A microwave photonics system for wide spectrum electromagnetic signal measurement

Abstract

This invention discloses a microwave photonic system for broadband electromagnetic signal measurement, belonging to the field of electromagnetic signal measurement. The system includes a first electro-optical comb, a first beam splitter, a second electro-optical comb, a second beam splitter, a first beam combiner, a second beam combiner, an electro-optical modulator, a power adjustment device, a balanced detector, and a data acquisition and processing unit. This system has advantages such as simple structure, high measurement accuracy, low cost, and a wide measurable signal frequency range.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic signal measurement, and more particularly to an electromagnetic signal measurement method. Background Technology

[0002] Electromagnetic environment testing is widely used in all aspects of electromagnetic spectrum management, including radio station site selection, frequency allocation, radio regulation, and electromagnetic environment assessment. With the increase in communication speeds, the signal frequencies and bandwidths in the electromagnetic environment are gradually moving towards higher frequencies and wider bandwidths.

[0003] When the electromagnetic signal to be measured over a wide spectrum is an unknown signal, traditional electronic measurement methods are mainly divided into two categories. One category is the technique of high-speed sampling of the signal to satisfy the Nyquist sampling theorem. This mainly uses a high-speed ADC to directly acquire the signal and then performs time-domain, frequency-domain, or time-frequency analysis on the acquired signal through autocorrelation algorithms, energy detection methods, and wavelet transform methods to complete the signal detection. The other category is the technique of recovering and analyzing the low-speed sampled signal when the Nyquist sampling theorem is not satisfied, using digital channel detection technology, adaptive multi-channel detection technology, compressed reception technology, and scanning superheterodyne technology to complete the signal detection.

[0004] Electromagnetic signal detection typically requires multiple filtering systems, which are complex and slow, making them unsuitable for measuring electromagnetic signals with a certain frequency conversion speed. Summary of the Invention

[0005] In view of this, the present invention provides a microwave photonic system for broadband electromagnetic signal measurement. The present invention has a simple structure, high measurement accuracy, low cost, and can measure a vast range of signal frequencies.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A microwave photonic system for broadband electromagnetic signal measurement includes a first electro-optic comb, a first beam splitter, a second electro-optic comb, a second beam splitter, a first beam combiner, a second beam combiner, an electro-optic modulator, a power adjustment device, a balance detector, and a data processing unit.

[0008] Among them, the first electro-optical comb and the second electro-optical comb are electro-optical combs with different comb tooth spacing;

[0009] The first beam splitter splits the signal from the first electro-optic comb into two paths, which then enter the first beam combiner and the second beam combiner, respectively.

[0010] The second beam splitter splits the signal from the second electro-optic comb into two paths, which then enter the first beam combiner and the second beam combiner, respectively.

[0011] The power of the signal entering the first optical combiner from the first optical comb is equal to the power of the signal entering the first optical combiner from the second optical comb, and the power of the signal entering the second optical combiner from the first optical comb is also equal to the power of the signal entering the second optical combiner from the second optical comb.

[0012] The signal output from the first optical combiner enters the electro-optic modulator, is modulated by the electromagnetic signal under test, and then enters one input port of the balanced detector; the signal output from the second optical combiner passes through the power adjustment device, and its power is equal to that of the electro-optic modulator signal, and then enters the other input port of the balanced detector.

[0013] The output signal of the balanced detector is acquired and processed by the data processing unit to obtain the characteristics of the electromagnetic signal under test.

[0014] Furthermore, the first and second beam splitting devices are fiber optic couplers, fiber optic beam splitters, or polarization beam splitters.

[0015] Furthermore, the electro-optic modulator can be an optical intensity modulator, an optical phase modulator, an optical polarization modulator, an acousto-optic modulator, or a magneto-optic modulator.

[0016] Furthermore, the signal output by the balanced detector is a down-converted electromagnetic signal of the test signal with background signals eliminated.

[0017] Furthermore, the data processing unit processes the data as follows: it performs time-frequency conversion on the acquired signal to obtain the frequency, amplitude, and phase of the down-converted signal; it divides the center frequency value of the signal by the difference in the tooth spacing between the first and second electro-optical combs to obtain the down-conversion factor; and then it performs inverse calculation to obtain the frequency, amplitude, phase, or change of the electromagnetic signal under test.

[0018] The beneficial effects of this invention are as follows:

[0019] 1. This invention uses microwave photonics to downconvert high-frequency electromagnetic signals to baseband for detection, thereby reducing the bandwidth requirements of the detector and enabling rapid measurement of unknown signals.

[0020] 2. This invention is capable of measuring the frequency domain information of electromagnetic signals within a wide spectrum of signals.

[0021] 3. This invention eliminates background noise through balanced detection, enabling highly sensitive frequency domain information measurement. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of a microwave photonic system for broadband electromagnetic signal measurement in an embodiment of the present invention. Implementation

[0023] like Figure 1As shown, a microwave photonic system for broadband electromagnetic signal measurement includes an electro-optic comb 1, a beam splitter 1, an electro-optic comb 2, a beam splitter 2, a beam combiner 1, a beam combiner 2, an electro-optic modulator, a power adjustment device, a balance detector, and a data processing unit.

[0024] In this design, electro-optical comb 1 and electro-optical comb 2 are electro-optical combs with different tooth spacing; beam splitter 1 splits the signal from electro-optical comb 1 into two paths, which enter beam combiner 1 and beam combiner 2 respectively; beam splitter 2 splits the signal from electro-optical comb 2 into two paths, which enter beam combiner 1 and beam combiner 2 respectively; the power of the signal from electro-optical comb 1 entering beam combiner 1 is equal to the power of the signal from electro-optical comb 2 entering beam combiner 1; the power of the signal from electro-optical comb 1 entering beam combiner 2 is also equal to the power of the signal from electro-optical comb 2 entering beam combiner 2; the signal output from beam combiner 1 enters the electro-optic modulator, is modulated by the electromagnetic signal under test, and then enters one input port of the balanced detector; the optical signal output from beam combiner 2 passes through a power adjustment device, and its power is equal to the signal from the electro-optic modulator, and then enters the other input port of the balanced detector; the output signal of the balanced detector is acquired and processed by the data processing unit to obtain the characteristics of the electromagnetic signal under test.

