock-synchronized frequency-modulated continuous terahertz dual-arm transceiver system, and more particularly to a clock-synchronized broadband frequency-swept source link and the principle architecture design of a terahertz transceiver link. Background Art

[0002] The statements in this section only provide background information related to the present disclosure and may not constitute prior art.

[0003] Terahertz waves exhibit great potential in many fields due to their unique frequency characteristics. Among them, terahertz non-destructive testing technology, compared with traditional non-destructive testing technologies such as infrared radiation, X-rays, and ultrasonic waves, has unique advantages such as low energy, high spatial resolution, and broadband spectral analysis capabilities. It can penetrate non-metallic and non-polar materials that cannot be penetrated by conventional testing technologies, thus providing a reliable technical method for research on non-metallic and non-polar material defect imaging, thickness measurement, etc. However, terahertz in-situ non-destructive testing and imaging technology faces many challenges.

[0004] Traditional terahertz detection and imaging systems often have problems such as complex architectures and insufficient synchronization accuracy. In terms of clock synchronization, it is difficult to achieve high-precision control, resulting in unstable signal transceiver timing, which in turn affects the accuracy and reliability of detection and imaging. For the broadband frequency-swept source link, existing designs are difficult to achieve efficient signal transmission and processing while ensuring wideband coverage, restricting the performance of terahertz waves in different frequency application scenarios. There are also some defects in the terahertz dual-arm transceiver link architecture that need to be urgently solved, such as poor coordination between the transceiver links, easy generation of signal interference and energy loss, reducing the overall signal-to-noise ratio and detection sensitivity of the system. Moreover, existing related technologies lack flexibility and applicability when dealing with complex detection environments and diverse detection requirements, and cannot meet the needs of terahertz in-situ non-destructive testing and imaging for high-performance and high-stability systems.

[0005] The spectral ellipsometry terahertz in-situ non-destructive testing and imaging technology uses the frequency modulation method of frequency-modulated continuous waves, which can not only perform image scanning defect detection but also defect and coating thickness detection. It is an innovative terahertz detection technology. It requires a clock-synchronized frequency-modulated continuous terahertz dual-arm transceiver. The zero-intermediate frequency architecture has a simple structure, high integration, and strong broadband support ability. Therefore, a terahertz linear frequency modulation system that mixes the signal source at the transmitting end with the local oscillator frequency-swept signal of the receiver to directly generate a baseband signal is proposed to further realize the transmission and reception of broadband and high-stability terahertz frequency-modulated continuous waves for spectral terahertz in-situ non-destructive testing and imaging technology. Summary of the Invention

[0006] The object of the present invention is to provide a clock synchronization frequency-modulated continuous terahertz dual-arm transceiver system, which includes a clock synchronization dual-channel broadband swept-frequency source signal module, a terahertz transmitting frequency multiplication module, and a terahertz receiving frequency multiplication module.

[0007] The technical solution of the present invention is as follows:

[0008] A clock synchronization frequency-modulated continuous terahertz transceiver system includes: a dual-channel broadband swept-frequency source module, a terahertz transmitting module, and a terahertz receiving module;

[0009] The dual-channel broadband swept-frequency source module generates two coherent swept-frequency signals based on the same low-phase-noise oven-controlled crystal oscillator. The first swept-frequency signal is input to the terahertz transmitting module, and the second swept-frequency signal is input to the terahertz receiving module. The phase consistency of the transceiver link is ensured through a synchronous trigger signal;

[0010] The terahertz transmitting module multiplies the first swept-frequency signal through a frequency multiplication link and then transmits the signal;

[0011] The terahertz receiving module multiplies the second swept-frequency signal through a frequency multiplication link to obtain a local oscillator signal. After mixing with an external signal carrying sample information received, a zero-intermediate-frequency signal is output and then output after IQ demodulation processing.

[0012] Further, the zero-intermediate-frequency signal contains the amplitude and phase information of the target, and the detection of the target can be realized through IQ demodulation processing.

[0013] Further, the dual-channel broadband swept-frequency source module generates two coherent swept-frequency signals in the range of 11.5 - 16 GHz based on the same low-phase-noise oven-controlled crystal oscillator. The first swept-frequency signal is input to the terahertz transmitting module, and the second swept-frequency signal is input to the terahertz receiving module. The phase consistency of the transceiver link is ensured through a synchronous trigger signal.

