CN102932067A - Microwave photon frequency measuring device based on technologies of compressed sampling and time domain broadening and method thereof - Google Patents

Abstract

The invention discloses a microwave photon frequency measuring device and method based on compressed sampling and time domain widening technology. The supercontinuum light source is broadened in time by a dispersive medium, and the frequency-to-time mapping is realized. The microwave signal to be measured is modulated on the time-broadened optical carrier through a Mach-Zehnder modulator. The modulated optical signal passes through the dispersion medium to further broaden the modulated optical signal, reducing the frequency of the microwave signal to be measured. The random bit sequence with ±1 is modulated on the broadened optical signal by the Mach-Zehnder modulator, and the observation data with the signal information to be measured is obtained through photoelectric conversion, low-pass filter, and electronic analog-to-digital converter. The spectrum of the original signal can be recovered by the existing compressed sampling recovery algorithm. Existing frequency measurement techniques based on compressed sampling require that the original signal be modulated on a random bit sequence up to the Quest frequency. The invention can reduce the frequency of the required random bit sequence, and at the same time further reduce the sampling frequency of the analog-to-digital converter in the system so as to improve the feasibility of the system.

Description

Microwave photon frequency measurement device and method based on compressed sampling and time domain widening technology

technical field

The invention relates to the field of optical communication and wireless communication, in particular to a microwave photon frequency measuring device and method based on compressed sampling and time domain widening technology.

Background technique

In recent years, due to the important application value of signal carrier frequency measurement technology in military reconnaissance systems, microwave signal frequency measurement technology has received extensive attention and in-depth research by researchers from various countries. Traditional electronic frequency measurement technology is limited in terms of bandwidth, resolution, dynamic range and stability, while microwave photon frequency measurement technology has the advantages of large bandwidth, light weight, low loss and anti-electromagnetic interference. A research hotspot in the field of technology. In the microwave photon frequency measurement technology, there are multi-frequency and single-frequency frequency measurement technologies. Among single-frequency frequency measurement technologies, microwave photon instantaneous frequency measurement technology has become the focus of research in recent years due to its advantages of simple structure, fast speed and wide bandwidth. This technology realizes the mapping from frequency to amplitude by designing optical power or microwave power comparison curve, and realizes the measurement of microwave signal frequency. The limitation of this type of method is that it can only measure a single-frequency microwave signal, but in many cases, we need to measure a multi-frequency microwave signal and restore its spectrum information. The traditional signal spectrum restoration method obtains the signal spectrum information through the analog-to-digital converter and the discrete Fourier transform. However, the traditional analog-to-digital conversion is limited by the Nyquist sampling law, which requires the sampling frequency to be higher than twice the highest frequency of the signal to be measured in order to restore the spectrum of the original signal, which limits the signal bandwidth that can be measured to a large extent. . Compressive sampling technology overcomes the limitations of the traditional Nyquist sampling law, and can restore the spectral information of multi-frequency signals at an observation frequency much lower than the Nyquist frequency.

The frequency measurement technology based on compressed sampling requires the signal to be measured to be sparse in the frequency domain. In many cases, the signal to be measured is sparse in the frequency domain, referred to as a sparse signal. Such as multi-carrier modulated signals, sound signals, and slowly changing smooth signals. D. L. Donoho, "Compressed Sensing," IEEE Trans. Inf. Theory, 2006, vol. 52, no. 4, pp. 1289-1306 proposed the concept of compressed sensing, the idea is to a sparse signal, It can be observed at a speed much lower than the Nyquist frequency, and the spectral information of the original signal can be obtained through the restoration algorithm. J. Tropp, J. N. Laska, M. F. Duarte, J. K. Romberg and R. G. Baraniuk, "Beyond Nyquist: efficient sampling of sparse bandlimited signals," IEEE Trans. Signal Process, 2010, vol. 56, no. 1, pp. 520-544 gives a compression sampling technique based on random sequence modulation. In this technique, a random bit sequence with ±1 is first multiplied by the signal under test. Wherein, the changing frequency of the random bit sequence is required to reach the Nyquist frequency of the signal to be tested. Then output the digital signal through a low-pass filter and an electronic analog-to-digital converter with a low sampling rate and use it as an observation signal. Finally, the restoration algorithm is used to realize the reconstruction of the original signal spectrum. J. M. Nichols, F. Bucholtz, "Beating Nyquist with light: a compressive sampled photonic link," Opt. Express, 2011, vol. 19, no. 8, pp. 7339-7348 based on J. Tropp et al. The compressed sampling principle realizes the microwave photon compressed sampling technology. The structure uses a Mach-Zehnder modulator to modulate the random bit sequence and the microwave signal to be measured on the optical signal, and then processes the signal through photoelectric conversion, low-pass filtering and electronic analog-to-digital conversion. Finally, the spectrum information of the original signal is obtained through the restoration algorithm. The method realizes the multiplication of the microwave signal and the random bit sequence in the optical domain. Since the bandwidth of the photoelectric modulator is larger than that of the electrical multiplier, the bandwidth of the signal that can be measured is increased.

