JPS585099A - Resonance variable type underwater transceiver - Google Patents

Abstract

PURPOSE:To efficiently transmit a frequency modulation wave, by applying a low frequency current to an oscillator made of amorphous alloy to vary the resonance. CONSTITUTION:A DC is applied to a winding 22 to give a bias magnetic field to an oscillator 21 of amorphous alloy. The resonance frequency of the oscillator 21 depends on the sound velocity in the alloy and the shape of oscillator. Since the sound velocity is changed with the intensity of a DC magnetic field, the resonance frequency is changed with the intensity of the bias magnetic field. Thus, when an AC current with lower frequency is superimposed on the DC current, the resonance frequency is varied correspondingly. A signal with the same frequency as the resonance frequency is transmitted and received via a winding 23. The oscillator 21 is bonded on a sound window 24 and the oscillation is radiated through the window 24.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a variable resonance underwater transducer that can change the resonance frequency.

An example of a conventional underwater transducer of this type that utilizes the magnetostrictive effect is shown in FIG. In the figure, reference numeral 1 denotes a vibrator, which is made of a ferrite material whose main raw materials are nickel oxide, copper oxide, iron oxide, etc., and which is compression-molded and then fired. A winding 2 generates a magnetic field by applying a signal current, causing a magnetostrictive phenomenon in the vibrator 1. However, if only a signal current is applied to the vibrator 1, the vibrator 1 simply stretches regardless of its polarity, but by providing a bias magnet 3, it is used in addition to a constant static expansion bar.

Therefore, by applying from the winding 2 a signal current that provides an alternating magnetic field that is sufficiently smaller than the magnetic field provided by the bias magnet 3, the vibrator 1 generates minute vibrations.

Note that the vibrator 1 is made of a material with good acoustic transparency.
The vibrations generated by the adhesive on the acoustic window 4 pass through the acoustic window 4 and are radiated as sound waves into water, which is a sound field medium.

Note that 5 is a cylindrical watertight housing.

The resonant frequency of this underwater transducer, the frequency at which the acoustic radiation is most efficient, is uniquely determined by the shape and mainly the length of the vibrator 1, and it is impossible to change that frequency electrically. there were.

Next, the resonance frequency f. The range with good radiation efficiency, centered around , is generally about 19 times the bandwidth. In the field of underwater acoustics, it is most common to use a sound wave frequency of several tens of kHz, but when transmitting sound waves at the resonant frequency of an underwater transducer, the bandwidth is 20 kHz at the resonant frequency.
If a signal having a bandwidth of about 2k) iz or more is transmitted, the waveform of the sound wave will be distorted into a shape different from that of the electrical signal. Therefore, for example, when an audio signal is
Underwater telephones and the like that transmit M-modulated waves have a problem in that they are not sufficient in terms of faithful transmission.

Furthermore, conventional underwater transducers are inappropriate for transmitting signals that require a wide bandwidth such as FM modulation.1. There was no way to solve those problems.

The present invention aims to eliminate such conventional drawbacks, and focuses on the property that some amorphous alloys exhibit a magnetostrictive effect, which changes depending on the magnitude of the sonic air direct current magnetic field, A vibrator made of a magnetic material made of an amorphous alloy is wound with a wire, and direct current and low frequency current are applied. An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a partially cutaway plan view showing an embodiment of the variable resonance underwater transducer of the present invention. In the figure, 21 is a vibrator made of an amorphous alloy, which is made by laminating thin plates of amorphous amorphous alloy whose main components are iron and Conol+, and heat-treated in a magnetic field. @22 is a vibrator made of a direct current and a winding for applying a low frequency current, 23 a winding for transmitting and receiving signals, 24
25 is an acoustic window, and 25 is a cylindrical watertight housing. ◎ The vibrator 21 made of this amorphous alloy does not generate vibrations proportional to the signal current unless a bias magnetic field is applied, similar to the vibrator made of ferrite material. Therefore, a direct current is applied to the winding 22 to provide a bias magnetic field. The resonant frequency of the vibrator 21 is determined by the speed of sound in the amorphous alloy and the shape of the vibrator, but since the speed of sound changes depending on the strength of the DC magnetic field, the resonant frequency also changes depending on the strength of the bias magnetic field. Therefore, if the DC current applied to the winding 22 to provide a DC bias magnetic field is slightly changed, the resonant frequency will change, so if an even smaller low-frequency alternating current is superimposed on the DC current and added, The resonant frequency of the vibrator 21 changes depending on the low frequency current.

Since it is most efficient to transmit and receive signals at that resonant frequency, signals at the same frequency as that resonant frequency are transmitted and received via the winding 23. Further, the vibrator 21 is bonded to an acoustic window 24, and the generated vibrations pass through the acoustic window 24 and are radiated as sound waves into water, which is a sound field medium. In addition, Z watertight housing 25
The inside of the case is kept waterproof.

