background image

Page 1 
 

bhi 

 

Copyright & Disclaimer

Copyright: This publication, including all photographs and illustrations is protected under 
international copyright laws, with all rights reserved. Neither this manual, nor any of the material 
within, may be copied or reproduced without the written consent of bhi Ltd.  
Disclaimer:  The information in this document is subject to change without notice. bhi Ltd. makes no 
representations or warranties with respect to the contents hereof and specifically disclaims any 
implied warranties of merchantability or fitness for any particular purpose. Furthermore, bhi Ltd. 
reserves the right to revise this publication and to make changes from time to time in the content 
hereof without obligation of bhi Ltd. to notify any person of such revision or changes.

 

 

1.

 

Introduction 

 The NEDSP1901-PCB module is designed to take line level audio signals and 

the NEDSP1901-PCB-MIC version is designed for use with various microphones. They are 
separate products and need to be ordered separately, and they are not interchangeable, 
although the NEDSP1901-PCB-MIC can also be used with line level audio signals.  
 
Note:  Go to page 12 for the specific NEDSP1901-PCB-MIC information 

 

NEDSP1901-PCB Version: 
 

The 

NEDSP1901-PCB

 module is an audio DSP noise cancelling module that is used to clean up noisy 

speech signals to give improved speech clarity in noisy conditions.  The 1901 module is pin for pin 
replacement module for the discontinued NEDSP1061-PCB

 

module.  It operates with a similar 

specification but incorporates the latest bhi DSP noise cancelling technology and maintains virtually 
the same physical dimensions as the NEDSP1061-PCB. 
 
 
         
 
 
 
 
 
 
 
 
 
                                   

DSP side of PCB  

 

 

                Rear side of PCB 

 

1.1

 

NEDSP 1901 Module Features: 

 

Fully adaptive to changing noise environments 

 

Input and output level controls 

 

Virtually no distortion to speech signals 

 

Up to 40 dB noise reduction in 8 selectable levels 

 

Audio bandwidth 300Hz to 5KHz 

 

Noise Reduction may be preset or remotely set during operation. 

 

7 to 18 Volt supply range 

 

Approximately 10 dB of signal gain with the ability to drive impedances of less than 1KOhm. 

 

Wide range of connection possibilities 

 

Mounting holes  

NEDSP1901-PCB User Manual Iss A 

NEDSP1901-PCB-MIC User Manual Iss A 

 

www.bhi-ltd.com

 

Summary of Contents for NEDSP1901-PCB

Page 1: ...e not interchangeable although the NEDSP1901 PCB MIC can also be used with line level audio signals Note Go to page 12 for the specific NEDSP1901 PCB MIC information NEDSP1901 PCB Version The NEDSP190...

Page 2: ...or Right angle pin headers or direct wiring This makes a flexible connection arrangement and allows the using to be mounted either vertically or horizontally plugged in or soldered directly to the tar...

Page 3: ...s low as possible supply voltage The power supply input is reverse polarity protected 1 4 DSP Noise Reduction The NEDSP1901 processes the incoming signal and uses known speech and noise patterns to di...

Page 4: ...als into and out of the module are capacitor coupled to ensure that no DC levels are pulled down or shorted when the module is used embodied as part of existing equipment The on board voltage regulato...

Page 5: ...s and mounting hole positions The Jumpers NS0 through NS2 highlighted in Figure 4 are solder jumper pads to allow the user to fix the Nosie Reduction level required Care must be taken so as not to spl...

Page 6: ...o signal and make sure that the 0V pin is grounded correctly with all signal grounds being reference to this pin 2 4 Controls The audio level control potentiometers VR2 Audio Out and VR1 Audio In prov...

Page 7: ...e Reduction Levels 8 Levels of noise reduction are available Noise and tone reduction is shown in the table below Notes 1 When processing signals with high levels of noise using the higher levels of N...

Page 8: ...l in the table containing 3 3 V may be taken up to or left open circuit Level N2 N1 N0 1 0 V 0 V 0 V 2 0 V 0 V 3 3 V 3 0 V 3 3 V 0 V 4 0 V 3 3 V 3 3 V 5 3 3 V 0 V 0 V 6 3 3 V 0 V 3 3 V 7 3 3 V 3 3 V 0...

Page 9: ...erefore if it is intended that the Microprocessor is to drive the 1901 lines High the Microprocessor should be operating from a 3 3 Volt supply as well Alternatively the control signals may be attenua...

Page 10: ...h a Microcontroller Important Note If the Microcontroller is driving the control pins both High and Low it should be operate from a 3 3 Volt supply only If this can t be achieved then consider using e...

Page 11: ...wer failing The following circuit uses a relay to route the audio signal directly In the event that the power fails the Relay will de energise and connect the Input to the Output directly It will be n...

Page 12: ...et or just Electret Capsules Dynamic or Magnetic Microphones These usually have a very low impedance between 30 Ohms and 600 Ohms and provide signal levels of between 55 dBV Pa and 40 dBV Pa As a word...

Page 13: ...d Some devices even have serial data converters built in such that they can be used directly with other digital circuits directly via I2 S these cannot be directly interfaced to the 1901 module Like t...

Page 14: ...trace that joins then Note Do not cut too deep as this PCB has several layers and you may sever traces on the underlying PCB layers Re connecting CH1 G0 is carried out using a solder link The other t...

Page 15: ...etting of 24dB should create a signal of 20dBV by simple addition which should give a signal of about 282mV P P maximum Using the AGC action As previously mentioned the module has an AGC system that m...

Page 16: ...7 97 50 8 943 49 10 03 48 11 26 27 47 12 63 46 14 17 45 15 9 44 17 84 Electret 43 20 02 42 22 46 41 25 2 24 40 28 28 39 31 73 38 35 6 37 39 95 36 44 82 35 50 29 34 56 43 33 63 31 18 MEMS 32 71 04 31 7...

Page 17: ...Page 17 Contact details bhi Ltd PO Box 318 Burgess Hill West Sussex RH15 9NR Tel 44 0 1444 870333 Email sales bhi ltd com Web www bhi ltd com...

Reviews: