Danville Signal Processing DSP-8200d User manual

Danville Signal Processing, Inc.
DSP-8200d
Tone Suppression &
Noise Reduction System
Operating Manual
Version 2.1

Page 2
Danville Signal Processing, Inc.
DSP-8200d Tone Suppression & Noise Reduction System
Operating Manual
Copyright © 2001 by Danville Signal Processing, Inc. All rights reserved. Printed in
USA.
Under the copyright laws, this manual can’t be reproduced in any form without prior
written permission from Danville Signal Processing, Inc.
Danville Signal Processing, Inc. strives to deliver the best product to our customers.
As part of this goal, we are constantly trying to improve our products. Danville Signal
Processing, Inc., therefore, reserves the right to make changes to product specification
or documentation without prior notice.
This manual may contain errors, omissions or “typos.” Please send your comments,
suggestions and corrections to:
Danville Signal Processing, Inc.
38570 100th Avenue
Cannon Falls, MN 55009-5534
Contact Information
Danville Signal Processing, Inc.
38570 100th Avenue
Cannon Falls, MN 55009-5534
E-mail: [email protected]
Web Site: http://www.danvillesignal.com
Voice: 507-263-5854
Fax: [phone]

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Table of Contents
Digital Signal Processing ……………………………… 4
Overview …………………………………………………… 4
System Description ……………………………………... 5
Card Cage …………………………………………….. 5
Control Module ……………………………………... 6
DSP Modules ……………………………………... 6
Power Supply Modules ………………………………. 7
Cable Connections & Jumper Configurations …………... 8
Connectors …………………………………………….. 8
DSP Module Jumper Configuration …………………. 8
Mode ………………………………………….. 8
Squelch ……………………………………….. 9
Nominal Input Level ………………………... 9
Control Module Configuration ………….….………. 10
Jumper Configuration …………...………….…. 10
Cabling ……………………………………….. 10
Terminal Configuration …………...………….…. 10
Troubleshooting & Checkout……………………………..... 11
DSP Modules ………………………………………….. 11
Test Procedure - DSP Modules ……………………... 11
Power Supply………………………………………….. 12
Test Procedure - Power Supply ……………………... 12
Product Warranty…………………………………………..... 13
Appendix A…………………………………………………… 14
Typical FAA Installation ……………………………… 14

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Digital Signal Processing
Digital Signal Processing (DSP) is a powerful and complex method of analyzing and
modifying analog signals, such as speech. Speech signals have fairly well known and
predictable characteristics; however, these characteristics are quite complex.
By converting the analog signal to a digital signal, a digital signal processor with a special
program can analyze the characteristics of the analog signal. The digital signal processor
can then modify the digital signal to enhance the desired characteristics and to remove
undesirable characteristics such as noise or tones. The processed signal is converted back
to an analog signal and sent on to a speaker or headphone.
In radio noise, DSP is capable of reducing or eliminating broadband noise and tone
interference.
Overview
This manual describes the DSP-8200d tone suppression and noise reduction system.
The DSP-8200d removes heterodynes (tones) caused during multiple aircraft-to-aircraft
and multiple aircraft-to-controller communications. It also attenuates unwanted signaling
tones that may be inadvertently applied to normal monitoring channels. This tone reduc-
tion wipes out potential hearing-impairing test and interference tones in milliseconds.
The DSP-8200d also provides bandpass filtering from 300 to 3400 Hz (voice telephone
bandwidth).
The DSP-8200d uses advanced digital signal processing technology to implement algo-
rithms that perform three basic audio functions or modes:
• Bandpass filtering from 300 to 3400 Hz
• Tone suppression
• Random noise reduction
There are five configurations of the above modes available in the DSP-8200d. They
include:
• Bandpass filtering and tone suppression
• Bandpass filtering and noise reduction
• Bandpass filtering
• Ground to Ground tone suppression (404, 1004, 2713, 2804, 3200 Hz)
• None

