Orban 8400 Service manual
Operating Manual
OPTIMOD
8400
Digital Audio Processor
Manual for Version 3.0 and Higher Software
IMPORTANT NOTE: Refer to the unit’s rear panel for your Model #.
Model Number: Description:
8400 OPTIMOD 8400, Stereo Encoder, Digital I/O, Protec-
tion Structure, Two-Band Structure, Multi-Band Structure, 115V (for 90-130V operation) or 230V (for 200250V operation), switchable to 50µs or 75µs.
8400HD FM OPTIMOD 8400HD FM, Stereo Encoder, Digital I/O,
Digital Radio and Internet Streaming Processing, Protection Structure, Two-Band Structure, Multi-Band
Structure, 115V (for 90-130V operation) or 230V (for
200-250V operation), switchable to 50µs or 75µs.
MANUAL:
Part Number: Description:
96107-300-01 8400 Operating Manual
CAUTION:
NO USER SERVICEABLE PARTS INSIDE. REFER SERVICING TO QUALIFIED SERVICE PERSONNEL.
WARNING: TO REDUCE THE RISK OF FIRE OR ELECTRICAL SHOCK,
DO NOT EXPOSE THIS APPLIANCE TO RAIN OR MOISTURE.
TO REDUCE THE RISK OF ELECTRICAL SHOCK, DO NOT REMOVE COVER (OR BACK).
This symbol, wherever it appears, alerts you to
the presence of uninsulated dangerous voltage
inside the enclosure voltage that may be
sufficient to constitute a risk of shock.
This symbol, wherever it appears, alerts you to important
operating and maintenance instructions in the accompanying literature. Read the manual.
All the safety and operating instructions should be read before the appliance is operated.
Retain Instructions: The safety and operation instructions should be retained for future reference.
Heed Warnings: All warnings on the appliance and in the operating instructions should be adhered to.
Follow Instructions: All operation and user instructions should be followed.
IMPORTANT SAFETY INSTRUCTIONS
Water and Moisture: The appliance should not be used near water (e.g., near a bathtub, washbowl, kitchen sink, laundry tub, in a wet base-
ment, or near a swimming pool, etc.).
Ventilation: The appliance should be situated so that its location or position does not interfere with its proper ventilation. For example, the appli-
ance should not be situated on a bed, sofa, rug, or similar surface that may block the ventilation openings; or, placed in a built-in installation, such as a
bookcase or cabinet that may impede the flow of air through the ventilation openings.
Heat: The appliance should be situated away from heat sources such as radiators, heat registers, stoves, or other appliances (including amplifiers)
that produce heat.
Power Sources: The appliance should be connected to a power supply only of the type described in the operating instructions or as marked on
the appliance.
Grounding or Polarization: Precautions should be taken so that the grounding or polarization means of an appliance is not defeated.
Power-Cord Protection: Power-supply cords should be routed so that they are not likely to be walked on or pinched by items placed upon or
against them, paying particular attention to cords at plugs, convenience receptacles, and the point where they exit from the appliance.
Cleaning: The appliance should be cleaned only as recommended by the manufacturer.
Non-Use Periods: The power cord of the appliance should be unplugged from the outlet when left unused for a long period of time.
Object and Liquid Entry: Care should be taken so that objects do not fall and liquids are not spilled into the enclosure through openings.
Damage Requiring Service: The appliance should be serviced by qualified service personnel when:
The power supply cord or the plug has been damaged; or
Objects have fallen, or liquid has been spilled into the appliance; or
The appliance has been exposed to rain; or
The appliance does not appear to operate normally or exhibits a marked change in performance; or
The appliance has been dropped, or the enclosure damaged.
Servicing: The user should not attempt to service the appliance beyond that described in the operating instructions. All other servicing should be
referred to qualified service personnel.
The Appliance should be used only with a cart or stand that is recommended by the manufacturer.
Safety Instructions (European)
Notice For U.K. Customers If Your Unit Is Equipped With A Power Cord.
WARNING: THIS APPLIANCE MUST BE EARTHED.
The cores in the mains lead are coloured in accordance with the following code:
GREEN and YELLOW - Earth BLUE - Neutral BROWN - Live
As colours of the cores in the mains lead of this appliance may not correspond with the coloured markings identifying the terminals in your plug, proceed as follows:
The core which is coloured green and yellow must be connected to the terminal in the plug marked with the letter E, or with the earth symbol, or coloured green, or green and yellow.
The core which is coloured blue must be connected to the terminal marked N or coloured black.
The core which is coloured brown must be connected to the terminal marked L or coloured red.
The power cord is terminated in a CEE7/7 plug (Continental Europe). The green/yellow wire is connected directly to the unit's chassis. If you need to change the plug and
if you are qualified to do so, refer to the table below.
WARNING: If the ground is defeated, certain fault conditions in the unit or in the system to which it is connected can result in full line voltage between chassis and earth
ground. Severe injury or death can then result if the chassis and earth ground are touched simultaneously.
Conductor WIRE COLOR
L LIVE BROWN BLACK
N NEUTRAL BLUE WHITE
E EARTH GND GREEN-YELLOW GREEN
Normal Alt
AC Power Cord Color Coding
Safety Instructions (German)
Gerät nur an der am Leistungsschild vermerkten Spannung und Stromart betreiben.
Sicherungen nur durch solche, gleicher Stromstärke und gleichen Abschaltverhaltens ersetzen. Sicherungen nie überbrücken.
Jedwede Beschädigung des Netzkabels vermeiden. Netzkabel nicht knicken oder quetschen. Beim Abziehen des Netzkabels den
Stecker und nicht das Kabel enfassen. Beschädigte Netzkabel sofort auswechseln.
Gerät und Netzkabel keinen übertriebenen mechanischen Beaspruchungen aussetzen.
Um Berührung gefährlicher elektrischer Spannungen zu vermeiden, darf das Gerät nicht geöffnet werden. Im Fall von Betriebsstörungen darf das Gerät nur Von befugten Servicestellen instandgesetzt werden. Im Gerät befinden sich keine, durch den Benutzer
reparierbare Teile.
Zur Vermeidung von elektrischen Schlägen und Feuer ist das Gerät vor Nässe zu schützen. Eindringen von Feuchtigkeit und
Flüssigkeiten in das Gerät vermeiden.
Bei Betriebsstörungen bzw. nach Eindringen von Flüssigkeiten oder anderen Gegenständen, das Gerät sofort vom Netz trennen und
eine qualifizierte Servicestelle kontaktieren.
Safety Instructions (French)
On s'assurera toujours que la tension et la nature du courant utilisé correspondent bien à ceux indiqués sur la plaque de l'appareil.
N'utiliser que des fusibles de même intensité et du même principe de mise hors circuit que les fusibles d'origine. Ne jamais
shunter les fusibles.
Eviter tout ce qui risque d'endommager le câble seceur. On ne devra ni le plier, ni l'aplatir. Lorsqu'on débranche l'appareil,
tirer la fiche et non le câble. Si un câble est endommagé, le remplacer immédiatement.
Ne jamais exposer l'appareil ou le câble ä une contrainte mécanique excessive.
Pour éviter tout contact averc une tension électrique dangereuse, on n'oouvrira jamais l'appareil. En cas de dysfonctionnement,
l'appareil ne peut être réparé que dans un atelier autorisé. Aucun élément de cet appareil ne peut être réparé par l'utilisateur.
Pour éviter les risques de décharge électrique et d'incendie, protéger l'appareil de l'humidité. Eviter toute pénétration
d'humidité ou fr liquide dans l'appareil.
En cas de dysfonctionnement ou si un liquide ou tout autre objet a pénétré dans l'appareil couper aussitôt l'appareil
de son alimentation et s'adresser à un point de service aprésvente autorisé.
Safety Instructions (Spanish)
Hacer funcionar el aparato sólo con la tensión y clase de corriente señaladas en la placa indicadora de características.
Reemplazar los fusibles sólo por otros de la misma intensidad de corriente y sistema de desconexión. No poner nunca los fusibles en
puente.