Figure 3 is a diagram illustrating the operation of the transducer of the present invention, where the vertical axis represents the resonant frequency and the horizontal axis represents the bias current, showing how the resonant frequency changes when a low frequency current of frequency fp is superimposed on the DC current. It shows.

FIG. 4 is a diagram illustrating how the resonant frequency moves back and forth between point A and point B due to the effect of low frequency current. Note that the vertical axis shows the transmission sensitivity and the horizontal axis shows the frequency.

Therefore, when the resonant frequency is at point A, the most efficient wave transmission can be performed by adding an alternating current of the frequency at point A as a signal. The same applies to point B (5), and it is most efficient to transmit sound waves at that frequency in response to changes in the resonance frequency.

If the resonant frequency is fo when only a certain level of direct current is applied without electrically applying the resonant frequency through the winding 22, then the frequency of the low frequency current cos2π
When f and t are superimposed and added to the DC current, the resonant frequency becomes 10+kcoszπ/t. Note that k is a proportionality constant, and the signal frequency is also the instantaneous frequency f + kcos2π
/p1 is most efficient. This 10+5ccos
2π/, 1 is the same form as the instantaneous frequency of a frequency modulated signal with 10 as the carrier frequency and jp as the modulating wave), and transmitting and receiving at this frequency means transmitting and receiving as a frequency modulated signal, so for example, Underwater telephones have the characteristics of frequency modulation, such as applying a low-frequency current proportional to the voice signal and transmitting the same voice signal as a frequency-modulated signal, which is efficient, has no distortion, and has excellent noise resistance. Can transmit waves.

In this case, the frequency of the transmitted signal is 7O-1-kcos2πf
Since the resonance frequency pt and (6) always match, there is no restriction due to the narrow bandwidth as in the conventional example.

FIG. 5 is a block diagram of an example in which the underwater transmitter/receiver of the present invention is applied to an underwater telephone. That is, the audio signal detected by the microphone 51 is amplified by a preamplifier 52, added to a DC current I0 by a DC adder 53, and amplified by a nokwarang 54 to become a current that provides a bias magnetic field for a transmitter 55. On the other hand, frequency! The carrier wave from the oscillator 56 oscillating at Lf0 is modulated by the modulated wave from the preamplifier 52 in the frequency modulator 57, amplified by the power amplifier 58, and applied to the transmitter 55 as a transmission signal. As already mentioned, the device 55 transmits signals underwater without distortion. 59 is a normal idrophone. Normally, since the idrophone has a wide band, it converts the received sound wave waveform into an electrical signal without distortion. After being suitably amplified by a preamplifier 60, it is demodulated by a frequency demodulator 62 using a carrier frequency signal from a local oscillator 61, amplified by an amplifier 63, and reaches the human ear through a signal generator 64. Although this embodiment shows a one-way block diagram, it goes without saying that mutual communication can be achieved in the opposite direction by using a similar block diagram. In addition, in Figure 2, direct current and low frequency current are applied through a single winding, but it is also possible to provide a separate winding for this trM, or to apply it superimposed on the winding that transmits and receives signals. produces the same effect. Further, since direct current provides a bias magnetic field, it can be replaced by using a bias magnet as in the conventional case. Although the so-called NA type oscillator shape is illustrated, the same effect can be obtained with a π type, cylindrical shape, rod shape, etc.

As explained in detail above, the present invention is capable of applying a low frequency current to an amorphous alloy vibrator to change its resonance, so frequency modulated waves can be transmitted efficiently, and therefore it can be used for underwater communications etc. It has a big effect.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway plan view showing a conventional underwater transducer using the magnetostrictive effect; FIG. 2 is a partially cutaway plan view showing an embodiment of the resonant variable underwater transducer of the present invention; FIG. FIG. 4 is a diagram illustrating the operation of the present invention, FIG. 4 is a diagram illustrating its effects, and FIG. 5 is a ten-step diagram showing an underwater communication system using the underwater transducer of the present invention. 21... Amorphous alloy vibrator, 22... Winding for applying direct current and low frequency current, 23... Winding for transmitting and receiving signals, 24... Acoustic window, 25... Water honey housing. (9) 61

Claims (1)

[Claims] In an underwater transducer, a transducer made by heat-treating a magnetic material made of an amorphous alloy in a magnetic field is wound and housed in a watertight housing, direct current and low-frequency current are passed through the same or separate windings. A resonant variable underwater transducer characterized in that a signal of a higher frequency than the low frequency current is applied and transmitted and received through the winding or a separate winding.