Belden Grass Valley HCO-3901 Instruction Manual

GUIDE TO INSTALLATION AND OPERATION
HCO-3901
HCO-3901
3G/HD/SD/ASI Change Over
with optional Clean Switch and ALC
Guide to Installation and Operation
M981-9900-125
2017-08-07

GUIDE TO INSTALLATION AND OPERATION
HCO-3901
Copyright and Trademark Notice
Copyright © 2012-2017, Grass Valley Canada. All rights reserved.
Belden, Belden Sending All The Right Signals, and the Belden logo are trademarks or registered trademarks of
Belden Inc. or its affiliated companies in the United States and other jurisdictions. Grass Valley, Miranda, HCO-3901,
iControl, and Densité are trademarks or registered trademarks of Grass Valley Canada. Belden Inc., Grass Valley
USA, LLC, and other parties may also have trademark rights in other terms used herein.
Terms and Conditions
Please read the following terms and conditions carefully. By using HCO-3901 documentation, you agree to the
following terms and conditions.
Grass Valley hereby grants permission and license to owners of HCO-3901 to use their product manuals for their own
internal business use. Manuals for Grass Valley products may not be reproduced or transmitted in any form or by any
means, electronic or mechanical, including photocopying and recording, for any purpose unless specifically authorized
in writing by Grass Valley.
A Grass Valley manual may have been revised to reflect changes made to the product during its manufacturing life.
Thus, different versions of a manual may exist for any given product. Care should be taken to ensure that one obtains
the proper manual version for a specific product serial number.
Information in this document is subject to change without notice and does not represent a commitment on the part of
Grass Valley.
Warranty information is available in the Support section of the Grass Valley Web site (www.grassvalley.com).

GUIDE TO INSTALLATION AND OPERATION
HCO-3901
Electromagnetic Compatibility
This equipment has been tested for verification of compliance with FCC Part 15, Subpart B requirements for
Class A digital devices.
NOTE: This equipment has been tested and found to comply with the limits for a Class A digital device, pursuant to
part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference
when the equipment is operated in a commercial environment. This equipment generates, uses, and can radiate
radio frequency energy and, if not installed and used in accordance with the instruction manual, may cause harmful
interference to radio communications. Operation of this equipment in a residential area is likely to cause harmful
interference in which case the user will be required to correct the interference at his own expense.
This equipment has been tested and found to comply with the requirements of the EMC directive
2004/108/CE:
•EN 55022 Class A radiated and conducted emissions
•ENV 50204 Radiated EMF Immunity – RF 900 MHz Pulsed
•EN 61000-3-2 Harmonic current emission limits
•EN 61000-3-3 Voltage fluctuations and flicker limitations
•EN 61000-4-2 Electrostatic discharge immunity
•EN 61000-4-3 Radiated electromagnetic field immunity – radio frequencies
•EN 61000-4-4 Electrical fast transient immunity
•EN 61000-4-5 Surge transient immunity
•EN 61000-4-6 Conducted disturbances immunity
•EN 61000-4-11 Voltage-dips, short-interruption and voltage variation immunity

GUIDE TO INSTALLATION AND OPERATION
HCO-3901
Table of Contents
1HCO-3901 3G/HD/SD/ASI Change Over with Clean Switch and ALC....................................1
1.1 Introduction..........................................................................................................................................1
1.2 Features...............................................................................................................................................1
1.3 Block Diagram .....................................................................................................................................2
1.4 Front Card-edge Interface...................................................................................................................3
2Installation................................................................................................................................4
2.1 Installation in the Densité frame..........................................................................................................4
2.2 Rear Connector Panels.......................................................................................................................4
3Operation..................................................................................................................................8
3.1 Control options ....................................................................................................................................8
3.2 Card-Edge Status LED........................................................................................................................8
3.3 Local control using the Densité frame control panel ...........................................................................9
3.4 Remote control using iControl...........................................................................................................10
3.4.1 The iControl graphic interface window.................................................................................10
3.4.2 The Switch panel..................................................................................................................11
3.4.3 The Alarms panel .................................................................................................................14
3.4.4 The Timing panel..................................................................................................................19
3.4.5 The Operation Mode panel...................................................................................................21
3.4.6 The Reference panel............................................................................................................21
3.4.7 The Audio Embed panel.......................................................................................................22
3.4.8 The ALC panel......................................................................................................................22
3.4.9 The Fingerprint panel ...........................................................................................................25
3.4.10 The RALM panel...................................................................................................................27
3.4.11 The Thumbnail panel............................................................................................................28
3.4.12 The Options panel................................................................................................................29
3.4.13 The Factory panel.................................................................................................................31
3.4.14 The Alarm Config panel........................................................................................................32
3.4.15 The Info panel.......................................................................................................................34
3.4.16 User Presets.........................................................................................................................35
3.4.17 Profiles..................................................................................................................................36
4Specifications ........................................................................................................................38
5Contact Us..............................................................................................................................40
Grass Valley Technical Support .................................................................................................................40
Corporate Head Office................................................................................................................................40
ANNEX – HCO-3901 User Interface ............................................................................................41

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HCO-3901 | 1
1 HCO-3901 3G/HD/SD/ASI Change Over with Clean Switch and ALC
1.1 Introduction
The HCO-3901 from Grass Valley, a Belden Brand, is a 3x1 3G/HD/SD/ASI change-over which support 16 channels
of embedded audio and metadata. The module can perform a video and audio “Clean and Silent Switch” between
sources using the CS option (not available with ASI signals). In the event of a power failure, the PGM signal is
protected by relays fitted on the rear module, maintaining the integrity of the selected signal at the output. Those
protection relays are fully controllable via GPI. With the addition of the HCO- 3901-3DRP-R-EX rear panel, the HCO
now supports paired outputs for 3G/HD/SD SDI (single outputs only for ASI).
Input selection can be performed automatically or manually.
•In automatic mode, the card will perform input selection between IN 1 and IN 2 based on internal signal analysis
with alarm parameters, and the status of the inputs.
•In manual mode, any three sources can be selected:
-from the Densité controller
-using the iControl software
-or simply by using a GPI input (3DRP rear only).
A GPI input can be triggered by an automation system or any simple GPI control panel.
The GPI outputs allow tallies to give status of the selected source.
The HCO-3901 provides up to eight 3G/HD/SD SDI video outputs (depending on the rear panel in use). The preview
outputs are user selectable to follow the main program output, video inputs IN 1, IN 2 or IN 3.
The HCO-3901 generates audio/video fingerprints for input 1 and input 2. In combination with other cards streaming
fingerprints for the same signals, an optional module in iControl can measure and report lip sync errors through the
entire chain of a broadcast facility.
Grass Valley’s automatic loudness control (ALC) option can eliminate objectionable loudness variations between
programs and commercials (not available with ASI signals).
The module provides streaming video and audio level metering so an operator can remotely and effectively monitor
the signal path using Grass Valley’s iControl facility monitoring and control system.
The HCO-3901 is a 3 RU card and is available with a one or two slot rear module. Up to 20 modules can fit in a 3 RU
Densité frame with a 1-slot rear module (or 19 with REF-1801).
1.2 Features
•Two Primary inputs: IN 1 & IN 2 plus one Secondary: IN 3
•Four Outputs: One Main Program plus three previews
•Eight outputs (with EX rear): paired outputs for Main Program and each of the three previews (single outputs only
for ASI)
•Supports 3G, HD (1080i50/59.94, 720p50/59.94) and SD (525, 625) or ASI input and output
•Electronic switching with relay backup (on rear module) maintains selected input with power loss for Primary
inputs IN 1 and IN 2
•Automatic mode using internal signal analysis with alarm parameters for IN 1 and IN 2
•Manual change-over by local frame controller, iControl, iControl Solo or GPI (3DRP rear) for 3 inputs

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2| HCO-3901
•Alarm reporting to iControl facility monitoring and control system
•Compatible with iControl end-to-end A/V fingerprint analyzer for lip sync error detection and measurement (not
available with ASI signals)
•GPI in and out (IN 1, IN 2, IN 3, auto, bypass)
•Optional clean switch function (video and 16 channels of audio) for IN 1 and IN 2 (not available with ASI signals)
•Optional on-board automatic loudness control by Grass Valley (not available with ASI signals)
•Reference input with passive loop through (3DRP rear only)
•Two line timing window with CS option (not available with ASI signals)
•Thumbnail and audio level meter streaming for IN 1, IN 2 and PGM OUT (not available with ASI signals)
•Loudness compliant to EBU R128-2014, ATSC A/85:2013 (FCC CALM compliant) and ARIB TR-B32 (ITU-R
BS.1770-3)
1.3 Block Diagram
The following block diagrams show the functionality of the HCO-3901 and its associated rear panels.
Figure 1-1 Functional Block Diagram - HCO-3901 (shown with the HCO-3901-3DRP-R rear panel)

