Xiamen TV HD OB Van system

Xiamen Broadcasting Group

I. General Overview

The Xiamen TV HD OB Van (outside broadcast van) system supports program recording and live broadcasting. Each audio and video subsystem is equipped with complete signal routing and switching devices as well as signal monitoring equipment, enabling independent technical functions. Signal scheduling between subsystems is achieved through routing switchers to meet the recording and playout requirements of different program types.

Figure 1: Xiamen HD OB Van

The Xiamen TV HD OB Van was another collaboration between us and SONY. The entire system comprises three software components: UMD & TALLY System, Monitoring System, and auxiliary debugging software. Due to a complexity level far exceeding previous systems, the implementation posed significant challenges.

Figure 2: Director area UMD & Tally indication

Figure 3: Technical area UMD & Tally indication

II. TALLY System

As an essential component of traditional audio/video production, the TALLY system has gained increasing importance with the advancement and growing complexity of audio/video systems. The UMD & TALLY System is a highly reliable Software Products suite with over 10 years of project experience, deployed at numerous provincial and municipal TV stations with consistently positive feedback. The TALLY system for this Xiamen TV OB Van (outside broadcast van) project is built on the UMD & TALLY System.
In this project, the video system deployed two switchers, one matrix, a multiviewer, TALLY light display units, and CCUs among other UMD devices. The UMD & TALLY System reliably retrieves crosspoint states from the matrix and switchers. Based on this data, the software analyzes and distributes source name information and TALLY information to the multiviewer, TALLY light display units, and CCUs. The TALLY system also supports simultaneous audio/video switching, enabling real-time, seamless failover when the primary and backup video systems switch over.
To ensure system stability and safety, the system is configured with primary and backup servers supporting hot failover. During normal operation, the primary server handles all TALLY system functions while the backup server monitors the primary server in standby mode. When the primary server goes down, the backup server detects this immediately and can automatically take over without manual intervention. When the primary server recovers, the backup server monitors it until stable operation is confirmed, then hands TALLY system functions back to the primary server. The entire process requires no manual intervention. For additional safety, the system also provides a manual failover mechanism.
The Xiamen HD OB Van system design differs significantly from previous projects. The overall design is relatively complex, incorporating one Evertz matrix and two SONY switchers. During production, the system can produce a single program or use both switchers simultaneously to produce two programs. Since the TALLY system must fully track changes in the video system state, achieving rapid state tracking became a critical challenge.
When the system is in single-program production mode, it operates in three states: normal state, first emergency state, and second emergency state.
In the normal state, the system operates normally and the TALLY bus follows the PGM bus of the primary switcher.
In the first emergency state, the primary switcher is unavailable and the backup switcher takes over. The TALLY bus follows the PGM bus of the backup switcher.
In the second emergency state, both primary and backup switchers are unavailable and the matrix takes over their functions. The TALLY bus follows the EMG port of the matrix.
For state switching, the system is configured with two 2X1 changeover panels. The software virtualizes the 2X1 changeover panel states as a 2X1 matrix for rapid system state adjustment. When the primary switcher is unavailable, the primary 2X1 changeover switch performs the failover. When both switchers are unavailable and the matrix must take over, the backup 2X1 changeover switch is used.
For system safety, the primary changeover switch has the highest priority and the backup changeover switch has secondary priority. The system architecture diagram is shown below:

Figure 4: System architecture diagram

In addition to single-program production, the system must also support simultaneous dual-program production. The audio/video system requires modifications, and the TALLY system must be adjusted accordingly. The main adjustment involves TALLY group determination. Following the original logic and dual-program production requirements: the primary director area video wall TALLY information follows the primary production group (including primary switcher and matrix) output changes; the backup director area video wall TALLY information follows the backup director group (backup switcher and matrix) output changes; while the technical area, audio area, EVS area, and camera TALLY must simultaneously follow both primary and backup TALLY groups.
When designing the TALLY follow logic, both single-program and multi-program switching requirements must be considered, so a comprehensive TALLY follow logic is required. The overall logic is shown below:

Figure 5: System logic diagram

As shown in the diagram above, the PGM bus is the TALLY logic output for single-program mode (the output of the primary changeover switch in the single-program diagram). A new 2X1 changeover switch is configured for dual-program use. R1 and R2 represent the primary TALLY group output and the backup TALLY group output, respectively.
During dual-program production, the primary and backup switchers each handle the recording of one program. The matrix EMG1 and EMG2 serve as the emergency signals for the primary and backup switchers respectively. Normal emergency failover for both programs is achieved through the primary and backup 2X1 changeover switches.
Taking the primary director group TALLY R1 as an example: when the system is in single-program mode with the dual-program 2X1 changeover panel in single-program state, R1 follows the PGM bus. When the system is in dual-program mode with the primary switcher functioning normally, R1 follows the primary switcher PGM1 bus. If the primary switcher fails, R1 follows the matrix EMG1 port. R2 follows the same failover principle as R1.
The state table for R1 and R2 is shown below:

Figure 6: R1 and R2 state table diagram

Different TALLY group display requirements for different areas are achieved through TALLY group binding. The primary director area only needs to bind the R1 group; the backup director area only needs to bind the R2 group; the technical area, audio area, EVS area, and camera CCU area need to bind the R1+R2 groups.

III. Monitoring System

The Xiamen OB Van (outside broadcast van) Monitoring System is another highlight of the system, providing automated device monitoring capabilities.
The Monitoring System covers three parts. Part one: traditional audio/video equipment; part two: environmental parameters; part three: power supply system.