The above-mentioned several compression sampling techniques require the random bit sequence adopted to reach the Nyquist frequency. Although these techniques greatly reduce the sampling frequency of the electronic analog-to-digital converters in the system, the required random bit sequence is still limited by the Nyquist sampling law. A microwave photon frequency measurement device and method based on compressed sampling and time domain stretching technology proposed in this paper introduces dispersion delay technology. By reducing the frequency of the microwave signal to be measured and increasing the relative frequency of the random bit sequence, the compressed sampling measurement Frequency technology has completely broken through the limitations of Nyquist's law.

Contents of the invention

The purpose of the present invention is to provide a microwave photon frequency measurement device and method based on compressed sampling and time domain widening technology, which can realize the spectrum reconstruction of high-frequency signals at a lower sampling frequency, breaking through the limitations of the traditional Nyquist law. limit. Compared with the existing compressed sampling frequency measurement technology, the sampling frequency of the system is reduced.

The microwave photon frequency measurement device based on compressed sampling and time domain widening technology includes the microwave signal to be measured, the observation matrix module, the observation signal, the digital signal processing module, and the signal output port; The signal processing module is output by the signal output port; the observation matrix module includes a supercontinuum light source, a first dispersion medium, a first Mach-Zehnder modulator, a second dispersion medium, a second Mach-Zehnder modulator, a high-speed photodetector, a low pass filter, electronic analog-to-digital converter, RF input port of the first Mach-Zehnder modulator, bias voltage input port of the first Mach-Zehnder modulator, RF input port of the second Mach-Zehnder modulator, second Mach-Zehnder modulator Bias voltage input port of Zünder modulator; supercontinuum light source, first dispersive medium, first Mach-Zehnder modulator, second dispersive medium, second Mach-Zehnder modulator, high-speed photodetector, low-pass filter , the electronic analog-to-digital converters are connected in sequence, and the first Mach-Zehnder modulator is provided with a radio frequency input port of the first Mach-Zehnder modulator, a bias voltage input port of the first Mach-Zehnder modulator, and a second Mach-Zehnder modulator. The modulator is provided with a radio frequency input port of the second Mach-Zehnder modulator and a bias voltage input port of the second Mach-Zehnder modulator.

Microwave photon frequency measurement method based on compressed sampling and time-domain broadening technology: the supercontinuum light source passes through the positive dispersion medium, and the delayed and broadened optical carrier is obtained in the time domain. The amount of time broadening behind the dispersive medium; the microwave signal to be measured is modulated on the optical carrier after time-domain broadening through the radio frequency input port of the first Mach-Zehnder modulator, the modulator works at the linear bias point, and the first Mach-Zehnder modulation The bias voltage input by the bias voltage input port of the device is half of the half-wave voltage of the first Mach-Zehnder modulator; the modulated signal passes through the second dispersion medium and is further broadened in the time domain; the random bit sequence passes through the second Mach The RF input port of the Zehnder modulator is modulated on the dimmed signal output by the first Mach-Zehnder modulator, the second Mach-Zehnder modulator works at the linear bias point, and the bias voltage input of the second Mach-Zehnder modulator The bias voltage input by the port is half of the half-wave voltage of the second Mach-Zehnder modulator; the output port of the second Mach-Zehnder modulator is connected in sequence with a high-speed photodetector, a low-pass filter, and an electronic analog-to-digital converter. Photoelectric conversion, filtering and analog-to-digital conversion functions.

