JPH0230788Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a transponder that can transmit various signals in response to a command signal included in a received signal.

FIG. 1 shows how a conventional transponder is used to measure the reception sensitivity of a passive sonar at the actual sea surface. In FIG. 1, 1 is a measurement ship, 2 is a transponder, and 3 is a sound source ship. The measurement ship 1 includes a passive sonar 4 for measuring reception sensitivity, its receiver array 4a, a distance measuring device 5, and its transducer. 5a. The transponder 2 is suspended underwater from the sound source ship 3, and the sound source ship 3 is also equipped with a test signal generator 6 for measuring the reception sensitivity of the passive sonar 4 and its transmitter 6a.

Next, we will discuss the measurement method. Here, the reception sensitivity of the passive sonar is defined as the minimum value of the test signal level that can detect the direction of the signal source, and the direct distance between the passive sonar 4 and the test signal generator 6, that is, the direct distance between the measurement vessel 1 and the sound source. It is assumed that it is defined by two quantities: the direct distance to the ship 3. First, the measurement vessel 1 and the sound source vessel 3 communicate with each other by wireless communication, etc., operate the test signal generator 6, and convert the test signal of the passive sonar into an acoustic signal of a predetermined level using the transmitter 6a. and radiate it into the water. As an example of the test signal, a noise-like continuous reading wave having a predetermined bandwidth is used.
The test signal propagated underwater is received by the passive sonar 4 via the receiver array 4a of the measurement boat 1, and the direction of the signal source, that is, the sound source boat 3, is detected. When the signal level is gradually lowered on the test signal generator 6 side, the level of the test signal received by the passive sonar 4 also decreases, making it difficult to detect the direction of the sound source ship 3. At this time, the minimum signal level that can detect the direction of the sound source ship 3 is determined through communication between the measurement ship 1 and the sound source ship 3.

Once the minimum value of the test signal is determined, the distance measuring device 5 on the measurement boat 1 side is activated and a pulse signal is emitted from the transducer 5a into the water. The pulse signal is received by the transducer 2a of the transponder 2. When the transponder 2 receives the pulse signal, it immediately emits a response pulse into the water from the transducer 2a. The response pulse is received again by the distance measuring device 5 via the transducer 5a, but the distance measuring device 5 detects the time difference between the transmission time of the pulse signal and the reception time of the response pulse, and the underwater sound signal of the acoustic signal at that time. Based on the propagation speed (usually about 1500m/s), measurement vessel 1 and sound source vessel 3
Calculate the direct distance between The reception sensitivity of the passive sonar 4 is determined from the minimum value of the test signal and the determined direct distance.

In this way, conventional transponders only had the function of receiving pulse signals and sending back response pulses, and were only used to measure the distance between the measurement vessel and the signal source. Measuring sensitivity, etc. requires a separate test signal generator and a sound source ship to install and operate the device, and communication between the measurement ship and the sound source ship must be made by radio communication, etc. There were some shortcomings.

In order to solve the above-mentioned conventional drawbacks, the present invention provides a transponder that receives a plurality of command signals transmitted from a passive sonar and generates signals corresponding to each of the command signals. It is equipped with a command signal decoder that decodes the command signal, and a signal generator that receives the decoded command signal and generates a response signal and a test signal at a preset transmission level corresponding to each command signal. The purpose of this invention is to provide a transponder that can independently test the reception sensitivity of passive sonar.
The drawings will be described in detail below.

FIG. 2 shows an embodiment of the transponder of the present invention. In FIG. 2, 71 is an acoustic signal receiver, 72 is a receiver, 73 is a command signal decoder, 74 is a signal generator, 75 is a transmitter, and 76 is an acoustic signal transmitter. Here, an example is shown in which the command signal decoder 73 uses 4-bit digital signals as shown in FIG. a serial-to-parallel conversion register 731 for serial-to-parallel conversion of the 4-bit digital signal received by the wave transmitter 71 and received and demodulated by the receiver 72;
Deciphers the bit digital signal and sends the command signal S.
0, S1, S2...S9 decoder 732
It is made up of. Further, the signal generator 74 generates a response signal and a test signal at a preset transmission level corresponding to each of the 10 decoded command signals. The signal processing unit 741 includes the command signal decoder 73
When the command signal SO is received from the oscillator 742
When the command signal S1, S2...S9 is received, the oscillator 743 is operated to generate a test signal for measuring the reception sensitivity of the passive sonar. At the same time, the transmission level of the transmitter 75 is changed to the command signal S.
1, S2, .