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HCO-3901 | 3
1.4 Front Card-edge Interface
The front card-edge of the HCO-3901 incorporates two elements:
•Status LED (see section 3.2)
•Select Button (see section 3.3)
An additional connector is present, intended for future use.
Figure 1-2 Functional block diagram - HCO-3901 (shown with the HCO-3901-3DRP-R-EX rear panel)
Figure 1-3 Front card-edge layout

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2 Installation
2.1 Installation in the Densité frame
The HCO-3901 and its associated rear connector rear panel must be mounted in a Densité-3 or Densité-3+ series
frame, or in a GV Node.
•It is not necessary to switch off the frame’s power when installing or removing the card.
•With a double-width rear panel installed, the HCO-3901 must be installed in the right-most of the two slots
covered by the panel in order to mate with the panel’s connectors.
•If it is placed in the wrong slot, the front panel LED will flash red. Move the card to other slot for correct
operation. No damage will result to the card should this occur.
See the manual for your Densité frame for detailed instructions on installing cards and their associated rear panels.
2.2 Rear Connector Panels
There are three rear panels available for the HCO-3901. The table summarizes their features, and their layouts are
shown in the figure below.
HCO-3901-3DRP-R-EX
HCO-3901-3DRP-R
HCO-3901-3SRP-R
Single-slot-width panel
♦
Double-slot-width panel
♦
♦
Bypass Relay
♦
♦
♦
CONNECTORS BNC BNC DIN
Ref IN
♦
♦
♦
Ref IN loop out
♦
♦
GPI I/O
♦
♦
3G/HD/SD IN
1 and 2
♦
♦
♦
3
♦
♦
3G/HD/SD OUT PGM 1
♦
♦
♦
PGM 2 (phase inverted)
♦
PVW 1A (phase inverted)
♦
PVW 1 (1B on –EX rear)
♦
♦
♦
PVW 2A (phase inverted)
♦
PVW 2 (2B on –EX rear)
♦
♦
PVW 3A (phase inverted)
♦
PVW 3 (3B on –EX rear)
♦
♦

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HCO-3901 | 5
HCO-3901-3DRP-R-EX – Double-width Densité-3 rear with bypass relay and DIN connectors. This rear
features extra PGM and PWV outputs. Outputs designated by a black circle
are phase-inverted and not suitable for ASI.
HCO-3901-3DRP-R – double-width Densité-3 rear with bypass relay and BNC connectors.
HCO-3901-3SRP-R – Single-width Densité-3 rear with bypass relay. The lower connector count is suitable
for situations where the third input, multiple preview outputs and GPI interface are
not required, saving a frame slot for another card.
The rear panel connections are as follows:
3G/HD/SD IN – serial digital 3G/HD/SD input
Connect up to three serial digital video signals, conforming to the SMPTE 292M standard for HD input signals,
SMPTE 259M standard for SD input signals or SMPTE-425M for 3Gbps signals (level A only; level B will be flagged
as an input error), to the BNCs labeled 3G/HD/SD SDI IN. DVB-ASI per EN 50083-9 is also supported. The HCO-
3901 will automatically switch to the detected line format.
OUT – serial digital video outputs
Figure 2-1 HCO-3901 Rear Panels