The beneficial effects that the present invention has are:

The existing compressed sampling technology needs to multiply the microwave signal to be measured with the random bit signal satisfying the Nyquist frequency. Although only a low-speed electronic analog-to-digital converter is connected at the end of the system, the frequency of the input signal is affected by the random bit signal. Limitation on the frequency of repetition of the bit sequence. The frequency measurement technology proposed by the invention does not need to input a random bit sequence satisfying the Nyquist frequency, which reduces the requirements for the realization of the frequency measurement system; it is beneficial to realize the spectrum reconstruction of high-frequency microwave signals, and improves the applicable range of the system.

Description of drawings

Fig. 1 is a structural schematic diagram of a compressed sampling frequency measuring device;

Fig. 2 is a detailed device connection diagram of Fig. 1;

In the figure: supercontinuum light source 1, first dispersive medium 2, first Mach-Zehnder modulator 3, second dispersive medium 4, second Mach-Zehnder modulator 5, high-speed photodetector 6, low-pass filter 7 , electronic analog-to-digital converter 8, the radio frequency input port 9 of the first Mach-Zehnder modulator, the bias voltage input port 10 of the first Mach-Zehnder modulator, the radio frequency input port 11 of the second Mach-Zehnder modulator, the second A bias voltage input port 12, a microwave signal to be measured 13, an observation matrix module 14, an observation signal 15, a digital signal processing module 16, and a signal output port 17 of the Mach-Zehnder modulator.

Detailed ways

The present invention will be further described below in conjunction with accompanying drawing:

As shown in Figures 1 and 2, the microwave photon frequency measurement device based on compressed sampling and time domain widening technology includes a microwave signal to be measured 13, an observation matrix module 14, an observation signal 15, a digital signal processing module 16, and a signal output port 17; The microwave signal 13 to be measured generates the observation signal 15 through the observation matrix module 14, and then outputs the signal output port 17 through the digital signal processing module 16; the observation matrix module 14 includes a supercontinuum light source 1, a first dispersive medium 2, a first Mach-Zehnder Modulator 3, second dispersion medium 4, second Mach-Zehnder modulator 5, high-speed photodetector 6, low-pass filter 7, electronic analog-to-digital converter 8, radio frequency input port 9 of the first Mach-Zehnder modulator , the bias voltage input port 10 of the first Mach-Zehnder modulator, the radio frequency input port 11 of the second Mach-Zehnder modulator, the bias voltage input port 12 of the second Mach-Zehnder modulator; the supercontinuum light source 1, the first The dispersive medium 2, the first Mach-Zehnder modulator 3, the second dispersive medium 4, the second Mach-Zehnder modulator 5, the high-speed photodetector 6, the low-pass filter 7, and the electronic analog-to-digital converter 8 are connected in sequence, The first Mach-Zehnder modulator 3 is provided with the radio frequency input port 9 of the first Mach-Zehnder modulator, the bias voltage input port 10 of the first Mach-Zehnder modulator, and the second Mach-Zehnder modulator 5 is provided with the first Mach-Zehnder modulator. The radio frequency input port 11 of the second Mach-Zehnder modulator, and the bias voltage input port 12 of the second Mach-Zehnder modulator.

The working principle of the present invention is as follows:

1. Assuming that the original signal x is a sparse signal represented by a set of N × N orthogonal matrices W, k is

；假设T是N×N的对角矩阵，代表第二色散介质的对微波信号的展宽过程；假设R是N×N的对角矩阵，代表带有±1的随机比特序列；假设F是N×N的矩阵，代表滤波器的滤波过程；假设D是L×N (L<<N)的矩阵，代表模数转换器的降采样过程；假设y是L×1的列向量，是最后输出的观测值矩阵。 Corresponding weight coefficients. Right now

;Assume that T is a diagonal matrix of N × N , representing the broadening process of the microwave signal of the second dispersive medium; Assume that R is a diagonal matrix of N × N , representing a random bit sequence with ±1; Assume that F is N The matrix × N represents the filtering process of the filter; assume that D is a matrix of L × N ( L <<N), representing the downsampling process of the analog-to-digital converter; assuming y is a column vector of L × 1, it is the final output The observation matrix of .

,其中是压缩采样系统的观测矩阵。y,

和W已知。选择合适的算法恢复k：

,其中

是稀疏优化项，得到原信号的近似估计:

。 2. According to principle 1, we can get

,in is the observation matrix of the compressed sampling system. y,

and W known. Choose an appropriate algorithm to recover k :

,in

is a sparse optimization item, and an approximate estimate of the original signal is obtained:

.