[0014] Further, the terahertz transmitting module multiplies the first swept-frequency signal to 276 - 384 GHz through a 24-fold frequency multiplication link and then transmits it.

[0015] Further, the terahertz receiving module multiplies the second swept-frequency signal to 138 - 192 GHz through a 12-fold frequency multiplication link as the local oscillator signal. After mixing with a received 276 - 384 GHz radar signal, a zero-intermediate-frequency signal is output and then output after IQ demodulation processing.

[0016] Further, the dual-channel broadband swept-frequency source module includes:

[0017] A frequency synthesizer unit that generates a basic swept-frequency signal of 0.7 - 1 GHz based on an oven-controlled crystal oscillator;

[0018] Two frequency doubling units, each of which uses a 4-stage cascaded doubler to perform 16-fold frequency doubling on a 0.7-1 GHz basic swept-frequency signal, and selects an 11.5-16 GHz signal as the swept-frequency signal output.

[0019] Further, the dual-channel broadband swept-frequency source module further includes:

[0020] A switch control module for independently controlling the output on / off of the two swept-frequency signals.

[0021] Further, the 24-fold frequency doubling link of the terahertz transmitting module includes:

[0022] A first-stage quadrupler that multiplies the 11.5-16 GHz signal by 4 to 46-64 GHz;

[0023] A second-stage doubler that multiplies the 46-64 GHz signal by 2 to 92-128 GHz;

[0024] A third-stage tripler that multiplies the 92-128 GHz signal by 3 to 276-384 GHz.

[0025] Further, a broadband power amplifier is provided between the second-stage doubler and the third-stage tripler in the 24-fold frequency doubling link.

[0026] Further, the 12-fold frequency doubling link of the terahertz receiving module includes:

[0027] A first-stage quadrupler that multiplies the 11.5-16 GHz signal by 4 to 46-64 GHz;

[0028] A second-stage tripler that multiplies the 46-64 GHz signal by 3 to 138-192 GHz;

[0029] A second-harmonic mixer. The 138-192 GHz signal is used as the local oscillator input of the second-harmonic mixer, and after mixing with the received 276-384 GHz radar signal, a zero-intermediate-frequency signal is output and output after IQ demodulation processing.

[0030] Compared with the existing technology, the beneficial effects of the present invention are:

[0031] The clock synchronization frequency-modulated continuous terahertz transceiver system proposed by the present invention has characteristics such as ultra-wideband and high resolution. It can transmit and receive frequency-modulated continuous terahertz waves with a center frequency of 330 GHz and a bandwidth greater than 90 GHz, and can be applied to in-situ non-destructive terahertz detection and imaging. Between the emission source and the local oscillator signal source of this system, a radio frequency reference signal is taken out through a coupler, and after passing through a mixer and a filter, an intermediate frequency reference signal is obtained. Since the same frequency-sweeping source after power division is adopted for the emission link and the reception link, the emission signal and the reception signal maintain a coherent relationship, solving the problems of synchronization and phase consistency of different signal sources. Description of the Drawings

[0032] Figure 1 It is a schematic diagram of a dual-channel broadband frequency-sweeping source module in a clock synchronization frequency-modulated continuous terahertz transceiver system;

[0033] Figure 2 It is a principle block diagram of the terahertz transceiver module link in a clock synchronization frequency-modulated continuous terahertz transceiver system;

[0034] Figure 3 It is a principle block diagram of a clock synchronization frequency-modulated continuous terahertz transceiver system. Detailed Embodiments

[0035] It should be noted that relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of additional identical elements in the process, method, article or device including the said element.

[0036] The features and performance of the present invention will be further described in detail below in conjunction with embodiments.

[0037] Embodiment 1

[0038] Please refer to Figures 1-3 , a clock synchronization frequency-modulated continuous terahertz transceiver system, specifically including: a dual-channel broadband frequency-sweeping source module, a terahertz emission module, and a terahertz reception module;

[0039] The dual-channel wideband frequency-sweeping source module generates two coherent frequency-sweeping signals in the range of 11.5 - 16 GHz based on the same low-phase-noise temperature-controlled crystal oscillator. The first frequency-sweeping signal is input to the terahertz transmitting module, and the second frequency-sweeping signal is input to the terahertz receiving module. The phase consistency of the transceiver link is ensured through a synchronous trigger signal. That is, the dual-channel wideband frequency-sweeping source module uses the same high-precision low-phase-noise temperature-controlled crystal oscillator as the system clock source. After splitting the signal into two paths and multiplying the frequency to the target frequency, it serves as the transmitting frequency source and the local oscillator frequency source, respectively, and is connected to the terahertz transmitting module and the terahertz receiving module.

