CN103984837A - Method for analyzing influence of time-varying channel of deep sea navigation XCTD on transmission performance - Google Patents

Abstract

The invention takes the transmission channel of the mobile disposable temperature, salinity and humidity profiler as a prototype, and proposes a method for dynamically analyzing the influence of the wired channel on the amplitude and phase of the transmission signal. With the continuous change of the pay-off length, the online parameters are constantly changing, and a stable channel cannot be guaranteed. This real-time changing channel impedance characteristic seriously affects the channel transmission stability of the deep-sea navigation disposable measuring instrument. The invention establishes a simplified transmission circuit model and the transmission function of the model. Through qualitative analysis, the influence of transmission frequency, distributed capacitance and winding inductance on signal phase is obtained. And use MATLAB software to analyze the influence of the channel on the signal amplitude and phase during the dynamic pay-out process of XCTD. It can further guide the circuit design of the disposable navigation measurement system, improve the accuracy of measurement data and the stability of signal transmission.

Description

Analysis method of influence of time-varying channel on transmission performance in deep-sea navigation XCTD

technical field

The invention takes the transmission channel of a mobile disposable temperature, salinity and humidity (XCTD) profiler as a prototype, and proposes a method for dynamically analyzing the influence of the wired channel on the amplitude and phase of the transmission signal.

Background technique

The main products of disposable measuring instruments are temperature profiler (XBT), temperature and salinity profiler (XCTD), sound velocity profiler (XSV) and ocean current profiler (XCP), among which XCTD is the most commonly used. This type of instrument is for one-time use. It consists of two parts: an underwater receiver and an underwater probe. After entering the water, the sensor in the probe starts to measure. The internal data collector completes the collection, processing and transmission of marine environmental parameters in real time, and transmits them to the ship synchronously in the form of digital signals through the thin transmission line in the probe, and finally forms a measurement profile. Due to the requirements of the environment, most of the signal transmission part of the deep-sea navigation disposable measuring instrument uses a wired channel. With the rapid decline of the probe, the transmission line originally wound on the spool is continuously released, and the inductance of the spool continues to decrease as the length of the pay-off line changes Small, the capacitance between the expanded transmission lines is increasing, the electrical impedance of the channel, and the capacitance between the lines is becoming more and more destructive to the integrity transmission of the signal, and the distribution parameters on the line are constantly changing, which cannot guarantee a stable channel. This dynamic real-time The changed channel impedance characteristics destroy the stability of signal transmission, and the signal distortion is serious, which seriously affects the channel transmission stability of deep-sea navigation disposable measuring instruments. Especially in high-speed communication, the commonly used digital communication methods are no longer applicable to this working condition, which brings great difficulties to signal demodulation.

According to some studies done, the XCTD (disposable salt, temperature, depth) profiler sinks to a certain depth, and the signal transmission is severely distorted. Therefore, the present invention first deduces the law that each circuit parameter varies with the channel length, and establishes a simplified The transmission circuit model of and the transfer function of this model. Through qualitative analysis, the influence of transmission frequency, distributed capacitance and winding inductance on signal phase is obtained. And use MATLAB software to analyze the channel's influence on the signal amplitude and phase during the dynamic pay-out process of XCTD, as well as the reason of the influence. It can further guide the circuit design of the disposable navigation measurement system, improve the accuracy of measurement data and the stability of signal transmission.

Contents of the invention

The purpose of the present invention is to solve the influence of the time-varying channel on the transmission performance in the process of XCTD signal transmission, and proposes a method for dynamically analyzing the influence of its wired channel on the amplitude and phase of the transmission signal.

The method of the invention establishes the model of the XCTD transmission channel according to the specific application environment, and uses MATLAB software to analyze the influence of the channel on the signal amplitude and phase of the XCTD in the dynamic payout process, and the cause of the influence.

The present invention takes the transmission channel of the disposable temperature, salinity, humidity (XCTD) profiler as the prototype, and estimates the length of the payout line and the capacitance (C), inductance (L), and resistance of the transmission line circuit under the conductor environment of seawater. (R), and accurately solve the channel impedance value, and further discuss the mutual influence relationship between parameters, establish an optimized variable parameter channel circuit model, and analyze the influence of each parameter change on the signal during the coil dynamic unwinding process within the range of 2000m. The impact of amplitude and phase, discussing the impact of this time-varying transmission channel on signal transmission performance, can solve the bottleneck problem of the technical development of disposable marine environmental monitoring instruments in our country.

