CC BY
17Journal of Siberian Federal University. Engineering & Technologies 3 (2015 8) 350-354
УДК 621.396.944
Using of Electromagnetic and Acoustic Interaction for Submarine Telecommunications
Georgy Ya. Shaidurov and Danil S. Kudinov*
Siberian Federal University 79 Svobodny, Krasnoyarsk, 660041, Russia
Received 12.12.2014, received in revised form 18.01.2015, accepted 26.02.2015
The article describes the potentiality of submarine reception of radio signals emitted by shore radio transmitter with a horizontal antenna in the wavelength range based on interaction radio and acoustic waves in skin-layer.
Keywords: radio, telecommunication, sea water, conductivity, acoustic waves.
Использование взаимодействия электромагнитных и акустических волн для подводной радиосвязи
Г.Я. Шайдуров, Д.С. Кудинов
Сибирский федеральный университет Россия, 660041, Красноярск, пр. Свободный, 79
В статье рассматривается взаимодействие электромагнитных и акустических волн в ионопроводящих средах, в частности, в морской воде для решения прикладной задачи обеспечения радиоприема подводными аппаратами на больших глубинах.
Ключевые слова: радио, телекоммуникации, морская вода, проводимость, акустические
The need for the reception of radio signals under water without surfacing of underwater vehicle (UV) emerges in many problems of both military and civilian technology, in particular for navigation and control of the UV including the under-ice diving, during the seismic sensing of the earth in the Polar Regions, when the sea surface is tightly covered with pack ice.
Consider the problem of signal reception under the sea surface making use of the effect of signal heterodyning in the skin layer of the electromagnetic wave by «highlighting» the water by ultrasound from the board of an underwater vehicle (Fig. 1).
© Siberian Federal University. All rights reserved
* Corresponding author E-mail address: [email protected]
In the figure, the electromagnetic wave (EW) emitted by coastal or aeronautical radio station carrying the message signal becomes elliptically polarized at the border water-air with a vertical component of the electric field Ez and horizontal components of the electric and magnetic fields E1x and H1y respectively. At the same time the water surface is irradiated with directional acoustic radiation 3, formed by means of ultrasonic emitters located on the hull of the underwater vehicle 4 (UV). As a result of parametric interaction of the horizontal component of the electric field E1x of frequency f with a power flux of the acoustic radiation of frequency fa the residual signal of frequency F = f - f is formed in the skin layer of the E-field radiation falling onto the surface. Subject to validity of the ratio F>>fe the electromagnetic signal of difference frequency penetrates to a depth h with a much smaller absorption as compared to the signal of frequency f and is received by the UV. The intensity vectors E2x and H2y of the EM field of the difference frequency F create signals of informational message at the receiving antennas of the UV.
The traditional scheme of underwater reception of radio signals today is realized by means of receiving by an electric antenna towed by the UV (floating cable), with a diving depth of UV of about 100m. Direct reception by the antenna, located on the UV, depending on the carrier frequency fe, is possible on the depths of about 10 m in the frequency range 50-100 kHz and 100-150 m in the range of hundreds ofHettz.
It is interesting Uo evaluate the possibility of reception of radio signals by means of the parametric method. Becausr of the complexity of the problem we gioe an approximate rstimation of parameters of the radio signal: s ignal strength, SNR foe g iven values of rate of data Iran sm ission for the c ast of a plane wave in the; recepeion are a and the oquivalent linear model (virtuel) electrom agnetic signal transmitter at the difference frequency F, formed in the interaction area between acoustic and electromagnetic waves on the water surface.
In the case of plane wave intensities of the field of difference frequency can be defined as:
Fig. 1. Radio reception by means of parametrical method: 1 - components of the electromagnetic wave vector; 2 - water surface; 3 - pattern of the acoustic radiation; 4 - UV
E2x = E, nEme Srh
'lz"E" V
(1)
(2)
4
where ns = - is the refraction coefficient of electromagnetic wave at the water-air boundary;
ACt 1 -9
=-- is t=e relative increment of electro conductivity of water. In the se formulas s0 =--10 -
C 36n
is nhe he rmittivity of fre e spacb; cos = 2nf3 - is the ffre;quency.
liquation (2) is determined by the approximate L eontovichboundary conditions [3] and corresponds Co tht co ntinuity of rhe hp rizontal component of the magnetic field at thc water-ai r lboundary. In accordant wiith [4,55]:
m,
bt ^tc - :to-r'6 [vtt^, (3)
where I - stands fou the intensity of acoustic radiation at the surface of water in W/m2.
When using etts seceivoa elsdtaksal antenna o° le;ng^tli, locttitie d sn the UV, the receivfd signal of frequ^o^ay to^ = 2nF can be found u sinf the rel^io n:
f^EdA (4)
For the case of the magnetic antenna :
C H = H20Is 1 tt * S A , (5)
wheat IW = 4% -lCT7 HP-2 - is tlc magcetic perme=4ility of One e space; i Vs tine effectivearea of the receiving magattie antenna.