[0040] The terahertz transmitting module multiplies the first frequency-sweeping signal to 276 - 384 GHz through a 24-fold frequency multiplication link and transmits it.

[0041] The terahertz receiving module multiplies the second frequency-sweeping signal to 138 - 192 GHz as the local oscillator signal through a 12-fold frequency multiplication link. After mixing with the received 276 - 384 GHz radar signal, it outputs a zero-intermediate-frequency signal and outputs it after IQ demodulation processing.

[0042] The zero-intermediate-frequency signal contains the amplitude and phase information of the target. Through IQ demodulation processing, the detection of the target can be realized. That is, the terahertz transceiver link obtains a zero-intermediate-frequency signal through the second mixing of the radio frequency signal and the local oscillator signal, which contains the amplitude and phase information of the target. The amplitude is related to the reflectivity and transmission attenuation of the target point, and the phase corresponds to the information of different layers of the target object. After intermediate-frequency amplification processing, it can be sampled by the acquisition system through AD, and finally transmitted to the host computer through the transmission system to realize the detection of the target.

[0043] The clock-synchronized frequency-modulated continuous terahertz transceiver system proposed in this embodiment has characteristics such as ultra-wideband and high resolution. It can transmit and receive frequency-modulated continuous terahertz waves with a center frequency of 330 GHz and a bandwidth greater than 90 GHz, and can be applied to in-situ non-destructive detection and imaging in terahertz. Between the transmitting source and the local oscillator signal source, a radio frequency reference signal is taken out through a coupler, and after passing through a mixer and a filter, an intermediate-frequency reference signal is obtained. Since the same frequency-sweeping source after power splitting is used for the transmitting link and the receiving link, the transmitted signal and the received signal maintain a coherent relationship, solving the problems of synchronization and phase consistency of different signal sources.

[0044] In this embodiment, specifically, the dual-channel wideband frequency-sweeping source module includes:

[0045] A frequency synthesizer unit that generates a basic frequency-sweeping signal of 0.7 - 1 GHz based on the temperature-controlled crystal oscillator.

[0046] Two frequency multiplication units. Each frequency multiplication unit uses a 4-stage cascaded doubler to multiply the 0.7 - 1 GHz basic frequency-sweeping signal by 16 times, and selects the 11.5 - 16 GHz signal as the frequency-sweeping signal output.

[0047] A switch control module for independently controlling the output on / off of two swept-frequency signals;

[0048] It should be noted that the frequency synthesizer unit mainly completes the function of outputting two independent swept-frequency signals. Inside, the radio frequency signal output by the same low-phase-noise frequency source is divided into two paths as the system clock of the swept-frequency source. The two independent swept-frequency sources output coherent swept-frequency signals, and a synchronous trigger signal is output externally in the swept-frequency mode, outputting two 11.5 - 16 GHz frequency source signals; that is, in the dual-channel wideband swept-frequency source module, the 0.7 - 1 GHz signal output by the DDS swept-frequency source is multiplied by 4 frequency doublers (16 times frequency multiplication) and filtered to output the radio frequency signal. Each radio frequency signal can be turned off by a switch, and finally two wideband swept-frequency source signals with frequencies of 11.2 - 16 GHz are output, and the 11.5 - 16 GHz signal is selected as the swept-frequency signal output, which is connected to the terahertz transceiver frequency multiplication module and used as the frequency source of the terahertz transmission signal and the local oscillator signal respectively.

[0049] In this embodiment, specifically, the 24 - times frequency multiplication link of the terahertz transmission module includes:

[0050] The first - stage 4 - times frequency doubler multiplies the 11.5 - 16 GHz signal to 46 - 64 GHz;

[0051] The second - stage 2 - times frequency doubler multiplies the 46 - 64 GHz signal to 92 - 128 GHz;

[0052] The third - stage 3 - times frequency doubler multiplies the 92 - 128 GHz signal to 276 - 384 GHz;

[0053] A broadband power amplifier is arranged between the second - stage 2 - times frequency doubler and the third - stage 3 - times frequency doubler in the 24 - times frequency multiplication link;

[0054] That is, the terahertz transmission frequency multiplication module structure adopts a 24 - times frequency multiplication circuit structure, which is connected to the frequency source transmitting end. The first - stage frequency doubler is a 4 - times frequency doubler with an output frequency of 46 - 64 GHz, the second - stage frequency doubler is a 2 - times frequency doubler with an output frequency of 92 - 128 GHz, and after passing through the power amplifier, the third - stage frequency doubler is a 3 - times frequency doubler, and finally the signal output frequency is 276 - 384 GHz.

