CN114047381A - Photonic auxiliary microwave frequency measurement method and device based on precision compensation - Google Patents
Photonic auxiliary microwave frequency measurement method and device based on precision compensation Download PDFInfo
- Publication number
- CN114047381A CN114047381A CN202111251234.XA CN202111251234A CN114047381A CN 114047381 A CN114047381 A CN 114047381A CN 202111251234 A CN202111251234 A CN 202111251234A CN 114047381 A CN114047381 A CN 114047381A
- Authority
- CN
- China
- Prior art keywords
- frequency
- signal
- optical
- modulator
- power
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000000691 measurement method Methods 0.000 title claims abstract description 21
- 238000005259 measurement Methods 0.000 claims abstract description 149
- 230000010287 polarization Effects 0.000 claims abstract description 143
- 230000003287 optical effect Effects 0.000 claims abstract description 140
- 238000012545 processing Methods 0.000 claims abstract description 54
- 230000004044 response Effects 0.000 claims abstract description 12
- 238000012544 monitoring process Methods 0.000 claims abstract description 10
- 239000000835 fiber Substances 0.000 claims abstract description 8
- 238000001514 detection method Methods 0.000 claims abstract description 5
- 238000000034 method Methods 0.000 claims description 19
- 230000005540 biological transmission Effects 0.000 claims description 15
- 230000009977 dual effect Effects 0.000 claims description 14
- 238000013507 mapping Methods 0.000 claims description 13
- 230000001629 suppression Effects 0.000 claims description 9
- 230000035559 beat frequency Effects 0.000 claims description 8
- 230000003321 amplification Effects 0.000 claims description 5
- 238000003199 nucleic acid amplification method Methods 0.000 claims description 5
- 238000006243 chemical reaction Methods 0.000 claims description 4
- 239000013307 optical fiber Substances 0.000 claims description 4
- 239000004576 sand Substances 0.000 claims description 4
- 230000008859 change Effects 0.000 claims description 3
- 238000003780 insertion Methods 0.000 claims description 2
- 230000037431 insertion Effects 0.000 claims description 2
- 230000010363 phase shift Effects 0.000 claims description 2
- 230000009467 reduction Effects 0.000 claims description 2
- 239000000523 sample Substances 0.000 claims description 2
- 238000004088 simulation Methods 0.000 claims description 2
- 230000001149 cognitive effect Effects 0.000 abstract description 2
- 230000008901 benefit Effects 0.000 description 7
- 238000001228 spectrum Methods 0.000 description 6
- 230000002238 attenuated effect Effects 0.000 description 4
- 230000000295 complement effect Effects 0.000 description 4
- 238000010586 diagram Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000003595 spectral effect Effects 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 1
- 238000003491 array Methods 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 238000012795 verification Methods 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R23/00—Arrangements for measuring frequencies; Arrangements for analysing frequency spectra
- G01R23/02—Arrangements for measuring frequency, e.g. pulse repetition rate; Arrangements for measuring period of current or voltage
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R23/00—Arrangements for measuring frequencies; Arrangements for analysing frequency spectra
- G01R23/16—Spectrum analysis; Fourier analysis
- G01R23/17—Spectrum analysis; Fourier analysis with optical or acoustical auxiliary devices
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Mathematical Physics (AREA)
- Optical Modulation, Optical Deflection, Nonlinear Optics, Optical Demodulation, Optical Logic Elements (AREA)
Abstract
Disclosed is an accuracy compensation photonics auxiliary frequency measuring device based on interference and power cancellation scanning, which comprises a laser source, a polarization multiplexing double-parallel Mach-Zehnder modulator, an arbitrary waveform generator, an erbium-doped fiber amplifier, a polarization controller, a polarization beam splitter, a Mach-Zehnder interferometer, a photoelectric detector, an optical power meter, an electric power meter and a processing unit. Also provides a two-step measurement precision compensation photonics auxiliary frequency measurement method: the first step is to estimate the frequency band of the unknown radio frequency signal quickly, and the second step is to scan and measure in the estimated frequency band to obtain the accurate frequency measurement result. The invention can cover a larger frequency monitoring range to carry out frequency measurement with high precision and higher response speed. In addition, the invention can further realize high-resolution multi-frequency measurement and is suitable for an integrated cognitive detection system in a complex electromagnetic environment.
Description
Technical Field
The invention relates to the field of microwave photon frequency measurement, in particular to a precision compensation photonics-assisted microwave frequency measurement method and device based on interference and power cancellation scanning.
Background
Frequency measurement of intercepted microwave signals is an important task of modern radar warning and electronic countermeasure systems, usually done by specially designed receivers. Radar warning requires monitoring of threat signals in a wide spectral range in electromagnetic space and providing real-time early warning. Radar alarms are typically provided by instantaneous frequency measurement receivers with a wide range, fast and medium accuracy of measurement. Electronic countermeasure requires interference or interference resistance to a specific frequency, which puts higher demands on measurement accuracy. Electronic countermeasure is typically performed by scanning receivers or channelized receivers. However, the existing radar alarm receiver and the electronic countermeasure receiver are two independent parts, and the separated receiver causes the system structure to be complex, the cost to be high, and the problem of serious electromagnetic interference exists. Therefore, with the trend of integration and miniaturization of cognitive detection systems in complex electromagnetic environments, a compact frequency measurement system capable of providing a wide range, high accuracy and appropriate measurement response speed is urgently required. However, modern electronic receivers have difficulty meeting these requirements simultaneously due to the presence of electronic bottlenecks. Fortunately, a photon assisted frequency measurement system that combines the advantages of electronics and photonics can overcome the limitations of conventional electrical frequency measurement systems.
In recent years, many photon-assisted frequency measurement methods based on microwave photonics (MWP) have been proposed. These methods are mainly divided into two categories: an Instantaneous Frequency Measurement (IFM) system and a Scanning Frequency Measurement (SFM) system. The main principle of the instantaneous frequency measurement system is to map the frequency information of an unknown microwave signal to the power ratio between two electrical or optical signals. This power ratio is also called Amplitude Comparison Function (ACF), and is generally constructed by two frequency-dependent power penalty functions with complementary characteristics obtained by optical processing means such as interference, dispersion, or polarization. The measurement error of the frequency-power mapping frequency measurement methods can reach hundreds of megahertz, and only the frequency of a single-frequency signal can be measured. In order to realize frequency measurement of a plurality of signals simultaneously, a frequency-space mapping frequency measurement method is provided. However, these methods typically require large filter arrays, which increases the complexity of system operation and incurs higher costs. Another way to implement frequency measurement of multiple signals is to scan the measurement SFM. Swept frequency measurement systems are typically implemented by frequency-time mapping methods such as fourier transforms, cyclic frequency shift loops, or swept optical sidebands. However, due to the scanning characteristic, the measurement response speed of the method is slow, and some short-term frequency components may be missed. Thus, instantaneous frequency measurements and swept frequency measurements can be combined, taking advantage of their complementary advantages to achieve better frequency measurements.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides a precision compensation photonics auxiliary frequency microwave measuring method and device based on interference and power cancellation scanning. In the first step, rough frequency measurement is carried out through the interference of a Mach-Zehnder interferometer (MZI), and the approximate frequency band range of the unknown microwave signal frequency is rapidly estimated. In the second step, the fine frequency measurement based on the power cancellation scanning can be focused in a smaller range for scanning, and finally, a high-precision frequency result is obtained. The invention can realize microwave frequency measurement with wide range, high precision and proper response speed. In addition, by expanding the scanning frequency measurement method based on power cancellation, the invention can also realize the frequency measurement of a plurality of signals with high resolution.
