System and method for underwater wireless communication

An underwater wireless communication system and method includes a sensor node for transforming measured underwater data into ultrasound signals, and transmitting the transformed ultrasound signals and receiving other ultrasound signals.

PRIORITY CLAIM

This application claims under 35 U.S.C. §119 the benefit of the filing date of May 9, 2007 of Korean Patent Application No. 10-2007-0045154, the disclosure of which is incorporated herein by reference in its entirety.

BACKGROUND

1. Technical Field

The present invention relates to data communication, and more particularly to an underwater data communication system and method for transmitting data produced by monitoring underwater environments.

2. Related Art

In an underwater environment, RF-based communications may not be appropriate because of a very low transmission range, requiring large antennae and high transmission power. Consequently, underwater communication relies on an acoustic or ultrasonic wave rather than a radio wave. Unlike a mobile communication in the air, factors such as slow speed of a sound wave (1.5 Km per hour), a narrow usable bandwidth, and reflection by the sea floor or sea surface may interfere with performance of underwater data communication. The existing submarines or remotely operated vehicles (“ROVs”) may not be practical solutions for measuring and monitoring underwater environments because such systems are not cost-effective. In addition, no underwater communication systems based on low-power and low-cost is currently available. Accordingly, there is a need of a system and method for underwater wireless communication that obviates drawbacks of the related art.

SUMMARY

By way of example, in one embodiment, an underwater wireless data communication system includes a memory, a sensor array, a controller and a data transmitter. The memory stores location data and the sensor array includes a plurality of sensors for measuring an underwater environment to generate and output a measured signal. The controller is operable to receive the measurement data, retrieve the location data and output the measurement data and the location data as a data signal. The data transmitter is operable to amplify the data signal up to a predetermined voltage level and transform the amplified data signal into an ultrasound signal to be emitted into water. The location data may specify the location of the sensor array.

In another embodiment, an underwater wireless data communication method of transforming measurement data into an ultrasound signal, and transmitting and receiving the ultrasound signal. The method includes generating the measurement data by monitoring an underwater environment by using the sensors, reading a location data indicative of the location of the data communication system, and outputting the location data and the measurement data as a data signal, generating a frequency signal having a predetermined amplitude at a predetermined interval and adding the data signal to the frequency signal as a modulated data signal, amplifying the modulated data signal up to a predetermined voltage level, and transforming the amplified data signal into an ultrasound signal to be transmitted.

In another embodiment, a method of receiving data in a data communication system having a plurality of sensor, including receiving an ultrasound signal transmitted through water and amplifying the ultrasound signal up to a predetermined voltage level, removing a noise from the amplified ultrasound signal based on a first reference voltage, obtaining an original data signal by detecting a predetermined envelop from the frequency signal without the noise, and converting the original data signal into a digital data signal based on a second reference voltage.

The accompanying drawings and the detailed description are just examples of the present invention for describing the present invention properly, it is not intended to limit the meaning or the scope of the present invention as claim. Thus, those who skilled in the art will understand that various changes and equivalent other embodiments may arise from accompanying drawings and the detailed description.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Since there can be a variety of permutations and embodiments of the present invention, certain embodiments will be illustrated and described with reference to the accompanying drawings. This, however, is by no means to restrict the present invention to certain embodiments, and shall be construed as including all permutations, equivalents and substitutes covered by the spirit and scope of the present invention. Throughout the drawings, similar elements are given similar reference numerals. Throughout the description of the present invention, when describing a certain technology is determined to evade the point of the present invention, the pertinent detailed description will be omitted.

FIG. 1is a block diagram of an underwater wireless communication system;FIG. 2is a block diagram of a sensor node;FIG. 3is a block diagram of a data transmitter; andFIG. 4is a block diagram of a data receiver. A sensor node110operates a data communication system for measuring an underwater environment and transmitting/receiving measurement data through water, and may be referred to as the sensor node110or data communication system according to its context.

Referring toFIG. 1, the underwater wireless communication system100includes the sensor node110, a sink node120, a gateway node130, and a data collecting server140. The sensor node110includes a plurality of sensors for data collection on the seafloor, and each sensor measures underwater environments such as seafloor temperature, water temperature, an amount of dissolved oxygen, a seismic wave, etc. Each sensor measures certain physical quantities under water and generates measurement data. The sensor node110transforms the measurement data into an ultrasound signal and transmits the ultrasound signal through water. The sensor node110may transmit the measurement data with location data indicative of where the sensor node110is located. The location data of the sensor node110can be recorded when the sensor node110is positioned at a certain location. Thus, the sensor node110transmits the measurement data and the location data to the data collecting server140for monitoring the underwater environment. In addition, the sensor node110receives an ultrasound signal emitted from another sensor node, obtain the measurement data and the location data and then transmit them to the sink node120. The sensor node110, on one hand, transforms the measurement data and the location data into the ultrasound signal to be emitted through water, and on the other hand, obtains the measurement data and the location data by receiving the ultrasound signal emitted from another sensor node and transmit the received measurement data and the location data to the sink node120.

