Signal flexible processing and sampling device based on quasi-continuous optical phase sampling

Abstract

The invention discloses a signal flexible processing and sampling device based on quasi-continuous optical phase sampling, and belongs to the technical field of signal processing. The device comprises a light source, and a tunable quasi-continuous light generation module, a phase modulator, an unequal arm light interference module and an electric rear end module which are sequentially connected along the signal output direction of the light source. The tunable quasi-continuous light generation module processes light pulse signals generated by the light source to generate a broadened light pulse sequence with time domain waveforms appearing at equal intervals and having duration, and the time domain appearance of each light pulse in the sequence is tuned according to target signal frequency extracted from a radio frequency signal to be received. The phase modulator carries out phase sampling on a to-be-received radio frequency signal, and the unequal-arm optical interference module carries out interference processing on the sampled signal and outputs an optical signal. And the electric rear-end module performs photoelectric conversion, filtering and digital sampling on the optical signal to obtain a target signal digitization result after analog processing.

Description

Technical Field

[0001] The invention relates to a signal flexible processing and sampling device based on quasi-continuous optical phase sampling, belonging to the technical field of signal processing. Background Art

[0002] With the rapid development of digital technology, the trend of information technology development is to digitize analog signals through analog-to-digital converters and store, process, transmit and display them. At the same time, the requirements of information technology for bandwidth and real-time processing speed are also constantly developing. The method of directly digitizing analog signals by analog-to-digital converters faces the problems of limited bandwidth and a surge in the amount of data processed in the digital domain. Therefore, before sampling and quantizing analog signals, it is often necessary to process the signals according to the needs of different applications.

[0003] Analog signal processing includes frequency selection, phase shifting and anti-interference of signals, and is a key technology in the field of electronics and communications. In modern telecommunications equipment and various control systems, filters are usually used to complete analog signal processing. Filters are widely used and are one of the most widely used and most technically complex electronic components. When meeting the processing requirements of broadband signals, multiple non-reconfigurable filters need to be switched in parallel, which greatly increases the size, weight and control difficulty of the system. Thanks to the large bandwidth and tunable characteristics of microwave photonic technology, broadband, flexible and reconfigurable signal filtering can be achieved with the help of microwave photonic technology. However, the output filtered signal is still a high-frequency signal and cannot be directly digitized by an analog-to-digital converter with limited bandwidth and sampling rate. It needs to be converted again by electro-optical conversion with the help of microwave photonic analog-to-digital conversion technology to successfully complete digitization, as shown in the paper. JS,et al.(2016). "Amonolithic integrated photonic microwavefilter."Nature Photonics 11(2):124-129. However, multiple photoelectric / electro-optical conversions will cause signal power loss and signal distortion. Although the integrated signal processing and digitization system based on optical domain periodic signal intensity modulation (Su F,Wu G,Chen J.Photonic analog-to-digital conversion with equivalent analog prefiltering by shaping sampling pulses[J].Optics Letters,2016,41:2779-2782) can simultaneously realize analog processing and sampling of broadband signals, it requires precise modulation bias control and sampling synchronization devices, and the system stability is limited and the implementation is difficult. Summary of the invention

[0004] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art and propose a flexible signal processing and sampling device based on quasi-continuous optical phase sampling, which samples and detects the phase of the received radio frequency signal through quasi-continuous light, and simultaneously completes the analog processing and digitization of the signal.