The specific technical scheme provided by the invention is as follows:
the invention provides a photon auxiliary frequency microwave measuring device with precision compensation,
the invention has the following advantages:
1. the method aims at the problems of complex system structure, high cost and serious electromagnetic crosstalk caused by independent work of the radar alarm receiver and the electronic countermeasure receiver in the existing electronic warfare. The frequency measurement system adopting the two-step measurement precision compensation is provided by combining the large bandwidth and the quick response of the instantaneous frequency measurement method and the complementary advantages of the high precision of the scanning frequency measurement method and the multi-frequency signal frequency measurement capability, so that the scanning range of the precision frequency measurement is greatly reduced. The frequency measurement with large bandwidth, high precision and fast response speed can be realized.
2. Aiming at application scenarios (such as electronic countermeasure under complex electromagnetic conditions) with higher measurement accuracy and multi-frequency signal measurement requirements, the high-resolution frequency measurement of the multi-frequency signal can be realized through a scanning frequency measurement method based on power cancellation.
3. In the electro-optical modulation part, the polarization multiplexing technology of an integrated polarization multiplexing double-parallel Mach-Zehnder modulator is adopted to replace the parallel structure of the traditional multi-modulator, and meanwhile, unknown microwave signals and scanning signals are modulated onto optical carriers. The system complexity can be simplified, the link stability can be improved, and a compact, stable and efficient frequency measurement framework is provided for future miniaturized and integrated detection receivers.
Drawings
FIG. 1 is a schematic structural diagram of a photonics-assisted microwave frequency measuring device according to the present invention;
FIG. 2 shows the internal structure and signal modulation arrangement of a polarization multiplexed dual parallel Mach-Zehnder modulator;
fig. 3 is a schematic diagram of the output spectrum principle after modulation of the modulator signal: wherein fig. 3(a) shows a carrier suppressed double sideband modulated optical signal spectrum output by the double parallel mach-zehnder modulator 1; FIGS. 3(b-i) and 3(b-ii) illustrate the spectral processing principle of the power cancellation scan frequency measurement method: FIG. 3(b-i) shows when fs≠fxWhen the optical signal spectrum is modulated, the carrier wave output by the double parallel Mach-Zehnder modulator 2 restrains the spectrum of the double-sideband modulation optical signal; FIG. 3(b-ii) shows when fs＝fsWhen the optical signal spectrum is modulated, the carrier wave output by the double parallel Mach-Zehnder modulator 2 restrains the spectrum of the double-sideband modulation optical signal;
FIG. 4(a) is a schematic illustration of the transmission response of the Mach-Zehnder interferometer and the frequency setting of the optical carrier; FIG. 4(b) shows theoretical curves of theoretical simulated output optical power and corresponding amplitude comparison function ACF for two output ports of the Mach-Zehnder interferometer;
fig. 5 shows the simulation measurement result of coarse frequency measurement: FIG. 5(a) shows the results of the calculation of the optical power and the associated amplitude comparison function ACF at the two output ports of the Mach-Zehnder interferometer; FIG. 5(b) shows a comparison between the input frequency and the measured frequency and the absolute measurement error;
FIG. 6(a) shows the frequency f of an unknown RF signalxWhen the frequency is 3GHz, a scanning result of the accurate frequency measurement based on the power cancellation method is obtained; FIG. 6(b) shows the scan results near the power notch; FIG. 6(c) shows a comparison between the input frequency of the fine measurement frequency and the measurement error;
fig. 7(a) shows a complex multi-frequency signal measurement result based on an extension of the power cancellation scanning frequency measurement method; fig. 7(b) shows the result of resolution verification in multi-frequency measurement of the power cancellation scanning frequency measurement method.
Detailed Description
The invention provides a precision compensation photonics-assisted microwave frequency measurement method and device based on interference and power cancellation scanning, which are further described with reference to the accompanying drawings.
Precision compensation photonics auxiliary frequency measuring device based on interference and power compensation scanning
A system link is shown in fig. 1, and an accuracy compensation photonic auxiliary microwave frequency measurement device based on Mach-Zehnder interference and power cancellation comprises a laser, a polarization multiplexing double-parallel Mach-Zehnder modulator (PDM-DPMZM), an arbitrary waveform generator, a erbium-doped fiber amplifier, a polarization controller, a polarization beam splitter, a Mach-Zehnder interferometer, a photoelectric detector, an optical power meter, an electric power meter, and a processing unit.
Inputting optical carrier generated by a laser, unknown radio frequency signal and scanning signal generated by an arbitrary waveform generator into polarization multiplexing dual-parallel Mach-ZehnderModulator at a DC bias voltage VbiasxAnd VbiasxCarrying out carrier suppression double-sideband modulation under the control of the optical fiber to obtain an orthogonal polarization multiplexing optical signal and then outputting the orthogonal polarization multiplexing optical signal. The orthogonal polarization multiplexing optical signal is input into an erbium-doped fiber amplifier for power amplification and then output. The amplified orthogonal polarization multiplexing optical signal is input into a polarization controller for polarization direction adjustment, and the polarization direction of the amplified orthogonal polarization multiplexing optical signal is output after being aligned with a main shaft of a polarization beam splitter. The orthogonal polarization multiplexing optical signal with the adjusted polarization direction is input into a polarization beam splitter for polarization demultiplexing processing, and two paths of optical signals working in the orthogonal polarization direction respectively are output.
After polarization demultiplexing, an optical signal working in the x polarization direction of an upper path is input into a Mach-Zehnder interferometer for interference processing, and two output ports of the Mach-Zehnder interferometer are respectively connected with an optical power meter. The data measured by the two optical power meters are input into a processing unit for optical power monitoring and amplitude comparison processing, and the processing unit obtains the rough measurement frequency f of the unknown radio frequency signal according to the amplitude comparison resultroughThen, the output signal is divided into two paths, one path is roughly measured for frequency froughInformation is directly output, and the frequency f is roughly measured by the other pathroughThe information is input into an arbitrary waveform generator, which is controlled to generate a scanning signal within a certain range.
After polarization demultiplexing, an optical signal of the lower circuit working in the y polarization direction is input into the photoelectric detector for beat frequency processing and then output, and the electrical signal after beat frequency is input into the electric power meter. The electric power meter inputs the measured power data into the processing unit, the processing unit maps the power data measured by the electric power meter and the frequency of the scanning signal generated by the arbitrary waveform generator one by one, records the mapping relation, finds the frequency of the scanning signal corresponding to the power notch position and outputs the frequency as a fine frequency measurement result faccurate。
Frequency result f of coarse frequency measurementroughThe position of the center frequency of the fine measurement is determined, and the maximum error of the coarse frequency measurement determines the bandwidth of the forward and backward scanning of the fine measurement. The result of the coarse frequency measurement is that the AWG generates a range of scanning signals.