Proteger el cable de alimentación contra toda clase de daños. No doblar o apretar el cable. Al desenchufar, asir el enchufe y no el
cable. Sustituir inmediatamente cables dañados.
No someter el aparato y el cable de alimentación a esfuerzo mecánico excesivo.
Para evitar el contacto con tensiones eléctricas peligrosas, el aparato no debe abrirse. En caso de producirse fallos de funcionamiento,
debe ser reparado sólo por talleres de servicio autorizados. En el aparato no se encuentra ninguna pieza que pudiera ser reparada por
el usuario.
Para evitar descargas eléctricas e incendios, el aparato debe protegerse contra la humedad, impidiendo que penetren ésta o líquidos
en el mismo.
En caso de producirse fallas de funcionamiento como consecuencia de la penetración de líquidos u otros objetos en el aparato,
hay que desconectarlo inmediatamente de la red y ponerse en contacto con un taller de servicio autorizado.
Safety Instructions (Italian)
Far funzionare l'apparecchio solo con la tensione e il tipo di corrente indicati sulla targa riportante i dati sulle prestazioni.
Sostituire i dispositivi di protezione (valvole, fusibili ecc.) solo con dispositivi aventi lo stesso amperaggio e lo stesso comportamento
di interruzione. Non cavallottare mai i dispositivi di protezione.
Evitare qualsiasi danno al cavo di collegamento alla rete. Non piegare o schiacciare il cavo. Per staccare il cavo, tirare la presa e mai
il cavo. Sostituire subito i cavi danneggiati.
Non esporre l'apparecchio e il cavo ad esagerate sollecitazioni meccaniche.
Per evitare il contatto con le tensioni elettriche pericolose, l'apparecchio non deve venir aperto. In caso di anomalie di funzionamento
l'apparecchio deve venir riparato solo da centri di servizio autorizzati. Nell'apparecchio non si trovano parti che possano essere riparate
dall'utente.
Per evitare scosse elettriche o incendi, l'apparecchio va protetto dall'umidità. Evitare che umidità o liquidi entrino nell'apparecchio.
In caso di anomalie di funzionamento rispettivamente dopo la penetrazione di liquidi o oggetti nell'apparecchio, staccare immediatamente
l'apparecchio dalla rete e contattare un centro di servizio qualificato.
PLEASE READ BEFORE PROCEEDING!
Manual
The Operating Manual contains instructions to verify the proper operation of this unit and initialization of certain
options. You will find these operations are most conveniently performed on the bench before you install the unit
in the rack.
Please review the Manual, especially the installation section, before unpacking the unit.
Trial Period Precautions
If your unit has been provided on a trial basis:
You should observe the following precautions to avoid reconditioning charges in case you later wish to return
the unit to your dealer.
Note the packing technique and save all packing materials. It is not wise to ship in other than the factory carton.
(Replacements cost $35.00).
(1) Avoid scratching the paint or plating. Set the unit on soft, clean surfaces.
(2) Do not cut the grounding pin from the line cord.
(3) Use care and proper tools in removing and tightening screws to avoid burring the heads.
(4) Use the nylon-washered rack screws supplied, if possible, to avoid damaging the panel. Support the unit
when tightening the screws so that the threads do not scrape the paint inside the slotted holes.
Packing
When you pack the unit for shipping:
(1) Tighten all screws on any barrier strip(s) so the screws do not fall out from vibration.
(2) Wrap the unit in its original plastic bag to avoid abrading the paint.
(3) Seal the inner and outer cartons with tape.
If you are returning the unit permanently (for credit), be sure to enclose:
• The Manual(s)
• The Registration/Warranty Card
• The Line Cord
• All Miscellaneous Hardware (including the Rack Screws and Keys)
• The Extender Card (if applicable)
• The Monitor Rolloff Filter(s) (OPTIMOD-AM only)
• The COAX Connecting Cable (OPTIMOD-FM and OPTIMOD-TV only)
Your dealer may charge you for any missing items.
If you are returning a unit for repair, do not enclose any of the above items.
Further advice on proper packing and shipping is included in the Manual (see Table of Contents).
Trouble
If you have problems with installation or operation:
(1) Check everything you have done so far against the instructions in the Manual. The information contained
therein is based on our years of experience with OPTIMOD and broadcast stations.
(2) Check the other sections of the Manual (consult the Table of Contents and Index) to see if there might be
some suggestions regarding your problem.
(3) After reading the section on Factory Assistance, you may call Orban Customer Service for advice during
normal California business hours. The number is (1) 510/351-3500.
Operating Manual
OPTIMOD
8400
Digital Audio Processor
This equipment generates, uses, and can radiate radio-frequency energy. If it is not
installed and used as directed by this manual, it may cause interference to radio
communication. This equipment complies with the limits for a Class A computing
device, as specified by FCC Rules, Part 15, subject J, which are designed to provide reasonable protection against such interference when this type of equipment
is operated in a commercial environment. Operation of this equipment in a residential area is likely to cause interference. If it does, the user will be required to eliminate the interference at the user’s expense.
WARNING
This digital apparatus does not exceed the Class A limits for radio noise emissions
from digital apparatus set out in the radio Interference Regulations of the Canadian
Department of Communications. (Le present appareil numerique n’emet pas de
bruits radioelectriques depassant les limites applicables aux appareils numeriques
(de las class A) prescrites dans le Reglement sur le brouillage radioelectrique
edicte par le ministere des Communications du Canada.)
WARNING
OPTIMOD 8400 is protected by U.S. patents 4,208,548; 4,460,871; 5,737,434; 6,337,999; 6,434,241. Other
patents pending.
Orban is a registered trademark.
All trademarks are property of their respective companies.
This manual is part number 96107-300-01
Perform the installation under static control conditions. Simply walking across a rug
can generate a static charge of 20,000 volts. This is the spark or shock you may
have felt when touching a doorknob or some other conductive item. A much
smaller static discharge is likely to completely destroy one or more of the CMOS
semiconductors employed in OPTIMOD-FM. Static damage will not be covered
under warranty.
There are many common sources of static. Most involve some type of friction between two dissimilar materials. Some examples are combing your hair, sliding
across a seat cover or rolling a cart across the floor. Since the threshold of human
perception for a static discharge is 3000, many damaging discharges will not even
be noticed.
Basic damage prevention consists of minimizing generation, discharging any accumulated static charge on your body or work station and preventing that discharge
from being sent to or through an electronic component. A static grounding strap
(grounded through a protective resistor) and a static safe workbench with a conductive surface should be used. This will prevent any buildup of damaging static.
