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Summary of Contents for BHI NEDSP1068-PCBA
- Page 1 Ltd PO Box 318, Burgess Hill, RH15 9NR England. Tel: +44 (0)1444 870333 Fax: +44 (0)845 217 9936 info@bhi-ltd.com, www.bhi-ltd.com NEDSP1068-PCBA NEDSP1068-PCBA-MIC DSP Noise Cancelling Modules With AGC action Preamplifier & on-board mic option Document: HBA09-001-70 Issue: 7 Date: 20-08-2012...
- Page 2 HBA09-001-70 HB-NEDSP1068 INDEX 1. Introduction 2. Basic Specifications 3. Installation 4. External Overload Indicator 5. Use with On-board Microphone 6. External Microphones or signals 6.1.1. Connecting and external Microphone Capsule or signal 6.1.2. Dynamic Microphones 6.1.3. Condenser Electret 6.1.4. External Signal Sources 6.1.5.
- Page 3 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.
- Page 4 Use of a personal grounding strap and static dissipative mat is recommended. The NEDSP1068-PCBA module can be used two ways. One is to treat it as a sub- assembly board and mount it directly to a mother board assembly using 0.1” pitch PCB Header pins.
- Page 5 HBA09-001-70 HB-NEDSP1068 6.1.1 Connecting an external microphone capsule or line signal Locate and identify the jumper J4 (see diagram in appendix A). See the table below for the correct connections for the different types of microphone. Pin Designation Operation I or In External Microphone External Microphone or low level audio input...
- Page 6 HBA09-001-70 HB-NEDSP1068 6.1.5 Using External Line Level Sources Both NEDSP1068 module versions have the same pin-outs for the noise cancellation level, power and audio in/out. To input a signal source that bypasses the Preamp/AGC signal, connect to pin 9 of J2, with the ground connected either to the MIC Ground or to the J2 Pin 7.
- Page 7 HBA09-001-70 HB-NEDSP1068 Disabling the AGC Action For certain applications the AGC system may need to be disabled such that the pre- amplifier is not limited in any way. To disable the AGC circuit, locate and remove R16 on the underside of the 1068 PCB as shown below. If the AGC system is disabled the user should be aware that too higher gain setting could give rise to overdriving of the DSP device, which may then cause it to malfunction.
- Page 8 HBA09-001-70 HB-NEDSP1068 Check to make sure that the audio is clear and distortion free. If there seems to be some spitting or distortion heard under sudden loud noises, then consider adjusting P2 (Audio in) again, counter clockwise very slightly and re-check under the same conditions.
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Page 9: Appendix A - Block Schematic And Pcb Outline
HBA09-001-70 HB-NEDSP1068 Appendix A – Block Schematic and PCB outline... - Page 10 HBA09-001-70 HB-NEDSP1068 PCB outline showing top side of PCB and user link pads R7 may be found on the reverse side of this PCB as shown opposite. On-Board microphone R7 location...
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Page 11: Appendix B - Connections And Jumper Settings
HBA09-001-70 HB-NEDSP1068 Appendix B - Connections and Jumper settings J2 – General Input/Output Port Pin Designation Operation Noise Cancelling level Selected when High, weak pull up Bit ‘1’ applied Noise Cancelling level Selected when High, weak pull up Bit ‘2’ applied Noise Cancelling level Selected when High, weak pull up... - Page 12 HBA09-001-70 HB-NEDSP1068 Internal Microphone to Pre-amplifier Routing Solder the ‘MIC’ Jumper, note: that this has to be removed for any external microphone use. Pre-amplifier to DSP Routing – Solder the ‘PRE’ Jumper, note that this has to be removed for any LINE level signal input to the DSP device. DSP Level Settings Level X –...
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Page 13: Appendix C - Pcb Dimensioned Drawing
HBA09-001-70 HB-NEDSP1068 Appendix C - PCB Dimensioned drawing...
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