The electro-optical modulation part is shown in figure 2, and the polarization multiplexing double-parallel Mach-Zehnder modulator is an integrated modulator and consists of two parallel double-parallel Mach-Zehnder modulators, a 180-degree electric phase shifter, a 90-degree polarization rotator and a polarization beam combiner. The double parallel Mach-Zehnder modulator is composed of two embedded sub-modulators and a main modulator. The DC bias points of 4 sub-modulators and 2 main modulators of the polarization multiplexing dual-parallel Mach-Zehnder modulator are all set on the minimum transmission bias point MITB (namely the DC voltage is V)π) Carrier suppressed double sideband modulation is performed. At the first double parallel Mach-Zehnder modulator x, the frequency is fxThe unknown radio frequency signal is divided into two paths with equal power. The phase of the input 180 degree electric phase shifter is shifted, the phase of the unknown RF signal is input to the first sub-modulator x1The radio frequency input port of (1). The unknown radio frequency signal of the lower path is divided into two paths by equal power again, wherein one path is input into a second sub-modulator x2And the other path of the first signal is input into a third sub-modulator Y of a second double-parallel Mach-Zehnder modulator Y1The radio frequency input port of (1). First sub-modulator x1And a second sub-modulator x2The output modulated optical signal is modulated by the primary modulator X of the first double-parallel Mach-Zehnder modulator X3And inputting the phase-inverted superposed signals into a polarization beam combiner. At the second double-parallel Mach-Zehnder modulator Y, the frequency is fsIs inputted to the fourth sub-modulator y2The radio frequency input port of (1). Third sub-modulator y1And a fourth sub-modulator y2The output carrier suppressed double sideband modulated optical signal is modulated by the main modulator Y of the second double parallel Mach-Zehnder modulator Y3And after the phase inversion superposition, the polarization state is input into a 90-degree polarization rotator, and the polarization state is rotated to the y polarization direction (the default polarization state is the x polarization direction). The optical signals after polarization rotation are input into a polarization beam combiner, and the polarization beam combiner combines the optical signals output by the first double-parallel Mach-Zehnder modulator X and the second double-parallel Mach-Zehnder modulator Y into a beam of orthogonal polarization multiplexing light.
Two-step measurement-based precision compensation photonics auxiliary frequency measurement method
The invention also provides a precision compensation photonics auxiliary frequency measurement method based on two-step measurement, and the main idea is to divide the precision compensation into two steps of rough frequency measurement and fine frequency measurement.
The first step is to perform coarse frequency measurement based on interference: orthogonal polarization multiplexing light output by the polarization multiplexing double-parallel Mach-Zehnder modulator is demultiplexed by the polarization beam splitter, carrier suppression double-sideband optical signals working in the x polarization direction are input into the Mach-Zehnder interferometer for interference processing, and then the two optical powers respectively monitor the optical powers P1 and P2 of the two output ports of the Mach-Zehnder interferometer. The processing unit constructs an amplitude comparison function ACF (amplitude comparison function) P1/P2 according to the monitored power value, and an ACF-frequency lookup table is established in advance. In practical application, the processing unit can calculate the corresponding ACF value according to the measured optical power value, and find out the frequency of the unknown rf signal according to the ACF-frequency lookup table. It should be noted that, due to the coarse frequency measurement principle and the limitation of the performance of the existing device, the frequencies obtained by the lookup table are only the coarse frequencies f of the unknown rf signalsrough。
The second step is to perform fine frequency measurement based on power cancellation scanning: based on the result of the coarse frequency measurement (coarse frequency f of the unknown radio frequency signal)roughAnd maximum measurement error Δ err), the arbitrary waveform generator is generated to operate at [ f [rough-Δerr，frough+Δerr]A scan signal within a range. And then mixing the scanning signal and the unknown radio frequency signal to an optical carrier wave, and carrying out scanning frequency measurement based on power cancellation. Due to the special arrangement of the double parallel Mach-Zehnder modulator y, the phases of the optical sidebands modulated by the scanning signal and the unknown radio frequency signal are completely opposite. As the frequency of the sweep signal varies, when the frequency of the sweep signal overlaps the frequency of the unknown radio frequency signal (i.e., f)s＝fx) The optical sidebands excited by the unknown radio frequency signal will be attenuated or even cancelled. This reflects that a power notch will be generated on the output power-sweep frequency mapping curve monitored by the processing unit, and the sweep signal frequency corresponding to the notch position is the fine frequency measurement result f of the unknown RF signalaccurate。
As shown in table 1, the precision compensated photonics assisted frequency measurement method based on interference and power cancellation scanning is roughly divided into six steps.
Table 1. approximate frequency measurement procedure.
The specific method steps are as follows:
step 1: and the unknown radio frequency signal is modulated and then input into a Mach-Zehnder interferometer for interference processing.
Inputting the intercepted unknown radio frequency signal into a double-parallel Mach-Zehnder modulator x and modulating the unknown radio frequency signal onto an optical carrier, and sending the modulated optical signal to a Mach-Zehnder interferometer to execute interference processing;
the specific method steps of the unknown radio frequency signal being modulated by the double parallel Mach-Zehnder modulator x and being interfered by the Mach-Zehnder interferometer are as follows:
s1.1 modulation processing: in a polarization multiplexing dual parallel mach-zehnder modulator, the dc voltages of two sub-modulators and one main modulator embedded in the dual parallel mach-zehnder modulator x are both set at the minimum transmission bias point MITP to perform carrier-suppressed dual sideband modulation. The intercepted unknown radio frequency signal is firstly divided into two paths with equal power. The phase of the input 180 degree electric phase shifter is shifted, and the phase-inverted unknown RF signal is input to the sub-modulator x1The radio frequency input port of (1). The unknown radio frequency signal of the lower path is divided into two paths by equal power again, wherein one path is input into a sub-modulator x2The radio frequency input port of (1). Sub-modulator x1And sub-modulator x2The output modulated optical signals are output after being subjected to phase inversion superposition by a main modulator x.
Suppose that the amplitude and frequency of the optical carrier generated by the laser are E0And
the unknown radio frequency signal is denoted VRF(t)＝V sin(2πfxt), where V represents the amplitude of the unknown radio frequency signal. Neglecting the insertion loss of the modulator, the output optical signal of the dual parallel mach-zehnder modulator x is represented as:
wherein, VπIs the half-wave voltage of the dual parallel mach-zehnder modulator x. In the case of small signal modulation, the optical sideband power above the first order is negligible due to the low power. Thus, equation (1) after Jacobi-Anger expansion can be expressed as:
wherein, J1(m) is a first order Bessel function of the first kind, modulation index mRF＝πVRF/Vπ。
S1.2, transmission processing: orthogonal polarization multiplexing optical signals output by the polarization multiplexing double-parallel Mach-Zehnder modulator are input into an erbium-doped optical fiber amplifier for power amplification treatment. The amplified polarization multiplexing light is input into a polarization controller, and two polarization states of the light signal are adjusted to be aligned to a main shaft of the polarization beam splitter. The orthogonal polarization multiplexing optical signal after passing through the polarization controller is subjected to polarization demultiplexing processing by a polarization beam splitter, and two paths of optical signals respectively working in orthogonal polarization directions (x polarization direction and y polarization direction) are output.
