Benthowave Instrument Inc.

BENTHOWAVE INSTRUMENT INC. Acoustic Transducer & System 

Signal Filter - Improving SNR of SONAR Signals

BII-2020 Series    Bandpass Filter - Improving SNR of SONAR Signals

BII-2020 series provides signal amplification and bandpass filtering with attenuation of -120dB/decade to eliminate the out-of-band ambient and front-end receiver noises, and improve the SNR (Signal-to-noise ratio) of the SONAR system: Echosounding, Communication, Navigation, Fishery, Oceanography, Seafloor-mapping, Sub-bottom Profiling, Marine Animals...

Features  
Bessel Filter: linear phase response
Customized pass band and gain
Differential output
Low power consumption
Low electronic noise
120 dB/decade attenuation
Suggested Application  
Improve SNR prior to signal detection Anti-aliasing Filter
Bank of Bandpass Filter, Spectral Analysis Hydrophone Preamplifier
Related Products  
BII-1090 Series Preamplifier With Programmable Gain BII-1030 Series Variable Gain Amplifier

Bandpass FilterSNR of SONAR Signals

Specification

Bandpass Filter Pass Band Gain Center Frequency fo Input Referred Noise Current(Quiescent)
BII-2021 0 dB 1Hz to 300kHz 6.7nV/√Hz and 1.0pA/√Hz@1kHz
6.6nV/√Hz and 0.8pA/√Hz@10kHz
6.57nV/√Hz and 0.56pA/√Hz@100kHz
6.57nV/√Hz and 0.53pA/√Hz@200kHz
3 mA
BII-2022 20 dB 1Hz to 300kHz 6.7nV/√Hz and 1.0pA/√Hz@1kHz
6.6nV/√Hz and 0.8pA/√Hz@10kHz
6.57nV/√Hz and 0.56pA/√Hz@100kHz
6.57nV/√Hz and 0.53pA/√Hz@200kHz
3 mA
BII-2023 40 dB 1Hz to 300kHz 6.7nV/√Hz and 1.0pA/√Hz@1kHz
6.6nV/√Hz and 0.8pA/√Hz@10kHz
6.57nV/√Hz and 0.56pA/√Hz@100kHz
6.57nV/√Hz and 0.53pA/√Hz@200kHz
3 mA
BII-2025 0 dB 100kHz to 1MHz 3.25nV/√Hz and 1.1pA/√Hz@100kHz
3.25nV/√Hz and 1.0pA/√Hz@500kHz
3.25nV/√Hz and 1.0pA/√Hz@1MHz
11 mA
BII-2026 20 dB 100kHz to 1MHz 3.25nV/√Hz and 1.1pA/√Hz@100kHz
3.25nV/√Hz and 1.0pA/√Hz@500kHz
3.25nV/√Hz and 1.0pA/√Hz@1MHz
11 mA
BII-2027 40 dB 100kHz to 1MHz 3.25nV/√Hz and 1.1pA/√Hz@100kHz
3.25nV/√Hz and 1.0pA/√Hz@500kHz
3.25nV/√Hz and 1.0pA/√Hz@1MHz
11mA
Response Type: Bandpass, Bessel (Linear Phase Response).
Attenuation: 120dB/Decade
-3dB Bandwidth BW: Customized, specify when ordering.
Input Type: Differential (either single ended or differential input signals are accepted).
Input Wiring: 1. Default: SC36. 0.15m Shielded Cable with wire leads and label "I"; White Wire: Signal+; Black Wire: Signal-; Shield: Common and Shielding.
2. Coax: 0.15m 50Ω Coax with male BNC with label "I"; Center Pin: Signal+; Metal Shield: Signal- or Common.
Maximum Input:  4.6 Vpp
Input Coupling: AC
Input Impedance:  200kΩ 
Output Type: Differential (it can also be used as Single Ended).
Output Wiring: 1. Default: SC36. 0.15m Shielded Cable with wire leads and label "0"; White Wire: Signal+; Black Wire: Signal-; Shield: Common and Shielding.
2. Coax. 0.15m 50Ω Coax with male BNC with label "0"; Center Pin: Signal+; Metal Shield: Signal- or Common.
Maximum Output:  4.6 Vpp
Output Coupling: AC
Output Impedance: 1. Default: 10Ω
2. Customized
Cable Drive Capability: 50m
Supply Voltage:    +6 to +15VDC   
Power Supply Wiring: 0.15m Cable with wire leads; Red Wire: +VDC; Black Wire: Common.
Suggested DC Supply: +9VDC Batteries, Marine Battery, Automobile Battery, Fixed DC Linear Power Supply, Not Included.
DO NOT use variable power supply whose maximum supply voltage is higher than the above rated voltage.
DO NOT use switching mode DC power supply.
Size: ΦDxH: Φ60x12mm or Φ89x12mm
Weight: 15.0 g
Operating Temperature: -40°C to 85°C  
Storage Temperature:   -50°C to 105°C  
   
How to order:    
BII-202x -fo -BW -Output Impedance -Input/Output Cable
Refer to specification Center Frequency
in kHz
-3dB Passband Bandwidth
in kHz
Blank: 10Ω
or customized
Blank: SC36
or Coax
Example: Description:
BII-2021-3.5-2: BII-2021, Bandpass Filter with 3.5kHz Center Frequency and 2kHz bandwidth.
BII-2021-200-15: BII-2021, Bandpass Filter with 200kHz Center Frequency and 15kHz bandwidth.
BII-2027-1000-100-50-Coax: BII-2027, Bandpass Filter with 1MHz center frequency and 100kHz bandwidth, 50Ω output impedance, Input and Output cable: 50Ω coax with BNC male.

Technical Notes:

Bandwidth of Pulsed SINE ≅ 1/T;  T - Pulse Width (seconds).
Transducer Bandwidth = fo/Qm;  fo - Resonant Frequency, Qm - Quality Factor.

Butterworth Filter: This filter provides maximally flat magnitude response in the pass-band. Some overshoot and ringing is exhibited in step response.

Bessel Filter: This filter provides linear phase response, and has excellent pulse response (minimal overshoot and ringing).  A Bessel filter shall be used in the system which needs a linear group delay, minimum overshoot and ringing of the signal.

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