[0055] In this embodiment, specifically, the 12 - times frequency multiplication link of the terahertz receiving module includes:

[0056] The first - stage 4 - times frequency doubler multiplies the 11.5 - 16 GHz signal to 46 - 64 GHz;

[0057] The second - stage 3 - times frequency doubler multiplies the 46 - 64 GHz signal to 138 - 192 GHz;

[0058] A second harmonic mixer, where the 138 - 192 GHz signal serves as the local oscillator input of the second harmonic mixer. After mixing with the received 276 - 384 GHz radar signal, a zero - intermediate - frequency signal is output and then output after IQ demodulation processing. That is, the terahertz receiving frequency - doubling module structure adopts a 12 - times frequency - doubling circuit structure, which is connected to the local oscillator end of the frequency source. Through two frequency - doublers, the final signal output frequency is 138 GHz - 192 GHz as the local oscillator input of the second harmonic mixer. The external signal passes through the receiving antenna, and mixing is completed in the second harmonic mixer to obtain an intermediate - frequency signal carrying sample information, which is then converted into I / Q two - channel digital signals and sent to the terminal to achieve terahertz imaging.

[0059] Specifically, an example of the two - channel broadband sweep source output signals of terahertz: A 100 MHz temperature - controlled crystal oscillator is used for low - phase - noise frequency - source phase - locking. Through external triggering, a frequency signal of 700 - 1000 MHz is output. The double - frequency channel uses 4 two - times frequency - doublers (16 - times frequency - doubling) to output a radio - frequency signal through filtering. Each radio - frequency signal can be turned off by a switch, and finally two broadband sweep source signals with a frequency of 11.2 - 16 GHz are output and connected to the terahertz transceiver module.

[0060] Specifically, an example of terahertz radio - frequency signal transceiver: The transmitting branch adopts a 24 - times frequency - doubling circuit structure. The signal transmitter is controlled by a synchronous clock. The first - stage frequency - doubler is a 4 - times frequency - doubler, and the output frequency is 46 - 64 GHz. The second - stage frequency - doubler is a 2 - times frequency - doubler, and the output frequency is 92 - 128 GHz. After passing through a power amplifier, the third - stage frequency - doubler is a 3 - times frequency - doubler, and finally the signal output frequency is 276 - 384 GHz. The receiving branch adopts a 12 - times frequency - doubling circuit structure. Through two frequency - doublers, the final signal output frequency is 138 GHz - 192 GHz as the local oscillator input of the second harmonic mixer.

[0061] In this embodiment, it should be noted that the system selects a relatively simple zero - intermediate - frequency architecture. Since the same sweep source after power splitting is used for the transmitting link and the receiving link, the transmitted signal and the received signal maintain a coherent relationship, so that the coherence of the intermediate - frequency signal can be achieved. An example of terahertz zero - intermediate - frequency signal generation: The external signal carrying sample information has a frequency of 276 - 384 GHz. After passing through the receiving antenna and then mixing with the second harmonic mixer with a local oscillator input of 138 GHz - 192 GHz, a zero - intermediate - frequency signal is obtained and output after filtering.

[0062] Figure 3Briefly describes the generation and measurement of terahertz chirped waves. The chirped signal in the microwave band is power-divided into two paths and fed into the frequency doubling link to generate terahertz signals. One path is used as the local oscillator input to the mixer, and the other path is radiated outward through the transmitting antenna and reflected by the target. The echo signal is received by the antenna and input into the mixer. The two signals are mixed to output the difference frequency signal containing target information, and the terminal is used to realize terahertz imaging.

[0063] The above-described embodiments only represent the specific implementation manners of the present application. The description is relatively specific and detailed, but it should not be construed as a limitation on the protection scope of the present application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the technical solution of the present application, several deformations and improvements can still be made, and these all belong to the protection scope of the present application.