Figure 7: Monitoring System global topology diagram

Supported monitoring devices

Traditional audio/video equipment: peripheral devices Evertz, switcher Sony, matrix Evertz, multiviewer Evertz
Environmental parameters: Temperature and Humidity Sensor
Power supply system: UPS, power sensors, etc.

Figure 8: Xiamen OB Van switcher system topology diagram

Figure 9: Xiamen OB Van camera signal source diagram

Figure 10: Xiamen OB Van equipment room diagram

Figure 11: Xiamen OB Van parameter monitoring

IV. System Features

1. Composition

System functions: Real-time monitoring of all in-vehicle equipment, with alarm notification within 3 seconds of fault occurrence, and accurate, rapid fault localization based on alarm information.

2. Real-Time Performance

The system meets the specific equipment monitoring needs of broadcast stations. The monitoring system interface is intuitive and visual, and monitoring operations conform to the station's operational practices.
Critical alarm information during program playout is captured in real time, with an average of 3 seconds from fault occurrence to alarm notification.

3. Accuracy and Speed

Closely integrated with the signal flow topology diagram familiar to operators, enabling rapid navigation to physical equipment locations.
Clear hierarchy of views. During centralized playout assurance, shortcut keys allow rapid switching to the core equipment topology, displaying the current status of critical playout devices.

4. Easy system maintenance

The software adopts a plug-in architecture internally; adding new equipment does not affect the stable operation of the existing system. All monitoring system configuration resources can be exported as standalone XML files. During fault recovery, simply importing the XML file restores the monitoring system, greatly reducing recovery time.

5. System reliability

System reliability: The Monitoring System uses device polling to read device status parameters, ensuring no alarm information is missed. Device inspection frequency is configurable to balance alarm timeliness with system performance.

6. Flexible and practical

For different operations such as OB Van (outside broadcast van) program production or live broadcasting, video or audio, users can select different operational interfaces. Different personnel can choose different focus areas for display.

7. Log management

The system includes alarm log query and statistics functions. Through query and statistics, users can clearly identify potential issues in the system for convenient troubleshooting.

8. O&M knowledge base

After an alarm is generated, the cause and resolution can be queried directly for on-site reference. When new alarms occur, on-site personnel can also enter new solutions into the system for future use.

V. On-Site Usage

The Monitoring System has three primary applications in daily use:

1. System health check

The Monitoring System is well suited for vehicle-mounted systems. In daily operations, the OB Van (outside broadcast van) frequently travels to various locations for broadcast assignments. Vibrations during transit may cause equipment faults. After system startup, the Monitoring System is routinely used for a system health check. Through the health check, equipment status can be accurately assessed. If issues are detected, the equipment rack diagram enables precise fault localization, and the O&M knowledge base assists on-site personnel in handling related alarms.

2. Alarm assessment

During normal operation, the system can detect alarms within 5 seconds. When a critical alarm occurs, on-site personnel are notified. Combined with the monitoring interface, the system supports alarm impact assessment. On-site personnel can use the assessment report to develop rapid response plans.

3. Routine O&M management

After a period of operation, the system requires maintenance. Regular maintenance effectively reduces system instabilities and ensures safe, stable playout. The Monitoring System supports log and report functions. Through log reports, system instabilities can be accurately identified, and combined with alarm logs, systematic fault diagnosis can be performed.

VI. Auxiliary Debugging Software

Auxiliary debugging software, as the name implies, assists on-site personnel with daily tasks and simplifies workflow. It is a category of Software Products. In this project, we also provided multiple auxiliary debugging software tools.

JOYSTICK software

In addition to the TALLY system and Monitoring System, the system also includes JOYSTICK functionality.
The JOYSTICK function serves as an auxiliary switching tool. At the shading workstation in the technical area, on-site personnel monitor four images simultaneously on a quad-split multiviewer. When shading adjustment is needed, they must view the corresponding single-screen signal and the waveform on the oscilloscope. The JOYSTICK system facilitates this workflow.

Figure 12: JOYSTICK flowchart

In addition to camera RCP image adjustment, the JOYSTICK also supports dynamic MSU adjustment. In system design, a monitor is typically placed above the MSU workstation, with its signal sourced from a matrix output port. When on-site personnel switch camera positions on the MSU, the matrix input source for that channel is switched accordingly, ensuring the output signal matches the MSU selection exactly for convenient operation.

Figure 13: MSU flowchart

VII. Auxiliary Debugging Tools

Auxiliary debugging tools are primarily used in the following scenarios:

1. Scene change scheduling

Used for multiviewer signal scheduling when the OB Van (outside broadcast van) or studio produces different programs. The system supports link state snapshot functionality. When switching between different programs, one-click switching can be performed using this software.

2. Multiviewer scheduling verification

Used to verify the correctness of multiviewer signal scheduling. The system can retrieve system link information, tracing the mapping between multiviewer signals and matrix or switcher ports to ensure switching accuracy.

Figure 14: Auxiliary debugging software interface

3. Maintenance needs

Used by technical personnel to check wiring during multiviewer replacement or maintenance. With one-click switching, device name, device port, corresponding matrix output port, matrix input port, and other information are displayed on screen. On-site personnel can intuitively view the complete link relationships, facilitating link troubleshooting.

Figure 15: Link diagram

VIII. Project History

From March to September 2013, our company carried out the integration of the Xiamen TV HD OB Van (outside broadcast van) project, including system commissioning and trial operation. The project included the TALLY system, Monitoring System, and auxiliary debugging system, and passed acceptance by the station's project team.
Starting from September 2013, the OB Van (outside broadcast van) entered trial operation. Performance during the trial was normal, and the system has since transitioned to full operational status.