Technical scheme of the present invention:

Based on the transmission channel of the underwater XCTD profiler, the present invention invents a method for modeling and analysis using MATLAB software. The capacitance between a metal wire and sea water. Finally, the two capacitance values obtained are compared with the theoretically calculated values to verify the correctness of the simulation results.

The method for analyzing the impact of the XCTD time-varying channel on the transmission performance of deep-sea navigation provided by the present invention, the specific steps are:

Step 1. Calculation of channel distributed capacitance

The present invention solves the capacitance between parallel conductors by configuring the image charge multiple times, replaces the distributed charge on the surface of the conductor with the concentrated charge system after multiple mirror images, and keeps the boundary conditions unchanged, thereby simplifying the solution process of the capacitance , which is mainly based on the uniqueness theorem in electromagnetic theory and the mirror image formula of circular cross-section conductors. The calculation model is shown in the left figure of Figure 1.

Step 2. Calculation of channel distributed winding inductance and distributed resistance

The coil of the present invention is wound as a standard spiral inductor, the inductance of which is tightly wound on a cylindrical frame, and the intermediate medium is air. The calculation model is shown in the right figure of Figure 1. According to the analysis, the Brooks Coil Inductance model is used to estimate the inductance of the winding bobbin, and the change law of the inductance value and the length of the bobbin is shown in Figure 2.

Step 3. Establishment of channel transmission model

The present invention establishes a simplified channel circuit model diagram, as shown in FIG. Since the transmission line is a double-strand enameled wire, the winding mode and the environment and other influencing factors are exactly the same, so the circuit model is symmetrical up and down, and the parameter values are equal.

Step 4: Analyze the static impedance of the 500m deep channel on the transmission phase

In order to improve the stability and quality of data transmission and reduce the bit error rate of data transmission in the process of large-depth measurement, phase-modulation encoding and demodulation are used for data transmission in the communication process, and the impact of dynamic changes in channel impedance is analyzed. The influence of the data transmission phase is of great significance.

Step 5. Analysis of 2000m channel dynamic impedance on transmission phase

Since the current large-depth measurement range is within 2000m, it is of great significance to analyze the dynamic impedance channel within the depth range of 2000m for signal phase distortion analysis.

Advantages and beneficial effects of the present invention:

The present invention is aimed at the dynamic change of XCTD transmission channel impedance in deep sea navigation will greatly affect the quality of signal transmission, and when the profiler sinks to a certain depth, the signal transmission is seriously distorted, and the change of parameters will damage the integrity of channel data transmission Therefore, an analysis method for the influence of time-varying channel transmission performance on deep sea navigation XCTD is proposed. It provides certain theoretical guidance significance by analyzing the transmission characteristics of variable parameter channel data.

Description of drawings

Figure 1 is a diagram of a transmission line model, where (a) is a model diagram of a winding inductor, and (b) is a cross-sectional diagram of a transmission line.

Figure 2 is a diagram of the change law of inductance with the length of the wire axis.

Figure 3 is a simplified circuit model diagram of the channel.

Figure 4 is a qualitative analysis diagram of the influence of circuit parameters and transmission frequency on the signal phase. In the figure (a) 1pH phase delay curve under 80nF parallel capacitor, (b) 8pF phase delay curve under 0.3H winding inductor, (c) 0.04H phase delay curve under 80nF parallel capacitor, (d) 0.3H winding inductor The following 8nF phase delay curve, (e) 0.3H phase delay curve under 80nF parallel capacitor, (f) 0.2uF phase delay curve under 0.3H winding inductor.

Fig. 5 is an analysis diagram of the influence of distributed capacitance and spiral inductance on signal phase. In the figure (a) the relationship between winding inductance and phase attenuation when the 1kHz transmission frequency is 80nf distributed capacitance, (b) the relationship between distributed capacitance and phase attenuation when the 1kHz transmission frequency is 0.25H winding inductance, (c) the winding inductance when the 1kHz transmission frequency is 200nf distributed capacitance The relationship between inductance and phase attenuation, (d) The relationship between distributed capacitance and phase attenuation when 1kHz transmission frequency 1H winds the inductor.