[0064] This background art section is provided to generally present the context of the present invention. The work of the currently named inventors, to the extent described in this background art section, and aspects of the work that are not prior art as of the filing date of this application are neither expressly nor impliedly admitted to be prior art to the present invention.

Claims

1. A clock-synchronized frequency-modulated continuous terahertz transceiver system, characterized in that: include: Dual-channel broadband swept frequency source module, terahertz transmitting module and terahertz receiving module; The dual-channel broadband sweep source module generates two coherent sweep signals based on the same low phase noise constant temperature crystal oscillator, wherein the first sweep signal is input to the terahertz transmitting module, and the second sweep signal is input to the terahertz receiving module, and the phase consistency of the transmitting and receiving links is ensured by a synchronous trigger signal; The terahertz transmitting module transmits a signal after multiplying the frequency of the first frequency sweeping signal through a frequency multiplication link; The terahertz receiving module multiplies the second swept frequency signal through a frequency multiplication link and uses it as a local oscillator signal, mixes it with the received external signal carrying sample information, outputs a zero intermediate frequency signal, and outputs it after IQ demodulation processing.

2. A clock-synchronized frequency-modulated continuous terahertz transceiver system according to claim 1, characterized in that: The zero intermediate frequency signal contains the amplitude and phase information of the target, and can detect the target after IQ demodulation processing.

3. The clock-synchronized frequency-modulated continuous terahertz transceiver system according to claim 1, characterized in that: The dual-channel broadband sweep source module generates two coherent 11.5-16GHz sweep signals based on the same low phase noise constant temperature crystal oscillator, wherein the first sweep signal is input to the terahertz transmitting module, and the second sweep signal is input to the terahertz receiving module, and the phase consistency of the transmit and receive links is ensured by a synchronous trigger signal.

4. A clock-synchronized frequency-modulated continuous terahertz transceiver system according to claim 3, characterized in that: The terahertz transmitting module multiplies the frequency of the first swept frequency signal to 276-384 GHz through a 24-fold frequency link and transmits the signal.

5. A clock-synchronized frequency-modulated continuous terahertz transceiver system according to claim 4, characterized in that: The terahertz receiving module multiplies the second swept frequency signal to 138-192 GHz as a local oscillator signal through a 12-fold frequency multiplication link, mixes it with the received 276-384 GHz radar signal, outputs a zero intermediate frequency signal, and outputs it after IQ demodulation processing.

6. The clock-synchronized frequency-modulated continuous terahertz transceiver system according to claim 5, characterized in that: The dual-channel broadband frequency sweep source module comprises: The frequency synthesis unit generates a 0.7-1GHz basic frequency sweep signal based on a constant temperature crystal oscillator; Two frequency multiplication units, each frequency multiplication unit adopts a 4-stage series 2-frequency multiplier to multiply the 0.7-1GHz basic sweep frequency signal by 16 times, and selects 11.5-16GHz signal as the sweep frequency signal output.

7. A clock-synchronized frequency-modulated continuous terahertz transceiver system according to claim 6, characterized in that: The dual-channel broadband swept frequency source module further includes: The switch control module is used to independently control the output on and off of two sweep frequency signals.

8. The clock-synchronized frequency-modulated continuous terahertz transceiver system according to claim 5, characterized in that: The 24-fold frequency link of the terahertz transmitting module includes: The first stage 4-frequency multiplier multiplies the 11.5-16GHz signal to 46-64GHz; The second stage 2 frequency multiplier multiplies the 46-64GHz signal to 92-128GHz; The third stage triple frequency multiplier multiplies the 92-128 GHz signal to 276-384 GHz.

9. The clock-synchronized frequency-modulated continuous terahertz transceiver system according to claim 8, characterized in that: In the 24-fold frequency multiplication link, a broadband power amplifier is arranged between the second-stage 2-fold frequency multiplier and the third-stage 3-fold frequency multiplier.

10. The clock-synchronized frequency-modulated continuous terahertz transceiver system according to claim 5, characterized in that: The 12-fold frequency link of the terahertz receiving module includes: The first stage 4-frequency multiplier multiplies the 11.5-16GHz signal to 46-64GHz; The second stage 3-frequency multiplier multiplies the 46-64GHz signal to 138-192GHz; The second harmonic mixer uses the 138-192 GHz signal as the local oscillator input of the second harmonic mixer, mixes with the received 276-384 GHz radar signal, outputs a zero intermediate frequency signal, and outputs it after IQ demodulation processing.

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