S1.3, interference treatment: after polarization demultiplexing, inputting an optical signal working in the x polarization direction into a Mach-Zehnder interferometer for interference treatment: the two arms of the mach-zehnder interferometer have different transmission responses, and the optical signals at the two output ports of the mach-zehnder interferometer can be expressed as follows by neglecting the loss of the two arms of the mach-zehnder interferometer:
wherein the optical path length (L) in both arms of the Mach-Zehnder interferometer1And L2) Induced phase shift Φi＝-2πfinLi/c，(i＝1，2)。f1And f2Horse stands for frequency f respectivelyc-fxAnd fc+fxThe time delay τ n (L) caused by the length difference between the two arms of the Mach-Zehnder interferometer1-L2) And c, the ratio of the total weight to the total weight of the product. n and c are the refractive index and the speed of light in vacuum, respectively.
Step 2: and respectively monitoring the optical power of two output ports of the Mach-Zehnder interferometer by using two optical power meters.
Respectively monitoring the optical power P1 and P2 of two output ports of the Mach-Zehnder interferometer by using two optical power meters;
the optical power at the two output ports of the mach-zehnder interferometer can be expressed as:
step 3: the processing unit constructs an amplitude comparison function ACF (amplitude comparison function) P1/P2 according to the monitored optical powers P1 and P2, establishes a frequency-ACF lookup table, searches corresponding frequencies according to the calculated ACF value, and obtains a coarse frequency measurement result frough。
The constructed magnitude comparison function ACF can be expressed as:
obviously, since the amplitude comparison function ACF is the power ratio of the two optical signals, the influence of power fluctuation (including optical power and microwave power) on the system link on the frequency measurement accuracy can be eliminated. Amplitude comparison function ACF depends on the time delay τ, the frequency of the optical carrier and the frequency of the unknown radio frequency signal. As shown in fig. 4(a), when the time delay τ is fixed, the optical carrier frequency is set at the peak or trough of the mach-zehnder interferometer transmission response. The theoretical analog optical power and amplitude comparison function ACF at the two output ports of the Mach-Zehnder interferometer is shown in FIG. 4 (b). The first monotonic range of ACF is 1/2 τ, where the mapping between ACF and microwave frequencies is unique. Therefore, an ACF-frequency lookup table can be established in the range, so that the corresponding frequency is searched according to the ACF value calculated by measuring the power, and the rough frequency measurement result f is obtainedrough。
The results of the simulated measurement of the coarse frequency measurement based on interference are shown in fig. 5: fig. 5(a) shows the result of calculating the optical power of the two output ports of the mach-zehnder interferometer measured by the optical power meter and the associated amplitude comparison function ACF. It can be seen that the measured value is consistent with the theoretical prediction, the power of the two optical signals after the interference processing has complementary characteristics, and the ACF calculated according to the measured power is highly consistent with the ACF calculated according to the theory of equation (6); fig. 5(b) shows a comparison between the input frequency and the measurement frequency and an absolute measurement error, which is less than 0.3GHz in the frequency range of 0.5GHz-39 GHz. This also means the maximum Error for coarse frequency measurement based on interferencemax＝0.3GHz。；
Step 4: according to the first step coarse frequency measurement result (estimated frequency f)roughAnd maximum measurement Errormax) Determining the scanning range of the scanning signal generated by the arbitrary waveform generator as [ frough-Errormax，frough+Errormax]. And then, mixing the scanning signal and the unknown radio frequency signal onto an optical carrier by using a polarization multiplexing double-parallel Mach-Zehnder modulator to perform power cancellation processing.
The specific method for determining scanning frequency, signal modulation mixing and power cancellation comprises the following steps:
s4.1 determining the scanning frequency: coarse interference-based frequency measurement (estimated frequency f) according to the first steproughAnd maximum measurement Errormax) Determining arbitrary waveform generationThe scanning range of the scanning signal generated by the device is frough-Errormax，frough+Errormax]。
S4.2, signal modulation mixing: in the polarization multiplexing double-parallel Mach-Zehnder modulator, the direct current voltages of two sub-modulators and one main modulator embedded in the double-parallel Mach-Zehnder modulator y are both set at the minimum transmission bias point MITP to perform carrier suppression double-sideband modulation. Unknown radio frequency signal input sub-modulator y1The radio frequency input port of (1). Scanning signal input sub-modulator y2The radio frequency input port of (1). Sub-modulator y1And sub-modulator y2The output carrier suppression double-sideband modulation optical signals are output after being subjected to phase inversion superposition by the main modulator y.
Suppose that the amplitude, frequency and initial phase of the scanning signal are VS，fsAnd
the output optical signal of the dual parallel mach-zehnder modulator y may be expressed as:
Vπis the half-wave voltage of the double parallel Mach-Zehnder modulator y and the modulation coefficient mS＝πVS/Vπ. Equation (7) after Jacobi-Anger expansion can be expressed as:
s4.3, power cancellation: due to the special arrangement of the double parallel Mach-Zehnder modulators y, the scanning signal fsAnd unknown radio frequency signal fxThe phases of the modulated optical sidebands are completely opposite. As the frequency of the sweep signal varies, when the frequency of the sweep signal overlaps the frequency of the unknown radio frequency signal (i.e., f)s＝fx) The optical sidebands excited by the unknown rf signal will be attenuated or even cancelled.
One special case that needs to be taken care of during scanning, i.e. when the scanning signal frequency overlaps with the unknown radio frequency signal frequency (f)s＝fx) The optical sidebands excited by the unknown rf signal will be attenuated or even eliminated. In this case, the optical signal output by the double parallel mach-zehnder modulator y is:
s4.4, transmission processing: in the polarization multiplexing dual-parallel Mach-Zehnder modulator, output optical signals of the dual-parallel Mach-Zehnder modulator x and the dual-parallel Mach-Zehnder modulator y are combined into a beam of orthogonal polarization multiplexing light by a polarization beam combiner. The orthogonal polarization multiplexing light is subjected to power amplification by the erbium-doped fiber amplifier and is subjected to polarization demultiplexing by the polarization beam splitter through the adjustment of the polarization controller to form two paths of polarization orthogonal optical signals. And after demultiplexing, the optical signal working in the y polarization direction is input into a photoelectric detector for beat frequency processing.
S5: an electrometer is used to measure the power of the electrical signal after passing through the photodetector.
Assuming that the gain of the erbium-doped fiber amplifier is G, the amplitude of the scanning signal is k times (i.e. V) of the unknown RF signalS＝kVRF). In the case of small signal modulation, J1(mRF)≈mRF/2，J1(mS)≈mS/2＝kmRF/2. Therefore, the optical signal output by the dual parallel mach-zehnder modulator y passes through the photodetector, and the detection current after the beat frequency processing can be expressed as:
wherein
Is the responsivity of the photodetector. It can be seen that the detected current contains a direct current component, a second order component and a conversion component (f)s-fxAnd fs+fx). Thus, the corresponding electrical power is expressed as:
when the scanning signal frequency overlaps with the unknown radio frequency signal frequency (f)x＝fx) The corresponding probe current can be expressed as:
comparing equation (10) and equation (12) it can be found that when fs＝fxTime, frequency conversion component fs-fxAre all cancelled out, resulting in a reduction in electrical power. At this time, the electric power is:
here, P (DC) represents the power of the direct current component, and P (2 f)x) And P (-2 f)x) Respective frequency component 2fxAnd-2 fxThe corresponding power. Obviously, when the scanning signal frequency overlaps with the unknown rf signal frequency, the total power will change, leaving only dc, 2fxAnd-2 fxThereby implementing a power notch.