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Overview Continued
The noise reduction functions of the DSP-8200d operate by examining a characteristic of
signals and noise called correlation, and dynamically filter out the undesired signals and
noise. The degree of correlation is relative. Random noise such as white noise or static is
uncorrelated. Speech is moderately correlated. Repetitive or continuous noise such as a
pure tone is highly correlated. The DSP-8200d combines these three basic functions to
reduce noise and interference and improve radio communication.
The DSP-8200d measures correlation and filters out signals and noise that are outside its
correlation thresholds. The amount of noise reduction varies according to the correlation
characteristics of the noise. Typical noise reduction ranges from 5 dB to 20 dB for
random noise and up to 50 dB for tones.
A squelch feature is also implemented in each mode. The DSP-8200d squelches silent
channels (no communication in progress) so that channel noise is very low. This feature
is particularly important when multiple channels are being monitored by the same
controller.
Should the need ever arise, each DSP module is field reprogrammable using an ordinary
notebook computer with an RS-232 serial interface.
System Description
The DSP-8200d consists of a 5-1/4 x 19 inch rack mounted card cage chassis, 12 plug-in
DSP modules, a Control module, and two redundant Power Supply modules.
Card Cage
The card cage chassis is built around Euro rack standards. Access to modules and cabling
is from the rear side of the chassis. Status LEDs are on the chassis front panel and
duplicated on each module.

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Control Module
The control module monitors each DSP module for proper operation. Through the use
of a computer interface, the Control Module offers three key functions for monitoring
and upgrading the DSP-8200d.
They include:
• Fault Detection
• Diagnostics
• Reprogrammability
In the event of a DSP module failure, an audible alarm will alert the operator that a
problem has occurred. To assist in identifying the failed module, the heartbeat indicator
will blink at 4 times the normal rate. In addition, the BNC connector will go into fault
position.
A relay switch closure output (BNC connector) is provided which will indicate if power
has been lost to the DSP-8200d as well as an individual module failure. This output may
be configured (via shorting jumper) as either normally open or normally closed.
Operators can connect the DSP-8200d to a standard terminal program using a RS-232
or USB cable. One such common terminal program that is included in all Windows
Operating Systems since Windows 95 is HyperTerminal.
To access the Control Module using HyperTerminal, hook up the terminal program and
hit the ‘Esc’ key. To access a list of commands available, press the ‘?’ key. While many of
the commands are specific to programming and updating, two commands will be useful
for system status and diagnostic purposes. They include:
‘A’ Command - reports jumper settings of each individual module
‘S’ Command - reports overall system settings, including Power Supply voltages
Please contact the factory for assistance in any other updating or reprogramming needs.
DSP Modules
Each DSP module has signal processing for two audio channels. Overload and Normal
Level indicators are provided for each channel. A Heartbeat Status LED flashes at a
one-second interval to show proper operation. The input and output audio interface
are balanced 600 ohm lines with audio transformers. A watchdog timer monitors circuit
operation and will reset each the module in the event of program failure. To insure
that audio is never interrupted, each audio channel is passively relay bypassed when
the unit is unpowered.

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DSP modules are hot swappable. This means that the individual modules may be
inserted or exchanged without powering down the cardcage and disrupting adjacent
circuits.
DSP-8200d DSP Module
(Actual Size)
Power Supply Modules
Each card cage has two power supply modules for redundant operation. Each power
supply module is fully capable of supplying all of the necessary power to operate all
the modules. If one of the power supply modules fail, the card cage will continue to
operate.
Each power supply module is supplied with a 5x20mm DIN 1A fuse. The power supply
modules can be configured for either 115V or 230V operation. Individual IEC320
connectors and matching cordsets are provided for each power supply module.
DSP-8200d
Overload
Normal
Overload
Normal
Heartbeat
B
A
B
A

