In recent decades, the principles of building radar and radio communication systems using radio photonic technologies have been rapidly developing in leading foreign countries. The rapid growth of the field of application of radio photonic technologies in radar is facilitated by the expansion of functionality, improvement of operational characteristics, reduction of overall dimensions, weight and power consumption, as well as the cost of radio photonic components. Initially, the principles of radio photonics were used in radar and radio communication systems for remote transmission of radio signals between the antenna and the transceiver equipment. Currently, these principles are also widely used in radio signal generation and processing devices, for example, in such promising shortrange radar systems (RSSR) as «microwave photonic MIMO radars of short range». This article discusses the possibilities of using radio photonic oscillators (RPO) as a source of microwave oscillations for multi-position communication and location systems, as well as a new type of transceiver devices, the so-called radio photonic autodynes (RPA) for promising SRRS. The fact is that RPOs today have unique noise characteristics and frequency stability. Therefore, the study of this type of autodyne and the determination of its capabilities in terms of improving their parameters and characteristics, as well as expanding the scope of application in EHF and UHF band systems seem very relevant. A typical RPO structure includes optical and radio engineering nodes. The optical node consists of: a semiconductor laser module, an electro-optical modulator (EOM) of radiation intensity, an optical amplifier, a fiber-optic delay line (FODL) and a photo detector module. An electro-optical traveling wave modulator based on an integral Mach-Zehnder interferometer is used as an EOM. The radio engineering unit consists of: a low-noise amplifier (LNA), a narrow-band filter, an amplifier and a power divider. In essence, a closed circuit from the output of the EOM to its control input, which includes a FODL, a photo detector module, an LNA, a narrow-band filter, an amplifier and a power divider, is a ring circuit of an self-oscillator with delayed feedback. The conditions for generating self-oscillations at the required frequency in the RPO are determined by a narrow-band filter. Provided that the modulus of the contour transmission coefficient of this ring in the mode of small oscillations is greater than one, self-oscillations increasing in amplitude inevitably occur in the system under consideration. The inclusion in the ring circuit of the RPO of a dividing-decoupling device (DDD), for example, a circulator, to the free port of which the antenna is connected, turns the RPO into a radio photonic autodyne RPA, which can be used in the SRRS. The radiation reflected from the location object is received by the antenna, and after passing from the second port to the third DDD, it interacts with the vibrations coming to the control input of the EOM. As a result of this interaction, an autodyne effect occurs in the self-oscillating RF system, which manifests itself in changes in the amplitude and frequency of oscillations in the vicinity of the stationary mode, as well as the power amplifier supply current. To isolate these changes in the RF, it is proposed to use an amplitude detector at the output of the LNA and/or a current sensor in the power amplifier power supply circuit. A comparison of the noise characteristics of RPOs and EHF and microwave range oscillators on semiconductor devices shows that RPOs provide an advantage of about 40 dB. Since the limiting potential of the transceivers used in the autodyne SRRS is defined as the ratio of the output power to the power of the generator's own noise, the use of RPO instead of conventional generators gives a gain in potential by the same amount, i.e. approximately 40 dB. The potential of homodyne SRRS exceeds the potential of autodyne systems by the amount of isolation between the receiver and the transmitter. Therefore, with a decoupling value of about 40 dB between them, the total gain will be about 80 dB. The obtained values of the gain from the use of RPO correspond to an increase in the maximum range of the autodyne SRRS by an order of magnitude, and homodyne - by two orders of magnitude. The improvement of these parameters indicates the prospects of using RPO in the SRRS, for example, in systems for detecting objects with low effective scattering area, such as unmanned aerial vehicles, for protection against which the use of conventional (long-range) radars is ineffective. In some applications, the range resource can be directed to reduce the output power of the SRRS radiation, which increases the secrecy of its operation. One of the directions of radar development is the creation of multi-position systems. At the same time, the components of radio engineering systems can be remote from each other at distances of up to several hundred and thousands of meters. In such systems, the requirements for the phase stability of the reference microwave signals are extremely high. Modern components of fiber-optic systems meet these requirements most fully. They provide both generation and formation of reference microwave signals, and their transmission over long distances with high phase stability. As an example, the article presents a block diagram of a radio photonic multi-position system (RPMPS) for detecting location objects. RPMPS contains a multichannel signal processing unit, RPO and a set of radio photonic radars (RPR). They are interconnected by means of fiber-optic transmission lines. Radio photonic RPR locators are installed at the viewing positions of the controlled space. Each of them contains an optical radiation divider into two channels, a photo detector module and an EOM. At the same time, it is possible to implement an RPR with one antenna and a circulator that provides isolation of the transmitting and receiving paths. Another variant of RPR with two antennas, due to the absence of a circulator, has a larger bandwidth of RPR operating frequencies and a better isolation of the transmitting and receiving paths. The proposed RPMPS can be used in security systems of geographically distributed objects, control of convergence with other objects on board vehicles, measurement of the parameters of the movement of wagons on the sorting hill and other purposes. In addition, the main nodes of this system can be used to build local communication systems.
Translated title of the contributionPROSPECTS FOR THE USE OF RADIO PHOTONIC OSCILLATORS IN SHORT-RANGE RADAR AND COMMUNICATION SYSTEMS
Original languageRussian
Pages (from-to)19-31
Number of pages23
JournalУспехи современной радиоэлектроники
Volume78
Issue number1
DOIs
Publication statusPublished - 2024

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