Step 6: the processing unit records the mapping relation between the measured electric power and the frequency of the scanning signal, finds the scanning frequency corresponding to the notch position of the power, and obtains a precise frequency measurement result faccurateAnd output.
As shown in equation (13), as the sweep signal frequency varies, when the sweep signal frequency overlaps with the frequency of the unknown RF signal (i.e., f)s＝fx) The optical sidebands excited by the unknown rf signal will be attenuated or even cancelled. This is reflected in a power notch being generated on the output power-sweep frequency mapping curve monitored by the processing unit, the notch position pairThe frequency of the scanning signal is the accurate frequency measurement result f of the unknown radio frequency signalaccurate。
As shown in fig. 6(a) and 6(b), in order to more intuitively show that the fine frequency measurement benefits from the coarse frequency measurement estimation, the scanning measurement is performed in a narrower range. We illustrate that when the actual frequency of the unknown radio frequency signal is 3GHz, the sweep signal frequency is swept from 2.7GHz to 3.3GHz in steps of 0.001 GHz. It is apparent that when the sweep signal frequency overlaps with the unknown radio frequency signal frequency (i.e., f)s≈fx) The optical sidebands excited by the unknown radio frequency signal are cancelled, thereby obtaining a power notch. In the ideal case of power cancellation, the depth of the power notch can be up to 23 dB. In theoretical analysis, only if the frequency of the sweep signal is exactly equal to the frequency of the unknown radio frequency signal (i.e., f)s＝fx) Then, power notch can be achieved. However, the width of the power notch is widened to 4MHz due to the line width of the optical carrier and the influence of noise in the link. The measurement result of the fine frequency measurement is shown in fig. 6 (c). It can be clearly seen that the measurement frequency is highly consistent with the frequency of the input radio frequency signal, with measurement errors below 4MHz in the range of 0.5GHz to 39 GHz. Compared with the result of coarse frequency measurement, the precision is obviously improved.
In addition, under the actual complex electromagnetic environment, the intercepted radio frequency signal often contains a plurality of frequency components, and the capability of single-frequency measurement is not enough. : the invention combines the characteristics of instantaneous frequency measurement and scanning frequency measurement, can expand the scanning measurement based on power cancellation, and realizes multi-frequency measurement under complex electromagnetic conditions. The minimum resolution in multi-frequency measurements was also further investigated. The parameter settings for the multifrequency measurements and resolution tests are shown in table 2.
TABLE 2 parameter settings for multifrequency measurements and resolution tests
The result of the multi-frequency measurement is shown in fig. 7 (a). It can be seen that power notches are observed at 3GHz, 7GHz, 11GHz and 14GHz, indicating that the frequency measurement is very good. In addition, the depth of the power notch varies due to differences in the power and random phase of the radio frequency signal. In addition, to investigate the resolution at the time of multi-frequency measurement, the dual parallel mach-zehnder modulator was driven by a two-tone signal at 9GHz and 9.01 GHz. The measurement results are shown in fig. 7 (b). It can be seen that when the frequency separation of the two signals exceeds 10MHz, a good distinction can be made, i.e. the multi-frequency measurement resolution of the system is 10 MHz.
In summary, the main principle of the photonic assisted frequency measurement method provided by the present invention is based on two-step measurement precision compensation: the first step is based on the rough frequency measurement of interference, and the frequency band where the unknown radio frequency signal is located is quickly estimated in a wider frequency monitoring range. According to the frequency band estimated by the rough frequency measurement, the second step is to scan and measure based on the power cancellation, and scan in a narrow frequency range to obtain an accurate frequency measurement result, so that the measurement precision and the measurement response speed are greatly improved. In addition, in the electro-optical modulation part, an unknown radio-frequency signal and a scanning signal are simultaneously modulated to an optical domain by using an integrated polarization multiplexing double-parallel Mach-Zehnder modulator, so that the system structure can be simplified, and the modulation stability can be improved.
The above description is only an example of the present application and is not intended to limit the present application; various modifications and changes may occur to those skilled in the art; any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.
Compared with the inventor's previous patent application of ' a functional flexible photonics auxiliary frequency measuring method and device (application number: 202110701008.0) ', the invention has the following advantages:
1. the frequency measurement precision is higher: compared with the previous patent, the frequency measurement precision is improved from 20MHz to 4 MHz. And a power cancellation technology is used in the fine frequency measurement part. Due to the special signal arrangement of the polarization multiplexing double-parallel Mach-Zehnder modulator, when the frequency of a scanning signal is equal to that of an unknown radio-frequency signal, the optical sideband intensities of the two modulated signals are mutually offset due to the fact that the phases are opposite, so that a power trapped wave with a very narrow bandwidth is achieved, and the frequency measurement precision is greatly improved.
2. The frequency measuring range is wider, and compared with the last patent, the frequency measuring range is widened from the frequency range of 1GHz-31GHz to 0.5GHz-39 GHz. The precision of the precise frequency measurement is improved, and larger measurement errors can be tolerated during the rough frequency measurement. Therefore, the monotone interval range of the ACF function can be enlarged by adjusting the time delay tau of the Mach-Zehnder interferometer, thereby widening the frequency measurement range.
3. The measurement capability of the frequency of the multi-frequency signal is increased: the last patent can only measure the frequency of the single tone signal. The scanning frequency measurement method is adopted, all detected frequency information can be recorded in one scanning period, multi-frequency measurement can be achieved, and the frequency resolution during multi-frequency measurement can reach 10 MHz. Therefore, the invention has stronger adaptability to frequency measurement in complex electromagnetic environment.
Claims (4)
1. The photonic-assisted microwave frequency measurement device based on precision compensation is characterized by comprising a laser, a polarization multiplexing double-parallel Mach-Zehnder modulator PDM-DPMZM, an arbitrary waveform generator, an erbium-doped fiber amplifier, a polarization controller, a polarization beam splitter, a Mach-Zehnder interferometer, a photoelectric detector, an optical power meter, an electric power meter and a processing unit; wherein
Inputting optical carrier generated by a laser, unknown radio frequency signals and scanning signals generated by an arbitrary waveform generator into a polarization multiplexing dual-parallel Mach-Zehnder modulator, and applying a DC bias voltage VbiasxAnd VbiasxCarrying out carrier suppression double-sideband modulation under the control of the optical amplifier to obtain an orthogonal polarization multiplexing optical signal and then outputting the orthogonal polarization multiplexing optical signal; the orthogonal polarization multiplexing optical signal is input into an erbium-doped optical fiber amplifier for power amplification and then output; inputting the amplified orthogonal polarization multiplexing optical signal into a polarization controller for polarization direction adjustment, and outputting after the polarization direction of the amplified orthogonal polarization multiplexing optical signal is aligned with a main shaft of a polarization beam splitter; the orthogonal polarization multiplexing optical signal with the adjusted polarization direction is input into a polarization beam splitter for polarization demultiplexing processing, and two paths of light working in the orthogonal polarization direction respectively are outputA signal;
after polarization demultiplexing, inputting an optical signal working in the x polarization direction in an upper path into a Mach-Zehnder interferometer for interference processing, wherein two output ports of the Mach-Zehnder interferometer are respectively connected with an optical power meter; the data measured by the two optical power meters are input into a processing unit for optical power monitoring and amplitude comparison processing, and the processing unit obtains the rough measurement frequency f of the unknown radio frequency signal according to the amplitude comparison resultroughThen, the output signal is divided into two paths, one path is roughly measured for frequency froughInformation is directly output, and the frequency f is roughly measured by the other pathroughInputting information into an arbitrary waveform generator, and controlling the arbitrary waveform generator to generate a scanning signal within a certain range;
after polarization demultiplexing, an optical signal of the lower circuit working in the y polarization direction is input into the photoelectric detector for beat frequency processing and then output, and the electrical signal after beat frequency is input into the electric power meter; the electric power meter inputs the measured power data into the processing unit, the processing unit maps the power data measured by the electric power meter and the frequency of the scanning signal generated by the arbitrary waveform generator one by one, records the mapping relation, finds the frequency of the scanning signal corresponding to the power notch position and outputs the frequency as a fine frequency measurement result faccurate；
Frequency result f of coarse frequency measurementroughDetermining the position of the center frequency of the fine measurement, and determining the bandwidth of forward and backward scanning of the fine measurement according to the maximum error of the coarse frequency measurement; the result of the coarse frequency measurement is that the AWG generates a range of scanning signals.