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Cable Connections & Jumper Configurations
RJ-45 Connector
Audio In - Pin 1 & 2 (600 Ohm Balanced)
Audio Out - Pin 3 & 6 (600 Ohm Balanced)
Ground - Pin 8
Reserved - Pins 4,5,7 (leave open)
Note: These connections are the same as
Ethernet 10BaseT; off-the-shelf
Cat 5 cables may be used.
DSP Module Jumper Configuration (JH1)
Mode* Jumper
3 2 1
Tone Reduction Off Off Off
Noise Reduction Off Off On
Bandpass Only Off On Off
Reserved Off On On
Reserved On Off Off
Ground/Ground tones - Narrow BW On Off On
Ground/Ground tones - Wide BW On On Off
Bypass On On On
Notes:
* 300-3400 Hz Bandpass in all Modes
except Bypass
WARNING:
DO NOT USE TONE REDUCTION FOR GUARD
FREQUENCIES 121.5 MHz AND 243.0 MHz. YOU MUST USE
BANDPASS MODE ONLY FOR THESE FREQUENCIES.

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DSP Module Jumper Configuration Continued
Squelch Jumper
4
Squelch Enabled Off
Squelch Disabled On
Nominal Input Level Jumper
8 7 6 5
- 8.0 dBm Off Off Off Off
Reserved Off Off Off On
Reserved Off Off On Off
Reserved Off Off On On
- 2.0 dBm Off On Off Off
- 3.5 dBm Off On Off On
- 5.0 dBm Off On On Off
- 6.5 dBm Off On On On
- 8.0 dBm On Off Off Off
- 9.5 dBm On Off Off On
- 11.0 dBm On Off On Off
- 12.5 dBm On Off On On
- 14.0 dBm On On Off Off
- 15.5 dBm On On Off On
- 17.0 dBm On On On Off
- 18.5 dBm On On On On
Notes:
Factory Default is -8.0 dBm setting
Changes take effect only after Power on Reset
The nominal input level adjustment is used to optimize the performance of the signal
processing algorithms and to maximize signal to noise without overload. Input/output
gain is constant for all settings. The squelch threshold is approximately 24dB below
the nominal input level.
When the DSP-8200d is properly configured, the yellow (normal) led will be on and the
red (overload) led will flash occassionally.

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Control Module Jumper Configuration
A 3-pin header (JH1) configures the relay switch closure. This header is located near the
front panel just behind the BNC connector.
If a system failure occurs, the switch closure is open when the shorting jumper is in
the NC position.
If a system failure occurs, the switch closure is closed when the shorting jumper is in
the NO position.
The factory default position is NC (closed during normal operation and open during
a failure).
Control Module Cables
The Control Module may be connected to a computer using either a RS-232 connec-
tion or a USB connection.
A standard DB9F to DB9M cable with no twists is used for the RS-232 connection.
A standard USB cable with a B connector on the Control Module side is used for a USB
connection. Consult the factory for USB device drivers.
Terminal Configuration
Port Settings should be set as listed:
Bits per second: 38400
Data bits: 8
Parity: None
Stop bits: 1
Flow control: None

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Troubleshooting & Checkout
DSP Modules
The DSP-8200d signal processing modules require no adjustments or calibration. All
signal processing functions are performed within the DSP processor.
The tone suppression and noise reduction modes of the DSP-8200d do not easily
lend themselves to traditional measurement techniques. These algorithms have been
designed for human speech and interfering noise or tones. As such, these algorithms
modify themselves dynamically with changing speech or noise conditions.
The easiest method to verify correct operation of a DSP-8200d module is to reconfigure
the mode to bandpass. Since all signal processing functions are performed exclusively
by mathematical calculation, a DSP-8200d module that passes this test will also operate
correctly in the other operating modes.
WARNING:
THIS PROCEDURE SHOULD NEVER BE PERFORMED IN AN
OPERATING COMMUNICATION CHANNEL!
IT IS INTENDED FOR OUT-OF-CIRCUIT TESTING ONLY.
TEST TONES WILL PASS THROUGH THE DSP
MODULE IN THIS TEST!!
Test Procedure - DSP Module
1. Remove the DSP module from the card cage and reconfigure the mode to bandpass.
2. Reinstall the DSP module in an off-line, unpowered DSP-8200d card cage.
3. Apply a signal to the input of each DSP channel. The signal should be passively
bypassed by a mechanical relay and therefore identical at the output of each
channel. If this test fails, it is an indication of a bad relay on the DSP module or a
connector/cabling problem.
c

