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Page 2 
 

1.2

 

Limitations  

 
This module is designed to pass speech.  Other signals such as data, music and morse (CW) will, to 
some degree pass through, but the integrity of these signals cannot be guaranteed.  Like the 
NEDSP1061-PCB module it is designed to be placed in a low-level audio path (up to 1V p-p) only, 
although there is a level adjustment on the module which will require adjustment.  The output will 
not drive a loudspeaker or other high-power load.

 

 
 
1.3

 

Module connection and Mounting 

 
Connections to the module are made by a row of 10 plated through holes to one end which form 
PL2

.  The holes are on a 2.54 mm (0.1”) pitch which allow the use of Straight 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 target system. 

 
 
 

 

 
 
 

 
 

 
 
 

 
 

 
 
 
 
 

 
 

 

 

 
PL1, seen on the right of the picture above, 
is meant for programming of the 1901-KBD 
module only. 
 
Connections to the 1901 are via PL2, as 
given in the table opposite. 
 
 
 
 
 
 

Whichever method of connection is used, ensure that the PCB is supported by using at least 2 of the 

Pin No 

Name 

Description 

N0 

BCD lsb noise reduction bit 0 

N1 

BCD noise reduction bit 1 

N2 

BCD msb noise reduction bit 2 

N/C 

Do Not Connect 

Vin 

Vin Supply Voltage (5V to 20 V) 

N/C 

Do Not Connect 

0v 

0V connection 

Noff 

Noise Reduction On/Off pin 

In 

Audio Input 

10 

Out 

Audio Output 

 

 

 

PL2 pin 1  

Input Level adjustment 

Output Level adjustment 

PL2 pin 10  

Overload 
LED  

Содержание NEDSP1901-PCB

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

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