2. The photonic-assisted microwave frequency measurement device based on precision compensation of claim 1, wherein the polarization multiplexing dual-parallel mach-zehnder modulator is an integrated modulator, and consists of two parallel dual-parallel mach-zehnder modulators, a 180 ° electrical phase shifter, a 90 ° polarization rotator and a polarization beam combiner; wherein
The double parallel Mach-Zehnder modulator is composed of two embedded sub-modulators and a main modulator; 4 sub-modulators of a polarization multiplexed dual parallel mach-zehnder modulator andthe dc bias points of the 2 main modulators are all set at the minimum transmission bias point MITB, i.e. the dc voltage is VπPerforming carrier suppressed double sideband modulation; at the first double parallel Mach-Zehnder modulator X, the frequency is fxThe unknown radio frequency signal is divided into two paths with equal power; the phase of the input 180 degree electric phase shifter is shifted, the phase of the unknown RF signal is input to the first sub-modulator x1The radio frequency input port of (1); the unknown radio frequency signal of the lower path is divided into two paths by equal power again, wherein one path is input into a second sub-modulator x2And the other path of the first signal is input into a third sub-modulator Y of a second double-parallel Mach-Zehnder modulator Y1The radio frequency input port of (1); first sub-modulator x1And a second sub-modulator x2The output modulated optical signal is modulated by the primary modulator X of the first double-parallel Mach-Zehnder modulator X3Inputting the phase-reversed superposed signals into a polarization beam combiner; at the second double-parallel Mach-Zehnder modulator Y, the frequency is fsIs inputted to the fourth sub-modulator y2The radio frequency input port of (1); third sub-modulator y1And a fourth sub-modulator y2The output carrier suppressed double sideband modulated optical signal is modulated by the main modulator Y of the second double parallel Mach-Zehnder modulator Y3Inputting the phase-inverted superposed signals into a 90-degree polarization rotator to rotate the polarization state to the y polarization direction; the optical signals after polarization rotation are input into a polarization beam combiner, and the polarization beam combiner combines the optical signals output by the first double-parallel Mach-Zehnder modulator X and the second double-parallel Mach-Zehnder modulator Y into a beam of orthogonal polarization multiplexing light.
3. A precision compensation-based photonics-assisted microwave frequency measurement method using the precision compensation-based photonics-assisted microwave frequency measurement device of claim 1 or 2, wherein the method is divided into two steps of precision compensation coarse frequency measurement and precision frequency measurement;
the first step is to perform coarse frequency measurement based on interference: orthogonal polarization multiplexing light output by the polarization multiplexing double-parallel Mach-Zehnder modulator is demultiplexed by the polarization beam splitter, and then the carrier suppression double-sideband optical signal working in the x polarization directionInputting the signal into a Mach-Zehnder interferometer for interference processing, and then respectively monitoring the optical power P1 and P2 of two output ports of the Mach-Zehnder interferometer by using the two optical powers; the processing unit constructs an amplitude comparison function ACF (amplitude characteristic parameter) P1/P2 according to the monitored power value, and an ACF-frequency lookup table is established in advance; in practical application, the processing unit can calculate the corresponding ACF value according to the measured optical power value and find out the frequency of the unknown radio frequency signal according to the ACF-frequency lookup table; it should be noted that, due to the coarse frequency measurement principle and the limitation of the performance of the existing device, the frequencies obtained by the lookup table are only the coarse frequencies f of the unknown rf signalsrough；
The second step is to perform fine frequency measurement based on power cancellation scanning: based on the result of the coarse frequency measurement, i.e. the coarse frequency f of the unknown radio signalroughAnd a maximum measurement error Δ err, the arbitrary waveform generator operating at [ f [ ]rough-Δerr，frough+Δerr]A scan signal within a range; then mixing the scanning signal and the unknown radio frequency signal to an optical carrier wave, and carrying out scanning frequency measurement based on power cancellation; due to the special arrangement of the double parallel Mach-Zehnder modulator y, the phases of the optical sidebands modulated by the scanning signal and the unknown radio frequency signal are completely opposite; when the frequency of the scanning signal is overlapped with the frequency of the unknown radio frequency signal along with the change of the frequency of the scanning signal, i.e. fs＝fxWhen the radio frequency signal is received, the optical sideband excited by the unknown radio frequency signal is weakened or even cancelled; this reflects that a power notch will be generated on the output power-sweep frequency mapping curve monitored by the processing unit, and the sweep signal frequency corresponding to the notch position is the fine frequency measurement result f of the unknown RF signalaxcurate。
4. The method for photonic-assisted microwave frequency measurement based on precision compensation according to claim 3, wherein the method for precision-compensated photonic-assisted frequency measurement based on interference and power cancellation scanning is divided into six steps as shown in table 1;
table 1. approximate frequency measurement procedure.
