JP2919350B2 - Signal detection method - Google Patents
Signal detection methodInfo
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- JP2919350B2 JP2919350B2 JP11741096A JP11741096A JP2919350B2 JP 2919350 B2 JP2919350 B2 JP 2919350B2 JP 11741096 A JP11741096 A JP 11741096A JP 11741096 A JP11741096 A JP 11741096A JP 2919350 B2 JP2919350 B2 JP 2919350B2
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- Prior art keywords
- signal
- noise
- frequency
- threshold
- azimuth
- Prior art date
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Description
【０００１】[0001]
【産業上の利用分野】本発明は、水中音の検出を行う信
号検出方式に関し、特に指向性受波器を有するソノブイ
による水中音のナローバンド信号の信号検出方式に関す
る。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal detection method for detecting underwater sound, and more particularly to a signal detection method for a narrow band signal of underwater sound by a sonobuoy having a directional receiver.
【０００２】[0002]
【従来の技術】従来の信号検出方式では、ナローバンド
信号を検出して、その周波数及び方位を求めるため、指
向性受波器を有するソノブイと、その信号処理を行う系
統から成っている。これを図を用いて説明する。2. Description of the Related Art A conventional signal detection system comprises a sonobuoy having a directional receiver for detecting a narrow band signal and obtaining its frequency and direction, and a system for processing the signal. This will be described with reference to the drawings.
【０００３】図２は従来の方式であり、送信側の指向性
ソノブイ１と受信側２とで構成される。ソノブイ１は無
指向性受波器１１と、磁北に対して南北にダイポール指
向性を有する南北ダイポール指向性受波器１２と、東西
にダイポール指向性を有する東西ダイポール指向性受波
器１３と、それらの受波器で受波した水中音を電波で観
測機等に送信する送信部１４とから成る。FIG. 2 shows a conventional system, which comprises a directional sonobuoy 1 on a transmitting side and a receiving side 2. The sonobuoy 1 includes an omnidirectional receiver 11, a north-south dipole directional receiver 12 having a dipole directivity north and south with respect to magnetic north, an east-west dipole directional receiver 13 having a dipole directivity east and west, And a transmitting unit 14 for transmitting the underwater sound received by these receivers to an observation device or the like by radio waves.
【０００４】受信側２は観測機等であり、ソノブイから
の電波を受信する受信部３と、ソノブイの３個の受波器
の信号を周波数分析する周波数分析部４，５，６と、周
波数分析結果を周波数成分毎に、時間的に積分する積分
部７，８，９と、無指向性受波器で受波した水中音の積
分された周波数分析結果から信号を検出する信号検出部
１０と、各々の受波器の受波レベルの関係から受波音の
到来方位を計算する方位計算部１１とから成る。[0004] The receiving side 2 is an observation device or the like, and includes a receiving unit 3 for receiving radio waves from the sonobuoy, frequency analyzing units 4, 5, and 6 for performing frequency analysis of signals of three receivers of the sonobuoy, Integrators 7, 8, and 9 for temporally integrating the analysis result for each frequency component, and a signal detector 10 for detecting a signal from the integrated frequency analysis result of the underwater sound received by the omnidirectional receiver. And an azimuth calculation unit 11 for calculating the azimuth of arrival of the received sound from the relationship between the reception levels of the respective receivers.
【０００５】次に動作について説明する。水中音源が放
射するナローバンド信号は指向性ソノブイ１において、
無指向性受波器１１、南北ダイポール指向性受波器１
２、東西ダイポール指向性受波器１３で受信される。そ
れぞれの受波音は送信部１４に送られ、周波数多重化さ
れた後、無線周波数に変調して電力増幅後、アンテナを
介して送出される。一方、この電波は受信側２において
はアンテナを介して受信部３に送られ、復調処理されて
無指向性受波器１１の受波音を周波数分析部４に南北ダ
イポール指向性受波器１２の受波音を周波数分析部５
に、東西ダイポール指向性受波器１３の受波音を周波数
分析部６にそれぞれ出力する。Next, the operation will be described. The narrow band signal emitted by the underwater sound source is
Omni-directional receiver 11, North-South dipole directional receiver 1
2. Received by the east-west dipole directional receiver 13. Each received sound is sent to the transmission unit 14, frequency-multiplexed, modulated to a radio frequency, amplified in power, and sent out via an antenna. On the other hand, on the receiving side 2, the radio wave is sent to the receiving unit 3 via the antenna, demodulated, and the received sound of the omnidirectional receiver 11 is transmitted to the frequency analyzing unit 4 by the north-south dipole directional receiver 12. Received sound is analyzed by frequency analysis unit 5
Then, the received sound of the east-west dipole directional receiver 13 is output to the frequency analyzer 6.