© Copyright 2002 Orban
IMPORTANT
1525 ALVARADO STREET, SAN LEANDRO, CA 94577 USA
Phone: (1) 510/351-3500; Fax: (1) 510/351-0500; E-Mail: custserv@orban.com; Site: www.orban.com
P/N: 96107-300-01
Table of Contents
8400
OPTIMOD-FM DIGITAL AUDIO PROCESSOR....................................................................1-2
User-Friendly Interface ........................................................................................................1-3
Absolute Control of Peak Modulation ..................................................................................1-3
Flexible Configuration..........................................................................................................1-4
Adaptability through Multiple Audio Processing Structures................................................1-4
Controllable..........................................................................................................................1-5
RESETS IN OPTIMOD-FM.......................................................................................................1-6
P
Factory Presets.....................................................................................................................1-6
User Presets..........................................................................................................................1-6
NPUT/OUTPUT CONFIGURATION................................................................................................1-6
I
Digital AES/EBU Left/Right Input/Output............................................................................1-7
Analog Left/Right Input/Output ............................................................................................1-7
Stereo Analog Baseband Composite Output.........................................................................1-8
Subcarriers ...........................................................................................................................1-8
Remote Control Interface .....................................................................................................1-8
Computer Interface...............................................................................................................1-9
OCATION OF OPTIMOD-FM .................................................................................................1-10
L
Optimal Control of Peak Modulation Levels......................................................................1-10
Best Location for OPTIMOD-FM ......................................................................................1-11
TUDIO-TRANSMITTER LINK....................................................................................................1-13
S
Transmission from Studio to Transmitter ...........................................................................1-13
Using the Orban 8100AST (or 8100A/ST) Studio Chassis with the 8400 ..........................1-16
STL and Exciter Overshoot.................................................................................................1-16
SING LOSSY DATA REDUCTION IN THE STUDIO .....................................................................1-17
U
BOUT TRANSMISSION LEVELS AND METERING ......................................................................1-17
A
Meters .................................................................................................................................1-17
Studio Line-up Levels and Headroom ................................................................................1-18
Fig. 1-1: Absolute Peak Level, VU and PPM Reading ................................................................. 1-18
Transmission Levels ...........................................................................................................1-19
INE-UP FACILITIES .................................................................................................................1-19
L
Metering of Levels ..............................................................................................................1-19
ONITORING ON LOUDSPEAKERS AND HEADPHONES ..............................................................1-20
M
TEST ................................................................................................................................1-22
EAS
ARRANTY, FEEDBACK...........................................................................................................1-23
W
User Feedback Form ..........................................................................................................1-23
NSTALLING THE 8400................................................................................................................2-2
I
Fig. 2-1: AC Line Cord Wire Standard).......................................................................................... 2-3
Fig. 2-2: Wiring the 25-pin Remote Interface Connector................................................................ 2-5
8400 REAR PANEL .....................................................................................................................2-6
UDIO INPUT AND OUTPUT CONNECTIONS ................................................................................2-7
A
Cable.....................................................................................................................................2-7
Connectors............................................................................................................................2-7
Analog Audio Input...............................................................................................................2-7
Analog Audio Output............................................................................................................2-8
AES/EBU
OMPOSITE OUTPUT AND SUBCARRIER INPUT ...........................................................................2-9
C
GROUNDING .............................................................................................................................2-11
DIGITAL INPUT AND OUTPUT ....................................................................................2-8
Fig. 2-3: Separation vs. load capacitance for 8400 and Orban stereo encoders using 8200-style line
driver (8200, 2200, 8208, and 8218). Test frequency = 15 kHz.................................................... 2-10
Power Ground ....................................................................................................................2-11
Circuit Ground ...................................................................................................................2-12
8400 FRONT PANEL ................................................................................................................. 2-12
NSTALLATION OF STUDIO LEVEL CONTROLLER (OPTIONAL) .................................................. 2-14
I
If you are using Orban 8200ST-Studio Chassis................................................................. 2-14
Fig. 2-4: 8200ST Jumper Settings (*Factory Configuration) ........................................................2-15
If you are using Orban 464A Co-Operator........................................................................ 2-17
Fig. 2-5: 464A Jumper Settings ..................................................................................................... 2-17
If you are using an Orban 4000 Transmission Limiter...................................................... 2-19
Fig. 2-6: 4000 Jumper Locations ................................................................................................... 2-20
Fig. 2-7: 4000 HF Limiter Jumpers ...............................................................................................2-20
Fig. 2-8: 4000 Pre-Emphasis Jumpers ...........................................................................................2-21
Fig. 2-9: 4000 Pre-Emphasis Jumpers ...........................................................................................2-21
Fig. 2-10: 4000 Stereo Coupling Jumpers .....................................................................................2-21
QUICK SETUP........................................................................................................................... 2-23
NALOG AND DIGITAL I/O SETUP ........................................................................................... 2-30
A
SING CLOCK-BASED AUTOMATION....................................................................................... 2-39
U
ECURITY AND PASSCODE PROGRAMMING.............................................................................. 2-40
S
To Unlock the Front Panel................................................................................................. 2-42
8400 User Interface Behavior during Lockout .................................................................. 2-43
Default ADMIN Passcode.................................................................................................. 2-43
Security and Orban’s PC Remote Application................................................................... 2-44
Doing a Software Update to an 8400 with Version 2.1 or Higher Already Installed:....... 2-44
If you have forgotten your “All Screens” passcode… .......................................................2-45
DMINISTERING THE 8400 THROUGH SERIAL PORT #2 ............................................................ 2-46
A
Connecting to the 8400 via a Terminal Program on a PC ................................................ 2-47
Administrative Operations ................................................................................................. 2-48
Diagnostic Operations ....................................................................................................... 2-51
EMOTE CONTROL INTERFACE PROGRAMMING ...................................................................... 2-51
R
ETWORKING ..........................................................................................................................2-52
N
ETTING UP AN 8400 MEMORY CARD ..................................................................................... 2-55
S
NSTALLING 8400 PC REMOTE CONTROL SOFTWARE.............................................................. 2-56
I
Installing the Necessary Windows Services ....................................................................... 2-56
Check Hardware Requirements ......................................................................................... 2-57
Running the Orban Installer Application........................................................................... 2-58
BOUT 8400/PD...................................................................................................................... 2-59
A
BOUT 8400HD ...................................................................................................................... 2-60
A
Delay Difference between Digital-Channel and FM Outputs............................................ 2-61
HD I/O Setup Controls....................................................................................................... 2-62
HD Audio Controls ............................................................................................................2-64
FRONT PANEL ................................................................................................................... 3-2
8400
NTRODUCTION TO PROCESSING ................................................................................................ 3-3
I
Some Audio Processing Concepts........................................................................................ 3-3
Distortion in Processing ...................................................................................................... 3-4
Loudness and Distortion ...................................................................................................... 3-4
OPTIMOD-FM—from Bach to Rock ................................................................................... 3-5
Fundamental Requirements: High-Quality Source Material and Accurate Monitoring ..... 3-5
BOUT THE 8400’S SIGNAL PROCESSING FEATURES ................................................................. 3-6