Fig. 6 is a graph showing the variation of signal amplitude gain and phase distortion during the payout process of a 2000-meter transmission line. In the figure (a) 1kHz transmission frequency 2000m underwater spool amplitude gain diagram, (b) 5kHz transmission frequency 2000m underwater spool amplitude gain diagram, (c) 1kHz transmission frequency 2000m underwater spool phase delay diagram, (d) 2000m underwater line axis phase delay diagram for 5kHz transmission frequency.

The specific implementation manners of the present invention will be further described below in conjunction with the drawings and examples.

Detailed ways

Embodiment one

The transmission channel of the XCTD profiler is a double-strand enameled wire as a transmission wire. The two wires of the cable are arranged in parallel in the ocean. The surface of the transmission line is covered with an insulating coating, and the upper and lower spools are tightly wound in a spiral. Its parallel ring wire structure is shown in Figure 2, the inner ring is a transmission cable, and the radius r is 0.05mm. The outer ring is insulated enamelled with a radius R of 0.0545mm, surrounded by seawater, and the signal is transmitted in a differential manner.

With the normal operation of the disposable instrument, the impedance of the transmission channel changes dynamically. With the expansion of the coil, these distributed capacitances increase rapidly and the equivalent inductance gradually decreases. Therefore, it is the key to the dynamic analysis of the unwinding process to establish the changing rules of the transmission line unwinding length (D) and winding inductance (L), distributed capacitance (C), and distributed resistance (R).

Step 1. Calculation of channel distributed capacitance:

Figure 1 is a cross-sectional view of two parallel wires, where τ is the amount of charge on the wires. According to the above formula, the result calculated by using the 20 iteration algorithm is shown in formula (1).

C＝2.901065×π×ε _r ×ε ₀ ＝210pF/m (1)

The total distributed capacitance of the transmission line is mainly composed of the capacitance formed by coil winding and the capacitance between parallel wires in parallel. The adjacent turn-to-turn capacitance consists of three parts. In order to facilitate the analysis, the cross-sectional diagram of the two-layer four-turn double-strand inductor coil is selected as the model of the basic structural unit of the distributed capacitance, and the winding is assumed to be symmetrical. The equivalent total capacitance of the inductance coil can be deduced, the same as the calculation of the distributed capacitance of the single-strand spiral inductance coil, the unit equivalent capacitance of the basic structural unit can be calculated using the parallel plate capacitor calculation formula.

Step 2. Calculation of channel distributed winding inductance and distributed resistance

The inductance calculation formula of Brooks Coil Inductance is used for estimation, and its theoretical calculation formula is shown in formula (2).

L＝1.699×10 ^-6 × _Router ×nturn ² (2)

Among them, L is the value of the winding inductance, R is the _outer diameter of the cylindrical skeleton, and nturn is the number of winding turns. According to the Pythagorean theorem, the length of the transmission line required to wind one circle can be calculated. Because the diameter of a single transmission line is about 0.1mm, the radius of the relative spool is relatively small, so the influence of the increase in _{the external} value of R due to multi-layer superposition is not considered, then the winding The calculation formulas for the number of turns (nturn) and the length of the transmission line (D) on the coil are shown in formula (3).

$\mathrm{<span\; class="notranslate">\; nturn</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; D.</span>}}{\sqrt{\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; d</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; \&pi;</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

After arrangement and simplification, the relationship between the pay-off length (D _put ) and the winding inductance in the transmission line system is shown in formula (4).

Where Ad is the distance between the winding coils, and R _is the outer diameter of the cylindrical skeleton, ignoring the inductance of the transmission line itself after unwinding, the length of the transmission line on the coil (D) is the difference between the total length of the transmission line ( _Dtotal ) and the length of the unwinding line ( _Dput ). , where L is the value of the winding inductance, and Ad is the spacing of the winding coils. The value here is small and can be ignored.