【０００６】周波数分析部４においては、無指向性受波
器１１で受波された水中音を周波数分析して、周波数ス
ペクトラムが得られる。水中に、ナローバンド信号が存
在すると周波数スペクトラムに狭帯域のスペクトルとし
てあらわれる。水中音には一般に周囲雑音が多く含まれ
るため周波数スペクトラムにおいても雑音があらわれ観
測時刻ごとに雑音スペクトルが変動しナローバンド信号
が検出しにくいため、積分部７に送って、各周波数成分
毎にあらかじめ決められた時間長さの積分を行う。次
に、積分結果は信号検出部１０へ送られる。信号検出部
１０においては雑音スペクトルの平均値を基準としてス
レッショルドを設定し、そのスレッショルドを越えるス
ペクトルを信号成分として検出している。その方法は次
のとおりである。The frequency analysis unit 4 analyzes the frequency of the underwater sound received by the omnidirectional receiver 11 to obtain a frequency spectrum. When a narrow band signal exists in water, it appears as a narrow band spectrum in the frequency spectrum. Underwater sounds generally contain a lot of ambient noise, so noise appears in the frequency spectrum, and the noise spectrum fluctuates at each observation time, making it difficult to detect narrow band signals. Integrate the length of time. Next, the integration result is sent to the signal detection unit 10. The signal detector 10 sets a threshold based on the average value of the noise spectrum, and detects a spectrum exceeding the threshold as a signal component. The method is as follows.
【０００７】まず、水中音の周波数成分データの雑音平
均値Ｍｐを式１により求める。なお、Ｎセル個の周波数
成分があり、周波数セルは昇順に並んでいるとする。First, the noise average value Mp of the frequency component data of the underwater sound is determined by the following equation (1). It is assumed that there are N cell frequency components and the frequency cells are arranged in ascending order.
【０００８】[0008]
【数１】 (Equation 1)
【０００９】ただし、Ｘｉ：ｉ番目のセルのレベル（ｉ
＝１〜Ｎ）、Ｍｐ：ｐ番目のセルに対する雑音平均値
（ｐ＝１〜Ｎ）、Ｗ：雑音平均値計算に用いるセルの数 なお、ｐ＜＝Ｗ／２または、ｐ＞＝Ｎ−Ｗ／２の場合
は、それぞれ、ｐ＝Ｗ／２＋１，ｐ＝Ｎ−Ｗ／２−１の
雑音平均値を用いる。また、雑音平均を計算するセルは
計算の対象からはずしている。Where Xi: the level of the ith cell (i
= 1 to N), Mp: noise average value for the p-th cell (p = 1 to N), W: number of cells used for noise average value calculation, p <= W / 2 or p> = N− In the case of W / 2, noise average values of p = W / 2 + 1 and p = N−W / 2-1 are used, respectively. Also, the cells for calculating the noise average are excluded from the calculation.
【００１０】次に、雑音平均値をもとにスレッショルド
Ｔｉを式２より求める。Next, a threshold value Ti is obtained from Equation 2 based on the noise average value.
【００１１】Ｔｉ＝Ｋ・Ｍｉ …式２ ただし、Ｋ：定数 そして、スレッショルドと周波数成分を比較して、スレ
ッショルドを越えるものを信号として検出する。Ti = K · Mi (2) where K is a constant. Then, the threshold and the frequency component are compared to detect a signal exceeding the threshold as a signal.
【００１２】一方、南北ダイポール指向性受波器１２の
受波音は、受信部３から周波数分析部５へ、更に東西ダ
イポール指向性受波器１３の受波音は周波数分析部６へ
送られ、各々周波数分析された後、各々積分部８，９へ
送られて、周波数成分毎にあらかじめ決められた時間長
の積分を行う。積分部８，９の出力は方位計算部１１へ
送られる。方位計算部１１では以下に説明するように信
号の到来方位を求める。図３は各受波器で到来信号Ｓ
（ｔ）を受波した様子を示している。南北ダイポール指
向性受波器の出力をＮＳ、東西ダイポール指向性受波器
の出力をＥＷとすると、On the other hand, the sound received by the north-south dipole directional receiver 12 is sent from the receiver 3 to the frequency analyzer 5, and the sound received by the east-west dipole directional receiver 13 is sent to the frequency analyzer 6. After the frequency analysis, the signals are sent to the integration units 8 and 9, respectively, and are integrated for a predetermined time length for each frequency component. Outputs of the integration units 8 and 9 are sent to a bearing calculation unit 11. The azimuth calculation unit 11 obtains the arrival azimuth of the signal as described below. FIG. 3 shows the arrival signal S at each receiver.