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6| HCO-3901
The HCO-3901 provides up to eight 3G/HD/SD SDI video outputs (depending on the rear panel in use), labeled PGM
(program) and PVW1, PVW2 and PVW3 (preview). The SDI video signals conform to the SMPTE 292M, SMPTE
259M-C and SMPTE 425M standards.
DVB-ASI per EN 50083-9 is also supported. Note: The phase-inverted outputs on the –EX rear panel (indicated by
white lettering in a black circle) are not suitable for DVB-ASI distribution.
REF IN – Studio reference input
For external synchronization, connect a black studio reference signal to the BNC labeled REF IN. NB: The REF IN
loop-through, when provided, must be terminated if not used.
GPI connector (3DRP rears only)
The double-width rear panels of the HCO-3901 include a GPI interface that allows control of the switch process.
When constructing and using an external GPI box, be aware of the following:
1. The HCO-3901 card monitors the external power supply voltage on the GPI input. If the voltage is less than
approximately 4V, an alarm will be raised.
2. GPI IN 1 and GPI IN 2 should NOT be activated at the same time – DAMAGE TO THE RELAY MAY RESULT.
3. GPI inputs trigger on a momentary pulse. To be recognized without ambiguity, a GPI trigger pulse should have a
duration of at least 40 ms.
The reference input must conform to SMPTE
170M/SMPTE 318M/ITU 624-4/BUT 470-6 for
standard definition signals and SMPTE 274M /
SMPTE 296M for high definition signals and is used to
phase the HD/SD SDI outputs to the studio. A
reference mismatch may occur if there is a difference
between the input video format’s frame rate and the
reference format’s frame rate. When a mismatch
occurs, an input error will be flagged and the card-
edge Status LED will turn red to indicate the
mismatch. The table shows the supported reference
signals with respect to the input signals:
Supported input signals Reference
525 (SMPTE-259M-C) NTSC (SMPTE-170M)
625 (SMPTE-259M-C) PAL (ITU 624-4)
1080i50 (SMPTE-274M) 1080i50, PAL
1080i59.94 (SMPTE-274M) 1080i59.94, NTSC
720p50 (SMPTE-296M) 720p50, PAL
720p59.94 (SMPTE-296M) 720p59.94, NTSC
3G Lvl A 50/60 NTSC, PAL
ASI (EN50083-9) -------
Figure
2-2 GPI input trigger pulse timing

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HCO-3901 | 7
The GPIO interface is implemented on an HD-15 connector. The pinout is as follows:
GPI Label Pin #
GPI-IN-1 4
GPI-IN-2 9
GPI-IN-3 3
GPI-BYPASS-IN 6
GPI-AUTO-IN 10
GPI-OUT-1 1
GPI-OUT-2 7
GPI-OUT-3 2
GPI-BYPASS-OUT 11
GPI-AUTO-OUT 5
GPI-PWR-IN 15
GND 8,12,13,14
Note: Users may find it convenient to purchase Grass Valley’s NSH-15M HD15-to-terminal-block adapter, which
provides easy access to the GPI-I/O pins.
Using the GPI interface
•Trigger the GPI-IN-1, GPI-IN-2 or GPI-IN-3 pin to select that input.
•Trigger the AUTO-IN or BYPASS-IN pin to select that mode
•Read the GPI-OUT-1, GPI-OUT-2 and GPI-OUT-3 pins to identify which output is selected (“0” indicates
selection)
•Read the AUTO-OUT and BYPASS-OUT pins to determine whether either of these modes is in operation (“0”
indicates selection).
Note: When a GPI INPUT is triggered while the card is operating in auto mode, the card switches to the input
selected by the GPI. It may switch to manual mode, or remain in auto mode, depending on the setting in the Switch /
Config Auto panel (see page 13). It is possible to select the input via GPI even when the HCO-3901 is in bypass
mode.
When GPI-IN-3 is triggered the card will switch to Manual mode and will have to be placed back in AUTO mode by the
user if desired. When the user configures AUTO mode again, the card will select IN1 by default unless the user has
previously selected IN2 manually.

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8| HCO-3901
3 Operation
3.1 Control options
The HCO-3901 can be controlled in different ways:
•The local control panel and its push-buttons can be used to move through a menu of parameters and to adjust
parameter values (see section 3.3).
•Grass Valley’s iControl system can be used to access the card’s operating parameters from a remote computer,
using a convenient graphical user interface (GUI). (see section 3.4)
3.2 Card-Edge Status LED
The status monitor LED is located on the front card-edge of the HCO-3901, and is visible through the front access
door of the DENSITÉ-3 frame. This multi-color LED indicates the status of the HCO-3901 by color, and by
flashing/steady illumination.
The chart shows how the various error conditions that can be flagged on the HCO-3901 affect the LED status.
•If a cell is gray, the error condition cannot cause the LED to assume that status
•If more than one LED status is possible for a particular error condition, the status is configurable.
See Section 3.4.14 for details.
•The factory default status is shown by a 
The LED will always show the most severe detected error status that it is configured to display, and in the chart error
severity increases from left to right, with green representing no error/disabled, and flashing red the most severe error.
LED Status
Error Condition
Green
Yellow
Red
Flashing
Red
No errors 
Backup Input 
Reference Presence

Bypass Mode 
Video error 
Expected video format error 
Input timing out of range 
Reference mismatch

Black detection 
Freeze detection 
Audio presence group 
Audio silence channel 
Rear presence error 
Card Fan

If the LED is Flashing Yellow, it means that the card is selected for local control using the Densité frame’s control
panel. See Section 3.3 for details.