With reference toFIG. 2, each structure of the sensor node110will be described in detail. As shown inFIG. 2, the sensor node110includes a sensor array210, a first data transceiver220, a second data transceiver230, a memory240, and a controller250. As described above, the sensor node110operates as a data transmission system with a plurality of sensor for measuring underwater environments to produce the measurement data and transforming the measurement data into the ultrasound signal for transmission to the data collecting server140on the ground.

The sensor array210includes the plurality of sensors that generates the measurement data and sends it to the controller250. The sensor array210further includes an analog-to-digital (AD) converter for converting the measurement data in analog form into digital data. The measurement data output from the sensor array210is the digital data after converted by the AD converter. The plurality of sensors in the sensor array210includes various types of sensors. By way of example, the sensor array210includes a temperature sensor for measuring water temperature, a three-dimensional acceleration sensor for measuring a seismic wave, a magnetic sensor, a pressure sensor, and a dissolved oxygen sensor for measuring the amount of oxygen dissolved in water.

The first data transceiver220transmits data by using a radio frequency (RF) signal to the ground or receives a control signal from the ground. Alternatively, or additionally, the gateway node130may include a data transceiver. The data transceiver included in the gateway node130may perform the substantially same function (i.e., transmitting data to the ground) as the first data transceiver220, which enables communication with the data collecting server140via a network.

The second data transceiver230includes a data transmitter233and a data receiver235. The data transmitter233transforms the measurement data and the location data into the ultrasound signal, and the data receiver235receives the emitted ultrasound signal to obtain the measurement data and location data from the ultrasound signal. Alternatively, the second data transceiver230may be integrated into the sink node120or the gateway node130.

FIG. 3is a block diagram illustrating structure of the data transmitter233ofFIG. 2. InFIG. 3, the data transmitter233includes a frequency generator310, a first amplifier320, and an ultrasound transmitter330. The frequency generator310generates a predetermined frequency, adds the measurement data and the location data from the sensor array210to the generated frequency, and outputs the added frequency to the first amplifier320. For example, the frequency generator310generates the predetermined frequency of 40 KHz at predetermined intervals and outputs the frequency of 40 KHz to the first amplifier320after adding to the measurement data and the location data from the sensor array110and modulating the amplitude of the frequency. The frequency generated by the frequency generator310may be applicable to the ultrasound transmitter330, which will be described later. The frequency to which the measurement data and the location data from the sensor array210are added is referred to as a modulated data signal.

The first amplifier320amplifies the modulated data signal from the frequency generator310based on a predetermine voltage level and outputs the modulated data signal to the ultrasound transmitter330. The signal amplified by the first amplifier320and outputted to the ultrasound transmitter330is referred as an amplified data signal. For example, the first amplifier320operates to amplify the modulated data signal in a voltage level range of −6V to +6V.

The ultrasound transmitter330transforms the amplified data signal from the first amplifier320into the ultrasound signal for emission through water. In one embodiment, the ultrasound transmitter330may be implemented, for example, to operate with a frequency of 40 KHz. Thus, the ultrasound transmitter330may operate with the frequency generated by the frequency generator310continuously, or at certain intervals. Alternatively, the ultrasound transmitter330may operate according to the amplified data signal from the first amplifier320.

The operation of the ultrasound transmitter330according to the amplified data signal from the first amplifier320will be described in detail. The ultrasound transmitter340operates with the amplified data signal from the first amplifier330, and emits the amplified data signal into water after transforming into the ultrasound signal. As described above in conjunction withFIG. 2, the data transmitter233under the control of the controller250transmits the measurement data and the stored location data in advance after transformation into the ultrasound signal. Referring back toFIG. 2, the data receiver235receives an ultrasound signal emitted by another sensor node, obtains the measurement data and location data from the ultrasound signal, and outputs them to the controller250.

FIG. 4is a block diagram illustrating structure of the data receiver235. Referring toFIG. 4, the data receiver235includes an ultrasound receiver410, a second amplifier420, a first comparator430, an envelop detector440, and a second amplifier450. The ultrasound receiver410receives the ultrasound signal emitted by another sensor node and outputs it to the second amplifier420. Each of the sensor nodes (e.g., the first sensor node110a, the second sensor node110b, . . . , the nth sensor node110n) transmits data by using ultrasound. Thus, the ultrasound receiver410receives the ultrasound signal water and outputs it to the second amplifier420.

The second amplifier420amplifies the ultrasound signal being received by the ultrasound receiver410up to the predetermined voltage level and outputs it to the first comparator430. For example, the second amplifier420amplifies the ultrasound signal up to a voltage level corresponding to 500 mV and then outputs it to the first comparator430. Due to the underwater characteristics, the ultrasound signal may have its amplitude changed by scattering and attenuation after being emitted into the water.

The first comparator430removes a noise of the ultrasound signal from the second amplifier420based on a predetermined reference voltage and outputs it to the envelop detector440. The reference voltage is, for example, 200 mV. Accordingly, the first comparator430may remove noise by comparing the predetermined reference voltage to the amplified ultrasound signal from the second amplifier420. Noise may be removed without a low pass filter or a high pass filter. The envelop detector440obtains an original signal (for the convenience of description, referred as an “original data signal”) by using the noise-free ultrasound signal from the first comparator430and a predetermined envelop signal, and outputs it to the second comparator450. For example, the envelop detector440passes the signal of between 0V and 1.12V to the second comparator450.

As described above, a few sensor nodes output the ultrasound signal as an output signal which contains the measurement data generated by those sensor nodes and the location data of the sensor nodes. Data obtained by the envelop detector440correspond to the measurement data generated by the sensor node that measures the underwater environment and the location data of the sensor node that generates the measurement data.

The second comparator450converts the original data signal from the envelop detector440into a digital signal based on the predetermined reference voltage, and outputs it to the controller50. For example, the second comparator450may convert the original data signal into a digital signal based on the reference voltage of 600 mV. The first comparator430, the envelop detector440, and the second comparator450may be integrated on a single integrated chip.

Referring toFIG. 2again, the memory240under control of the controller250stores the measurement data from the sensor array210, the data being obtained from a certain sensor node, and the location data of the sensor node110. The memory240also stores a program including an algorithm for operating the sensor node110. The controller250performs a function of controlling components of the sensor node110(e.g., sensor array210, the first data transceiver220, the second data transceiver230, the memory240, etc.).

Although not shown inFIG. 2, the sensor node110further includes a power connector through which power used for operation of the sensor node110is externally supplied. The sensor node110includes a connector for testing the sensor node using a user terminal (for example, a computer, etc.) such as UART, JATG, ISP, etc.

Referring toFIG. 1again, the sink node120receives an output signal from a plurality of sensor node (the first sensor node111a, the second sensor node111b, . . . , the nth sensor node111n), and transmits it to the gateway node130. As described above, limitations such as slow speed of a sound wave (1.5 Km per second) under water, a narrow usable bandwidth, and reflection from the sea floor or sea surface, may affect the data transmission range of the sensor node110. A relay or a repeater such as the sink node120may be installed to relay the measurement data from the sensor node110to the gateway node130. The sink node120may include a component having the substantially same function as the second data transceiver of the sensor node110.

The gateway node130receives an output signal from a plurality of sink node (i.e., the first sink node120a, the second sink node120b, . . . , the nth sink node120n), and transmits it to the data collecting server140via a network using an RF signal (e.g., a mobile communication network, a satellite network, etc).

In one embodiment, the gateway node130includes a plurality of transceiver for transmitting data. One of the transceivers performs the same function as the first data transceiver220of the sensor node110, and the other of the transceivers performs the same function as the second data transceiver230of the sensor node110. Thus, the operations of the first data transceiver220and the second transceiver230may be applicable to the first and the second transceivers. One transceiver may transmit data from the sink node120to the data collecting server140via a network using an RF signal. Also, the other transceiver can receive control signal for controlling the sink node120and the sensor node110from the data collecting server140and control the sink node120and the sensor node110.

The data collecting server140receives and stores the output signal being sent from the sensor node110via a plurality of gateway node130. In one embodiment, the data collecting server140may distinguish the measurement data and the location data, and store them separately. The data collecting server140may transmit the collected data to a user terminal that is coupled to a wired/wireless network and requests the data.