Step 3. Establishment of channel transmission model

In this paper, a simplified channel circuit model is established, as shown in Figure 3, according to the changing law of each parameter in the payout process. Among them, Li, Cmi, and Ri are the circuit parameters of the above-water spool respectively, among which L1 to LN are the inductance of the released parallel lines, R1 to RN are the distributed resistances of the released parallel wires, Cml to CmN are the distributed capacitances of the released parallel lines, Cdi to CdN are the capacitances of the parallel transmission lines to ground, and Cmo, Lo, and Ro are the electrical parameters of the underwater spool. Since the transmission line is a double-strand enameled wire, the winding method, the environment and other influencing factors are exactly the same, so the circuit model is symmetrical up and down, and the parameter values are equal.

According to the simplified circuit model diagram of the channel in Fig. 3. Select the sampling resistor Rm of 1MΩ at the load end, and the equation formula of the input signal is shown in formula (5):

y=cos(2πf ₀ t)u(t)=cos(ω ₀ t)u(t) (5)

Its Laplace transform is shown in formula (6):

$\mathrm{<span\; class="notranslate">\; \&zeta;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; S</span>}}{{\mathrm{<span\; class="notranslate">\; S</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 6</span>}<span\; class="notranslate">\; )</span>$

Step 4. Effect of 500m deep channel static impedance on transmission phase

In order to improve the stability and quality of data transmission and reduce the bit error rate of data transmission in the process of large-depth measurement, phase-modulation encoding and demodulation are used for data transmission in the communication process, and the impact of dynamic changes in channel impedance is analyzed. The influence of the data transmission phase is of great significance. A large number of experimental research results show that the measurement point of 500m depth is one of its key measurement depths. The present invention uses the Agilent4294A impedance analyzer to measure the channel parameters of the 500m standard underwater bobbin, wherein the spiral inductance is about 300mH, and the total value of distributed capacitance is about is 80nF, and the distribution resistance is 1.08KΩ. Select the frequency range from 0Hz to 15kHz (the baud rate used in the actual communication test is usually 800Hz to 9600IHz) for simulation analysis, and fix the distributed capacitance value to 80nF and the spiral inductance value to 0.3H respectively. Use Matlab to analyze the variation trend of the amplitude-frequency characteristics and phase-frequency characteristics with the transmission frequency to analyze the influence of the channel on the phase delay of the transmission signal under different transmission frequencies and the influence of different channel parameters on the phase delay of the transmission signal.

Step 5. Effect of 2000m channel dynamic impedance on transmission phase

Since the current large-depth measurement range is within 2000m, it is of great significance to analyze the dynamic impedance channel within the 2000m depth range for signal phase distortion analysis. According to the existing winding inductance (L), distributed capacitance (C), and 2000m distributed resistance value of 4.5kΩ. The transformation law of pay-off length is based on the simplified channel transmission model transfer function, and the transmission line with a bus length of 2000m is analyzed.

Simulation and Analysis Results

(1) After simplification and calculation, the inter-turn capacitance C ₁₂ of the same layer adjacent to the same strand is about 8.8pF, the inter-turn capacitance C ₂₃ of the same layer adjacent to different strands is 0.2pF, and the inter-turn capacitance C ₁₅ of the same layer adjacent to the same strand is 0.4 pF. It can be seen from this that the capacitance between parallel wires of 210pF/m is dominant. Therefore, the dynamic change law of the distributed capacitance of the transmission line of the present invention is mainly based on the capacitance between parallel wires, and the capacitance change formed by coil winding is ignored.

(2) From the relationship between the pay-off length (D _put ) and the winding inductance in the transmission line system, the change rule of the inductance with the length of the line axis can be obtained, as shown in Figure 2. Use the Agilent4294A impedance analyzer to measure the equivalent inductance value under the seawater medium in the frequency range of 40Hz to 10kHz and compare it with the estimated result. The measured value of the 500-meter spool is about 261mH, the calculated value is 101mH, and the error ratio is 258%. The measured value of 1100 meter bobbins is about 435mH, the calculated value is 350mH, and the error ratio is 124%. Analysis and comparison, it can be seen that the coil calculated by the Brooks formula is a regular square and the side length is equal to the radius. In the present invention, the coil is dynamically changing Time is not the standard Brooks similarity, so there is a certain difference between the calculation result and the actual measurement. As the coil model gradually approaches the similarity type, the error ratio between the calculation and the actual is gradually reduced, and the fluctuation of the ratio also tends to be stable. There is a certain difference between the calculation result and the actual measurement. According to the test and comparison, when the winding inductance of the bobbin is less than 500mH, the winding inductance has little effect on the signal, and when it is greater than 500mH, its influence is gradually obvious. The Brooks formula is used for estimation. When the winding length is small, although there is a certain error, the influence of the inductance on the signal is small at this time, and the influence of the error can basically be ignored. When the winding length reaches more than 1500 meters, the bobbin model is basically Brooks Similar type, less error. Therefore, the Brooks formula can be used to quickly estimate the bobbin winding inductance when it is difficult to measure.