(T) is received. Assuming that the output of the north-south dipole directional receiver is NS and the output of the east-west dipole directional receiver is EW,
【００１３】[0013]
【数２】 (Equation 2)
【００１４】ここでＫは音圧感度等の定数である。上式
においてHere, K is a constant such as sound pressure sensitivity. In the above formula
【００１５】[0015]
【数３】 (Equation 3)
【００１６】であるので、 ＥＷ／ＮＳ＝ｓｉｎα／ｃｏｓα＝ｔａｎα 従って、α＝ａｒｃｔａｎ（ＥＷ／ＮＳ） ところで、上式のみでは方位の象限が決まらないが、受
波器の出力特性として、南北ダイポール指向性受波器に
おいては北側から音が入射されると無指向性受波器の出
力と同相となり、南側からから音が入射されると無指向
性受波器の出力と逆相となるようにしており、同様に東
西ダイポール指向性受波器では、東から入ると同相、西
から入ると逆相となっており、各受波器の位相関係を図
４の表によって調べることにより、象限の決定を行う。
前記の方位計算は、周波数分析した周波数成分の各々に
ついて実行され方位が決められる。Therefore, EW / NS = sin α / cos α = tan α Therefore, α = arctan (EW / NS) Incidentally, the quadrant of the azimuth is not determined only by the above equation. In a directional receiver, when sound is incident from the north side, the output will be in phase with the output of the omnidirectional receiver, and when sound is incident from the south side, the output will be in phase opposite to the output of the omnidirectional receiver. Similarly, in the case of the east-west dipole directional receiver, the phase is the same when entering from the east and the opposite phase when entering from the west. By examining the phase relationship of each receiver using the table in Fig. 4, Make a decision.
The azimuth calculation is performed for each of the frequency components subjected to the frequency analysis to determine the azimuth.
【００１７】以上説明したように従来方式ではレベルの
大小を基準としてスレッショルドによりナローバンド信
号か否かの判定を行っていた。As described above, in the conventional system, whether or not a signal is a narrow band signal is determined based on the threshold based on the level of the level.
【００１８】[0018]
【発明が解決しようとする課題】この従来の信号検出方
式では、ナローバンド信号が存在するか否かはレベルの
大小によってのみ判断しているため、低Ｓ／Ｎのナロー
バンド信号を検出しようとするとスレッショルドを下げ
る必要がある。すると雑音成分も検出される確率が高ま
るので誤検出が多くなって実用に価しなくなってしまう
という問題があった。In this conventional signal detection method, the presence or absence of a narrow band signal is determined only by the magnitude of the level. Therefore, when an attempt is made to detect a low S / N narrow band signal, a threshold is used. Need to be lowered. Then, the probability that the noise component is also detected increases, so that there is a problem that the number of erroneous detections increases, which is not practical.
【００１９】[0019]
【課題を解決するための手段】本発明の信号検出方式
は、ソノブイの無指向性受波器、南北ダイポール指向性
受波器及び東西ダイポール指向性受波器の各々の受波音
を各々周波数分析する手段と、その結果を周波数成分毎
に時間積分する手段と、積分結果の周波数成分について
従来より低いレベルのスレッショルドを設けて信号と雑
音を１次判別する信号検出手段と、前記３種の受波音の
周波数成分の積分結果のレベル比及び位相判定から周波
数成分毎の方位を計算する手段と、これを時系列的に記
憶する手段と、信号検出手段で信号であると１次判別さ
れた周波数成分の時系列的な方位の分散を計算する手段
と、１次判別された周波数成分のうち、方位の分散値が
所定のスレッショルド以下のものを信号であると２次判
別する信号判定手段とを備えている。SUMMARY OF THE INVENTION A signal detection system according to the present invention is a frequency-analyzing method for each of the received sounds of a sonobuoy omnidirectional receiver, a north-south dipole directional receiver, and an east-west dipole directional receiver. Means for time-integrating the result for each frequency component, signal detection means for providing a lower-level threshold for the frequency component of the integration result as compared with the prior art, and first-order distinction between signal and noise. Means for calculating the azimuth for each frequency component from the level ratio and phase determination of the integration result of the frequency component of the wave sound, means for storing this in a time-series manner, and the frequency at which the signal is first determined to be a signal by the signal detection means Means for calculating the variance of the time-series azimuth of the components, and signal determination means for second-orderly determining that the variance of the azimuth of the primary-determined frequency components is equal to or less than a predetermined threshold. It is equipped with a.