A
Dual-Mono Architecture ...................................................................................................... 3-6
Signal Flow .......................................................................................................................... 3-6
ITU-R 412 Compliance ...................................................................................................... 3-11
Two-Band Purist Processing ............................................................................................. 3-12
Digital Radio Processing ................................................................................................... 3-12
Input/Output Delay ............................................................................................................ 3-13
Summary ............................................................................................................................ 3-13
USTOMIZING THE 8400’S SOUND........................................................................................... 3-13
C
Basic Modify ...................................................................................................................... 3-14
Intermediate Modify........................................................................................................... 3-15
Advanced Modify ................................................................................................................3-15
Gain Reduction Metering ...................................................................................................3-16
BOUT THE PROCESSING STRUCTURES ....................................................................................3-16
A
ACTORY PROGRAMMING PRESETS..........................................................................................3-17
F
Factory Programming Presets ...........................................................................................3-17
Table 3-1: Factory Programming Presets...................................................................................... 3-19
EQUALIZER CONTROLS ............................................................................................................3-24
Table 3-2: Five-Band Equalization Controls................................................................................. 3-24
STEREO ENHANCER CONTROLS................................................................................................3-28
Table 3-3: Stereo Enhancer Controls ............................................................................................ 3-29
AGC CONTROLS ......................................................................................................................3-30
Table 3-4: AGC Controls .............................................................................................................. 3-30
Advanced AGC Controls ....................................................................................................3-33
LIPPER CONTROLS .................................................................................................................3-35
C
Table 3-5: Clipper Controls........................................................................................................... 3-36
Fig. 3-1: 0-100 kHz Baseband Spectrum (Loud-Hot preset)......................................................... 3-39
Fig. 3-2: 19 kHz Pilot Notch Filter Spectrum (Loud-Hot preset; detail)....................................... 3-39
Advanced Clipper Controls ................................................................................................3-40
HE TWO-BAND STRUCTURE ...................................................................................................3-41
T
The Protection Presets........................................................................................................3-41
Setting Up the Two-Band Structure for Classical Music....................................................3-41
Customizing the Settings.....................................................................................................3-43
The Two-Band Structure’s Full Setup Controls .................................................................3-43
Table 3-6: Two-Band Controls...................................................................................................... 3-43
Advanced Two-Band Controls............................................................................................3-46
HE FIVE-BAND STRUCTURE ...................................................................................................3-47
T
Putting the Five-Band Structure on the Air........................................................................3-47
Customizing the Settings.....................................................................................................3-48
The Five-Band Structure’s Full Setup Controls .................................................................3-48
Table 3-7: Multiband Controls...................................................................................................... 3-48
Table 3-8: MB Attack/Release Controls ....................................................................................... 3-49
Table 3-9: MB Band Mix Controls ............................................................................................... 3-49
Advanced Multiband and Band Mix Controls ....................................................................3-54
MULTIPLEX POWER CONTROLLER ................................................................................3-57
ITU-R
EST MODES ............................................................................................................................3-59
T
Table 3-10: Test Modes ................................................................................................................ 3-59
GETTING THE BASS SOUND YOU WANT...................................................................................3-60
SING THE 8400 PC REMOTE CONTROL SOFTWARE ................................................................3-62
U
Navigation Using the Keyboard .........................................................................................3-66
OUTINE MAINTENANCE............................................................................................................4-2
R
EMOVING AND REPLACING PARTS AND ASSEMBLIES ...............................................................4-2
R
IELD AUDIT OF PERFORMANCE.................................................................................................4-8
F
Table 4-1: Decoder Chart for Power Supervisor ........................................................................... 4-10
Table 4-2: Layout Diagram of J7, with expected voltages on each pin......................................... 4-11
Table 4-3: Typical Power Supply Voltages and AC Ripple.......................................................... 4-11
PROBLEMS AND POTENTIAL SOLUTIONS ....................................................................................5-2
Headphones Don’t Work ......................................................................................................5-2
RFI, Hum, Clicks, or Buzzes.................................................................................................5-2
Poor Peak Modulation Control ............................................................................................5-2
Audible Distortion On-Air ....................................................................................................5-3
Audible Noise on Air.............................................................................................................5-3
Whistle on Air, Perhaps Only in Stereo Reception...............................................................5-4
Interference From Stereo Into SCA ......................................................................................5-5
Shrill, Harsh Sound ..............................................................................................................5-6
Dull Sound ............................................................................................................................5-6
System Will Not Pass Line-Up Tones at 100% Modulation .................................................5-6
System Will Not Pass Emergency Alert System (“EAS” USA Standard) Tones at the Legally
Required Modulation Level.................................................................................................. 5-6
System Receiving 8400’s Digital Output Will Not Lock....................................................... 5-7
19 kHz Frequency Out-of-Tolerance ................................................................................... 5-7
L–R (Stereo Difference Channel) Will Not Null With Monophonic Input............................ 5-7
General Dissatisfaction with Subjective Sound Quality....................................................... 5-7
Security Passcode Lost (When Unit is Locked Out)............................................................. 5-7
Connection Issues between the 8400 and a PC, Modem, or Network.................................. 5-8
Troubleshooting Connections .............................................................................................. 5-9
OS-Specific Troubleshooting Advice.................................................................................... 5-9
ROUBLESHOOTING IC OPAMPS .............................................................................................. 5-14
T
ECHNICAL SUPPORT............................................................................................................... 5-15
T
ACTORY SERVICE .................................................................................................................. 5-15
F
HIPPING INSTRUCTIONS ......................................................................................................... 5-15
S
PECIFICATIONS ........................................................................................................................ 6-2
S
Performance......................................................................................................................... 6-2
Installation ........................................................................................................................... 6-2
IRCUIT DESCRIPTION ............................................................................................................... 6-6
C
Overview ..............................................................................................................................6-6
Control Circuits ................................................................................................................... 6-7
User Control Interface and LCD Display Circuits .............................................................. 6-7
Input Circuits .......................................................................................................................6-8
Output Circuits................................................................................................................... 6-10
DSP Circuit........................................................................................................................ 6-12
Power Supply .....................................................................................................................6-12
BBREVIATIONS ...................................................................................................................... 6-13
A
ARTS LIST.............................................................................................................................. 6-14
P
Obtaining Spare Parts ....................................................................................................... 6-15
Power Supply .....................................................................................................................6-15
Input/Ouput Circuit Board................................................................................................. 6-16
