bhi ltd P.O. Box 136 Bexhill on Sea East Sussex TN39 3WD tel: +44 (0)870 240 72 58 fax: +44 (0)870 240 72 59 sales@bhi-ltd.co.uk www.bhi-ltd.co.
Important Information Notes: 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.
Packing List: 7. Machining details Hole machining details. Please check the contents of the box. n n n n n DSP PCB Mounting hole detail 27.3mm Operating manual NEDSP1061-KBD assembly Z bracket Self adhesive mounting pads bhi NEDSP label 21.0mm To install this module you will need the following additional items: n service manual/circuit diagram of the equipment in which the module is to be installed.
Contents 1. Introduction 1.1 NEDSP1061-KBD features 1.2 Limitations 1.3 Audio DSP noise cancellation 5 5 6 6.3.2 Demonstration 2: Follow the procedure as above. Wait for the second 2 tone beep, then release the key. In this mode the filter level is set to level 3. 2. Module description 2.1 Module layout 2.2 Connections 2.3 Electrical characteristics 2.4 Controls 2.4.1 Input level 2.4.2 Output level 2.4.3 Beep volume level 2.4.4 Overload LED 2.5 Module mounting 7 7 8 8 8 8 8 8 9 Installation 3.
Noise cancellation on/off. Press and release the button and the led will extinguish, and the noise cancellation will be activated. A short beep will acknowledge the key press. Changing the filter level. Hold down the button. The led will flash the filter level, and if the button is held it will step through all the levels. When the desired level has been reached release the button. This new value will be stored in the modules’ memory and will be the default setting the next time the unit is powered up. 6.3.
This module is designed for communication type applications. The upper frequency limit is 4.5KHz and therefore not suitable for hi fidelity applications. 1.3 Audio DSP Noise cancellation. The bhi DSP processes the incoming audio signal and then differentiates the speech from the noise. The unwanted noise and interference is then attenuated to leave only the speech. The following diagrams are taken from actual audio signals and illustrate how the audio signal is being processed.
5. Troubleshooting 2. Module description 2.1 Module Layout. Start The following diagram shows the layout of the NEDSP1061-KBD module. Audio Distortion Overload LED Illuminates (P1) Yes Output level Overload LED Input level (P2) + + Keyboard PCB + Reduce Input Level using P2. No Reduce Output Level using P1.
2.3 Electrical characteristics. 4. Setup Electrical Characteristics Parameter Description V in Supply voltage Iin Supply current In Audio input signal Out Audio output signal (1.7 Xs input max) Min Typ Max Units 5 9 15 V 45 50 mA 50 300 Vrms 630 Vrms Table 1. NEDSP1061-KBD Electrical characeristics The levels come factory set to the maximum position. This should be adequate for most applications. However the module can be adjusted as follows.
connection (this screens the cable and acts as a mechanical fixing for the cable, protecting the capacitor pads). 3.3.2 Power connections. 5 - 15VDC (9V typically) is required to operate the module. The lower the voltage, the less heat the module will have to dissipate. Locate a convenient point to connect the power. Ensure that this point is connected after the power switch, otherwise the DSP module will be drawing power all the time, and may flatten the batteries (where fitted).
Audio source Pre-amp Volume Control Loudspeaker Audio Out (Blue) 3.2 Circuit location. The NEDSP1061-KBD module is inserted into the path of noisy audio. Using the input and output level controls allows the unit to appear transparent to the audio signal. Coupling Capacitor Audio In (Red) 3.1 Introduction. Before commencing installation study the equipment’s service manual/circuit diagram thoroughly to familiarise yourself with the circuit diagram and disassembly procedure.
