RU2799112C1 - Fiber-optical system for measuring instant frequencies of multiple microwave signals - Google Patents

Abstract

FIELD: measurements.

SUBSTANCE: fibre optic system refers to the technique of optoelectronic measurements, to devices for measuring the instantaneous frequencies of microwave signals. A fibre-optic system for measuring instantaneous frequencies of a plurality of microwave signals comprises a source of narrow-band optical radiation, an optical splitter, a Mach-Zehnder modulator, which is the input of the system, a phase modulator, a comb microwave signal generator, an optical combiner, a photodetector, and a microwave signal frequency determination controller, the radiation source through the input and the first output of the optical splitter is connected by means of light guides to the optical input of the Mach-Zehnder modulator, the phase modulator, the optical output of which is connected in series through the light guides through the input and the second output of the optical combiner and the photodetector to the microwave signal frequency determination controller, and the comb microwave signal generator is connected to the RF input of the phase modulator, the radiation source is connected to the optical input of the phase modulator through the input and the second output of the optical splitter, and the optical output of the Mach-Zehnder modulator is connected to the photodetector through the input and the first output of the optical combiner.

EFFECT: measurement of frequencies of several microwave signals simultaneously.

1 cl, 4 dwg

Description

A fiber-optic system refers to the technique of optoelectronic measurements, in particular, to devices for measuring instantaneous frequencies of microwave signals by recording the power of beat signals with components of a symmetrical frequency comb decreasing in power, in which there is a dependence of the change in power depending on the frequency of the measured signals .

A device is known for measuring the instantaneous frequency of microwave signals (see the electronic resource https://elibrary.ru/item.asp?id=41216821/ published on 10/16/2019). This device, chosen as a prototype, contains a narrow-band optical signal source connected in series, an optical splitter, two parallel cascades of amplitude and phase Mach-Zander modulators, an optical combiner, an optical circulator, an optical filter based on a concave fiber Bragg grating and a photodetector unit connected to the controller determining the frequency of the microwave signal, in which the mathematical processing of the spectral shift is performed, by which the instantaneous frequency of the microwave signal is determined.

The device works as follows. Narrow-band optical radiation is generated in a laser emitter, which, through an optical splitter, enters two parallel cascades of amplitude and phase Mach-Zehnder modulators. In the upper cascade, narrow-band optical radiation is modulated with a measured unknown microwave signal, and in the lower cascade, narrow-band optical radiation is modulated with a known microwave signal to form a frequency comb component uniform in power with the number of components to cover the measured frequency range and with a frequency step equal to the frequency of the modulating microwave -signal. Next, the upper and lower channels are combined in an optical combiner, the output spectrum from the output of which is fed through an optical circulator to a concave fiber Bragg grating, where the amplitudes of the spectral components of the frequency comb and the spectral components of the measured signal that fall between them change according to the envelope of the concave fiber Bragg grating. The spectrum obtained in this way is reflected from a concave fiber Bragg grating and is received through a circulator in a photodetector unit, the frequency band of which is limited by the width of one frequency comb channel, determined by the frequency of the modulating microwave signal, from the output of which the spectrum passes to the spectral analysis unit of the received radiation, where it is determined the measurement channel and the unknown instantaneous frequency of the microwave signal based on a comparison of the ratio of the power of the beat frequencies of the spectral components of the measured signal with two nearby spectral components of the frequency comb between which they are located.

The disadvantage of this device is the inability to measure the frequencies of several microwave signals simultaneously.

The technical problem of this device is the impossibility of measuring the frequencies of several microwave signals simultaneously.

The technical problem to be solved (technical result) in the fiber-optic system for measuring the instantaneous frequencies of a plurality of microwave signals is to measure the frequencies of several microwave signals simultaneously.