[0005] The technical solution of the present invention is:

[0006] A flexible signal processing and sampling device based on quasi-continuous light phase sampling, comprising a light source, and a tunable quasi-continuous light generating module, a phase modulator, an unequal-arm light interference module, and an electrical back-end module sequentially connected along the signal output direction of the light source;

[0007] A light source, emitting a periodic light pulse signal;

[0008] A tunable quasi-continuous optical generation module processes an optical pulse signal to generate a quasi-continuous optical signal, the time domain waveform of the quasi-continuous optical signal is a sequence of stretched optical pulses that appear at equal intervals and have a duration, and the time domain shape of each optical pulse in the sequence is tuned according to the target signal frequency extracted from the radio frequency signal to be received;

[0009] A phase modulator receives a quasi-continuous optical signal and a radio frequency signal to be received, and performs phase sampling of the radio frequency signal to be received using the quasi-continuous optical signal;

[0010] The unequal-arm optical interference module performs interference processing on the sampled signals and outputs optical signals;

[0011] The electrical back-end module performs photoelectric conversion, filtering, and digital sampling on the optical signal output by the unequal-arm optical interference module to obtain the digital result of the target signal after analog processing.

[0012] Furthermore, the time domain profile p(t) of the quasi-continuous optical signal is tuned according to the target signal frequency and is expressed as:

[0013] p(t)=P0·Σ i α i ·cos(2πf c,i t)

[0014] In the formula, f c,i According to the target receiving frequency f i The generated optical signal time domain envelope frequency, f c,i With f i The difference is not greater than the bandwidth of the electrical back-end module; P0 is the total power of the optical signal, α i The receiving gain for each receiving frequency signal is normalized by the maximum gain among all target receiving frequencies.

[0015] Furthermore, the optical delay difference τ between the two arms of the unequal-arm optical interference module is less than or equal to the inverse of the maximum frequency of the target signal, and is consistent with the frequency f of the target signal. i Need to meet Where k is an arbitrary integer.

[0016] Furthermore, the electrical back-end module includes a photodetector, an anti-aliasing filter and an analog-to-digital converter connected in sequence; the photodetector converts the optical signal into an electrical signal, the anti-aliasing filter filters the electrical signal, and the analog-to-digital converter samples the filtered electrical signal, and the sampling position is located at a fixed position at each sampling period interval, and the sampling interval is equal to the period of the quasi-continuous light.

[0017] Further, the anti-aliasing filter includes a low-pass filter and an adjustable delay device;

[0018] The low-pass filter performs anti-aliasing filtering before analog-to-digital conversion. The bandwidth of the low-pass filter is not less than T s is the optical pulse signal period;

[0019] The adjustable delay device controls the delay of the output signal of the low-pass filter so that the peak value of the output signal after filtering in each sampling interval is aligned with the sampling position of the analog-to-digital converter.

[0020] Furthermore, the electrical back-end module performs photoelectric conversion, filtering, and digital sampling on the optical signal output by the unequal-arm optical interference module to obtain the digital result of the target signal after analog processing, which is:

[0021]

[0022] Among them, h A (t) is the time domain impulse response of the signal processing performed by the device as a whole, T s is the optical pulse signal period;

[0023] The equivalent frequency response of the signal processing is:

[0024]

[0025] In the formula, is the spectrum of the quasi-continuous optical signal in the time domain p(t); H E (f) is the frequency response of the electrical back-end module, and τ is the delay difference between the two arms of the unequal-arm optical interference module.

[0026] Furthermore, the equivalent frequency response H of the electrical back-end device E The bandwidth of (f) is not less than half of the target bandwidth.

[0027] Furthermore, the inverse of the period of the optical pulse signal is greater than or equal to the bandwidth of the target signal.

[0028] Furthermore, the light source is a mode-locked laser, and the tunable quasi-continuous light generating module is a programmable optical filter.

[0029] The advantages of the present invention compared with the prior art are:

[0030] (1) The present invention achieves reconstruction of analog signal processing functions by changing the time domain shape of quasi-continuous light. Signal processing is not limited by the bandwidth of the electrical back-end module, and can achieve tunable signal processing of ultra-wideband RF signals. It has strong applicability and avoids frequent changes in device parameters for extracting multiple frequencies in traditional technologies.

[0031] (2) The present invention simultaneously outputs the results of ultra-wideband signal analog processing and digital sampling, avoiding multiple photoelectric and electro-optical conversions and simplifying the system structure.