[0025] Optical splitter 1 and optical splitter 2 can be fiber couplers, fiber beam splitters or polarization beam splitters.

[0026] Electro-optic modulators can be optical intensity modulators, optical phase modulators, optical polarization modulators, acousto-optic modulators, or magneto-optic modulators.

[0027] The signal output by the balanced detector is a down-converted electromagnetic signal of the test signal with background signals eliminated.

[0028] The data processing unit calculates the frequency, amplitude, phase, or change of the electromagnetic signal under test based on the tooth spacing of electro-optical comb 1 and electro-optical comb 2 and the output signal of the balance detector.

[0029] Here is a more specific example:

[0030] A microwave photonic system for broadband electromagnetic signal measurement includes an electro-optic comb 1, a beam splitter 1, an electro-optic comb 2, a beam splitter 2, a beam combiner 1, a beam combiner 2, an electro-optic modulator, a power adjustment device, a balance detector, and a data processing unit; beam splitter 1, beam splitter 2, beam combiner 1, and beam combiner 2 are all fiber optic couplers.

[0031] In this design, the tooth spacing of electro-optical comb 1 and electro-optical comb 2 is 1 GHz and 1.00001 GHz, respectively. The signal under test is a frequency-hopping signal. Optical splitter 1 splits the signal from electro-optical comb 1 into two paths, which are then fed into optical combining device 1 and optical combining device 2, respectively. Optical splitter 2 splits the signal from electro-optical comb 2 into two paths, which are then fed into optical combining device 1 and optical combining device 2, respectively. The power of the signal from electro-optical comb 1 entering optical combining device 1 is equal to that of the signal from electro-optical comb 2 entering optical combining device 1. The power of the signals from electro-optical comb 1 and electro-optical comb 2 entering optical combining device 2 is also equal. The signal output from optical combining device 1 enters an electro-optic modulator, is modulated by the frequency-hopping signal under test, and then enters one input port of a balanced detector. The optical signal output from optical combining device 2, after passing through a power adjustment device, has a power equal to that of the electro-optic modulator signal and enters the other input port of the balanced detector. The output signal of the balanced detector is input to a data processing unit, undergoes analog-to-digital conversion, and then undergoes Fourier transform to convert from the time domain to the frequency domain, resulting in a mixed down-converted signal of the signal under test and electro-optical comb 1 and electro-optical comb 2. Because a balanced detector is used, the obtained signal is a mixed down-converted signal with background interference eliminated. Based on the mixed down-converted signal and the difference in the tooth spacing of the two electro-optical combs, the down-conversion factor of the signal under test can be obtained, and then the frequency domain information of the original frequency hopping signal can be retrieved.

[0032] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can make appropriate changes or modifications within the scope of the technology disclosed in the present invention, and such changes or modifications should be covered within the scope of protection of the present invention.

Claims

1. A microwave photonic system for broadband electromagnetic signal measurement, characterized in that, It includes a first electro-optical comb, a first beam splitter, a second electro-optical comb, a second beam splitter, a first beam combiner, a second beam combiner, an electro-optical modulator, a power adjustment device, a balance detector, and a data processing unit; Among them, the first electro-optical comb and the second electro-optical comb are electro-optical combs with different comb tooth spacing; The first beam splitter splits the signal from the first electro-optic comb into two paths, which then enter the first beam combiner and the second beam combiner, respectively. The second beam splitter splits the signal from the second electro-optic comb into two paths, which then enter the first beam combiner and the second beam combiner, respectively. The power of the signal entering the first optical combiner from the first optical comb is equal to the power of the signal entering the first optical combiner from the second optical comb, and the power of the signal entering the second optical combiner from the first optical comb is also equal to the power of the signal entering the second optical combiner from the second optical comb. The signal output from the first optical combiner enters the electro-optic modulator, is modulated by the electromagnetic signal under test, and then enters one input port of the balanced detector; the signal output from the second optical combiner passes through the power adjustment device, and its power is equal to that of the electro-optic modulator signal, and then enters the other input port of the balanced detector. The output signal of the balanced detector is acquired and processed by the data processing unit to obtain the characteristics of the electromagnetic signal under test.

2. The microwave photonic system for broadband electromagnetic signal measurement as described in claim 1, characterized in that, The first and second beam splitting devices are fiber optic couplers, fiber optic beam splitters, or polarization beam splitters.

3. The microwave photonic system for broadband electromagnetic signal measurement as described in claim 1, characterized in that, Electro-optic modulators can be optical intensity modulators, optical phase modulators, optical polarization modulators, acousto-optic modulators, or magneto-optic modulators.

4. A microwave photonic system for broadband electromagnetic signal measurement as described in claim 1, characterized in that, The signal output by the balanced detector is a down-converted electromagnetic signal of the test signal with background signals eliminated.

5. A microwave photonic system for broadband electromagnetic signal measurement as described in claim 1, characterized in that, The data processing unit processes the signal as follows: it performs time-frequency conversion on the acquired signal to obtain the frequency, amplitude, and phase of the down-converted signal; it divides the center frequency value of the signal by the difference in the tooth spacing between the first and second electro-optical combs to obtain the down-conversion factor; and then it performs inverse calculation to obtain the frequency, amplitude, and phase of the electromagnetic signal to be measured.

Images