RU128726U1 - DEVICE FOR EVALUATING THE DIFFERENCE OF THE MOMENTS OF RECEIVING RADIO SIGNALS IN TWO SPACED RECEIVING POINTS - Google Patents

Abstract

A device for estimating the difference in moments of reception of a signal from a radio emission source at two spaced receiving points, consisting of a central and peripheral points, while the central receiving and processing center includes a first antenna, the output of which is connected to the input of the first analog-to-digital converter, the output of which is connected to the first input of the first storage device, and to the second input of which the output of the first chronizer is connected, the input of which is connected to a single time system, the output of the storage device The device is connected to the input of the first signal processing device, the computational unit, the output of which is connected to the second input of the display unit, includes a second antenna, the output of which is connected to the input of the second analog-to-digital converter, the output of which is connected to the first input of the second a storage device, and the output of the second chronizer is connected to the second input, the input of which is connected to a single-time system, characterized in that in addition to the peripheral item a signal processing device is provided, the first input of which is connected to the output of the second memory device, and the second input with the fourth output of the first signal processing device, an additional unit for estimating the delay of direct signals is added to the central point, the first and second inputs of which are connected respectively to the first outputs of the first and the second signal processing device, and the output with the first input of the display unit, the evaluation unit of the delay of the reflected signal relative to the direct one, the first and second inputs of which are connected

Description

The utility model relates to radio engineering, and can be used in the development of systems for determining the coordinates of a radio emission source (IRI), as well as in passive radar.

A device for estimating the difference in the moments of reception of signals, described in the description of the invention under the name "Difference-range measuring method of direction finding of a source of radio emission and its device" [1]. The device comprises a first and second antenna, a meter of the difference in time of signal reception, a computing unit and an indication unit, the output of the first and second antennas being connected respectively to the first and second inputs of the meter of the time difference, the outputs of which are connected to the input of the computing unit, the output of which is connected to the input of the unit indication. In this device, the estimation of the difference in reception times is implemented in a time difference meter, and only direct signals are used to estimate the time difference.

The disadvantage of this device is the low accuracy of determining the difference in reception times at low direct signal power, as well as during propagation in a multipath channel.

Closest to the claimed device is a device described in the description of the invention under the name: "Diversity difference-range finder direction finder" [2]. The device consists of two spaced receiving points, one of which is peripheral, connected by a communication channel to a central receiving and processing point, while the peripheral receiving point includes an antenna, the output of which is connected to the input of an analog-to-digital converter, the output of which is connected to the first input a memory device, to the second input of which a chronizer output is connected, the input of which is connected to a single time system, the control input of the memory device is connected to the output of the device a board designed to generate commands for transmitting to the control channel the corresponding fragment of the stored information, and the output of the storage device is connected to the communication channel with a central point of reception and processing; the central receiving and processing center includes an antenna, the output of which is connected to the input of an analog-to-digital converter, the output of which is connected to the first input of the storage device, to the second input of which the output of the chronizer is connected, the input of which is connected to the single-time system, the output of the storage device is connected to the input of a signal processing device for detecting a signal of a radio emission source, measuring a spectrum width of a detected signal, searching for and extracting a signal fragment, having the appropriate duration and width of the spectrum, the first output of the signal processing device connected to the input of the buffer storage device, and the second output to the input of the query generator, the output of which is connected through the communication channel to the input of the control device, which is part of the peripheral receiving point, the buffer input a storage device is connected through a communication channel to the output of the storage device included in the peripheral receiving point; the output of the buffer storage device is connected to the first input of the meter of the difference in time of signal reception, the output of the buffer memory is connected to the second input of the first meter of the difference of time of signal reception.

The accuracy of estimating the difference in the moments of signal reception at spaced receiving points depends on the level of the direct signal at the input of the receiver, as well as the influence of the multipath propagation channel of radio waves. With a low direct signal level, the accuracy of the estimate is reduced. The disadvantage of the prototype device is the low accuracy of determining the difference in the moments of signal reception during propagation in the multipath channel, as well as at a low level of the direct signal.

The task to which the proposed technical solution is directed is to increase the accuracy of estimating the difference in the moments of reception of IRI signals at two spaced receiving points. The solution to this problem is achieved by the fact that the device for estimating the difference in the moments of reception of the IRI signal at two spaced receiving points, consisting of a central and peripheral points, while the central receiving and processing center includes a first antenna, the output of which is connected to the input of the first analog a digital converter, the output of which is connected to the first input of the first storage device, and to the second input of which the output of the first chronizer is connected, the input of which is connected to the system of a single time nor, the output of the storage device is connected to the input of the first signal processing device, the computing unit, the output of which is connected to the second input of the display unit, includes a second antenna, the output of which is connected to the input of the second analog-to-digital converter, the output of which connected to the first input of the second storage device, and the output of the second chronizer, the input of which is connected to a single time system, is connected to the second input, as part of the peripheral point of the accessory A signal processing device is introduced, the first input of which is connected to the output of the second memory device, and the second input with the fourth output of the first signal processing device, an additional unit for estimating the delay of direct signals, the first and second inputs of which are connected to the first outputs, respectively, is added to the central point the first and second signal processing devices, and the output with the first input of the display unit, the evaluation unit of the delay of the reflected signal relative to the direct one, the first and second inputs of which are connected respectively with the second outputs of the first and second signal processing devices, and the output with the first input of the computing unit, the delay evaluation unit of the reflected signals, the first and second inputs of which are connected respectively to the third outputs of the first and second signal processing devices, and the output with the second input of the computing unit .