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HCO-3901 | 9
3.3 Local control using the Densité frame control panel
There are two types of local control panel:
Panel type Frame models Appearance
Physical Densité-2, Densité-3, Densité-3+FR1,
Touch screen Densité 3+FR4, GV Node
The local control panel is fastened to the front of the controller card.
•The physical panel is accessed by opening the front door of the frame.
•The touch screen panel is accessed through an aperture in the frame door.
The panel consists of a display capable of displaying two lines of text, each 16 characters in length, and four
pushbuttons. The functionality of the pushbuttons is as follows:
[+] [–] Used for menu navigation and value modification
[SEL] Gives access to the next menu level. When a parameter value is shown, pushing this button once
enables modification of the value using the [+] and [–] buttons; a second push confirms the new value
[ESC] Cancels the effect of parameter value changes that have not been confirmed; pushing [ESC] causes the
parameter to revert to its former value.
Pushing [ESC] moves the user back up to the previous menu level. At the main menu, [ESC] does not
exit the menu system. To exit, re-push the [SEL] button for the card being controlled.
If no controls are operated for 30 seconds, the controller reverts to its normal standby status, and the selected card’s
STATUS reverts to its normal operating mode.
To assign the local control panel to the HCO-3901:
•Physical Panel: Push the SELECT button on the HCO-3901 card edge (see Section 1.4).
•Touch-screen panel: In the home screen, touch the virtual button corresponding to this HCO-3901.
The STATUS LED on the HCO-3901 flashes yellow, and the touch-screen status shows yellow for the IPG-3901.
Use the control panel buttons to navigate through the menu, as described above.
The complete menu structure is shown in ANNEX – HCO-3901 User Interface, beginning on page 41.

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10 | HCO-3901
3.4 Remote control using iControl
The operation of the HCO-3901 may be controlled using Grass Valley’s iControl system.
•This manual describes the control panels associated with the HCO-3901 and their use.
•Please consult the iControl User’s Guide for information about setting up and operating iControl.
In iControl Navigator or iControl Websites, double-click on the HCO-3901 icon to open the control panel.
3.4.1 The iControl graphic interface window
The basic window structure for the HCO-3901 is shown in figure 3.2. The window identification line gives the card type
(HCO-3901) and the slot number where the card installed in its Densité frame.
There are four main sections in the window itself, identified in figure 3.2:
1. The Status Icon area shows a series of seven icons that report
the status of some card parameters. Figure 3.3 shows the
various forms that may appear; their meaning is described below.
Icon 1 – Control status
•A: Green - Remote Control via iControl
•B: Yellow - Local control using the menu
Icon 2 – Reference status
•A: Green - Locked to external reference
•B: Red - Reference is missing
•C: Grey - No reference
Figure 3.2 HCO-3901 iControl graphic interface window
1
2
3
4
Figure 3.3Status Icons
A
B
C
1 2 3 4 5 6 7

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HCO-3901 | 11
Icon 3 – Input 1 status
•A: Green - Status OK; format shown
•B: Red – Error
Icon 4 – Input 2 status
•A: Green - Status OK
•B: Red - Error
Icon 5 – Input 3 status
•A: Green - Status OK
•B: Red - Error
Icon 6 – Bypass Status
•A: Bypass not active – switch operational
•B: Bypass activated
Icon 7 – Card Heath status
•A: Green - Fan OK and GPI Power OK
•B: Red - Fan error or GPI Power Error
When an icon shows an error state, a message describing the error will appear beneath the icons. If there is more
than one error, they will cycle through the display.
•The icon whose status or error message is shown is highlighted with a mauve background
•Move the cursor over an icon to display its status message. Error message cycling will resume when the
cursor is no longer over an icon
2. The left-hand side of the panel contains a series of buttons that control the contents of the main window (section
4). Click on one to access the indicated controls. The selected button is highlighted (darker) and the main panel
heading matched the button name.
3. At the bottom are the controls for the User presets.
4. This section contains the main operating controls and displays for managing the HCO-3901’s feature set. The
contents are selected by clicking a button on the left-hand side of the screen.
The left side of the window, containing sections 2 and 3, can be hidden or revealed by clicking the arrow icon at the
center of the left side border.
Each of the panels associated with the groups accessed from the buttons in Section 2, and shown in Section 4, is
described individually in the following sections.
3.4.2 The Switch panel
The HCO-3901 has three modes of switch operation, selected from the Select tab in the Switch control panel.
Clean switching in any of these modes is enabled by selecting the Clean Switch Enable checkbox.
This activates the Timing panel, where the clean switch timing requirements can be set up. See section 3.4.4
NOTE – Input 3 is a secondary input, and has limitations:
•It is not included in the AUTO switch mode and the associated alarm-setting functionality.
•Clean switches are not supported.
•It does not generate thumbnails or fingerprints.
•It is not selectable for audio level metering (RALM) or ALC.

