RU110501U1 - DEVICE FOR TWO-FREQUENCY MEASUREMENT OF THE CO-RANGE OF THE TRANSIONOSPHERIC COMMUNICATION CHANNEL - Google Patents

Abstract

 A dual-frequency device for measuring the coherence band of a transionospheric communication channel includes a receiving antenna (1), the output of which is connected to the first input of the dual-frequency receiver (2); the output of the dual-frequency receiver is connected to the first input of the analog-to-digital primary processing processor (4); the output of the analog-to-digital primary processing processor (4) is connected to the input of the signal phase path calculation unit (5); the output of the phase signal path calculation unit (5) is connected to the first input of the full electronic ionosphere content calculation unit (6); the first output of the reference generator and frequency synthesizer (3) is connected to the second input of the dual-frequency receiver (2), the second input of the analog-to-digital primary processing processor (4), the second input of the block for calculating the total electronic content of the ionosphere (6); the second output of the reference generator and frequency synthesizer (3) is connected to the third input of the dual-frequency receiver (2), the third input of the analog-to-digital primary processing processor (4), and the third input of the block for calculating the total electronic content of the ionosphere (6); the output of the unit for calculating the total electronic content of the ionosphere (6) is connected to the input of the output device information (7), characterized in that the unit is entered into the device for calculating the standard deviation of the total electronic content of the ionosphere (8), the input of which is connected to the output of the unit for calculating the total electronic content of the ionosphere (6), and the output is with the first input of the transionospheric communication channel coherence band calculation unit at the first carrier frequency (11) and the first input of the trans coherence band calculation unit ionosphere

Description

The proposed utility model relates to satellite radio navigation and communication and can be used in monitoring systems for the state of the ionosphere and parameters of the communication channel.

As is known, the impact on the ionosphere of a number of factors caused by solar activity, such as ionospheric magnetic storms and bursts of absorption, lead to a change in its basic parameters and have a significant effect on the propagation of radio waves [1, 2].

One of the main parameters of the ionosphere, affecting the propagation of radio waves, is its total electronic content I, the value of which can be measured at two-frequency operation (at carrier frequencies f ₁ and f ₂ ) of satellite navigation systems [4]. In the general case, I represents a Gaussian random process and at any time is defined as the sum (I = Ī + ΔI) of the average value Ī of the total electronic content of the ionosphere and its fluctuation ΔI relative to Ī. Fluctuations in the total electronic content of the ionosphere ΔI are characterized by standard deviation

One of the most important parameters of the communication channel is the frequency coherence band ΔF _K ~ 1 / σ _ΔI , which inversely depends on the standard deviation of the fluctuations of the total electronic content of the ionosphere σ _ΔI [2].

It is known that at the operating frequencies of satellite communication systems (f _1.2 ~ 1 GHz) under normal ionosphere (when σ _ΔI ~ 10 ¹⁴ e / m ² ) the frequency coherence band is ΔF _K1.2 ~ 10 GHz, and with ionospheric disturbances (when σ _ΔI can reach ~ 10 ¹⁸ el / m ² ) it can narrow to values ΔF _K1,2 <1 MHz or less [2]. In this case, when transmitting signals with a spectral width ΔF ₀ = 1 ... 10 MHz in satellite communication and navigation channels, the conditions (ΔF ₀ > ΔF _{Kl, 2} ) of occurrence of frequency-selective fading of the received signals will be satisfied.

The goal is to develop a device that allows you to determine the coherence band of the _{transionospheric} communication channel ΔF _K1,2 according to the results of two-frequency (at carrier frequencies f ₁ and f ₂ ) measurements of the total electronic content of the ionosphere I = Ī + ΔI.

The technical result that can be obtained using the proposed utility model is reduced to the possibility of adapting the signal spectrum width (ΔF ₀ ) of satellite radio navigation systems in order to eliminate frequency-selective fading (ΔF ₀ <ΔF _K1,2 ) with ionosphere disturbances and a narrowing of the coherence band transionospheric channel up to ΔF _K1,2 <1 MHz.