Solved technical problem (technical result) in a fiber-optic system for measuring instantaneous frequencies of a plurality of microwave signals, containing a source of narrow-band optical radiation, an optical splitter, a Mach-Zehnder modulator, while the radio-frequency input of the Mach-Zehnder modulator is the input of a fiber-optic system for measuring instantaneous frequencies of a plurality of microwave signals, a phase modulator, a comb microwave signal generator, an optical combiner, a photodetector, and a controller for determining the frequencies of microwave signals, which has an output that is the output of a fiber optic system for measuring instantaneous frequencies of a plurality of microwave signals, and the source of narrow-band optical radiation through the input and the first output of the optical splitter by means of fiber light guides is connected to the optical input of the Mach-Zehnder modulator, the phase modulator, the optical output of which is connected in series to the controller for determining the frequencies of microwave signals through the input and second output of the optical combiner and the photodetector via fiber light guides, and the generator The microwave signal of the comb is connected to the RF input of the phase modulator is achieved by the fact that the source of narrow-band optical radiation through the input and the second output of the optical splitter is connected to the optical input of the phase modulator by means of optical fibers, and the optical output of the Mach-Zehnder modulator is connected through the input and the first output of the optical combiner through fiber light guides connected to a photodetector.

In FIG. 1 is a block diagram of a fiber optic system for measuring the instantaneous frequencies of a plurality of microwave signals.

In FIG. Figure 2 shows the power dependences of the harmonic pairs of signals of three unknown frequencies of microwave signals, after modulation of a narrow-band optical signal, that fell between different components of the frequency comb in different measuring channels.

In FIG. 3 shows the power ratios of the harmonics of the frequency comb, based on the comparison with which the measurement channel is determined.

In FIG. 4 shows the algorithm of the controller for determining the frequencies of microwave signals.

The power supply system required for the source of narrow-band optical radiation, the Mach-Zehnder modulator, the phase modulator, the microwave signal generator of the comb, and the controller for determining the frequencies of the microwave signals in FIG. 1 is not shown.

The fiber optic system for measuring the instantaneous frequencies of a plurality of microwave signals shown in FIG. 1, contains a source of narrow-band optical radiation 1, an optical splitter 2, a Mach-Zehnder modulator 3, while the radio frequency input of the Mach-Zehnder modulator 3 is the input of a fiber-optic system for measuring the instantaneous frequencies of a plurality of microwave signals, a phase modulator 4, a microwave signal generator combs 5, an optical combiner 6, a photodetector 7, and a controller for determining the frequencies of microwave signals 8, which has an output that is the output of a fiber optic system for measuring the instantaneous frequencies of a plurality of microwave signals, and a source of narrow-band optical radiation 1 through the input and first output of the optical splitter 2 is connected by fiber light guides to the optical input of the Mach-Zehnder modulator 3, the phase modulator 4, the optical output of which is connected in series through the input and second output of the optical combiner 6 and the photodetector 7 via fiber light guides to the controller for determining the frequencies of microwave signals 8, and the microwave generator is signal of the comb 5 is connected to the RF input of the phase modulator 4, characterized in that the source of narrow-band optical radiation 1 through the input and the second output of the optical splitter 2 is connected to the optical input of the phase modulator 4 by means of fiber fibers, and the optical output of the Mach-Zehnder modulator 3 through the input and the first The output of the optical combiner 6 is connected to the photodetector 7 via optical fibers.

Let us consider the operation of a fiber-optic system for measuring instantaneous frequencies of microwave signals.

Beforehand, the values of the power ratio of the measuring channels, which are shown in FIG. 3 and a program operating according to the algorithm shown in FIG. 4.

The power supply system for the blocks is connected to the source of a narrow-band optical signal 1, the Mach-Zehnder modulator 3, the phase modulator 4, the microwave signal generator of the comb 5, the controller for determining the frequencies of the microwave signals 8.

At the input of the Mach-Zehnder modulator 3, for example, microwave signals with measured frequencies are fed from the receiving antenna.

To measure the instantaneous frequencies of microwave signals using a narrow-band optical signal source 1, a signal with a frequency ƒ _l is generated, which, passing through an optical splitter 2, is then modulated in a Mach-Zehnder modulator 3, operating at the zero operating point of the modulation characteristic for carrier suppression, by the measured microwave signals with frequencies ƒ _i ... ƒ _j , and in the phase modulator 4 they modulate the microwave signal ƒ _gr of the microwave signal generator of the comb 5 to create an equidistant and symmetrical in frequency with respect to the suppressed carrier frequency comb with odd harmonic components of the spectrum with amplitudes decreasing relative to the central harmonics, determined by the coefficients of the Fourier series E _n =2E ₀ /πn, where n=1, 3, 5 is the number of the expansion component in terms of the modulating frequency.