Front Panel Subassembly................................................................................................... 6-18
Display Circuit Board........................................................................................................ 6-18
Display Interface Circuit Board......................................................................................... 6-19
Composite Input/Output Circuit Board.............................................................................. 6-20
Control Circuit Board........................................................................................................ 6-20
CHEMATICS, ASSEMBLY DRAWINGS ...................................................................................... 6-21
S
Figure 6-1: Main Circuit Board Locator........................................................................................ 6-22
Index
analog I/O 1- · 7
4
4000 Transmission
Limiter 2- · 19
8
8100A/ST 1- · 16
8100A1 1- · 16
8100AST 1- · 16
8100AXT2 1- · 16
8200ST 2- · 14, 17
8400 OPTIMOD-FM
1- · 2
A
Abbreviations 6- · 13
AC Line Cord Standard
2- · 3
analog input 2- · 7
analog input clip level
2- · 30
analog input ref level
I/O setup 2- · 32
analog landline 1- · 16
assembly drawings 6- ·
21
audio
connections 2- · 7
input 2- · 7
output 2- · 8
B
balance adjust
I/O setup 2- · 34
balanced
C
cable
shielding 2- · 11
cable 2- · 7
chassis
ground 2- · 11
chassis ground 2- · 12
circuit description 6- ·
6
circuit ground 2- · 12
CIT25 2- · 10
clip level
I/O setup 2- · 30
clock reset
remote control 2- · 52
common-mode rejection
2- · 11
AES/EBU I/O 2- · 8
AGC
defeating 3- · 19, 30
meter 2- · 13, 3
AGC (external) setup
2- · 14
analog
output 2- · 8
analog baseband
outputs 1- · 8
inputs 2- · 7
output transformer 2- · 8
buttons · 12, 2
Escape 2- · 13, 2
bypass
locally 1- · 22
remote interface 1- · 22
test mode 1- · 20
composite
isolation transformer 2- ·
10
composite 2
output control 2- · 26
composite 2Lpilot
reference 2- · 27
composite baseband
microwave STL 1- ·
14
composite level output
1- · 19
composite metering 1- ·
19
composite output
cable lengths 2- · 9
I/O setup 2- · 36
impedance 2- · 9
level control 2- · 9
meter 2- · 14
composite output 2- · 9
composite outputs 1- ·
8
computer interface
Ethernet card 2- · 6
Modem card 2- · 6
serial 1 2- · 6
computer interface 1- ·
9
dual microwave STLs
1- · 14
E
EAS test tones 1- · 22
Enter button 2- · 12, 2
Escape button 2- · 13, 2
Ethernet card 2- · 6
exciter overshoot 1- ·
16
F
factory preset
selecting 2- · 28
factory presets 1- · 6,
56
fuse 2- · 3, 6
headphones 1- · 20
I
I/O
AES/EBU 2- · 8
connections 2- · 4
In meters 2- · 13, 2
input
analog 2- · 7
subcarrier 2- · 9
input level
line-up 1- · 18
input level meters 1- ·
19
input selector
I/O setup 2- · 30
inspection of contents
2- · 2
computer intertface
RS-232 2- · 6
connectors
audio 2- · 7
connectors 2- · 7
control knob 2- · 13, 2
D
digital I/O 1- · 7
digital links 1- · 13
G
gate indicators 2- · 13,
3
ground lift switch 2- ·
3, 6
grounding 2- · 11
H
headphone
jack 2- · 12, 2
level control 2- · 12, 2
installation 2- · 1
introduction 1- · 1
ITU-R 412
requirements 2- · 29
J
joystick 2- · 13, 2
L
language 2- · 24
line voltage 2- · 2
line-up tones 1- · 20
Locate joystick 2- · 13,
2
location 1- · 10
lossy data reduction 1-
· 17
M
meters
studio 1- · 17
modem card 2- · 6
monitoring 1- · 20
Multiband
gain reduction meters 2- ·
13, 3
multiplex
power 2- · 14, 3
N
networking 2- · 52
NICAM 1- · 14
output level
I/O setup 2- · 34
output levels
quick setup 2- · 27
output meters 1- · 19
overshoot reduction 1- ·
16
P
parts list 6- · 14
passcode
programming 2- · 40
PC card port 2- · 6
peak control criteria 1-
· 10
pilot 1- · 8
pop-up menu 2- · 13, 2
power
cord 2- · 3, 6
ground 2- · 11
power 2- · 2
Q
quick setup 2- · 23
R
rack-mounting unit 2- ·
4
rear panel 2- · 6
registration card 2- · 2
remote control
bypass 1- · 22
connecting 2- · 4
programming 2- · 51
wiring 2- · 5
remote control 2- · 6
remote control interface
connecting 2- · 4
programming 2- · 51
remote control interface
1- · 8
remote interface
wiring 2- · 5
O
Out meters 2- · 14
output
analog 2- · 8
composite 2- · 9
output configuration 2-
· 26
power supply
circuit description 6- · 12
pre-empahsis
quick setup 2- · 24
presets
factory 1- · 6, 56
user presets 1- · 6
remote interface 2- · 8
remote interface
connector 2- · 6
right channel balance
I/O setup 2- · 34
RS-232 connector 2- ·
6
S
schematics 6- · 21
screen display 2- · 13, 2
screens
System Setup 2- · 23
security 2- · 40
serial 1 connector 2- · 6
serial 2 connector 2- · 6
setup
I/O 2- · 30
quick 2- · 23
software updates 1- · 5
spare parts
obtaining 6- · 15
STL systems
exciter overshoot 1- · 16
STL systems 1- · 13, 14
studio chassis mode 2-
· 24
studio-transmitter link
1- · 13
subcarrier input 1- · 8
subcarrier input 2- · 9
switches
ground lift 2- · 3, 6
voltage select 2- · 2, 6
system setup
quick setup 2- · 23
System Setup screen 2-
· 23
T
technical data 6- · 1
time & date 2- · 24
U
unpacking 2- · 2
user presets 1- · 6
V
voltage select switch 2-
· 2, 6
W
warranty 1- · 23
warranty 6- · 6
Section 1
Introduction
8400 OPTIMOD-FM Digital Audio Processor.............................1-2
Presets in OPTIMOD-FM..............................................................1-6
Input/Output Configuration......................................................1-6
Location of OPTIMOD-FM........................................................1-10
Studio-Transmitter Link..............................................................1-13
Using Lossy Data Reduction in the Studio..............................1-17
About Transmission Levels and Metering...............................1-17
Line-Up Facilities .......................................................................1-19
Monitoring on Loudspeakers and Headphones...................1-20
EAS Test......................................................................................1-22
Warranty, Feedback................................................................1-23
1-2
INTRODUCTION ORBAN Model 8400
8400 OPTIMOD-FM Digital Audio Processor
Orban’s all-digital 8400 OPTIMOD-FM Audio Processor can help you achieve the highest audio quality in FM stereo broadcasting. Because all processing is performed by highspeed mathematical calculations within Motorola DSP56362 Digital Signal Processing
chips, the processing has cleanliness, quality, and stability over time and temperature that
is unmatched by analog processors.
OPTIMOD-FM 8400 is descended from the industry-standard OPTIMOD-FM audio
processors. Thousands of these processors are on the air all over the world. They have
proven that the “OPTIMOD sound” attracts and keeps an audience even in the most competitive commercial environment.
Because OPTIMOD-FM incorporates several audio processing innovations exclusive to Orban products, you should not assume that it can be operated in the same
way as less sophisticated processors. If you do, you may get disappointing results.
Take a little time now to familiarize yourself with OPTIMOD-FM. A small investment of
your time now will yield large dividends in audio quality.
The rest of Section 1 explains how OPTIMOD-FM fits into the FM broadcast facility.
Section 2 explains how to install it. Section 3 tells how to operate OPTIMOD-FM. Section 4 through Section 6 provides reference information.
OPTIMOD-FM was designed to deliver a high quality sound while simultaneously increasing the average modulation of the channel substantially beyond that achievable by
“recording studio”-style compressors and limiters. Because such processing can exaggerate flaws in the source material, it is very important that the source audio be as clean as
possible.
For best results, feed OPTIMOD-FM unprocessed audio. No other audio processing is
necessary or desirable.
If you wish to place level protection prior to your studio/transmitter link (STL), use the
Orban 8200ST OPTIMOD-Studio Compressor/Limiter/HF Limiter/Clipper. The 8200ST
can be adjusted so that it substitutes for the broadband AGC circuitry in OPTIMOD-FM,
which is then defeated.
OPTIMOD-FM 8400 is available in two main configurations—the 8400 has a fullfeatured front panel, while the 8400/PD has a blank front panel and must be controlled by
Orban’s PC Remote application running on Microsoft Windows 98 or later. Both units
have identical sound and features except for the difference in their front panels. Both
units run the same software.
Both the 8400 and 8400/PD can accept Orban’s HD (“High-Definition Digital Radio”)
hardware plug-in, 8400HD. 8400HD adds an extra AES/EBU output to drive the digital
channel in the iBiquity system. This output provides look-ahead peak limiting that oper-
OPTIMOD-FM INTRODUCTION
ates in parallel with the FM peak limiting. The look-ahead limiting is optimized to make
the most of the limited bit-rate codec used in the iBiquity system’s digital channel. By
eschewing any clipping, the HD output prevents the codec from wasting precious bits
encoding clipping distortion products, allowing the codec to instead use its entire bit
budget to encode the desired program material.
15 kHz band-limiting on the digital output also optimizes the operation of the low bit-rate
codec. By not wasting bits encoding the 15-20 kHz frequency range that few radio listeners can hear, the codec instead provides higher quality encoding of the crucial 20-15,000
Hz band.
8400HD also adds a second analog output to the 8400 system. This can be configured to
emit the 8400’s low-latency monitor signal, or to emit the signal that is processed for the
HD digital channel.
User-Friendly Interface
• A large (quarter-VGA) color liquid crystal display (LCD) makes setup, adjustment
and programming of OPTIMOD-FM easy. Navigation is by a miniature joystick, two
dedicated buttons, and a large rotary knob. The LCD shows all metering functions of
the processing structure in use (8400 only; 8400PD has no display).
1-3
• Use the Locate joystick to navigate through a menu that lets you Recall a preset,
Modify processing (at three levels of expertise), or to access the system’s Setup controls (8400 only).
Absolute Control of Peak Modulation
• The 8400 provides universal transmitter protection and audio processing for FM
broadcast. It can be configured to interface ideally with any commonly found transmission system in the world.
• The 8400 provides pre-emphasis limiting for the internationally used pre-emphasis
curves of 50µs and 75µs. Its pre-emphasis control is seldom audibly apparent, producing a clean, open sound with subjective brightness matching the original program.
• The 8400 achieves extremely tight peak control at all its outputs—analog left/right,
AES/EBU left/right, and composite baseband.
• The stereo encoder has two outputs with independent level controls, each capable of
driving 75Ω in parallel with 47,000pF, (100ft/30m of coaxial cable).
• By integrating the stereo encoder with the audio processing, the 8400 eliminates the
overshoot problems that waste valuable modulation in traditional external encoders.
• The 8400 prevents aliasing distortion in subsequent stereo encoders or transmission
links by providing bandwidth limiting and overshoot compensated 15 kHz low-
pass filters ahead of the 8400’s audio outputs and stereo encoder.
1-4
INTRODUCTION ORBAN Model 8400
Flexible Configuration
• The OPTIMOD-FM Audio Processor is supplied with analog and AES/EBU digital
inputs and outputs. Both digital input and digital output are equipped with samplerate converters and can operate at 32 kHz, 44.1 kHz, and 48 kHz sample rates. The
pre-emphasis status and output levels are separately adjustable for the analog and
digital outputs.
• OPTIMOD-FM has an internal, DSP-based stereo encoder (with a proprietary
composite processor) to generate the pilot tone stereo baseband signal and control its
peak level.
• The analog inputs are transformerless, balanced 10kΩ instrumentation-amplifier
circuits, and the analog outputs are transformerless balanced, and floating (with 50Ω
impedance) to ensure highest transparency and accurate pulse response.
• OPTIMOD-FM has two independent composite baseband outputs with digitally
programmable output levels. Robust line drivers enable them to drive 100 feet of RG59 coaxial cable without audible performance degradation.
