# Method of finding coordinates of radio-frequency radiation source

FIELD: radio engineering.

SUBSTANCE: method can be used for high precision measurement of coordinates of radio-frequency radiation sources which radiate continuous or quazi-continuous signals by means of flying vehicles. Method is based upon reception of signals from radio-frequency radiation sources at three flying vehicles, re-translation of signals to central processing board and calculation of coordinates of radio-frequency radiation sources from difference in radial velocities of flying vehicles. Signals being re-translated from flying vehicles are subject to additional mutual correlation processing. Difference in radial velocities is calculated on the base of measurement of compression factors determined by maximizing of mutual correlation function of signals re-translated from flying vehicles. Coordinates of radio-frequency radiation sources radiating wideband signals is provided.

EFFECT: widened functional capabilities.

The invention relates to the field of radio, namely to passive systems of monitoring, in particular can be used for accurate positioning of emitters (IRI), emitting continuous or quasi-continuous signals, using aircraft.

A well-known system of coordinates system PLSS intended for IU-stoopidity IRI differential-ranging way, placed on the aircraft [1]. However, this system is inefficient in determining the coordinates of the sources, emitting continuous or quasi-continuous signals.

Of the known methods, the closest analogue (prototype) of the proposed method to the technical essence is a differential-Doppler method for determining coordinates of radio emission sources (RES) with continuous emission [2]. The method consists in the reception signal IRI on three aircraft, relay signals to a Central processing point, the differencing of the radial velocities of the aircraft at the Doppler difference frequency signals that are relayed from the aircraft, with the subsequent calculation of coordinates (IRI difference of radial velocities.

However, the device prototype has a drawback - the device is not operable when determining coordinatori, emitting broadband signals, since in this case it is impossible to accurately measure the frequency difference between signals [2, 3], relayed from the aircraft (broadband, here we will call the signals with a bandwidth from tens of Hertz to several kilohertz).

The aim of the present invention is to enhance the functionality, i.e. the definition of the coordinates of the IRI emitting broadband signals.

This objective is achieved in that in the known method of determining the coordinates of the IRI, which consists in the use of signals IRI on three aircraft, relay signals to a Central processing point and the calculation of coordinates (IRI difference of radial velocities of aircraft, the signals relayed from the aircraft, additionally are mutually correlation processing, and the difference of radial velocities are calculated based on the measured compression ratios.

Comparative analysis of the prototype shows that the inventive method is characterized by the fact that on the Central point of processing the signals relayed from the aircraft, are more mutually correlation processing. Thus, the claimed method meets the criteria of the invention of "novelty."

Comparison of proposed method with other methods for the AMI shows the need to implement well-known operations - reception of signals IRI on aircraft, relay signals to a Central processing point differencing radial velocities of the aircraft and calculating the coordinates of the IRI. However, in the present method the difference of radial velocities are calculated through the ratio, calculated on the basis of maximizing mutually correlation functions of the signals, which allows to make a conclusion on the conformity of the proposed method the criterion of "substantial differences".

Calculating compression ratios can be achieved by the introduction on the Central point of the two processing units for measurement of compression ratios.

Known application of units of measurement compression ratios in acoustics. The purpose and the device, as well as detailed analysis of the operation of the unit described, for example, [4].

The essential difference is the use of this unit in electrical engineering, and design changes in accordance with the operation mode in radio systems.

The coordinates of Iran in accordance with the inventive method is carried out as follows. Let the inputs of the relays of aircraft 1 and 2 receives signals from Iran. Given that the radial velocity of the 1st and 2nd aircraft V_{R1}and V_{R2}much less than the speed of light can burn

where S_{}
(t) and S_{2}(t) the signals received at the first and second aircraft, respectively; Δτ_{12}that Δτ'_{12}Δτ"_{12}- the delay of the second signal relative to the first and its derivatives.

Given that during the observation time T delay Δτ_{12}≈const restrict only the first derivative of the delay Δτ_{12}

Delay and its derivative can be written asmoreover, V_{Ri}>0, if the speed is directed towards Iran, and V_{Ri}<0, if from Iran. Rewriting (1) otherwise S_{1}(t)=S_{2}(g_{12}t+Δτ_{12}), where q_{12}=1+Δτ'_{12}see that the time axis of the signal S_{1}compressed (expanded) compared to the time axis of the signal S_{2}.