Microwave photon frequency measurement method based on compressed sampling and time-domain broadening technology: the supercontinuum light source 1 passes through the positive dispersion medium 2, and obtains the delayed and broadened optical carrier in the time domain, and the repetition time interval of the supercontinuum light source 1 is equal to that of the light The amount of time broadening after the pulse passes through the first dispersive medium 2; the microwave signal to be measured is modulated on the optical carrier through the time domain broadening through the radio frequency input port 9 of the first Mach-Zehnder modulator 3, and the modulator works at the linear bias point , the bias voltage input by the bias voltage input port 10 of the first Mach-Zehnder modulator 3 is half of the half-wave voltage of the first Mach-Zehnder modulator 3; the modulated signal passes through the second dispersion medium 4, in the time domain be further broadened; the random bit sequence lower than the Nyquist frequency is modulated on the dimmed signal output by the first Mach-Zehnder modulator 3 through the radio frequency input port 11 of the second Mach-Zehnder modulator 5, and the second Mach-Zehnder modulator The Zender modulator 5 works at the linear bias point, and the bias voltage input by the bias voltage input port 12 of the second Mach-Zender modulator 5 is half of the half-wave voltage of the second Mach-Zender modulator 5; The output port of the del modulator 5 is sequentially connected with a high-speed photodetector 6, a low-pass filter 7, and an electronic analog-to-digital converter 8 to realize photoelectric conversion, filtering and analog-to-digital conversion functions.

Claims (2)

1. the microwave photon frequency measuring device based on compression sampling and time domain broadening technology is characterized in that comprising microwave signal to be measured (13), observing matrix module (14), observation signal (15), digital signal processing module (16), signal output (17); Microwave signal to be measured (13) produces observation signal (15) through observing matrix module (14) and is exported by signal output (17) by digital signal processing module (16); Observing matrix module (14) comprises super continuum source (1), the first dispersive medium (2), first Mach increases Dare modulator (3), the second dispersive medium (4), second Mach increases Dare modulator (5), high-speed photodetector (6), low pass filter (7), electronic analogue-to-digital converter (8), first Mach of rf input port (9) that increases the Dare modulator, first Mach of bigoted voltage input (10) that increases the Dare modulator, second Mach of rf input port (11) that increases the Dare modulator, second Mach of bigoted voltage input (12) that increases the Dare modulator; Super continuum source (1), the first dispersive medium (2), first Mach increase Dare modulator (3), the second dispersive medium (4), second Mach and increase Dare modulator (5), high-speed photodetector (6), low pass filter (7), electronic analogue-to-digital converter (8) and link to each other in turn; First Mach increases Dare modulator (3) and is provided with first Mach and increases the rf input port (9) of Dare modulator, the bigoted voltage input (10) that first Mach increases the Dare modulator, second Mach increases Dare modulator (5) and is provided with second Mach of rf input port (11) that increases the Dare modulator, second Mach of bigoted voltage input (12) that increases the Dare modulator.

2. microwave photon frequency measuring method based on compression sampling and time domain broadening technology that use is installed as claimed in claim 1, it is characterized in that: super continuum source (1) is by the first dispersive medium (2), light carrier after time domain obtains delaying time broadening, the repetition interval of super continuum source (1) equal light pulse by the time explanation amount behind the first dispersive medium (2); Microwave signal to be measured is modulated on the light carrier through time domain broadening by first Mach of rf input port (9) that increases Dare modulator (3), modulator is operated in the linear bias point, and the bias voltage of first Mach of bigoted voltage input (10) input that increases Dare modulator (3) is first Mach and increases half of Dare modulator (3) half-wave voltage; Signal after the modulation obtains further broadening by the second dispersive medium (4) in time domain; Random bit sequence is modulated on first Mach of modulated optical signal that increases Dare modulator (3) output by second Mach of rf input port (11) that increases Dare modulator (5), second Mach increases Dare modulator (5) and is operated in the linear bias point, and second Mach of bias voltage that increases bigoted voltage input (12) input of Dare modulator (5) is second Mach and increases half of Dare modulator (5) half-wave voltage; Second Mach of delivery outlet that increases Dare modulator (5) links to each other in turn with high-speed photodetector (6), low pass filter (7), electronic analogue-to-digital converter (8) and realizes opto-electronic conversion, filtering and analog-digital conversion function.

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