The functional diagram of the proposed device is shown in figure 1, which indicates: 1, 13 - the first and second antennas, 2, 12 - the first and second analog-to-digital converters, 3, 11 - the first and second storage devices, 4, 15 - the first and the second chronizers, 5, 14 - the first and second signal processing device, 6 - unit for evaluating the delay of direct signals, 7 - unit for evaluating the delay of the reflected signal relative to the direct, 8 - unit for evaluating the delay of the reflected signals, 9 - computing unit, 10 - display unit , 16 - the system of a single time.

Detailed description of the device:

The basis of the operation of the device is the assumption that the source of radio emission and reflectors have different angular positions relative to the receiving point, and therefore, direct and reflected signals can be resolved by the angle of arrival. A prerequisite for signal resolution is a fairly narrow antenna radiation pattern (AR) at the receiving point and the ability to scan a given viewing sector. Phased array antennas satisfy these conditions, since when using a large number of antenna elements, a rather narrow beam (units of degrees) is formed, and the introduction of the corresponding phase shifts into each element of the array will provide electronic control of the position of the maximum radiation pattern of the antenna system. Given the above assumptions, we assume that for each angular position, the antenna system provides only one signal (either direct or reflected). Thus, at each receiving point, direct and reflected signals are recorded, which are allowed by the angle of arrival. The geometry of the model is presented in figure 2, which indicates: 1, 2 - the first and second receiving points, 3 - the source of radio emission, 4, 5, 6 - reflectors.

IRI signals are received by the antennas of the central 1 and peripheral 13 receiving points, the voltage at the output of the antenna is digitized using the first 2 and second 12 analog-to-digital converters. Further, the samples of the digitized signal are stored in the memory of the central 3 and peripheral 11 points and are tied to a single time scale using a chroniser 15 connected to a single time system 16. After that, the direct and reflected signals are extracted in the first 5 and second 14 signal processing devices, taken at the central and peripheral collection points. Processing devices 5 and 14, extract direct and reflected signals, and also evaluate the power of the received signals. If the power of the direct signals exceeds the power of the re-reflected signals, or the re-reflected signals were not recorded, then the direct signals are digitally input to the input unit for evaluating the delay of direct signals 6. In block 6, the difference in the moments of reception of direct signals only for the direct signals is estimated the difference can be estimated by the position of the maximum VKF of two direct signals [3]:

where T is the duration of the recording signal; s _1ПР (t), s _2ПР (t) - direct IRI signals normalized by average power, received at the central and peripheral points, respectively.

предлагается использовать те отраженные сигналы, уровень которых выше или сравним с уровнем прямого сигнала. Математические модели каналов распространения сигналов в современных системах связи предполагают наличие до 15…20 отраженных сигналов, причем при принятых допущениях (фиг.2) можно полагать, что уровень отраженных сигналов будет выше уровня прямого сигнала [5].Quite often, the following situation occurs: a direct signal is emitted at the receiving points, emitted from the side lobe of the IR antenna beam, and the radiation along the main lobe is directed towards reflecting objects (Fig. 2). According to studies [3, 4], the accuracy of estimating the MP difference increases with increasing signal-to-noise ratio; therefore, to increase the accuracy of the resulting estimate

It is proposed to use those reflected signals whose level is higher or comparable with the level of the direct signal. Mathematical models of signal propagation channels in modern communication systems suggest the presence of up to 15 ... 20 reflected signals, and with the assumptions made (Fig. 2), it can be assumed that the level of reflected signals will be higher than the level of the direct signal [5].

прямых сигналов в вычислительном блоке 9 рассчитывается следующим образом:If the power of the direct signals is lower than the power of the rereflected ones (the direct signal is received by the lateral radiation of the transmitting antenna), then the direct and rereflected signals are digitally supplied to the first and second inputs of the block 7 for evaluating the reflected signal relative to the direct one, also the reflected signals are fed to the first and the second inputs of the block 8 estimates the delay of the reflected signals. The evaluation units 7 and 8, as well as the computing unit 9, implement the following algorithm for evaluating the moments of reception of direct signals. In block 7, the estimates between the direct and reflected signals for the central and peripheral points are calculated; we denote these estimates, respectively, as t_1 and t_2. Then, in block 8, the mutual delay between the reflected signals received at the central and peripheral points of the system is calculated; we denote the delay as t_12. To estimate the values of t_1, t_2 and t_l2, cross-correlation processing is also used [3]. The desired difference in reception times

direct signals in the computing unit 9 is calculated as follows:

Figure 3 shows the signals recorded at the Central and peripheral receiving point.