[0032] (3) The present invention adopts optical phase sampling, which is different from the optical intensity sampling scheme. It does not require the use of a bias point control device and has the advantages of easy implementation, good stability and high reliability. The sampling output result is the same as the result of sampling the signal to be processed through a reconfigurable filter. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0034] Figure 1 It is a structural schematic diagram of a flexible signal processing and sampling device based on quasi-continuous optical phase sampling of the present invention;

[0035] Figure 2 This is a system block diagram of a flexible signal processing and sampling device based on quasi-continuous optical phase sampling according to an embodiment of the present invention;

[0036] Figure 3 The quasi-continuous optical signal of the embodiment of the present invention, (a) is a time domain diagram, (b) is a frequency domain diagram and (c) is a spectrum diagram of the electrical back-end response;

[0037] Figure 4 Schematic diagram of the adjustment of the equivalent frequency response of signal processing according to the time domain shape of a periodic signal according to an embodiment of the present invention, (a) is an effect diagram of the equivalent frequency response of signal processing, and (b) is a tuning diagram of the equivalent frequency response of signal processing. DETAILED DESCRIPTION

[0038] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0039] The present invention proposes a flexible signal processing and sampling device based on quasi-continuous optical phase sampling, which realizes different signal processing functions by reconstructing the time domain shape of the quasi-continuous optical signal according to the characteristics of the radio frequency signal to be received.

[0040] like Figure 1 As shown, it includes a light source, a tunable quasi-continuous light generating module, a phase modulator, an unequal-arm light interference module, a photodetector, an anti-aliasing filter and an analog-to-digital converter in sequence.

[0041] The tunable quasi-continuous optical generation module generates a quasi-continuous optical signal. The quasi-continuous optical signal is a sequence of stretched optical pulses with a certain duration that appear at equal intervals in the time domain. The shape of each optical pulse in the sequence is tunable. The time domain shape p(t) of the quasi-continuous optical signal is configured according to the requirements of the received signal so that its time domain envelope contains cos(2πf c,i t), specifically:

[0042] p(t)=P0·∑ i α i ·cos(2πf c,i t)

[0043] In the formula, f c,i According to the target receiving frequency f i The generated optical signal time domain envelope frequency, f c,i With f i The difference is not greater than the bandwidth of the electrical back-end module; P0 is the total power of the optical signal, α i is the receiving gain of each receiving frequency signal, which is normalized by the maximum gain among all target receiving frequencies. c,i The difference between the frequency f1 of the RF signal to be received and the frequency f2 is less than the bandwidth f of the anti-aliasing filter. E .

[0044] The phase modulator uses a quasi-continuous optical signal to perform phase sampling on the received radio frequency signal x(t).

[0045] The optical delay difference τ between the two arms of the unequal-arm optical interference module is less than or equal to the inverse of the maximum receiving frequency, and must satisfy the frequency f1 of the RF signal to be received. Where k is an arbitrary integer.

[0046] The photoelectric detector performs photoelectric conversion on the output signal of the unequal-arm optical interference module and outputs an electrical signal.

[0047] The analog-to-digital converter samples the filtered signal to obtain the processing and sampling results of the received RF signal x(t). The sampling position is located at a fixed position at each sampling period interval, and the sampling interval is equal to the period T of the quasi-continuous light. s .

[0048] The equivalent frequency response of signal processing can be flexibly configured by changing the time domain shape p(t) of the quasi-continuous optical signal, thereby achieving tuning of the signal processing function. A (f) is:

[0049]

[0050] In the formula, It is the Fourier transform of the intensity of the time domain shape p(t) of the quasi-continuous optical signal, that is, the spectrum of p(t), including all frequencies f to be received. i The non-zero component at E (f) is the equivalent frequency response of the electrical backend of the photodetector, anti-aliasing filter and analog-to-digital converter as a whole, which determines the bandwidth and shape of the signal processing. τ is the delay difference between the two arms of the unequal-arm optical interferometer module.