【００２０】[0020]
【実施例】次に本発明について図面を参照して説明す
る。図１は本発明の一実施例である。使用する送信側の
ソノブイは従来通りのものであり、図２の指向性ソノブ
イ１と同様であり、図１では省略してある。DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 1 shows an embodiment of the present invention. The sonobuoy on the transmitting side to be used is the same as the conventional one, which is the same as the directional sonobuoy 1 in FIG. 2 and is omitted in FIG.
【００２１】図１で、ソノブイから伝送された電波が受
信部３に送られて、無指向性、南北ダイポール指向性、
東西ダイポール指向性の各々の受波器の受波音に復調さ
れ、各々周波数分析部４，５，６において周波数分析さ
れた後、積分部７，８，９において周波数成分毎に時間
積分されるのも従来通りである。さらに、それら３種の
受波器の受波音の周波数成分の積分値のレベル比及び位
相判定から、周波数成分毎の方位を方位計算部１１にお
いて計算するが、これも従来方式のとおりである。In FIG. 1, a radio wave transmitted from a sonobuoy is sent to a receiving unit 3 and is omnidirectional, north-south dipole directivity,
The demodulated sound is received by each of the receivers of the east-west dipole directivity, frequency-analyzed by the frequency analysis units 4, 5, and 6, and then time-integrated by the integration units 7, 8, and 9 for each frequency component. Is the same as before. Further, the azimuth calculation unit 11 calculates the azimuth for each frequency component from the level ratio of the integrated value of the frequency component of the received sound of the three types of receivers and the phase determination, which is also the same as the conventional method.
【００２２】一方、信号検出部１０においては従来方式
の式１，式２によってレベルのスレッショルドを設定す
るが、式２における定数Ｋとしては従来よりも小さい値
とする。ここで図５にレベルのスレッショルドについて
示す。信号成分は水中雑音に重畳されるため、レベル毎
の発生頻度をとると雑音成分の分布とそれよりもレベル
の高い所にピークをもつ信号成分の分布が得られる。同
図にあるようにレベルのスレッショルドＴＨで信号を判
別すると、黒い部分は雑音を信号と誤って検出する即
ち、誤警報となる。一般には、必要な検出率（図５の斜
線部）と誤警報で決まるレベルにスレッショルドを設定
する。本発明では従来方式よりもスレッショルドを下げ
る。これによって従来よりも低いＳ／Ｎの信号について
も検出できるようになる。ところがスレッショルドを下
げると誤警報が増加するが、本発明ではこれに対して
は、次に示すように方位の一貫性を２次判別として調べ
ることにより、雑音成分を除去している。On the other hand, in the signal detecting section 10, the level threshold is set by the conventional formulas 1 and 2, but the constant K in the formula 2 is set to a value smaller than the conventional value. FIG. 5 shows the level threshold. Since the signal component is superimposed on the underwater noise, the distribution of the noise component and the distribution of the signal component having a peak at a higher level than the noise component can be obtained by taking the occurrence frequency for each level. When the signal is determined based on the level threshold TH as shown in the figure, the black portion erroneously detects noise as a signal, that is, a false alarm. Generally, the threshold is set to a level determined by a necessary detection rate (shaded portion in FIG. 5) and a false alarm. In the present invention, the threshold is lower than in the conventional method. As a result, it is possible to detect a signal having a lower S / N than the conventional one. However, when the threshold is lowered, false alarms increase. In the present invention, however, the noise component is removed by examining the azimuth consistency as a secondary determination as described below.
【００２３】図１にもどり、方位記憶部１２は、方位計
算部１１で計算された周波数成分毎の方位の値を時系列
的に記憶する。方位分散計算部１３では、信号検出部１
０で、レベルをもとに信号であると１次判別された周波
数成分について、方位記憶部１２から一定時間区間の方
位値を読み出しその分散を計算する。信号判定部１４に
おいては、その方位の分散値がスレッショルドと比較し
て大きいか小さいかにより信号と雑音を２次判別する。
雑音は等方性とみなせるので分散は大となり、一方信号
は雑音が重畳しているため方位はバラつくものの、信号
自体は方向性を有するため、方位の分散は雑音のみの時
に比べて小さくなる。この点を利用して、１次判別の中
に誤って含まれている雑音成分を除去することができ
る。Returning to FIG. 1, the azimuth storage unit 12 stores the azimuth values for each frequency component calculated by the azimuth calculation unit 11 in time series. In the azimuth variance calculation unit 13, the signal detection unit 1
At 0, the azimuth value of a certain time section is read from the azimuth storage unit 12 for the frequency component that is primarily determined to be a signal based on the level, and its variance is calculated. The signal determination unit 14 performs second-order determination of the signal and the noise based on whether the variance value of the azimuth is larger or smaller than the threshold.