Next, a method of measuring the receiving sensitivity of a passive sonar using the above transponder will be explained with reference to FIG. In FIG. 4, 1 is a measurement ship, 4 is a passive sonar, 4a is a receiver array, 5 is a ranging device, 5a is a transducer, 7 is a transponder having the above-mentioned configuration, and 8 is a transponder 7 placed underwater. This is a buoy for hanging. First, when measuring the receiving sensitivity of the passive sonar 4, the command signal S1 based on the above-mentioned 4-bit digital value is subjected to frequency shift keying from the distance measuring device 5, and then radiated into the water via the transducer 5a. do. The transponder 7 receives a signal including the command signal S1 and emits a passive sonar test signal at the highest level into the water. In the measurement ship 1, the receiver array 4a of the passive sonar 4 receives the test signal and detects its direction. Hereinafter, the command signals S2, S from the distance measuring device 5
3... Sequentially send out signals including S9, change the level of the test signal sent from the transponder 7, and repeat detection in that direction, but when the direction of the test signal can no longer be detected, From the command signal, the minimum value of the test signal with which the passive sonar 4 can detect the direction is determined.

Next, when measuring the direct distance between the measuring ship 1 and the transponder 7, the distance measuring device 5 emits a signal including the command signal S0, and the transponder 7 returns a response pulse. The response pulse is received by the distance measuring device 5, and the direct distance is determined in the same manner as in the conventional example. Therefore, the minimum value of the test signal that can detect the direction, the measurement ship 1 and the transponder 7
The reception sensitivity of the passive sonar 4 can be determined from the direct distance between the two.

In this way, the above transponder can transmit not only a response pulse for distance measurement, but also a test signal for passive sonar reception sensitivity measurement. It is possible to measure passive sonar reception sensitivity without the need for a separate test signal generator or sound source vessel. Further, the signal level is known for each designated command signal, and communication by other means with the signal source side is not required.

In the above embodiment, only the response pulse for distance measurement and the test signal for passive sonar reception sensitivity measurement were described as transmission signals, but the number is not limited to this, and the number of command signals may also be changed.
It is not limited to 10 pieces.

As explained above, according to the present invention, a transponder that receives a plurality of command signals transmitted from a passive sonar and generates a signal corresponding to each command signal decodes the command signal included in the received signal. a command signal decoder to receive the decoded command signal;
Since it is equipped with a signal generator that generates response signals and test signals at preset transmission levels in response to each command signal, it can also be used as a generator for various test signals, and can be used for acoustic sensors such as passive sonar. When used for performance tests on the actual sea surface, it has the advantage of not requiring any other signal generator or a sound source ship to operate it, and is very effective in operation.

[Brief explanation of drawings]

The drawings are used to explain the present invention. Figure 1 is an explanatory diagram showing how passive sonar reception sensitivity is measured at sea level using a conventional transponder, and Figure 2 shows an example of the transponder of the present invention. FIG. 3 is an explanatory diagram showing the contents of the command signal, and FIG. 4 is a diagram similar to FIG. 1 using the transponder of the present invention. 1...Measurement ship, 4...Passive sonar, 4a
...Receiver array, 5...Distance measuring device, 5a...Transducer/receiver, 7...Transponder, 8...Buoy, 7
1... Receiver, 72... Receiver, 73... Command signal decoder, 74... Signal generator, 75... Transmitter, 76... Transmitter, S0, S1, S2... S9
...Command signal.

Claims (1)

[Claims for Utility Model Registration] In a transponder that receives a plurality of command signals transmitted from a passive sonar and generates a signal corresponding to each of the command signals, a command signal that decodes the command signal included in the received signal. A transponder comprising: a decoder; and a signal generator that receives the decoded command signal and generates a response signal and a test signal at a preset transmission level corresponding to each command signal.