A device for measuring the total electronic content of the ionosphere I in the dual-frequency mode of operation of satellite radio navigation systems [4], which includes: a receiving antenna (1), a dual-frequency receiver (2), a reference generator and frequency synthesizer (3), an analog-to-digital primary processor processing (4), a block for calculating the phase path of the signal (5), a block for calculating the total electronic content of the ionosphere (6), an information output device (7) (Fig. 1). The disadvantage of this device is that it does not allow us to estimate the coherence band of the transionospheric communication channel.

A known device for measuring the total electronic content of the ionosphere in the dual-frequency mode of operation of satellite navigation systems works as follows. The receiving antenna (1) receives electromagnetic waves emitted by navigation satellites. From the output of the receiving antenna (1), the voltage u _in (t) is supplied to the input of the dual-frequency receiver (2). From the output of the dual-frequency receiver (2) to the input of the analog-to-digital primary processing processor (4), a vector for evaluating digital signals y (t _j ) is presented, consisting of signals j = 1 ... n of visible navigation satellites. The reference generator and frequency synthesizer (3) generates the nominal values of the operating frequencies f ₁ and f ₂ at the inputs of the dual-frequency receiver (2), the analog-to-digital primary processing processor (4), and the unit for calculating the total electronic content of the ionosphere I (6). An analog-to-digital primary processing processor (4) implements search and tracking schemes for signal parameters. From the output of the analog-to-digital primary processing processor (4), estimates of the propagation phase time τ _Ф1,2 (t _k ) of the radio signal at the carrier frequencies f ₁ and f ₂ are fed to the input of the phase path calculation unit of the signal (5) that implements the algorithm D _Ф1,2 (t _k ) = cτ _Ф1,2 (t _k ) with a step Т _k = t _k -t _k-1 = 0.02 s, where Д _Ф1 and Д _ф2 are phase signal paths (phase measurements of pseudorange) at frequencies f ₁ and f _2, respectively. The values of D _{f1,2 (} t _k) are fed to the input of the block for calculating the total electronic content of the ionosphere I (6). From the output of the unit for calculating the full electronic content of the ionosphere (6), the data is supplied to the information output device (7).

The implementation of the proposed device, which allows to determine the value of the coherence band of the _{transionospheric} communication channel ΔF _K1,2 depending on the change in the mean square deviation of the total electronic content of the ionosphere σ _ΔI, will allow the implementation of a dual-frequency measurement of the coherence band of the transionospheric communication channel, the diagram of which is shown in Figure 2. The expression for calculating the coherence band of the transionospheric communication channel has the form [2]:

where f is the carrier frequency [Hz];

c = 3 · 10 ⁸ m / s is the speed of light;

σ _ΔI is the standard deviation of the fluctuation of the total electronic content of the ionosphere in its small-scale inhomogeneities [e / m ² ];

80.8 - constant coefficient [m ³ / s ² ];

- coefficient characterizing the increase in diffraction effects in the wave front as it propagates;

l _s is the characteristic scale of inhomogeneities (l _s = 400 m);

h _e - equivalent thickness of the ionospheric layer (h _E = 5 · 10 ⁵ m);

h ₁ - the distance it is the lower boundary of the ionosphere to the receiving point (h ₁ = 10 ⁵ m).

To solve this problem, in the well-known (Figure 1) device for measuring the total electronic content of the ionosphere at a two-frequency mode of operation of satellite radio navigation systems [4], the following blocks were added: a unit for calculating the standard deviation of the total electronic content of the ionosphere (8), a unit for calculating the coefficient characterizing the increase in diffraction effects in the wave front as it propagates on the carrier frequency f ₁ (9), the coefficient calculation unit, characterized by an increase of the diffraction effect in the wave front as it propagates on the carrier frequency f ₂ (10), the calculating unit transionospheric coherence bandwidth communication channel at the carrier frequency f ₁ (11) and the calculating unit transionospheric coherence bandwidth of the communication channel at the carrier frequency f ₂ (12).

