21 - Active Figure of Merit Flashcards
1
Q
How is Source Level (SL) related to Active FOM?
A
Your SONAR’s sonic transmission
Active FOI = ping frequency
2
Q
What is Target Strength (TS)?
A
Based on the “strength” of the reflected sound
Dependent on target physical properties
MASS: Material, Aspect Angle, Size, Shape
3
Q
What is Reverberation Level (RL)?
A
Backscatter noise from your active SONAR ping
4
Q
What is Reverb Limited?
A
- Echo returns before reverberations have decayed below NLambient
- DI loses it’s meaning, as reverberation is not isotropic
RL > NL - DI
Your SONAR ping echoes off other more stuff than the target
5
Q
What is Noise Limited ?
A
Target return is too quiet compated to ambient (background) noise
NL - DI > RL
6
Q
How to improve the FOM?
A
- Increase Source Level (SL)
- Decrease Noise Level
- Increase Directivity Index (DI)
- Decrease Detection Threshold (DT)