The method comprises the following specific steps:
step 1: after being modulated, unknown radio frequency signals are input into a Mach-Zehnder interferometer for interference processing;
inputting the intercepted unknown radio frequency signal into a double-parallel Mach-Zehnder modulator x and modulating the unknown radio frequency signal onto an optical carrier, and sending the modulated optical signal to a Mach-Zehnder interferometer to execute interference processing;
the specific method steps of the unknown radio frequency signal being modulated by the double parallel Mach-Zehnder modulator x and being interfered by the Mach-Zehnder interferometer are as follows:
s1.1 modulation processing: in the polarization multiplexing double-parallel Mach-Zehnder modulator, the direct-current voltages of two sub-modulators and a main modulator embedded in the double-parallel Mach-Zehnder modulator x are both arranged on a minimum transmission bias point (MITP) so as to carry out carrier suppression double-sideband modulation; firstly, dividing intercepted unknown radio frequency signals into two paths with equal power; the phase of the input 180 degree electric phase shifter is shifted, and the phase-inverted unknown RF signal is input to the sub-modulator x1The radio frequency input port of (1); the unknown radio frequency signal of the lower path is divided into two paths by equal power again, wherein one path is input into a sub-modulator x2The radio frequency input port of (1); sub-modulator x1And sub-modulator x2The output modulated optical signal is output after being inverted and superposed by a primary modulator x;
suppose that the amplitude and frequency of the optical carrier generated by the laser are E0And
the unknown radio frequency signal is denoted VRF(t)＝V sin(2πfxt), where V represents the amplitude of the unknown radio frequency signal; neglecting the insertion loss of the modulator, the output optical signal of the dual parallel mach-zehnder modulator x is represented as:
wherein, VπIs the half-wave voltage of the dual parallel mach-zehnder modulator x; under the condition of small signal modulation, the optical sideband power of more than one order is low, so that the optical sideband power can be ignored; thus, equation (1) after Jacobi-Anger expansion is expressed as:
wherein, J1(m) is a first order Bessel function of the first kind, modulation index mRF＝πVRF/Vπ；
S1.2, transmission processing: orthogonal polarization multiplexing optical signals output by the polarization multiplexing double-parallel Mach-Zehnder modulator are input into an erbium-doped optical fiber amplifier for power amplification treatment; inputting the amplified polarization multiplexing light into a polarization controller, and adjusting two polarization states of the light signal to align the two polarization states to a main shaft of a polarization beam splitter; the orthogonal polarization multiplexing optical signal after passing through the polarization controller is subjected to polarization demultiplexing processing by a polarization beam splitter, and two paths of optical signals respectively working in orthogonal polarization directions, namely the x polarization direction and the y polarization direction, are output;
s1.3, interference treatment: after polarization demultiplexing, inputting an optical signal working in the x polarization direction into a Mach-Zehnder interferometer for interference treatment: the two arms of the Mach-Zehnder interferometer have different transmission responses, the loss of the two arms of the Mach-Zehnder interferometer is ignored, and the optical signals of the two output ports are expressed as follows:
wherein the optical path length (L) in both arms of the Mach-Zehnder interferometer1And L2) Induced phase shift Φi＝-2πfinLi/c，(i＝1，2)；f1And f2Horse stands for frequency f respectivelyc-fxAnd fc+fxMach-Zehnder interferometer two armsTime delay tau due to length difference of (d) is n (L)1-L2) C; n and c are the refractive index and the speed of light in vacuum, respectively;
step 2: respectively monitoring the optical power of two output ports of the Mach-Zehnder interferometer by using two optical power meters;
respectively monitoring the optical power P1 and P2 of two output ports of the Mach-Zehnder interferometer by using two optical power meters;
the optical power at the two output ports of the mach-zehnder interferometer is expressed as:
step 3: the processing unit constructs an amplitude comparison function ACF (amplitude comparison function) P1/P2 according to the monitored optical powers P1 and P2, establishes a frequency-ACF lookup table, searches corresponding frequencies according to the calculated ACF value, and obtains a coarse frequency measurement result frough；
The constructed magnitude comparison function ACF can be expressed as:
obviously, since the amplitude comparison function ACF is the power ratio of the two optical signals, the influence of power fluctuation on the frequency measurement accuracy by the system link is eliminated; the amplitude comparison function ACF depends on the time delay tau, the frequency of the optical carrier and the frequency of the unknown radio frequency signal; when the time delay tau is fixed, the optical carrier frequency is set at the wave crest or the wave trough of the transmission response of the Mach-Zehnder interferometer; the first monotonous interval range of the theoretical simulation optical power and amplitude comparison function ACF is 1/2 tau, and the mapping relation between the ACF and the microwave frequency in the range is unique; therefore, an ACF-frequency lookup table can be established within this range, thereby calculating from the measured powerThe obtained ACF value is searched for corresponding frequency to obtain a coarse frequency measurement result frough；
Step 4: from the result of the first coarse measurement, i.e. from the estimated frequency froughAnd maximum measurement ErrormaxDetermining the scanning range of the scanning signal generated by the arbitrary waveform generator as [ frough-Errormax，frough+Errormax](ii) a Then, mixing the scanning signal and the unknown radio frequency signal to an optical carrier by using a polarization multiplexing double-parallel Mach-Zehnder modulator to perform power cancellation processing;
the specific method for determining scanning frequency, signal modulation mixing and power cancellation comprises the following steps:
s4.1 determining the scanning frequency: according to the interference-based coarse frequency measurement result of the first step, determining the scanning range of the scanning signal generated by the arbitrary waveform generator as frough-Errormax，frough+Errormax]；
S4.2, signal modulation mixing: in the polarization multiplexing double-parallel Mach-Zehnder modulator, the direct-current voltages of two sub-modulators and a main modulator embedded in the double-parallel Mach-Zehnder modulator y are both arranged on a minimum transmission bias point (MITP) so as to carry out carrier suppression double-sideband modulation; unknown radio frequency signal input sub-modulator y1The radio frequency input port of (1); scanning signal input sub-modulator y2The radio frequency input port of (1); sub-modulator y1And sub-modulator y2The output carrier suppression double-sideband modulation optical signals are output after being subjected to reverse phase superposition by the main modulator y;
suppose that the amplitude, frequency and initial phase of the scanning signal are VS，fsAnd
the output optical signal of the dual parallel mach-zehnder modulator y is represented as:
Vπis the half-wave voltage of the double parallel Mach-Zehnder modulator y and the modulation coefficient mS＝πVS/Vπ(ii) a Equation (7) after Jacobi-Anger expansion is expressed as:
s4.3, power cancellation: due to the special arrangement of the double parallel Mach-Zehnder modulators y, the scanning signal fsAnd unknown radio frequency signal fxThe phases of the modulated optical sidebands are completely opposite; as the frequency of the sweep signal varies, when the frequency of the sweep signal overlaps the frequency of the unknown radio frequency signal, i.e., fs＝fxWhen the radio frequency signal is excited, the optical sideband excited by the unknown radio frequency signal is weakened or even cancelled;
one special case that needs to be taken care of during scanning, i.e. when the scanning signal frequency overlaps with the unknown radio frequency signal frequency (f)s＝fx) The optical sideband excited by the unknown radio frequency signal is weakened or even eliminated; in this case, the optical signal output by the double parallel mach-zehnder modulator y is:
s4.4, transmission processing: in the polarization multiplexing double-parallel Mach-Zehnder modulator, output optical signals of a double-parallel Mach-Zehnder modulator x and a double-parallel Mach-Zehnder modulator y are combined into a beam of orthogonal polarization multiplexing light by a polarization beam combiner; after the orthogonal polarization multiplexing light is amplified by the power of the erbium-doped fiber amplifier, the orthogonal polarization multiplexing light is polarized and demultiplexed into two paths of polarization orthogonal optical signals by the polarization beam splitter through the adjustment of the polarization controller; an optical signal which works in the y polarization direction after demultiplexing is input into a photoelectric detector for beat frequency processing;
