HBA09-001-70
HB-NEDSP1068
3
1. Introduction
The NEDSP1068 module is a small DSP noise cancellation module, designed mainly
for cleaning up noisy voice communications in the microphone path. It is based on the
proven bhi NEDSP1061 pcb module, but has the added feature of an on-board AGC
mic preamplifier with various options. This enables the module to be fitted easily into
the microphone path of a target audio system, as well as in the receive path for use with
line level audio signals. There are two options: The basic module is the NEDSP1068-
PCBA, which has an adjustable AGC mic pre-amplifier circuit, and is able to operate
with either an external electret or dynamic microphone. The NEDSP1068-PCBA-MIC
has an on-board SMD microphone, and the adjustable AGC MIC pre-amplifier circuit.
2. Specifications
DSP Noise cancelling
9 to 35dB
Input Power
5 – 18v D.C.
Input
Current
30mA
Audio input level
Before Preamp and AGC - 4mV to 100mV p-p dependent on
preamp gain setting - Line Input - 800mV p-p
Input Impedance
Pre-amplifier -100KOhm
Line
in
direct
-
10KOhm
Audio Output level
Adjustable from 0v to 2.0v p-p
Output Impedance
10 K Ohm
Preset Controls
DSP input level, DSP Output level
Optional PIC ‘beep tone’ level control (Tx)
Settings
Pre-amplifier
Gain
AGC Attack and Release Times
Internal/External Microphone
Noise Cancelling Level
Indications
On-board
Overload
LED
Off
-board
Overload
LED
Drive
capability
Board size
30mm x 36.5mm *
Mounting Hole pitch
24mm x 27.5mm *
Connectors
Pitch
0.1”
*
Options
On board controller for use with additional keyboard circuitry
*- See Appendix C – PCB Dimensioned Drawing