Because the coherence band measuring device of the transionospheric communication channel, the circuit of which is shown in FIG. 2, is implemented at two carrier frequencies f ₁ and f ₂ , then expressions (1) and (2) for the carrier frequency f ₁ will take the form

for carrier frequency f ₂

The proposed device (figure 2) works as follows. The receiving antenna (1) receives electromagnetic waves emitted by navigation satellites. From the output of the antenna (1), the voltage u _I (t) is supplied to the input of the dual-frequency receiver (2), intended to amplify and select the received signals. From the output of the dual-frequency receiver (2) to the input of the analog-to-digital primary processing processor (4), a vector for evaluating digital signals y (t _j ) consisting of signals j = 1 ... n of visible navigation satellites is fed. The reference generator and frequency synthesizer (3) generates the nominal values of the operating frequencies f ₁ and f ₂ at the inputs of the dual-frequency receiver (2), the analog-to-digital primary processing processor (4), the unit for calculating the total electronic content of the ionosphere I (6); nominal frequencies f ₁ to the inputs of the coefficient calculation unit, which characterizes the increase in diffraction effects in the wave front as it propagates on the carrier frequency f ₁ (9) and the unit for calculating the coherence band of the transionospheric communication channel ΔF _K1 at the carrier frequency f ₁ (11); nominal frequencies f ₂ at the inputs of the coefficient calculation unit, characterizing the increase in diffraction effects in the wave front as it propagates at the carrier frequency f ₂ (10) and the unit for calculating the coherence band of the transionospheric communication channel ΔF _K2 at the carrier frequency f ₂ (12). An analog-to-digital primary processing processor (4) implements search and tracking schemes for signal parameters. From the output of the analog-digital processor (4) to the input of the phase signal path calculation block of the signal (5) that implements the algorithm D _Ф1,2 (t _k ) = cτ _Ф1,2 (t _k ) with a step T _k = t _k -t _{k- 1} = 0.02 s estimates of the propagation phase time τ _Ф1,2 (t _k ) are _received . From the output of the block for calculating the phase path of the signal (5), the values of Д _Ф1,2 (t _k ) go to the input of the block for calculating the total electronic content of the ionosphere I = Ī + ΔI (6). Then, from the output of the block for calculating the total electronic content of the ionosphere I (6), estimates of the total electronic content I = Ī + ΔI are input to the block for calculating the standard deviation of the total electronic content of the ionosphere (8) where centering, squaring, averaging, and square root extraction operations take place [5]. From the output of the unit for calculating the standard deviation of the total electronic content of the ionosphere σ _ΔI (8), the values of the standard deviation of the total electronic content of the ionosphere σ _ΔI go to the input of the unit for calculating the coherence band of the transionospheric communication channel ΔF _K1 at the carrier frequency f ₁ (11) and the input of the unit for calculating the coherence band transionospheric communication channel ΔF _K2 at a carrier frequency f ₂ (12). At the second input of the unit for calculating the coherence band of the transionospheric communication channel ΔF _K1 at the carrier frequency f ₁ (11), the values of the coefficient characterizing the increase in diffraction effects are received determined in the block for calculating the coefficient characterizing the increase in diffraction effects in the wave front as it propagates at the carrier frequency f ₁ (9) according to expression (4). At the second input of the unit for calculating the coherence band of the transionospheric communication channel ΔF _K2 at the carrier frequency f ₂ (12), the values of the coefficient characterizing the increase in diffraction effects determined in the block for calculating the coefficient characterizing the increase in diffraction effects in the wave front as it propagates at the carrier frequency f ₂ (10) according to expression (6). In the unit for calculating the coherence band of the transionospheric communication channel ΔF _K1 at the carrier frequency f ₁ (11) and the unit for calculating the coherence band of the transionospheric communication channel ΔF _K2 at the carrier frequency f ₂ , the values of the coherence band are determined according to expressions (3) and (5), respectively. The calculated values of the coherence band ΔF _K1 and ΔF _K2 at the carrier frequencies f ₁ and f _{2 are} displayed in the information output device (7).

Thus, in the developed device (Figure 2), based on the standard deviation of the total electronic content of the ionosphere σ _ΔI according to the well-known [2] expression (1), the values of the coherence band of the transionospheric communication channel are determined quickly (with a step T _k = 0.02 s) according to the results of two-frequency measurements (at carrier frequencies f ₁ and f ₂ ) of the total electronic content of the ionosphere I = Ī + ΔI.

Brief Description of the Drawings

Figure 1 presents a functional diagram of a known device for measuring the total electronic content of the ionosphere in the dual-frequency mode of operation of satellite radio navigation systems [4]; figure 2 presents a functional diagram of the proposed device dual-frequency measurement of the coherence band of the transionospheric communication channel.

List of sources used

1. Grudinskaya G.P. Propagation of radio waves. Textbook for radio technology. specialist. universities. Ed. 2nd, rev. and add. Moscow, "Higher. School ", 1975-280 p.

2. Pashintsev V.P., Solchatov M.E., Gakhov R.P. The influence of the ionosphere on the characteristics of space-based information transfer systems: Monograph. - Moscow: Fizmatlit, 2006 .-- 184 p.

3. Pashintsev V.P. The influence of frequency selective fading on the measurement of the delay time of signals in space communication systems // Radio Engineering and Electronics, 1989 - Volume 43 - No. 4 - p.410-414.

4. Pashintsev V.P., Galushko Yu.I., Spirin A.M., Koval S.A. A device for measuring the total electronic content of the ionosphere in the dual-frequency mode of operation of satellite radio navigation systems. Utility Model Patent No. 81340 of March 10, 2009

5. Smirnov NN, Fedosov VP, Tsvetkov F.V. Measurement of characteristics of random processes / Under. ed. V.P. Fedosova: Textbook. manual for universities. - M.: SAYNS-PRESS, 2004 .-- 64 p.

Claims (1)

A dual-frequency device for measuring the coherence band of a transionospheric communication channel includes a receiving antenna (1), the output of which is connected to the first input of the dual-frequency receiver (2); the output of the dual-frequency receiver is connected to the first input of the analog-to-digital primary processing processor (4); the output of the analog-to-digital primary processing processor (4) is connected to the input of the signal phase path calculation unit (5); the output of the phase signal path calculation unit (5) is connected to the first input of the full electronic ionosphere content calculation unit (6); the first output of the reference generator and frequency synthesizer (3) is connected to the second input of the dual-frequency receiver (2), the second input of the analog-to-digital primary processing processor (4), the second input of the block for calculating the total electronic content of the ionosphere (6); the second output of the reference generator and frequency synthesizer (3) is connected to the third input of the dual-frequency receiver (2), the third input of the analog-to-digital primary processing processor (4), and the third input of the block for calculating the total electronic content of the ionosphere (6); the output of the unit for calculating the total electronic content of the ionosphere (6) is connected to the input of the output device information (7), characterized in that the unit is entered into the device for calculating the standard deviation of the total electronic content of the ionosphere (8), the input of which is connected to the output of the unit for calculating the total electronic content of the ionosphere (6), and the output is with the first input of the transionospheric communication channel coherence band calculation unit at the first carrier frequency (11) and the first input of the trans coherence band calculation unit ionospheric communication channel at a second carrier frequency (12); a unit for calculating a coefficient characterizing the increase in diffraction effects in the wave front as it propagates at the first carrier frequency (9), the input of which is connected to the first output of the reference generator and frequency synthesizer (3), and the output - with the second input of the unit for calculating the transionospheric channel coherence band communication at the first carrier frequency (11); a coefficient calculation unit characterizing the increase in diffraction effects in the wave front as it propagates at the second carrier frequency (10), the input of which is connected to the second output of the reference generator and frequency synthesizer (3), and the output is with the second input of the transionospheric channel coherence band calculation unit communication at the second carrier frequency (12); a unit for calculating the coherence band of the transionospheric communication channel at the first carrier frequency (11), the third input of which is connected to the first output of the reference generator and frequency synthesizer (3), and the output to the input of the information output device (7); block for calculating the coherence band of the transionospheric communication channel at the second carrier frequency (12), the third input of which is connected to the second output of the reference generator and frequency synthesizer (3), and the output is connected to the input of the information output device (7).