Because the signal transmission frequency is about 800Hz, which is relatively low, this paper uses the calculation formula of the DC resistance value of the wire such as formula (7) to estimate the channel distribution resistance value.

$\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; \&rho;</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; C\; j</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 7</span>}<span\; class="notranslate">\; )</span>$

In the formula (7), R represents the resistance of the parallel wires, ρ represents the resistivity at the working temperature, Cj is the stranding coefficient, 1.02 for multi-strand wires, L is the length of the wires, and A is the cross-sectional area of the wires. Assuming that the properties of the material do not change with the change of the environment, according to formula (8), it can be seen that the change of resistance is proportional to the length of the line, and the calculated value of the distributed resistance is about 2.26Ω/m.

(3) In Figure 3, the reactance characteristics of the bobbins are mainly inductive, and only the influence of Li, Ri, Lo, and Ri on the signal is considered. The main reactance characteristics of the released parallel lines are mainly capacitive, and only Cm1 to CmN and R1 to R1 are considered. The influence of RN on the signal can basically be ignored due to the small value of the capacitance Cd of the parallel transmission line to the ground, mainly in the pF level. Let L be the series sum of Li and Lo, R be the series sum of Ri and Ro and R1 to RN, and C be the parallel sum of Cmi, Cmo, Cm1 to CmN, then the transfer equation of the function is shown in formula (8):

$\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; R\; m</span>}}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; CLR</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; S</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; CRRm</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; S</span>}<span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; R\; m</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 8</span>}<span\; class="notranslate">\; )</span>$

(4) Analysis of the influence of the channel on the phase delay of the transmission signal under different transmission frequencies and the analysis results of the influence of different channel parameters on the phase delay of the transmission signal are shown in Figure 4. When the winding inductance of 0.3H is fixed, when the distributed capacitance When the frequency is small, the phase delay can be basically ignored. Therefore, the existence of distributed capacitance is the main factor causing phase distortion. When the frequency is large, the phase attenuation approaches a constant value. However, when the transmission frequency is below 5kHz, as the distributed capacitance increases, the phase change rate gradually accelerates. When the parallel capacitance of 80nF is fixed, the phase delay will still occur when the winding inductance value is small, and the effect of the parallel capacitance on the phase delay Similarly, when the frequency is high, the phase attenuation tends to a constant value, but when the transmission frequency is below 5kHz, as the winding inductance increases, the phase change rate gradually accelerates.

Since the current main transmission frequency of disposable instruments is between 800Hz and 1200Hz, and the transmission frequency of 1kHz is fixed, according to the simplified circuit transfer equation obtained by formula (8), at the fixed frequency, the parameters of distributed capacitance and spiral inductance are respectively fixed to further explore the distributed capacitance. and winding inductance parameters on the signal phase, the results are shown in Figure 5. It can be seen that at a transmission frequency of 1 kHz, the winding inductance is fixed, and the phase attenuates sharply during the increase of the distributed capacitance. As the capacitance increases, the phase attenuation gradually becomes gentle, and the maximum phase attenuation is 180 degrees. The severity is proportional to the fixed distributed capacitance value, which is similar to the influence of distributed capacitance on the phase. With the value of fixed distributed capacitance, as the winding inductance increases, the signal phase delay changes gradually. The larger the fixed distributed capacitance value, the more severe the early decay process.