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12 | HCO-3901
The graphic at the top of the panel identifies the input
that is currently selected, and indicates the validity of
all 3 inputs by the color of their icons.
1. Manual switch
Manually switches the HCO-3901 output between
the three possible sources: input 1, input 2 or
input 3.
•Click the Manual button. The three possible
sources are shown on the left. The graphic on
the page shows which input is currently
active.
•Click the Manual Switch button for a different
source. The selection shows green, and the
Take button is activated, appearing red.
•A countdown (from 10 seconds) underneath
the Take button shows how long the Take
button will remain active before it times out.
•Click the Take button while it is active to
switch the HCO-3901 output over to the other
source.
2. Auto switch
Auto switch uses Alarms based on the status of the
selected input to determine whether the other input
should be selected.
•Click the Auto mode button in the Select tab to
activate the Auto mode.
•NOTE – AUTO mode is only available for inputs 1
and 2. If you select AUTO mode while input 3 is
active, you will be warned that if you proceed, the
input selection will automatically fall over to Input 1
In addition, if you select Input 3 using GPI-IN-3 while in Auto mode, you will force the selection of input 3, and
the card will revert to Manual mode.
Figure 3.5Manual Switch controls
Figure 3.6Auto Mode
Figure 3.4 Switch panel

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Auto mode operation:
•If Input 1 fails with an alarm level of higher priority than input 2, the HCO-3901 will automatically switch over
to Input 2
•If the Switch Mode has been set to Switch and Return (see below), the HCO-3901 can automatically switch
back to Input 1 if it has a lower alarm priority than input 2.
•If the Switch Mode has been set to Switch To (see below), the HCO-3901 will not switch back to Input 1 even
if it has a lower alarm priority.
•NOTE: for certain errors, the switch-over is delayed by 0.5 second beyond the selected duration because it
often happens that the same signal is feeding both inputs, possibly offset by a frame or two. The delay
ensures that the alternate feed is indeed error-free before switching to it. The errors affected are:
oVideo error (when detection duration is 1 second or more)
oBlack detect
oFreeze detect (when detection duration is 1 second or more)
oAudio silence detect
Select the Config Auto tab to select the Auto Mode functionality:
In the Switch Mode box, select:
oSwitch To: switches to the input #2 (if it is valid)
when the alarm conditions trigger a switch
oSwitch and Return: switches to input #2 (if it is
valid) when the alarm conditions trigger a
switch, and then switches back after a
predetermined interval, counted from the time
the original input returns to a valid state. Use
the slider at the bottom of the tab to set the
interval (0 to 59 seconds, 1 to 10 minutes).
oToggle:switches to the other input (if it is valid)
when the alarm conditions trigger a switch. It will stay on that input until an alarm condition appears for
that input in which case it will switch to the other input again (if it is valid).
In the GPI Control Event box, select whether the HCO-3901 will change to manual mode, or remain in auto
mode, when a switch is triggered from a GPI while the HCO-3901 is in auto mode.
3. Bypass
Bypass triggers relays located on the rear panel to connect the inputs directly to the outputs. When the HCO-3901 is
in Bypass:
•The currently selected input (IN 1 or IN2) is connected to PGM OUT
•IN 3 is not protected by the bypass relays, and cannot appear on PGM OUT
•The PVW (preview) outputs are disabled
•There is no video / audio / metadata analysis
The bypassed HCO-3901 card is electrically disconnected from the Densité signal system, and can be removed from
the frame with no discontinuity in the signal path.
NOTE: Grass Valley recommends that you set the HCO-3901 in BYPASS before removing it from the Densité frame
to ensure no disruption in the signal when the card is removed and reinserted.
The Operating Mode can also be selected using the Menu from the local control panel (see Section 3.3), and
via the GPI interface on the rear connector panel (see Section 2.2)
Figure 3.7Configure the Auto Switch Mode