Noise can be regarded as isotropic, so the variance is large.On the other hand, the azimuth of the signal is scattered because the noise is superimposed, but the directional variance is smaller than that of the noise alone because the signal itself has directionality. . By utilizing this point, noise components erroneously included in the primary determination can be removed.
【００２４】ここで分散の計算について説明する。ある
周波数に対して、周波数分析の周期毎に得られるＮ個の
方位値データをｘ1 ，ｘ2 ，…，ｘN を考えると、分散
は次式で得られる。Here, the calculation of the variance will be described. Considering x 1 , x 2 ,..., X N for N azimuth value data obtained for each frequency analysis cycle for a certain frequency, the variance can be obtained by the following equation.
【００２５】[0025]
【数４】 (Equation 4)
【００２６】また、得られた分散に対するスレッショル
ドレベルは、方位の値が０〜３６０°の間で一様に分布
していると仮定したときの偏差（分散の平方根）は約１
０４であるから、これを１／Ｋ′倍した値を設定する。
Ｋ′の値は例えば実海面の種々の状況に対応して可変す
ればよい。The threshold level for the obtained variance has a deviation (square root of variance) of about 1 when it is assumed that the azimuth values are uniformly distributed between 0 and 360 °.
Since it is 04, a value multiplied by 1 / K 'is set.
The value of K 'may be varied, for example, in accordance with various situations on the actual sea level.
【００２７】[0027]
【発明の効果】以上説明したように本発明によれば、検
出レベルのスレッショルドを下げて従来より低いＳ／Ｎ
の信号を処理でき、これによって増加する誤検出を方位
の分散の大小に着目して抑圧するので従来にくらべて、
Ｓ／Ｎの悪い音響信号に対しても、目的とする信号を検
出することができるという効果を有する。As described above, according to the present invention, the threshold of the detection level is lowered and the S / N is lower than in the prior art.
Can be processed, and the erroneous detection that increases by focusing on the magnitude of azimuth dispersion is suppressed.
This has an effect that a target signal can be detected even for an audio signal having a poor S / N.
【図１】本発明の一実施例のブロック図。FIG. 1 is a block diagram of one embodiment of the present invention.
【図２】従来方式のブロック図。FIG. 2 is a block diagram of a conventional system.
【図３】指向性ソノブイの指向性パターンと受波の説明
図。FIG. 3 is an explanatory diagram of a directivity pattern of a directivity sonobuoy and a reception wave.
【図４】検出信号の方位の象限の決定を示す表。FIG. 4 is a table showing determination of a quadrant of an azimuth of a detection signal.
【図５】信号と雑音のレベルの頻度分布とスレッショル
ド説明図。FIG. 5 is an explanatory diagram of a frequency distribution of signal and noise levels and a threshold.
