Sonar Sound Navigation and Ranging Echosounder Fishfinder Horizontal

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Sonar: Sound Navigation and Ranging Echosounder 魚探, 聲探 Fishfinder 魚探 Horizontal Sonar 水平式魚探 Sonar

Sonar: Sound Navigation and Ranging Echosounder 魚探, 聲探 Fishfinder 魚探 Horizontal Sonar 水平式魚探 Sonar 聲納

Transducer (音鼓) + +

Transducer (音鼓) + +

Basic acoustic system

Basic acoustic system

Acoustic Data: amplitude, time How do you identify targets?

Acoustic Data: amplitude, time How do you identify targets?

Typical Echogram (回波圖判讀)

Typical Echogram (回波圖判讀)

Typical Echogram (回波圖判讀)

Typical Echogram (回波圖判讀)

聲波波長計算 • c=λf λ=波長=音速/f Ex. c=1450～ 1550 m/s Ex. F=10 KHz then λ=1500/10000 =0.

聲波波長計算 • c=λf λ=波長=音速/f Ex. c=1450～ 1550 m/s Ex. F=10 KHz then λ=1500/10000 =0. 15 m =15 cm

Nd. B = 10 log (I 2/I 1) • Source Level (音源強度或音波發射 強度): 指距音鼓

Nd. B = 10 log (I 2/I 1) • Source Level (音源強度或音波發射 強度): 指距音鼓 1 m處所測得之音壓, 以該 處測得音壓為 1μPa時為 0 d. B。例如測得 之音壓為 200000 Pa SL=10 log (200000/0. 000001)2 =20 log (200000/0. 000001) =226 d. B//1μPa (re 1μPa) =106 d. B// Pa (re 1 Pa)

習 (1)230 d. B//μpa = 題 d. B//pa = Pa 230 d. B// μpa

習 (1)230 d. B//μpa = 題 d. B//pa = Pa 230 d. B// μpa = 10(230/20)*10 -6 pa = 20 log (10 (230/20)*10 -6 ) d. B//pa = 20 log(105. 5) =110 d. B//pa (2)120 d. B//k. W = 120 d. B//k. W=10 d. B//W = (120/10) k. W = 10 W (120/10)*10 3 =10 log 1012+3=10 log 1015= 150 d. B//W (3)90 d. B//μpa = dyne/cm 2 W

音束指向性損失因子 等價音束角(Equivalent beam angle) 10 logΨ= -20. 82 d. B 理論 實測 10 logΨ=

音束指向性損失因子 等價音束角(Equivalent beam angle) 10 logΨ= -20. 82 d. B 理論 實測 10 logΨ= -20. 39 d. B

Large Target (Reflection) 水中物體的聲波反射 (極端狀況) Small target (Scattering)

Large Target (Reflection) 水中物體的聲波反射 (極端狀況) Small target (Scattering)

haddock黑線鱈 cod mackerel herring mackerel 箱網內TS實測 herring sandeel

haddock黑線鱈 cod mackerel herring mackerel 箱網內TS實測 herring sandeel

Multiple Target (考慮音鼓指向性) b 2 b 2 b b 2

Multiple Target (考慮音鼓指向性) b 2 b 2 b b 2

習題 TS為-46 d. B的鯖魚一群, 密度為 100尾/m 3, 距音鼓 500 m, 聲探之音 源強度為 200 d.

習題 TS為-46 d. B的鯖魚一群, 密度為 100尾/m 3, 距音鼓 500 m, 聲探之音 源強度為 200 d. B//μPa, 脈波延遲為 10 ms, 20㏒Ψ=-26 d. B, 吸收係數 為 15 d. B/km, 則音鼓接收之音壓為? EL= SL+TS+10 logρ+10 log Cτ+20 logΨ-2αR-20 log. R = 200 -46+20+11. 7 -26 -2 x 15 x 0. 5 -54 = 90. 7 d. B//μPa 10 log Cτ=10 log(1500 * 0. 01)=10*1. 17

能量積分法(Echo Integration) EL=SL+10㏒ρ+TS+20㏒b(θ, ψ)-2αR-20㏒R+10㏒cτ SV= 10㏒ρ+TS = EL-SL- 20㏒b(θ, ψ)+2αR+20㏒R-10㏒cτ

能量積分法(Echo Integration) EL=SL+10㏒ρ+TS+20㏒b(θ, ψ)-2αR-20㏒R+10㏒cτ SV= 10㏒ρ+TS = EL-SL- 20㏒b(θ, ψ)+2αR+20㏒R-10㏒cτ

TVG Squarer Integr. Per mile Integr. Per Trans. ECHO SOUNDER INTEGRATOR Speed compensation GPS

TVG Squarer Integr. Per mile Integr. Per Trans. ECHO SOUNDER INTEGRATOR Speed compensation GPS ：Volume Backscattering strength 2 1 R 3 Transmissions R 1 m R 2 ΔR Elementary Sampling Distance Unit (ESDU=1 n. mi)

常用兩種指標代表水體中生物量情況 1 Sa: 總反射截面積(m 2/平方浬)，代表總量多寡 TS= Target strength (d. B) σbs= 10 TS/10 r=

常用兩種指標代表水體中生物量情況 1 Sa: 總反射截面積(m 2/平方浬)，代表總量多寡 TS= Target strength (d. B) σbs= 10 TS/10 r= depth to the target Ψ=equivalent beam angle (d. B) Ψ= 10 d. B. value/10 2 Sv: 水體總反射強度，可換算為密度 Sv=10 log D +TS D: 密度 (ind/m 3)

習 題 聲納程式中SL=220 d. B, τ=20 ms, DI=-12 d. B, α=10 d. B/km, 今水深

習 題 聲納程式中SL=220 d. B, τ=20 ms, DI=-12 d. B, α=10 d. B/km, 今水深 100 m處一群鯖魚群的回音強度為 110 d. B, 若鯖魚之平均TS為 40 d. B, 則此魚群密度為若干？(10%) hint: log 3=0. 48 EL=SL+10㏒ρ+TS+20㏒b(θ, ψ)-2αR-20㏒R+10㏒Cτ 110=220 + 10 logρ-40 -12 -2*10*0. 1 -20 log 100+10 log 0. 02*1500 110= 220 - 92. 52 + 10 logρ= -17. 48 ρ= 10 -1. 748 fish/m 3

Example (Density Variation Info) 釣船集魚燈下魚群群集密度 Hr) (10

Example (Density Variation Info) 釣船集魚燈下魚群群集密度 Hr) (10

Example (Cont. ) Davg=0. 059 魚群集密度計算

Example (Cont. ) Davg=0. 059 魚群集密度計算

Example (TS distribution)

Example (TS distribution)

Example (Average TS)

Example (Average TS)

Example (Sa distribution)

Example (Sa distribution)

Example (Density for single species) Fish/m 3

Example (Density for single species) Fish/m 3