• OPTIMOD-FM has a subcarrier input that is mixed with the output of OPTIMOD-
FM’s stereo encoder before application to the composite output connectors.
• All input, output, and power connections are rigorously RFI-suppressed to Orban’s
traditional exacting standards, ensuring trouble-free installation.
• OPTIMOD-FM precisely controls the audio bandwidth to 15 kHz. This prevents
overshoots in uncompressed digital links operating at a 32 kHz-sample rate and prevents interference to the pilot tone and RDS (or RBDS) subcarrier.
• OPTIMOD-FM Audio Processor is designed to meet all applicable international
safety standards.
Adaptability through Multiple Audio Processing Structures
• A processing structure is a program that operates as a complete audio processing
system. Only one processing structure can be on-air at a time, although both are active simultaneously to permit mute-free switching between them. OPTIMOD-FM realizes its processing structures as a series of high-speed mathematical computations
made by Digital Signal Processing (DSP) chips.
• OPTIMOD-FM features two processing structures: Five-Band (or Multiband) for a
consistent, “processed” sound, free from undesirable side effects, and Two-Band for
a transparent sound that preserves the frequency balance of the original program material. A special Two-Band preset creates a no-compromise “Protect” function that is
functionally similar to the “Protect” structures in earlier Orban digital processors.
OPTIMOD-FM INTRODUCTION
• OPTIMOD-FM can increase the density and loudness of the program material by
multiband compression, limiting, and clipping — improving the consistency of the
station’s sound and increasing loudness and definition remarkably, without producing
unpleasant side effects.
• OPTIMOD-FM rides gain over an adjustable range of up to 25 dB, compressing dy-
namic range and compensating for both operator gain-riding errors and gain inconsistencies in automated systems.
• OPTIMOD-FM’s Two-Band processing structure is phase-linear to maximize audi-
ble transparency.
Controllable
• OPTIMOD-FM can be remote-controlled by 5-12V pulses applied to eight pro-
grammable, optically isolated ports.
• OPTIMOD-FM is equipped with a serial port to interface to an IBM-compatible
computer running Orban’s PC Remote software. The connection can either be direct
or through an external modem.
1-5
• OPTIMOD-FM has a second serial port that allows the user to set up security and
communications parameters through a simple ASCII terminal program running on
any PC. It also permits simple ASCII strings to trigger preset recall, facilitating interface to automation systems that can emit such strings through an RS232 serial port.
• OPTIMOD-FM can be connected to a TCP/IP network through an optional rear-
mounted Ethernet PC card.
• A Bypass Test Mode can be invoked locally or by remote control to permit broadcast
system test and alignment or “proof of performance” tests.
• OPTIMOD-FM's software can be upgraded remotely through its
nected to an external modem) or PC-Card Port (via an optional Ethernet card), or locally (by connecting a Windows® computer to its
null modem cable) and running Orban-supplied downloadable upgrade software.
• OPTIMOD-FM’s user presets can be saved, recalled, and archived through its PC
Remote software or to a PC-Card memory card plugged into its front PC Card port.
• OPTIMOD-FM Audio Processor contains a built-in line-up tone generator, facilitat-
ing quick and accurate level setting in any system.
• The 8400 Audio Processor contains a versatile real-time clock, which allows automa-
tion of various events (including recalling presets) at pre-programmed times.
Serial 1 port through the supplied
Serial 1 port (con-
1-6
INTRODUCTION ORBAN Model 8400
Presets in OPTIMOD-FM
There are two distinct kinds of presets in OPTIMOD-FM: Factory Presets and User Presets.
Factory Presets
The Factory Presets are our “factory recommended settings” for various program formats
or types. The description indicates the processing structure and the type of processing.
Each Factory Preset on the Preset list is really a library of 20 separate presets, selected by
entering
or less processing.
Factory Presets are stored in OPTIMOD-FM’s non-volatile memory and cannot be
erased. You can change the settings of a Factory Preset, but you must then store those
settings as a User Preset, which you are free to name as you wish. The Factory Preset remains unchanged.
Basic Modify and using the Less/More control to adjust OPTIMOD-FM for more
User Presets
User Presets permit you to change a Factory Preset to suit your requirements and then
store those changes.
You may store up to 64 User Presets. You may enter in any name you wish, up to 20
characters. The only exception is that you cannot name a User Preset the same as a Factory Preset, regardless of upper or lower case. (For example, if a Factory Preset is called
“Jazz,” you cannot have a User Preset called “jazz” or “JAZZ.”)
User Presets cannot be created from scratch. You must always start by recalling a Factory
Preset. You can then immediately store this in a User Preset, name it as you wish, and
then make changes to the settings. Alternatively, you can recall a Factory Preset, make
the changes, and then store this in a User Preset.
Either way, the Factory Preset remains for you to return to if you wish.
User Presets are stored in non-volatile memory that does not require battery backup.
Input/Output Configuration
OPTIMOD-FM is designed to simultaneously accommodate:
• Digital AES/EBU left/right inputs and outputs.
• Digital AES/EBU sync reference input.
OPTIMOD-FM INTRODUCTION
• Analog left/right inputs and outputs.
• Composite stereo outputs.
• Subcarrier (SCA and RDS/RBDS) input.
The 8400HD option adds:
• A second AES/EBU digital output, which carries the HD-processed signal.
• A second stereo pair of analog outputs, switchable between the low-latency “moni-
tor” signal and the HD-processed signal.
• A second AES/EBU sync input. The sample rate of the HD-processed signal can be
genlocked to this input, independent of the sample rate of the main (FM-processed)
AES/EBU output.
Digital AES/EBU Left/Right Input/Output
The digital input and output conform to the professional AES/EBU standard. They both
have sample rate converters to allow operation at 32, 44.1, and 48 kHz sample frequency.
1-7
The left/right digital input is on one XLR-type female connector on the rear panel; the
left/right digital output is on one XLR-type male connector on the rear panel.
OPTIMOD-FM simultaneously accommodates digital and analog inputs and outputs.
You select whether OPTIMOD-FM uses the digital or analog input on the Input/Output
screen or by remote interface. Both analog and digital outputs are active continuously.
Level control of the AES/EBU input is via software control through the
screens.
In addition, an AES/EBU sync input can accommodate house sync. It will lock the
8400’s output to this sync even if the digital input is asynchronous to house sync.
Input/Output
Analog Left/Right Input/Output
The left and right analog inputs are on XLR-type female connectors on the rear panel.
Input impedance is greater than 10kΩ; balanced and floating. Inputs can accommodate up
to +27 dBu (0 dBu = 0.775Vrms).
The left and right analog outputs are on XLR-type male connectors on the rear panel.
Output impedance is 50Ω; balanced and floating. They can drive 600Ω or higher impedances, balanced or unbalanced. The peak output level is adjustable from –6 dBu to +24
dBu.
Level control of the analog inputs and outputs is accomplished via software control
through System Setup. (See step 3 on page 2-30 and step 4 on page 2-32.)
1-8
INTRODUCTION ORBAN Model 8400
Stereo Analog Baseband Composite Output
The stereo encoder has two unbalanced analog baseband outputs on two BNC connectors
on the rear panel. Each output can be strapped for 0 or 75Ω source impedance, and can
drive up to 8V peak-to-peak into 75Ω in parallel with up to 0.047µF (100ft/30m of RG59/U cable) before any significant audible performance degradation occurs (see footnote
on page 1-12 and refer to Fig. 2-3 on page 2-10). Independent level control of each output is via software in the Input/Output: Composite screen. A ground lift switch is available on the rear panel. This is useful to prevent ground loops between the 8400 and the
transmitter.
The second composite output can be reconfigured in software to provide the stereo pilot
tone only, which can provide a pilot reference for an RDS subcarrier generator.
Subcarriers
The stereo encoder has two unbalanced 600Ω subcarrier (SCA) inputs with rear-panel
BNC connectors to accept any subcarrier at or above 23 kHz. The subcarriers are mixed
into each composite output. Their level will not be affected by the composite level control for that output.
The mixing occurs after D/A conversion and is analog. Subcarriers are not
digitized by the 8400.