To test the operability of the proposed method, we performed mathematical modeling in the MATLAB environment. The purpose of the simulation is to obtain statistical characteristics of differences in arrival times for the case of receiving a signal from the IRI by two spatially separated receiving points of the monitoring system.

Initial parameters for modeling: signal from IRI - OFDM, D / = 10 kHz, 5 = 1024; the delay of the reflected signal is set arbitrarily; the number of sales for averaging is 5000.

по формуле (1) можно лишь с точностью до одного временного дискрета, определяемого частотой дискретизации аналого-цифрового преобразователя (АЦП) в приемных пунктах. Для обеспечения временного разрешения внутри дискрета и повышения точности оценки

применена сплайн-интерполяция по пяти точкам [6].Determine the estimate of the difference MP

according to the formula (1), it is possible only up to one time discretion, determined by the sampling frequency of the analog-to-digital converter (ADC) at the receiving points. To provide temporal resolution within the discrete and increase the accuracy of the estimate

spline interpolation at five points was applied [6].

от отношения энергии отраженного сигнала к энергии прямого сигнала.Figure 4 shows the dependence of the standard deviation of the resulting estimates

from the ratio of the energy of the reflected signal to the energy of the direct signal.

, вычисленных по различным отраженным сигналам, позволяет увеличить точностьAccording to the results shown in figure 4, it is seen that the weighted summation of estimates

calculated from various reflected signals allows increasing accuracy

resulting score.

Improving the accuracy of estimating the difference in the moments of reception of direct signals, at a low level of the direct signal, at two spaced receiving points in the proposed device, is achieved by introducing additional units that allow the use of reflected signals that can be distinguished by the angle of arrival, and can reach 30% compared with prototype method.

Used sources

1. Pat. RF №2258242, IPC G01S 3/46, G01S 11/02. Difference-range measuring method of direction finding of a source of radio emission and device realizing it. Publ. 08/10/2005

2. Pat. RF №2382378, IPC G01S 3/46. Diversity differential range finder. Publ. 02/20/2010

3. Gromov V.A. Estimation of the difference in the moments of arrival of a signal by a group of spatially separated small spacecraft / V.A. Gromov, E.P. Voroshilin, M.V. Mironov // Reports of Tomsk State University of Control Systems and Radio Electronics (Tomsk). - Tomsk: Publishing house "V-Spectrum". - 2010. - No. 2 (22), part 2. - S.7-13.

4. Improving the accuracy of determining coordinates using the differential-range measuring method using a grouping of low-orbit small spacecraft / V. A. Gromov, E. P. Voroshilin, M. V. Mironov, G. S. Sharygin // Reports of Tomsk State University of Control Systems and radio electronics (Tomsk). - Tomsk: Publishing house "V-Spectrum". - 2010. - No. 2 (22), part 2. - S.14-16.

5. Channel Models: A Tutorial, 2007 [Electronic resource]. - Access mode: http://www1.cse.wustl.edu/~jain/cse574-08/ftp/channel_model_tutorial.pdf, free (accessed: 02/10/2012).

6. Ayficher E.S. Digital signal processing: a practical approach / E.S.Aificher, B.U. Jervis. - M .: Williams, 2004 .-- 992 p.

Claims (1)

A device for estimating the difference in moments of reception of a signal from a radio emission source at two spaced receiving points, consisting of a central and peripheral points, while the central receiving and processing center includes a first antenna, the output of which is connected to the input of the first analog-to-digital converter, the output of which is connected to the first input of the first storage device, and to the second input of which the output of the first chronizer is connected, the input of which is connected to a single time system, the output of the storage device The device is connected to the input of the first signal processing device, the computational unit, the output of which is connected to the second input of the display unit, includes a second antenna, the output of which is connected to the input of the second analog-to-digital converter, the output of which is connected to the first input of the second a storage device, and the output of the second chronizer is connected to the second input, the input of which is connected to a single-time system, characterized in that in addition to the peripheral item a signal processing device is provided, the first input of which is connected to the output of the second memory device, and the second input with the fourth output of the first signal processing device, a unit for estimating the delay of direct signals, the first and second inputs of which are connected respectively to the first outputs of the first and the second signal processing device, and the output with the first input of the display unit, the evaluation unit of the delay of the reflected signal relative to the direct one, the first and second inputs of which are connected respectively to the second outputs of the first and second signal processing units, and an output to a first input of the computing unit, the estimation delay of the reflected signals, the first and second inputs of which are respectively connected to third outputs of the first and second signal processing units, and an output to a second input of the computing unit.

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