(5) The change process of amplitude gain and phase distortion from 1m to 2000m. Part of the data is shown in Table 1, and the change results are shown in Figure 6. It can be seen that in the initial stage of unwinding, because the bobbin is not unfolded, there is a winding inductance of about 16H in the transmission circuit. According to the previous analysis, the winding inductance is large and the amplitude The attenuation is rapid, and the phase distortion is -169.24 degrees. With the process of unwinding, the coil is opened, the winding inductance decreases, and the distributed capacitance increases. During the 1000m unwinding process, the winding inductance decreases from 16.41H to 12.30H, and the distributed capacitance From 3.98e-9F to 4.06E-6F, the amplitude gain at 1kHz transmission frequency is severely attenuated from 0.88 to 6.2E-4; at 5kHz transmission frequency, the amplitude gain is attenuated from 0.02 to 2.08E-5. According to the analysis in Section 3.2 , the effect of distributed capacitance and winding inductance on the phase is basically the same. At the same time, the reduction of winding inductance is not large, so the phase delay is maintained at 173 degrees at 1kHz transmission frequency, and the phase delay at 5kHz transmission frequency is maintained at 177 to 179 degrees. Between. With the continuous pay-off effect on the pay-off, due to the decrease in the number of coil layers, the inductance decreases, the winding inductance decreases rapidly, and the value of the distributed capacitance increases steadily, so the phase delay gradually decreases. After left and right, this effect is more pronounced. Comparing the 1kHz transmission frequency and 5kHz transmission frequency gain and phase change with the length of the wire, it can be seen that the low-frequency transmission signal has a larger gain, but the phase distortion is not constant due to the asynchronous increase rate of the winding inductance and distributed capacitance value in the later stage of wire release. The situation is more obvious, on the contrary, in the high-frequency transmission state, the phase distortion fluctuation is small, but the signal amplitude gain is small.

Table 1 Amplitude Gain and Phase Distortion Variation Data Sheet

Claims (6)

1. the deep-sea analytical approach of XCTD time varying channel on transmission performance impact of walking to navigate, is characterized in that concrete steps are:

The calculating of the 1st step, channel distribution electric capacity

Solve the electric capacity between parallel wire by the method for configuration mirroring electric charge repeatedly, replace the distributed charge of conductive surface with the concentrated electric charge system after mirror image repeatedly, and it is constant to maintain all boundary conditions, thereby the solution procedure of electric capacity is simplified, and its main basis is uniqueness theorem and the circular section wire mirror image formula in electromagnetic theory;

The 2nd step, channel distribution are wound around the calculating of inductance and distributed resistance

Coil winding is master screw inductance, and its inductance is wrapped on column type skeleton closely, and intermediate medium is air, according to analysis, adopts Brooks Coil Inductance model assessment to be wound around the inductance value of bobbin;

The foundation of the 3rd step, transmission model

According to the Changing Pattern of the each parameter in unwrapping wire process, set up the channel circuit illustraton of model of simplifying, because transmission line is bifilar enameled wire, the influence factors such as canoe and environment of living in are identical, so circuit model is symmetrical up and down, parameter values equates;

The 4th step, carry out 500m deeply convince static impedance to transmission phase place analysis

Channel parameter to 500m standard water lower lower is measured, and analyzes the impact on signal transmission phase delay of the impact of different transmission frequency lower channels on signal transmission phase delay and different channel parameter;

The 5th step, the analysis of 2000m dynamics of channels impedance to transmission phase place

Analyzing total line length is the transmission line of 2000m, the amplitude gain from 1m to 2000m and phase distortion change procedure.

2. analytical approach according to claim 1, is characterized in that, the calculating of described channel distribution electric capacity adopts the repeatedly method of configuration mirroring electric charge.

3. analytical approach according to claim 1, is characterized in that, the calculating that described channel distribution is wound around inductance and distributed resistance adopts Brooks Coil Inductance model assessment to be wound around the inductance value of bobbin.

4. analytical approach according to claim 1, is characterized in that, the foundation of described transmission model adopts circuit model symmetrical up and down, the mode that parameter values is equal.

5. analytical approach according to claim 1, it is characterized in that, described 500m channel static impedance is measured the channel parameter of bobbin the analysis and utilization Agilent4294A electric impedance analyzer of transmission phase place, carry out amplitude versus frequency characte and the phase-frequency characteristic variation tendency with transmission frequency with Matlab, analyze the impact on signal transmission phase delay of the impact of different transmission frequency lower channels on signal transmission phase delay and different channel parameter.

6. analytical approach according to claim 1, it is characterized in that, described 2000m dynamics of channels impedance adopts to the analysis of transmission phase place the method that transmission channel is simplified, on the basis of transition function of the transmission model based on simplifying, the transmission line that analyzing total line length is 2000m.