The gain from the subcarrier input to the composite output is fixed at –20 dB. Therefore,
the gain is scaled so that 1.5V peak at the subcarrier input produces 10% subcarrier injection with reference to 3.0Vp-p=100% modulation of the FM carrier. This –20 dB gain
minimizes the effect of any noise picked up on the subcarrier input cable while still accommodating most subcarrier generators.
The correct peak level of the stereo program applied to the stereo encoder sometimes depends on the number of subcarriers in use. Some regulatory authorities require that total
baseband peak modulation be maintained within specified limits. Thus, the level of the
stereo main and subchannel must be reduced when a subcarrier is turned on. The 8400’s
remote control feature allows you to reduce the stereo main and sub-channel level by
connecting an on/off signal from your subcarrier generator (See page 2-9). You define
the amount of reduction in % on the Input/Output screen (See page 2-32). See page 2-51
for information on programming the remote control.
Remote Control Interface
The Remote Control Interface is a set of eight optically isolated inputs on a dB-25 connector that can be activated by 5-12V DC. They can control various functions of the
8400:
• Recall any Factory Preset, User Preset, Test Mode state (Bypass or Tone), or exit
from a Test Mode to the previous processing preset.
OPTIMOD-FM INTRODUCTION
• Switch the stereo encoder to stereo, mono from left, mono from right, or mono from
sum audio input.
• Switch the 8400 to use either the analog input or the digital input.
• Reduce the stereo main and subchannel modulation to compensate for transmitter
overshoot and subcarrier inputs (SCAs).
The remote control of overshoot compensation and SCA modulation (see page
2-51) is not latching. You must supply a continuous current to the programmed
remote input to hold the gain at its compensated level. Use the status outputs
of your transmitter and/or SCA generators to provide the switching signal so
the compensation will automatically follow the transmitter and/or subcarrier
generator on the air.
• Reset the 8400’s internal clock to the nearest hour or to midnight.
The functions of the eight inputs can be re-configured by the user via System
Setup Network/Remote. For example, if you are not using the stereo encoder,
the three inputs ordinarily dedicated to controlling the state of the stereo encoder can instead be re-configured to call three additional presets. See page 251 for information on programming the remote control interface.
1-9
Computer Interface
On the rear panel of the 8400 is a serial port and a PC-Card port for interfacing to IBMcompatible PCs. These computer interfaces support remote control and metering, and
downloading software upgrades.
Each 8400 package ships with 8400 PC Remote software, a program for any IBMcompatible PC with VGA graphics or higher (running Microsoft Windows 98 or higher).
8400 PC permits you to adjust any 8400 preset by remote control, or to do most anything
else that you can do from the 8400’s front panel controls. The program displays all of the
8400’s LCD meters on the computer screen to aid remote adjustment.
RS-232 Serial Port (Serial 1)
8400 PC Remote can communicate via modem or direct connection between the computer and the 8400 through their RS-232 serial ports.
RS-232 Serial Port (Serial 2)
A computer (running a simple ASCII terminal program like Hyperterminal®) can communicate with the 8400 through direct cable connection between their RS-232 serial
ports. This connection can administer communications and security, and can recall presets.
PC-Card Port (for Ethernet Cards)
An optional Ethernet PC card can be plugged into the PC-Card Port on the rear panel of
the 8400 to connect to any Ethernet-based network that supports the TCP/IP protocol.
The Ethernet card is supplied standard on 8400/PD units.
1-10
INTRODUCTION ORBAN Model 8400
Location of OPTIMOD-FM
Optimal Control of Peak Modulation Levels
The audio processing circuitry in OPTIMOD-FM produces a signal that is preemphasized to either the 50µs or 75µs standard curve. It is precisely and absolutely high
frequency-controlled and peak-controlled to prevent over-modulation, and is filtered at
15 kHz to protect the 19 kHz pilot and prevent distortion caused by aliasing-related nonlinear crosstalk. If this signal is fed directly into a stereo encoder, peak modulation levels
on the air will be precisely controlled. However, if the audio processor’s signal is fed to
the stereo encoder through any circuitry with frequency response errors and/or nonconstant group delay, the peaks will be magnified. Peak modulation will increase, but
average modulation will not. The modulation level must therefore be reduced to accommodate the larger peaks. Reduced average modulation level will cause reduced loudness
and a poorer signal-to-noise ratio at the receiver.
Landline equalizers, transformers, and 15 kHz low-pass filters and pre-emphasis networks in stereo encoders typically introduce frequency response errors and non-constant
group delay. There are three criteria for preservation of peak levels through the audio system:
1) The system group delay must be essentially constant throughout the frequency range
containing significant energy (30-15,000Hz). If low-pass filters are present, this may
require the use of delay equalization. The deviation from linear phase must not exceed ±10° from 30-15,000Hz.
2) The low-frequency −3 dB point of the system must be placed at 0.15Hz or lower (this
is not a misprint!). This is necessary to ensure less than 1% overshoot in a 50Hz
square wave and essentially constant group delay to 30Hz.
3) Any pre-emphasis used in the audio transmission system prior to the stereo encoder
must be canceled by a precisely complementary de-emphasis: Every pole and zero in
the pre-emphasis filter must be complemented by a zero and pole of identical complex frequency in the de-emphasis network. An all-pole de-emphasis network (like
the classic series resistor feeding a grounded capacitor) is not appropriate.
In this example, the network could be fixed by adding a second resistor between ground
and the capacitor, which would introduce a zero.
Low-pass filters (including anti-aliasing filters in digital links), high-pass filters, transformers, distribution amplifiers, and long transmission lines can all cause the above criteria to be violated, and must be tested and qualified. It is clear that the above criteria for
optimal control of peak modulation levels are most easily met when the audio processor
directly feeds the stereo encoder. In the 8400, no circuit elements that might distort the
shape of the waveform are interposed between the audio processor and the stereo encoder. We therefore recommend using the 8400 with its built-in stereo encoder whenever
practical.
OPTIMOD-FM INTRODUCTION
Best Location for OPTIMOD-FM
The best location for OPTIMOD-FM is as close as possible to the transmitter, so that its
stereo encoder output can be connected to the transmitter through a circuit path that introduces the least possible change in the shape of OPTIMOD-FM’s carefully peaklimited waveform — a short length of coaxial cable. If this is impossible, the next best
arrangement is to feed the 8400’s AES/EBU digital output through an all-digital, uncompressed path to the transmitter's exciter.
Use the 8400’s left and right analog audio outputs in situations where the stereo encoder
and exciter are under the jurisdiction of an independent transmission authority, and where
the programming agency’s jurisdiction ends at the interface between the audio facility
and the link connecting the audio facility to the transmitter. (The link might be telephone/post lines, analog microwave radio, or various types of digital paths.) This situation is not ideal because artifacts that cannot be controlled by the audio processor can be
introduced by the link to the transmitter, by transmitter peak limiters, or by the external
stereo encoder.
If the transmitter is not accessible:
All audio processing must be done at the studio, and you must tolerate any damage that
occurs later. If you can obtain a broadband (0-75 kHz) phase-linear link to the transmitter, and the transmitter authority will accept the delivery of a baseband encoded signal,
use the 8400’s internal stereo encoder at the studio location to feed the STL. Then feed
the output of the STL receiver directly into the transmitter’s exciter with no intervening
processing.
1-11
If an uncompressed AES/EBU digital link is available to the transmitter, this is also an
excellent means of transmission, although it will not pass the effects of the 8400’s composite processor (if you are using it). However, if the digital link employs lossy compression, it will disturb peak levels.
If only an audio link is available, use the 8400’s left and right audio outputs and feed the
audio, without pre-emphasis, directly into the link. If possible, request that any transmitter protection limiters be adjusted for minimum possible action — OPTIMOD-FM does
most of that work. Transmitter protection limiters should respond only to signals caused
by faults or by spurious peaks introduced by imperfections in the link. To ensure maximum quality, all equipment in the signal path after the studio should be carefully aligned
and qualified to meet the appropriate standards for bandwidth, distortion, group delay and
gain stability, and such equipment should be re-qualified at reasonable intervals. (See
Optimal Control of Peak Modulation Levels on page 1-10).