At the output of the optical combiner 6, the emission spectra from the outputs of the Mach-Zehnder modulator 3 and phase modulator 4 are combined and the spectral components of the unknown measured signals fall between the two nearest components of the frequency comb, forming the measuring channels. The combined spectrum enters the photodetector 7, the frequency of which is limited by the width of one measuring channel, at the output of which an array of beat signals f _iBgr …f _jBgr is formed due to the beats of each harmonic of the measured signal with two adjacent comb components f _{GR i} and f _{GR i+1} .

The resulting beats are sent to the controller for determining the frequencies of microwave signals 8, where digitization, discrete Fourier transform, and determination of the frequencies and powers of the beat signals are carried out. The formed array of beats is sorted according to the algorithm of the controller operation, and then the ratio of the powers of pairs of beats symmetric with respect to f _GR is calculated, the ratio of the powers of which is compared with the ratio of the powers of the harmonics of the frequency comb for each of the channels shown in Fig. 3, which, due to the difference in the power of the harmonics, will be individual for each channel, which makes it possible to determine its number. The frequency within each of the channels is defined as the difference between the known frequencies of the frequency comb components and the measured beat frequencies.

The received data from the controller for determining the frequencies of microwave signals 8 can be displayed on the screen and recorded in the memory of the controller for determining the frequencies of microwave signals 8.

The accuracy of measuring the instantaneous frequencies of a plurality of microwave signals is determined by the performance of the processor, which is the basic part of the controller for determining the frequencies of microwave signals 8.

A fiber-optic system for measuring the instantaneous frequencies of a plurality of microwave signals can be implemented on the following elements, designed to operate at a wavelength of 1300 nm (other wavelengths are possible), for example:

As a source of narrow-band optical radiation 1 can be selected laser diode IDL10S-1300 Research Institute "Polyus" or DMPO131-22 LLC NPF "Dilaz";

As an optical splitter 2, an optical splitter 1x2 1310/1550 nm from OPTEL LLC can be selected;

As a Mach-Zehnder 3 modulator, modulators based on the Mach-Zehnder interferometer 500-x-13 from Laser2000 can be selected;

As a phase modulator 4, a phase modulator SSP-P-13-10 - 1310 nm, 10 GHz from Rofea Optoelectronics can be selected;

A microwave analog signal generator Agilent Technologies N5183A-532 can be selected as a microwave signal generator of comb 5;

As an optical combiner 6, an optical combiner 2x1 of LLS JSC can be selected;

As a photodetector 7, a high-speed fiber optic InGaAs microwave broadband PIN photodetector from Optilab, for example, PD-40-MM, can be selected;

As a controller for determining the frequencies of microwave signals 8, a microprocessor controller based on chips from Atmel, Microchip, etc. can be selected;

Standard cords or cables TELECOM-TEST of the LLC Production and Trade Company SOKOL can be chosen as fiber light guides.

To build a fiber-optic system for measuring the instantaneous frequencies of a plurality of microwave signals, all of the above blocks for generating, receiving and processing signals can be made on a single chip or in an integrated design.

All this allows us to speak about the achievement of the solution of the set technical problem (technical result) - the measurement of instantaneous frequencies simultaneously of a plurality of microwave signals of a fiber-optic system for measuring instantaneous frequencies of several microwave signals simultaneously.

Claims (1)

A fiber-optic system for measuring instantaneous frequencies of a plurality of microwave signals, comprising a source of narrow-band optical radiation, an optical splitter, a Mach-Zehnder modulator, while the radio-frequency input of the Mach-Zehnder modulator is the input of a fiber-optic system for measuring instantaneous frequencies of a plurality of microwave signals, a phase modulator , a comb microwave signal generator, an optical combiner, a photodetector, and a controller for determining the frequencies of microwave signals, which has an output that is the output of a fiber optic system for measuring the instantaneous frequencies of a plurality of microwave signals, and a source of narrow-band optical radiation through the input and the first output of the optical The splitter is connected via fiber light guides to the optical input of the Mach-Zehnder modulator, the phase modulator, the optical output of which is connected in series through the input and second output of the optical combiner and the photodetector via fiber light guides to the controller for determining the frequencies of microwave signals, and the microwave signal generator of the comb is connected to the radio frequency input of the phase modulator, characterized in that the source of narrow-band optical radiation through the input and the second output of the optical splitter by means of fiber light guides is connected to the optical input of the phase modulator, and the optical output of the Mach-Zehnder modulator through the input and the first output of the optical combiner by means of fiber light guides is connected to the photodetector.

Images