１ 指向性ソノブイ ２ 受信側 ３ 受信部 ４〜６ 周波数分析部 ７〜９ 積分部 １０ 信号検出部 １１ 方位計算部 １２ 方位記憶部 １３ 方位分散計算部 １４ 信号判定部 DESCRIPTION OF SYMBOLS 1 Directivity sonobuoy 2 Receiving side 3 Receiving part 4-6 Frequency analyzing part 7-9 Integrating part 10 Signal detecting part 11 Direction calculating part 12 Direction storing part 13 Direction dispersion calculating part 14 Signal judging part
───────────────────────────────────────────────────── フロントページの続き (72)発明者 山本 琢 東京都港区芝五丁目７番１号 日本電気 株式会社内 (56)参考文献 特開 昭62−87880（ＪＰ，Ａ) 特開 平５−93772（ＪＰ，Ａ) 特開 昭53−145669（ＪＰ，Ａ) 特開 平６−201811（ＪＰ，Ａ) 特開 平５−203715（ＪＰ，Ａ) (58)調査した分野(Int.Cl.6，ＤＢ名) G01S 3/80 - 3/86 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Taku Yamamoto 5-7-1 Shiba, Minato-ku, Tokyo NEC Corporation (56) References JP-A-62-87880 (JP, A) JP-A-5 -93772 (JP, A) JP-A-53-145669 (JP, A) JP-A-6-201811 (JP, A) JP-A-5-203715 (JP, A) (58) Fields investigated (Int. . 6, DB name) G01S 3/80 - 3/86
Claims (3)
指向性受波器からの出力を所定の誤報率を認める第１の
スレッショルドと比較し信号か雑音かを１次判別する第
１の判別手段と、指向性受波器からの出力を受け前記第
１の判別手段により信号と判別されたとき受波信号の到
来方向を求める方向検出手段と、前記方向検出手段から
の検出結果の時系列的な分散を求める分散計算手段と、
前記分散を第２のスレッショルドと比較し信号か雑音か
を２次判別する第２の判別手段とを具備する信号検出方
式。An omni-directional receiver, a directional receiver, and an output from the omni-directional receiver are compared with a first threshold for recognizing a predetermined false alarm rate to determine whether a signal or noise is primary. A first discriminating means for discriminating, a direction detecting means for receiving an output from the directional receiver and obtaining an arrival direction of the received signal when the signal is discriminated by the first discriminating means; Variance calculation means for obtaining a time-series variance of the detection result of
A second determining means for comparing the variance with a second threshold to secondarily determine whether the signal is noise or noise.
各周波数帯毎に信号か雑音かを判定する請求項１の信号
検出方式。2. Dividing the received signal into a plurality of frequency bands,
2. The signal detection method according to claim 1, wherein whether the signal or the noise is determined for each frequency band.
ール指向性受波器及び東西ダイポール指向性受波器の各
々の受波音を各々、周波数分析する手段と、周波数分析
結果を周波数成分毎に時間積分する手段と、積分結果の
周波数成分について所定の誤報率を認める第１のスレッ
ショルドを設けて信号と雑音を１次判別する信号検出手
段と、前記３種の受波音の周波数成分の積分結果のレベ
ル比及び位相判定から周波数成分毎の方位を計算する手
段と、信号であると１次判別された周波数成分の時系列
的な方位の分散を計算する手段と、１次判別された周波
数成分のうち、方位の分散値が第２のスレッショルド以
下のものを信号であると２次判別する信号判定手段を備
えている信号検出方式。3. A means for frequency-analyzing the received sound of each of the sonobuoy omnidirectional receiver, the north-south dipole directional receiver, and the east-west dipole directional receiver. Means for time-integrating the signal, signal detecting means for providing a first threshold for recognizing a predetermined false alarm rate with respect to the frequency component of the integration result, and signal detecting means for first-order discrimination between signal and noise; Means for calculating the azimuth for each frequency component from the resulting level ratio and phase determination; means for calculating the variance of the time-series azimuth of the frequency component that is primarily determined to be a signal; A signal detection method comprising signal determination means for secondarily discriminating a component having a azimuth variance value equal to or smaller than a second threshold as a signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11741096A JP2919350B2 (en) | 1996-05-13 | 1996-05-13 | Signal detection method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11741096A JP2919350B2 (en) | 1996-05-13 | 1996-05-13 | Signal detection method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH09304500A JPH09304500A (en) | 1997-11-28 |
| JP2919350B2 true JP2919350B2 (en) | 1999-07-12 |
Family
ID=14710967
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP11741096A Expired - Lifetime JP2919350B2 (en) | 1996-05-13 | 1996-05-13 | Signal detection method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2919350B2 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007017309A (en) * | 2005-07-08 | 2007-01-25 | Hitachi Ltd | Target detector |
| JP6236755B2 (en) * | 2012-08-02 | 2017-11-29 | 日本電気株式会社 | Passive sonar device, transient signal processing method and signal processing program thereof |
| JP2015087132A (en) * | 2013-10-28 | 2015-05-07 | 株式会社東芝 | Signal detection device and signal detection method |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS53145669A (en) * | 1977-05-24 | 1978-12-19 | Nec Corp | Azimuth signal processing system |
| JPS6287880A (en) * | 1985-10-14 | 1987-04-22 | Nec Corp | Transponder |
| JPH0593772A (en) * | 1991-09-30 | 1993-04-16 | Nec Corp | Detecting device for underwater acoustic signal |
-
1996
- 1996-05-13 JP JP11741096A patent/JP2919350B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH09304500A (en) | 1997-11-28 |
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