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Troubleshooting & Checkout Continued
4. Apply power to the DSP-8200d card cage. The normal and overload LEDs will flash
alternately during the power up stage and the heartbeat will begin the pulse at a
one-second rate. The DSP card cage control module alarm will go off.
5. Apply a 1000 Hz sine wave to each input and adjust the level so that the yellow
(normal) led is on and the red (overload) led is off. The output will be slightly higher
than the input when loaded into 600 ohms.
6. Vary the input frequency from 100 Hz to 5000 Hz. The signal will attenuate
outside of a 300-3400 Hz bandwidth. If it does not, it indicates that the signal is
being bypassed by the relay. An open transistor or defective relay could cause this
symptom.
7. If the DSP module passes these tests, reconfigure the mode to the desired operating
configuration.
Power Supply Modules
Each power supply module consists of an unregulated linear supply and a low noise 5.3
volt switching regulator. Diode rectifiers on the back plane of the card cage isolate each
power supply module from the other.
Test Procedure - Power Supply
1. Remove the power supply module from the card cage.
2. Apply power via the IEC power connector. Remember 110 Volt or 230 Volt AC is
present on the circuit traces.
3. Verify that the green led is lit. If the led is off, check the 1 Amp fuse.
4. Typical output voltages (unloaded).
Row (pins a,b,c of DIN connector)
7,8 GND
10 +5.3 Vdc (Digital)
11 +15 Vdc (Analog)
12 -15 Vdc (Analog)

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Product Warranty
Danville Signal Processing, Inc. products carry the following warranty:
Danville Signal Processing products are warranted against defects in materials and
workmanship. If Danville Signal Processing receives notice of such defects during the
warranty period, Danville Signal Processing shall, at its option, either repair or replace
hardware products which prove to be defective.
Danville Signal Processing software and firmware products which are designated by
Danville Signal Processing for use with a hardware products are warranted not to fail to
execute their programming instructions due to defects in materials and workmanship.
If Danville Signal Processing receives notice of such defects during the warranty period,
Danville Signal Processing shall, at its option, either repair or replace software media
or firmware which do not execute their programming instructions due to such defects.
Danville Signal Processing does not warrant that operation of the software, firmware, or
hardware shall be uninterrupted or error free.
The warranty period for each product is one year from date of installation.
Limitation of Warranty:
The forgoing warranty shall not apply to defects resulting from:
• Improper or inadequate maintenance by the Buyer;
• Buyer-supplied software or interfacing;
• Unauthorized modification or misuse;
• Operation outside the environmental specification of the product;
• Improper site preparation and maintenance.
Exclusive Remedies:
The remedies provided herein are the Buyer’s sole and exclusive remedies. In no event
shall Danville Signal Processing, Inc. be liable for direct, indirect, special, incidental or
consequential damages (including loss of profits) whether based on contract, tort, or
any other legal theory.

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Appendix A
Typical FAA Installation:
The DSP-8200d is useful in many FAA applications. Each module can be configured for
tone suppression or broadband noise reduction.
Tone suppression prevents loud signaling tones from reaching air traffic controllers and
eliminates or reduces naturally occurring heterodynes between air traffic control and
multiple airplanes.
Noise reduction is useful in applications where channel signal to noise is poor and may
be used to enhance intelligibility and reduce listener fatigue.
The DSP-8200d is installed prior to controller switching equipment in the receive audio
chain and does not require any FAA equipment modification.
Application sites may include FAA Control Centers, Automatic Flight Service Stations,
TRACONs, Control Towers, and Flight Service Stations.
Receive Audio
RCE ZDSP-8200d
Receive Audio
ZVSCS
ICSS
8165