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14 | HCO-3901
Preview Output tab
Use this tab to select the source for the three preview outputs.
•Auto Selects the Preview output based on the
current program output:
Program Preview
Input 1 Input 2
Input 2 Input 1
Input 3 Input 3
•Input 1 Rear panel input 1
•Input 2 Rear panel input 2
•Input 3 Rear panel input 3
•Program: The same as the Program output
3.4.3 The Alarms panel
The HCO-3901 continuously monitors the condition and
status of the input signals it is processing. The information is
used to decide whether the input must be switched in Auto
mode. It is also used to flag the status of the card in the
iControl system.
Note that, because Auto mode involves only inputs 1 and 2,
input 3 is not considered in the alarm process, and does not
appear in this panel.
In general:
•A number of parameter values are continuously
tested against user-defined thresholds or for
presence/absence.
•Each parameter test is assigned a Level, to
determine the extent to which it contributes to the
changeover decision.
Many alarms can be enabled or disabled using the Enable
checkbox in their control panel (see below).
An alarm that is enabled:
•Contributes to the switch decision process based on
its LEVEL.
•Is reflected in the device status as reported to iControl (LEVEL has no bearing on this)
Each alarm is assigned a LEVEL that determines its contribution to the switch decision process. Possible levels are:
•1 – highest significance
•2 – lower significance
•OFF – not used in the switch decision process
Figure 3.9Alarms panel
Figure 3.8 Preview output source selection

GUIDE TO INSTALLATION AND OPERATION
HCO-3901 | 15
Some alarms are arbitrarily assigned as Level 1 and cannot be
changed by the user (e.g. Video Error is always a Level 1 alarm).
Their Enable checkbox is ticked, and greyed-out.
Other alarms have a pulldown in their control panel that allows the
user to set the level.
The HCO-3901 uses the most significant alarm detected for an
input as the alarm level for that input, and then uses the truth table
shown here to decide whether to switch from input 1 to input 2 and
back.
The Alarms section of the iControl panel gives access to all alarm-
related settings.
•The Video and Audio tabs show lists of the parameters for
which alarms exist, and show the current settings for each,
for both inputs.
•Click on one to select it, and the control panel for adjusting that parameter appears at the bottom of the
screen.
Video – Video Error alarm
This error is always ENABLED and the level set to 1, 2 or OFF. The
factory default value is level 1.
Use the slider to set the duration for which the error must
continuously exist before the alarm is flagged. The nominal range of
durations is 0.05 to 90 seconds. When durations ≥1 sec are
selected, there is an additional 0.5 seconds intrinsic to the error
detection algorithm that will prevent switching when there are nearly-
coincident errors at the two inputs.
In AUTO MODE, if switching is not desired when input 1 changes
video format, set the Duration to at least 0.5 seconds
The LED color is not configurable.
NOTE: This is the only error that can be triggered in the ASI
operating mode. All other errors will be disabled.
Figure 3.10 Video Error alarm configuration

GUIDE TO INSTALLATION AND OPERATION
16 | HCO-3901
Video – Format Mismatch
The user sets an expected format for each input using the pulldown in the control panel. The HCO-3901 compares
this with the actual format detected at the input, and flags an error if
they do not match, after a 0.5 second delay.
Formats listed in the pulldown are:
•525
•625
•1080i 59.94 Hz
•1080i 50 Hz
•1080p 59/50
•720p 59.94 Hz
•720p 50 Hz
•SD
•HD
This error can be Enabled using the checkbox, and the level set to 1,
2 or OFF.
Use the LED Color pulldown to choose the color that will be
displayed by the status LED on the card edge when a Format
Mismatch error is detected. Choices are:
•Green, Yellow, Red, Flashing Red
Video – Timing Error
This error is generated if the timing offset between the output signal
and the video input is greater than 2 lines.
•This alarm is always enabled, but is not a switch condition for
either of the inputs.
The LED color is not configurable for this alarm.
Figure 3.11 Format Mismatch alarm config
Figure 3.12 Timing Error alarm Config.