[0051] Embodiments of the present invention Figure 2 As shown, the system includes a mode-locked laser 1, a programmable optical filter 2, a phase modulator 3, a double-arm interferometer 4, a photodetector 5, a low-pass filter 6, an adjustable delay line 7 and an analog-to-digital converter 8, which extracts a frequency of f1 = 10 GHz, f2 = 45 GHz and a signal bandwidth of f from the radio frequency signal x(t) to be received. bw =100MHz target signal and output the digitized result.

[0052] The mode-locked laser 1 generates a period of T s The optical pulse signal has a period T s The reciprocal of is greater than or equal to the bandwidth of the target signal. After the optical pulse signal is processed by the programmable optical filter 2, a quasi-continuous optical sampling signal p(t) is generated. The signal waveform is as follows: Figure 3 As shown in (a), the signal spectrum is Figure 3 As shown in (b), the frequency response of the electrical back end is Figure 3 In this embodiment, f i = 10GHz and 40GHz. In order to receive the target signal, the period T of the optical pulse signal generated by the mode-locked laser s Greater than or equal to 10ns.

[0053] The optical phase modulator 3 receives the quasi-continuous optical signal p(t) and the radio frequency signal to be received x(t), performs quasi-continuous optical phase sampling, and then the signal is sent to the double-arm interferometer 4 with a delay difference of τ. The delay difference τ of the double arms should satisfy Where k is an arbitrary integer.

[0054] The photoelectric converter 5 converts the output signal of the dual-arm interferometer 4 into an electrical signal, which is then sent to the input end of the low-pass filter 6 .

[0055] The low-pass filter 6 performs anti-aliasing filtering before analog-to-digital conversion, and the bandwidth of the low-pass filter 6 is not less than In this embodiment, the received signal bandwidth=100 MHz, and the bandwidth of the low-pass filter 6 is not less than 50 MHz.

[0056] The adjustable delay device 7 controls the delay of the output signal of the low-pass filter 6 so that the peak value of the output signal after filtering in each sampling interval is aligned with the sampling position of the analog-to-digital converter 8.

[0057] Analog-to-digital converter 8 with T s The output signal is sampled at the sampling interval, and the sampling result is:

[0058]

[0059] Among them, h A (t) is the time domain impulse response of the signal processing. The equivalent frequency response of the signal processing is H A (f), the response effect is as follows Figure 4 As shown in (a) of the figure, the output digital signal is the received signal x(t) after the impulse response is h A (t) is tunable and down-converted to the digital result of the baseband. In this embodiment, the output v[k] is the center frequency f1=10GHz, f2=40GHz separated from the received signal x(t), and the bandwidth f bw =The digitized result of down-converting the target signal of 100MHz to the baseband.

[0060] In order to achieve the center frequency f1 = 10GHz, f2 = 40GHz, bandwidth f bw =100MHz signal reception, equivalent frequency response of the electrical back-end device H E The bandwidth of (f) should be no less than 50 MHz; the spectrum of the quasi-continuous optical sampling signal shaped by the programmable optical filter 2 contains non-zero frequency components of f=f1 and f=f2.

[0061] By adjusting the programmable optical filter 2 to change the quasi-continuous optical signal shape p(t), the equivalent frequency response H of the signal processing can be adjusted. A (f), the equivalent frequency response of the signal processing is tuned as Figure 4 As shown in (b).

[0062] The above-described embodiments are only preferred specific implementations of the present invention. Common changes and substitutions made by those skilled in the art within the scope of the technical solution of the present invention should be included in the protection scope of the present invention.