Repeaters lines transmit signals S_{1}; and S_{2}at the Central processing point, then they enter the unit of measurement ratio that calculates the maximum of two-dimensional mutually correlation functions

When α_{12}= g_{12}and τ_{12}=Δτ_{12}function With_{M}(τ, α) will show a maximum. Similar operations are performed with the signals S_{2}and S_{3}.

These compression ratios q_{12}and q_{32}calculate what agnosti radial velocities.
Using the equation of the sphere of Earth, the coordinates of the aircraft and the difference of radial velocities, determine the coordinates of Iran.

Compare the accuracy of the measurement of the difference of radial velocities of the proposed method and the method of the prototype. Take the case of the most favorable conditions for the work of the prototype method is when Iran emits monochromatic signal at frequency f_{0}. In the proposed method, the aircraft 1 and 2 will be accepted signals with frequenciesand. In this case, the determination of the compression ratio to determine the ratio

where

Due to the fact that V_{R1}≪ c V_{R2}≪ with (as mentioned above), using the decompositiondiscarding the members in the second degree and above, will receive

On the basis of (2) and (3) can be written

Root mean square error (RMSE) values of U=f(x_{1};x_{2};...;x_{n}) is calculated by the formula

where ρ_{ij}. the correlation coefficient between x_{i}and x_{j}.

Suppose that the measurement frequency f_{1}and f_{2}independent, that is ρ
_{ij}=0, then RMS determine the difference of radial velocities on the basis of (4) and (5) can be written

where σ_{f1}and σ_{f2}- SKO determination of the frequencies of f_{1}and f_{2}respectively.

Let σ_{f1}=σ_{f2}= σ_{f}and since f_{1}≈f_{2}≈f_{0}you can record

Given that the Doppler frequency and the radial velocity of the aircraft connected by the relation f_{1}=f_{0}V_{R1}/c and f_{2}=f_{0}VR_{2}a /c, the difference of radial velocities in the method prototype is determined from the relationship

Assuming, as before σ_{f1}=σ_{f2}=σ_{f}f_{1}≈f_{2}≈f_{3}≈f, ρ_{12}=0, we get MSE of the determination of the difference between the radial velocities device-prototype

that is, the error determination of the difference between the radial velocities of the proposed method is equal to the error of the prototype method.

Analysis of the proposed method in comparison with the method of the prototype shows that the inventive method provides for the determination of the coordinates of the IRI emitting wideband signals, in contrast to devices of the prototype.

Thus, the goal of the claimed method is an extension function is tional opportunities, providing coordinates IRI radiating wideband signals is achieved.

Technical and economic effect resulting from the application of this method is to enhance the functionality and improve the accuracy of determination of coordinates Iran without complication of the apparatus of funds, and therefore increase the efficiency of passive monitoring systems in General.

The quantitative value of the expected technical and economic effect from the use of the proposed method depends on the type of system is subject to monitoring and the importance of this system; its definition is possible after implementation of the proposed method in specific systems of radio control.

Sources of information

1. International Defence Review, USA, 9/1978, pp. 1440-1441.

2. Kondrat'ev V.S., and other Multi-radio system. - M.: Radio and communication, 1986. 264 C.

3. Tomerry DJ. Statistical Theory of Passive Location Systems// NECK Trans. 1984. V. AE-20. No. 2. R.

4. Comparision of the Deskewed Short Correlator and the Maximum Likelihood Correlator// IEEE Trans. Acoust., Speech, Signal Processing, vol. ASSP-32, No. 2, Apr. 1984.

The method of determining the coordinates of the emitters (IRI), which consists in the reception of signals IRI on three aircraft, relay signals to a Central processing point, the differencing of the radial velocities of the aircraft, followed the m calculation of coordinates (IRI difference of radial velocities, characterized in that the signals relayed from the aircraft, additionally are mutually correlation processing, and the difference between the radial velocities of the aircraft are calculated based on the compression ratios of the signals determined by finding the maximum of mutually correlation function of the signals relayed from the aircraft.

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