s5: measuring the power of the electric signal passing through the photoelectric detector by using an electric dynamometer;
scanning the signal assuming an erbium-doped fiber amplifier gain of GThe amplitude being k times, i.e. V, the unknown radio frequency signalS＝kVRF(ii) a In the case of small signal modulation, J1(mRF)≈mRF/2，J1(mS)≈mS/2＝kmRF2; therefore, the optical signal output by the dual parallel mach-zehnder modulator y passes through the photodetector, and the detection current after the beat frequency processing can be expressed as:
wherein
Is the responsivity of the photodetector; it can be seen that the detected current contains a direct current component, a second order component and a conversion component (f)s-fxAnd fs+fx) (ii) a Thus, the corresponding electrical power is expressed as:
when the scanning signal frequency overlaps with the unknown radio frequency signal frequency (f)s＝fx) The corresponding probe current is expressed as:
comparing equation (10) and equation (12) it can be found that when fs＝fxTime, frequency conversion component fs-fxAre all cancelled out, resulting in a reduction in electrical power; at this time, the electric power is:
here, P (DC) represents DCPower of quantity, P (2 f)x) And P (-2 f)x) Respective frequency component 2fxAnd-2 fxA corresponding power; obviously, when the scanning signal frequency overlaps with the unknown rf signal frequency, the total power will change, leaving only dc, 2fxAnd-2 fxThereby implementing power notching;
step 6: the processing unit records the mapping relation between the measured electric power and the frequency of the scanning signal, finds the scanning frequency corresponding to the notch position of the power, and obtains a precise frequency measurement result faccurateAnd outputting;
as shown in equation (13), as the frequency of the sweep signal varies, when the frequency of the sweep signal overlaps with the frequency of the unknown RF signal, i.e., fs＝fxWhen the radio frequency signal is excited, the optical sideband excited by the unknown radio frequency signal is weakened or even cancelled; this reflects that a power notch will be generated on the output power-sweep frequency mapping curve monitored by the processing unit, and the sweep signal frequency corresponding to the notch position is the fine frequency measurement result f of the unknown RF signalaccurate。
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111251234.XA CN114047381A (en) | 2021-10-26 | 2021-10-26 | Photonic auxiliary microwave frequency measurement method and device based on precision compensation |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111251234.XA CN114047381A (en) | 2021-10-26 | 2021-10-26 | Photonic auxiliary microwave frequency measurement method and device based on precision compensation |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN114047381A true CN114047381A (en) | 2022-02-15 |
Family
ID=80205986
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202111251234.XA Pending CN114047381A (en) | 2021-10-26 | 2021-10-26 | Photonic auxiliary microwave frequency measurement method and device based on precision compensation |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114047381A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115085819A (en) * | 2022-07-26 | 2022-09-20 | 陕西浩兴坤达新能源科技有限公司 | Information transmission method and system of natural electromagnetic pulse vector signal energy spectrum |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102546007A (en) * | 2011-12-30 | 2012-07-04 | 浙江大学 | Device and method for realizing frequency measurement of multifrequency microwave signals by using Brillouin scattering |
| CN109981181A (en) * | 2019-02-19 | 2019-07-05 | 西北工业大学 | Microwave photon converter plant and adjusting method can be switched in a kind of binary channels |
| RU193095U1 (en) * | 2019-06-07 | 2019-10-14 | Федеральное государственное бюджетное образовательное учреждение высшего образования "Казанский национальный исследовательский технический университет им. А.Н. Туполева - КАИ" (КНИТУ-КАИ) | Fiber optic device for measuring instantaneous frequencies of multiple microwave signals |
| CN113315573A (en) * | 2021-05-28 | 2021-08-27 | 重庆邮电大学 | Optical auxiliary broadband microwave instantaneous frequency measurement method and device |
| CN113472445A (en) * | 2021-06-25 | 2021-10-01 | 西北工业大学 | Dual-band RoF system based on PDM-DPMZM and adjusting method |
-
2021
- 2021-10-26 CN CN202111251234.XA patent/CN114047381A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102546007A (en) * | 2011-12-30 | 2012-07-04 | 浙江大学 | Device and method for realizing frequency measurement of multifrequency microwave signals by using Brillouin scattering |
| CN109981181A (en) * | 2019-02-19 | 2019-07-05 | 西北工业大学 | Microwave photon converter plant and adjusting method can be switched in a kind of binary channels |
| RU193095U1 (en) * | 2019-06-07 | 2019-10-14 | Федеральное государственное бюджетное образовательное учреждение высшего образования "Казанский национальный исследовательский технический университет им. А.Н. Туполева - КАИ" (КНИТУ-КАИ) | Fiber optic device for measuring instantaneous frequencies of multiple microwave signals |
| CN113315573A (en) * | 2021-05-28 | 2021-08-27 | 重庆邮电大学 | Optical auxiliary broadband microwave instantaneous frequency measurement method and device |
| CN113472445A (en) * | 2021-06-25 | 2021-10-01 | 西北工业大学 | Dual-band RoF system based on PDM-DPMZM and adjusting method |
Non-Patent Citations (1)
| Title |
|---|
| 张华林;: "一种改善实时性的光辅助微波频率测量方法的研究", 中国激光, no. 12 * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115085819A (en) * | 2022-07-26 | 2022-09-20 | 陕西浩兴坤达新能源科技有限公司 | Information transmission method and system of natural electromagnetic pulse vector signal energy spectrum |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN110031832B (en) | Microwave photon Doppler frequency shift measurement system and adjusting method thereof | |
| EP2220794B1 (en) | Photonic based cross-correlation homodyne detection with low phase noise | |
| CN107528638B (en) | Broadband microwave signal arrival angle estimation method based on microwave photon filtering | |
| US9923631B1 (en) | Optical signal processing characterization of microwave and electro-optic devices | |
| CN113541787B (en) | Functional flexible photonics auxiliary frequency measuring method and device | |
| CN109613335B (en) | Microwave signal frequency measurement device and method based on cyclic frequency shift | |
| Liu et al. | High-accuracy multiple microwave frequency measurement with two-step accuracy improvement based on stimulated Brillouin scattering and frequency-to-time mapping | |
| CN111693988A (en) | Laser millimeter wave integrated distance and speed measuring radar method and device | |
| Kang et al. | 6–40 GHz photonic microwave Doppler frequency shift measurement based on polarization multiplexing modulation and I/Q balanced detection | |
| CN104767562A (en) | Microwave source phase noise measuring device and method based on microwave photon technology | |
| CN111781588A (en) | Radar signal processing method and system based on photon fraction Fourier converter | |
| JP2016118539A (en) | System and method for determining phase angle | |
| CN110535527B (en) | Method and device for measuring frequency spectrum response of coherent optical receiver | |
| CN109696300B (en) | Precise extraction method and device for frequency response characteristic of high-frequency broadband electro-optic intensity modulator | |
| Li et al. | Photonic system for simultaneous and unambiguous measurement of angle-of-arrival and Doppler-frequency-shift | |
| Zuo et al. | Photonic-assisted filter-free microwave Doppler frequency shift measurement using a fixed low-frequency reference signal | |
| CN109728862B (en) | Method and device for measuring parameters of coherent optical receiver based on dual-frequency modulation | |
| CN114047381A (en) | Photonic auxiliary microwave frequency measurement method and device based on precision compensation | |
| Wen et al. | Precise identification of wideband multiple microwave frequency based on self-heterodyne low-coherence interferometry | |
| CN108540219B (en) | coherent optical receiver parameter measurement method and device based on frequency shift modulation | |
| JP3262311B2 (en) | Frequency sweep error detection method and circuit, optical frequency sweep light source, and optical frequency domain reflection measurement circuit | |
| Zhang et al. | Photonic approach to wideband Doppler frequency shift estimation system based on a DPMZM and a Sagnac loop | |
| Tang et al. | Photonics-assisted joint radar detection and frequency measurement system | |
| CN113595629A (en) | Microwave photon frequency measuring device based on phase shift gain ratio | |
| Chen et al. | Simplified Doppler frequency shift measurement enabled by Serrodyne optical frequency translation |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| AD01 | Patent right deemed abandoned |
Effective date of abandoning: 20240507 |
|
| AD01 | Patent right deemed abandoned |