If the transmitter is accessible:
You can achieve the most accurate control of modulation peaks by locating OPTIMODFM at the transmitter site and using its stereo encoder to drive the transmitter. You can
usually also obtain good results by locating OPTIMOD-FM at the studio and connecting
the baseband output of its stereo encoder to the transmitter through a composite baseband
STL (see page 1-14). However, many composite baseband STLs do not control peaks
perfectly because of bounce (see page 1-15), and locating OPTIMOD-FM at the transmit-
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INTRODUCTION ORBAN Model 8400
ter site (where it can control peaks just prior to the transmitter’s RF exciter) is thus likely
to maximize loudness.
Because OPTIMOD-FM controls peaks, it is irrelevant whether the audio link feeding
OPTIMOD-FM’s input terminals is phase-linear. However, the link should have low
noise, the flattest possible frequency response from 30-15,000Hz, and low non-linear distortion.
We strongly recommend that you use the 8400’s internal stereo encoder to feed the output of the encoder directly to the baseband input of the exciter through less than 100 feet
(30 meters) of coaxial cable.
100 feet of coaxial cable (assuming 30pF/foot capacitance) will reduce measured separation at 15 kHz (worst case) to approximately 60 dB. This separation is comfortably above
the separation (approximately 20 dB) that starts to cause perceptible changes in the stereo
1
image.
You will achieve a louder sound on the air, with better control of peak modulation, than
if you use most external stereo encoders.
An exception is Orban’s 8218 stereo encoder, which does not add overshoot. However,
because it accepts audio in left/right form, the 8218 will not let you exploit the 8400’s
composite limiter.
The shorter the baseband cable from OPTIMOD-FM to exciter, the less likely that ground
loops or other noise problems will occur in the installation. If you require a long cable
run, you can use Orban’s CIT25 Composite Isolation Transformer to break any ground
loops. This transformer will ordinarily cure even the most stubborn hum or noise caused
by the composite connection between OPTIMOD-FM and the exciter. Its instruction
manual contains complete information on its installation and application.
If a separate stereo encoder must be used, feed the encoder directly from the 8400’s left
and right analog outputs. If possible, bypass the pre-emphasis network and the input lowpass filters in the encoder so that they cannot introduce spurious peaks. Because of their
special design, OPTIMOD-FM’s pre-emphasis network and low-pass filters perform the
same functions while retaining tight peak control.
1
Julie M. Adkins and Robert D. Sorkin: “Effect of Channel Separation on Earphone-Presented
Tones, Noise, and Stereophonic Material,” J. Audio Engineering Society, vol. 33 pp. 234-239,
1985.
Subjects listened to 500-Hz tones, broa dBand noise, and stereophonic program material through
earphones and adjusted the channel separation, via a manual control, until the degradation of the
spatial effect became detectable. Mean channel separations ranged from 10 to 15.9 dB for the musical selections employed and from 13.7 to 16.8 dB for the noise and tonal stimuli. The results are
discussed in terms of existing data on detectable stereo separation and on the discrimination of
interaural time differences. [Abstract ©Audio Engineering Society, Inc.]
OPTIMOD-FM INTRODUCTION
Studio-Transmitter Link
Transmission from Studio to Transmitter
1-13
There are five types of studio-transmitter links (STLs) in common use in broadcast service: uncompressed digital, digital with lossy compression (like MPEG, Dolby
®
), microwave, analog landline (telephone/post line), and audio subcarrier on a video
x
microwave STL.
STLs are used in three fundamentally different ways. They can either (1) pass unprocessed audio for application to the 8400’s input, (2) they can pass the 8400’s peakcontrolled analog or digital left and right audio outputs, or (3) they can pass the 8400’s
peak-controlled composite stereo baseband output. The three applications have different
performance requirements. In general, a link that passes unprocessed audio should have
very low noise and low non-linear distortion, but its transient response is not important.
A link that passes processed audio doesn’t need as low a noise floor as a link passing unprocessed audio. However, its transient response is critical. At the current state of the art,
an uncompressed digital link using digital inputs and outputs to pass audio in left/right
format achieves best results. We will elaborate below.
Digital Links
Digital links may pass audio as straightforward PCM encoding, or they may apply lossy
data reduction processing to the signal to reduce the number of bits per second required
for transmission through the digital link. Such processing will almost invariably distort
peak levels, and such links must therefore be carefully qualified before you use them to
carry the peak-controlled output of the 8400 to the transmitter. For example, the MPEG
Layer 2 algorithm can increase peak levels up to 4 dB at 160kB/sec by adding large
amounts of quantization noise to the signal. While the desired program material may psychoacoustically mask this noise, it is nevertheless large enough to affect peak levels severely. For any lossy compression system the higher the data rate, the less the peak levels
will be corrupted by added noise, so use the highest data rate practical in your system.
®
, or APT-
It is practical (though not ideal) to use lossy data reduction to pass unprocessed audio to
the 8400’s input. The data rate should be at least of “contribution quality” — the higher,
the better. If any part of the studio chain is analog, we recommend using at least 20-bit
A/D conversion before encoding.
Because the 8400 uses multiband limiting, it can dynamically change the frequency response of the channel. This can violate the psychoacoustic masking assumptions made in
designing the lossy data reduction algorithm. Therefore, you need to leave “headroom” in
the algorithm so that the 8400’s multiband processing will not unmask quantization
noise. This is also true of any lossy data reduction applied in the studio (such as hard disk
digital delivery systems).
For MPEG Layer 2 encoding, we recommend 384kB/second or higher.
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INTRODUCTION ORBAN Model 8400
Some links may use straightforward PCM (pulse-code modulation) without lossy data
reduction. If you connect to these through an AES/EBU digital interface, these can be
very transparent provided they do not truncate the digital words produced by the devices
driving their inputs. Because the 8400’s output is tightly band-limited to 15 kHz, it can
be passed without additional overshoot by 32, 44.1 or 48 kHz links equally well.
Currently available sample rate converters use phase-linear filters (which have constant
group delay at all frequencies). If they do not remove spectral energy from the original
signal, the sample rate conversion, whether upward or downward, will not add overshoot
to the signal. This is not true of systems that are not strictly band-limited to 15 kHz,
where downward sample rate conversion will remove spectral energy and will therefore
introduce overshoot.
If the link does not have an AES/EBU input, you must drive its analog input from the
8400’s analog output. This is less desirable because the link’s analog input circuitry may
not meet all requirements for passing processed audio without overshoot.
NICAM is a sort of hybrid between PCM and lossy data reduction systems. It uses a
block-companded floating-point representation of the signal with J.17 pre-emphasis.
Older technology converters (including some older NICAM encoders) may exhibit quantization distortion unless they have been correctly dithered. Additionally, they can exhibit
rapid changes in group delay around cut-off because their analog filters are ordinarily not
group-delay equalized. The installing engineer should be aware of all of these potential
problems when designing a transmission system.
Any problems can be minimized by always driving a digital STL with the 8400’s
AES/EBU digital output, which will provide the most accurate interface to the STL. The
digital input and output accommodate sample rates of 32 kHz, 44.1 kHz, and 48 kHz.
Composite Baseband Microwave STLs
The composite baseband microwave STL carries the standard pilot-tone stereo baseband,
and is therefore fed from the output of a stereo encoder located at the studio site. The receiver output of the composite STL is the stereo baseband signal, which is applied directly to the wideband input of the FM broadcast transmitter’s exciter. Thus, no stereo
encoder is needed at the transmitter.
In general, a composite microwave STL provides good audio quality, as long as there is a
line-of-sight transmission path from studio to transmitter of less than 10 miles (16 km). If
not, RF signal-to-noise ratio, multipath distortion, and diffraction effects can cause serious quality problems. Where a composite STL is used, use the 8400’s stereo encoder to
drive the composite STL transmitter.
Dual Microwave STLs
Dual microwave STLs use two separate transmitters and receivers to pass the left and
right channels in discrete form. Dual microwave STLs offer greater noise immunity than
composite microwave STLs. However, problems include gain- and phase-matching of the
left and right channels, overloads induced by pre-emphasis, and requirements that the
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