Consequents, the ttnol ait tgg output of the recoivtnf antenoas rct be eciimated as:
p ^Ik. p = f^^Lnt., (6)
* t ' R
where I - is the input se ^i st^nc ei o( ttr r^ceiivC^]r, 1s 11°,, - tlie teansmiosion co^^ficii^n^ of antenna feeder.
The total power ofexternal inte rfe re nc e and the intrinsic noise of the receiver can be written as:
Vi=Hi + iO>NS (7)
¿w2
whnre ty = —221.; uin - stands foi tf amplitude of she external electromagnetic noise, at a depti hi
R,n
Dn = kT^O.F - m yht pawt e cf the rmal dole of cde receiver; f = 1. -8-1 0-23 W 'Hz - is; the Boltzmann's
c(t nt-aect; T^ - is ^Icee 2e mpeeaiuse ot ithe input ccrcuits of the re c eiiten and AF - is thr bandwidth of ihe oeceivtc.
External noise at the diffeeenct frequency F attenuates in s-awater in the same way as the received electaomagnetic signal at this frequency.
it^fV-^, (8)
H . = H z - 5 H •
Consequently:
UAXI = Ex2ILa ; uH = hi v0sa0h (9)
We allow to determine the required intensity of the electrical component of the field of the signal at the surface of the water as:
Ez =
a (H ) * t - *
mi B
V n /
a Y2 H H I tAu-
1 20n (10)
B 1
E,
q)>2 ei
He re H1 j = EBU— _ Taki ng this i nto account 1220n
^l-bl (1 1)
\B J ma
F-om (11) it is obnious thhiit ttlrn^ reliability o0 recaiving menages deqends on the parameters q, B, mf ((, U).
Ou tqc sueface of" tlin seu t-hteit; level of ^ lies horizontal compooe nt of [he elert/ic field c;or^e^j)onds to the fCrequency range of1100-1000 H:z (-MO) to t-^ dBCVdm2 Hz.
The magnetic fiotd inteniity of:" ooise on the sueface o0 the water 1s: Hu= (-120) e (-140) dB/V2/ m2 Hz.
Ii Hu = 10t AAqsHz; ma = rO-3; q = 10i we oqtam from (U) a oumerical estincaite of tlhe requlred field intensity at tlf eeceiving jtxatlrit:
= 210 • 4E4 V/m = 21 mV m-Hz. (12)
Tli(t estimatioo Fn ac co rdinu Ito ((4) Fa = 160i dBgives:
e: = c-m- HmnHr = io-4WmmCHn i a a li v / ml) . 11:3)
a UoaoJ 10= ' '
turnc;^ 1te impedance o) air i^ OU" = 177 Ohms, the magnetic field intensihy of noise coriesponding to the levci of Eu (13) i( equal ^o:
dW ne77nn2O-na.27iia-6 A/mylHz : C1Oe
nt w i 77 c
Aecording to o^lie:r dat:;3i 120], tlie li^iv^l of £i^:oioi]tli^riLi^ neise at a Vcequency ef :100 Hz catresponds Co Ea sc 212211 v/mifCHz . In CCis case it is nececsao. lo ensure tilsat on the lu-Oo-e o4 ^itie sea:
E nO,l.■],:arl- = 2nu V-mr^h-• (15)
Thus, ac cording Co various esümates , Ilte requirect electric fimld [trength ait the se a su-face varies ovei a woie range Crom ac uoneptable value (tt 3), 114) to an unattainable at tocg dli 115). Note
that theie estimctes do not take into account the depth of He UV and the required Crensmil power of the slution iti determined onil1^ t)y: rhe leve1 olf uncorseleted noise at the sen surface.
- 353 -
Since the magnitude of the electrical conductivity of water is mainly determined by the concentration of ions of impurity salts, the oscillating pressure of the ultrasound, causing an intense shift of the impurity ions in the direction of the power flux of sound, leads to an intense increase of conduction current, which explains the above mentioned effect of ultrasound on the electrical conductivity. At the modulation frequency F = f- fa =1 Hz signal reception is possible at a depth of 100 m, which is unattainable using any other method of transmission.
References
[1] Romanova G.N., Shaidurov G.Ya. // Journal of Communications Technology and Electronics. 1991. T. 36. № 2. P. 410.
[2] Shaidurov G.Ya., Kudinov D.S. // Journal of Radioelectronic. 2012. № 2. P. 1-5.
[3] Solovyov V.I., Novik L.I., Morozov I.D. The sea communication. L.: Sudostroenie, 1978. (Rus).
[4] Shaidurov G.Ya., Lukyanchikov V.N., Romanova G.N. // Journal of Communications Technology and Electronics. 1985. T. 30. № 11. P. 21-36.
[5] Popov N.I., Fyodorov K.N., Orlov V.M. The sea water. M.: Nauka, 1979. 310 p.