FIG. 5is a flowchart operation of the sensor node110that transmits data. Referring toFIG. 5, a method of transmitting the measurement data in the form of ultrasound is described. In this embodiment, the sensor node110generates the measurement data and transmits it to another sensor node. In another embodiment, the sensor node110may receive the measurement data from another sensor node.

In block510, the sensor array210measures the underwater environment and generates the measurement data to be outputted to the controller250. The controller250generates an output signal based on the location data specifying where the sensor node110is located and the measurement data from the sensor array210. The controller250outputs the measurement data and the location data of the sensor node110stored in the memory as a data signal to the frequency generator310. For example, the sensor array210can include a temperature sensor for measuring the water temperature, an acceleration sensor for measuring the seismic wave, a magnetic sensor, a pressure sensor, etc. Additionally, the sensor array210may include various other sensors. Thus, the sensor array210generates the measurement data after measuring the underwater environment by using the sensors and outputs it to the frequency generator310under the control of the controller250.

In block515, the frequency generator310generates a certain frequency with predetermined amplitude at certain intervals. The frequency generator310adds the measured signal from the controller250and the location data to the frequency and outputs it to the first amplifier320. As such, by adding the measurement data and the location data, both in the form of digital signal, to the frequency signal from the frequency generator310, the digital signal may be converted into an analog signal.

In block520, the first amplifier320amplifies the modulated data signal from the frequency generator310up to the predetermined voltage level and outputs it to the ultrasound transmitter330. As described above, the first amplifier320amplify the modulated data signal in the voltage level of between −6V and +6V. In block525, the ultrasound transmitter330operates with the amplified data signal from the first amplifier320to transform the amplified data signal into an ultrasound signal and emits it into the water.

The ultrasound transmitter330may be implemented, for example, to operate with a frequency (40 KHz) generated by the frequency generator310. Thus, the amplified data signal is a sum of the frequency signal from the frequency generator310and the measurement data and the location data, and the ultrasound transmitter may operate with the amplified data signal. Alternatively, or additionally, the frequency generator310may output a frequency signal to the frequency transmitter330at certain intervals, and the frequency transmitter330can operate with the frequency signal from the frequency generator310.

FIG. 6is a flowchart showing receiving operation of the sensor node110. Referring toFIG. 6, the method of receiving the ultrasound signal having a measurement data from another sensor node and obtaining the measurement data is described in detail. As described above, the sink node120receives the ultrasound signal emitted from a sensor node and obtains the measurement data in the same manner that the sensor node110receives the ultrasound signal from another sensor node. The process of obtaining an output signal in the sensor node110is described in detail. In block610, the ultrasound receiver410receives the ultrasound signal emitted from another sensor node and outputs it to the second amplifier420. The ultrasound signal includes the measurement data and location data of another sensor node.

In block615, the second amplifier420amplifies the ultrasound signal from the ultrasound receiver410up to the predetermined voltage level and outputs it to the first comparator430. For example, the second amplifier420can amplify the ultrasound signal up to a voltage level corresponding to 500 mV.

In block620, the first comparator430removes noise of the amplified ultrasound signal from the second amplifier420based on the predetermined reference voltage (e.g., 200 mV) and outputs it to the envelop detector440. As described above, the first comparator430removes noise from the second amplifier420based on the predetermined reference voltage such that the noise may be removed without an additional filter (e.g., low pass filter, high pass filter, etc.). In block625, the envelop detector440detects the predetermined envelop from the ultrasound signal without noise to obtain an original data signal and outputs it to the second comparator450. For example, the envelop detector440obtains a signal in the range of between 0V and 1.12V from the ultrasound signal without noise and outputs it as the original data signal to the second comparator450.

In block630, the second comparator450converts the original data signal from the envelop detector440into a digital signal based on the predetermined reference voltage (e.g., 600 mv) and outputs it to the controller250. As such, the controller250transforms the output signal into an ultrasound signal and transmits it to the sink node by using the data transmitter233. Thus, the underwater environment may be effectively monitored.

The underwater wireless communication system and method described above transmits and receives measurement data by transforming measured underwater data into ultrasound signals. The system and method may operate with a low power via a low-power based acoustic modem, which operates with a 3.3V power supply, and extend the lifetime of an underwater communication system. The system and method may replace high-cost equipment such as a submarine or an ROV and perform a cost-effective task.

The drawings and detailed description are only examples of the present invention, serve only for describing the present invention and by no means limit or restrict the spirit and scope of the present invention. Thus, any person of ordinary skill in the art shall understand that a large number of permutations and other equivalent embodiments are possible. The true scope of the present invention must be defined only by the ideas of the appended claims.