Claims

1. A flexible signal processing and sampling device based on quasi-continuous optical phase sampling, characterized in that: It includes a light source, and a tunable quasi-continuous light generating module, a phase modulator, an unequal-arm light interference module, and an electrical back-end module which are sequentially connected along the signal output direction of the light source; A light source, emitting a periodic light pulse signal; A tunable quasi-continuous optical generation module processes an optical pulse signal to generate a quasi-continuous optical signal, the time domain waveform of the quasi-continuous optical signal is a sequence of stretched optical pulses that appear at equal intervals and have a duration, and the time domain shape of each optical pulse in the sequence is tuned according to the target signal frequency extracted from the radio frequency signal to be received; A phase modulator receives a quasi-continuous optical signal and a radio frequency signal to be received, and performs phase sampling of the radio frequency signal to be received using the quasi-continuous optical signal; The unequal-arm optical interference module performs interference processing on the sampled signals and outputs optical signals; The electrical back-end module performs photoelectric conversion, filtering, and digital sampling on the optical signal output by the unequal-arm optical interference module to obtain the digital result of the target signal after analog processing.

2. The signal flexible processing and sampling device based on quasi-continuous optical phase sampling according to claim 1, characterized in that: The time domain shape p(t) of the quasi-continuous optical signal is tuned according to the target signal frequency and is expressed as: p(t)=P0·Σ i a i ·cos(2πf c,i t) In the formula, f c,i According to the target receiving frequency f i The generated optical signal time domain envelope frequency, f c,i With f i The difference is not greater than the bandwidth of the electrical back-end module; P0 is the total power of the optical signal, α i The receiving gain for each receiving frequency signal is normalized by the maximum gain among all target receiving frequencies.

3. The signal flexible processing and sampling device based on quasi-continuous optical phase sampling according to claim 2, characterized in that: The optical delay difference τ between the two arms of the unequal-arm optical interference module is less than or equal to the inverse of the maximum frequency of the target signal, and is consistent with the target receiving frequency f i Need to meet Where k is an arbitrary integer.

4. The signal flexible processing and sampling device based on quasi-continuous optical phase sampling according to claim 1, characterized in that: The electrical back-end module includes a photodetector, an anti-aliasing filter and an analog-to-digital converter connected in sequence; the photodetector converts the optical signal into an electrical signal, the anti-aliasing filter filters the electrical signal, and the analog-to-digital converter samples the filtered electrical signal, and the sampling position is located at a fixed position at each sampling period interval, and the sampling interval is equal to the period of the quasi-continuous light.

5. The signal flexible processing and sampling device based on quasi-continuous optical phase sampling according to claim 4, characterized in that: The anti-aliasing filter includes a low-pass filter and an adjustable delay device; The low-pass filter performs anti-aliasing filtering before analog-to-digital conversion. The bandwidth of the low-pass filter is not less than T s is the optical pulse signal period; The adjustable delay device controls the delay of the output signal of the low-pass filter so that the peak value of the output signal after filtering in each sampling interval is aligned with the sampling position of the analog-to-digital converter.

6. The signal flexible processing and sampling device based on quasi-continuous optical phase sampling according to claim 1, characterized in that: The electrical back-end module performs photoelectric conversion, filtering, and digital sampling on the optical signal output by the unequal-arm optical interference module to obtain the digital result of the target signal after analog processing, which is: Among them, h A (t) is the time domain impulse response of the signal processing performed by the device as a whole, T s is the optical pulse signal period; The equivalent frequency response of the signal processing is: In the formula, is the spectrum of the quasi-continuous optical signal in the time domain p(t); H E (f) is the frequency response of the electrical back-end module, and τ is the delay difference between the two arms of the unequal-arm optical interference module.

7. The signal flexible processing and sampling device based on quasi-continuous optical phase sampling according to claim 6, characterized in that: The equivalent frequency response H of the electrical back-end device E The bandwidth of (f) is not less than half of the target bandwidth.

8. The signal flexible processing and sampling device based on quasi-continuous optical phase sampling according to claim 1, characterized in that: The reciprocal of the period of the optical pulse signal is greater than or equal to the bandwidth of the target signal.

9. The signal flexible processing and sampling device based on quasi-continuous optical phase sampling according to claim 1, characterized in that: The light source is a mode-locked laser, and the tunable quasi-continuous light generating module is a programmable optical filter.

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