There was a time in our industry when monitoring signals from a distant location was neither practical nor necessary. Broadcasters acted locally instead of over large expanses or territory.
Then two dynamics made remote monitoring both important and profitable. First, as some broadcast stations grew, it became harder to find qualified transmitter engineers. Second, labor costs became an issue to owners who began to feel the inexorable rise in costs.
For these reasons, controlling a transmitter from a remote studio location was technically possible and useful from a business standpoint. By using a modem over a leased loop from the local telephony carrier, a broadcaster could return data that allowed control and monitoring of meter readings.
Over the last two decades, the importance of remote monitoring has grown considerably. Fueled by business imperatives and erosion of profit margins, the ability to remotely monitor and control has become important to broadcasters.
Borrowing from the IT world
Modern digital technology, especially IP-based networked systems, has facilitated an explosion of applications that makes good technical and business sense. Our narrow and rather small industry has been able to borrow techniques from the much larger IT world. These techniques have made facilities more reliable and more maintainable.
For example, SNMP has been in use for a long time in the IT world, monitoring the infrastructure of management information systems all over the world. It can monitor the health and operational parameters of disk arrays, robotic archives, IP routers and desktop computers, making large and complex systems much easier to maintain.
When an SNMP-enabled system detects an incipient failure, it sends a message to a management system, which then displays an error message. SNMP management systems allow logging of errors and remote control when the devices support it.
The first system I worked with was an HP OpenView SNMP system, which managed DiviCom (now Harmonic) MPEG encoders. By using an existing SNMP product, DiviCom showed that broadcasters could successfully monitor and control hardware using common platforms.
Broadcast monitoring systems
In the last eight years, several companies deeply entrenched in broadcast hardware have developed systems for monitoring both their own hardware and that of companies who recognize the value of integrating product lines. Some companies have brought expertise in multi-image display technology directly into the monitoring system, allowing the display to be reconfigured when error messages are important enough to force them to the monitor wall.
This ability to highlight maintenance information only during critical events is extremely powerful for operations personnel. It reduces the number of displays required in a control room and permits complex graphics displays that show, for example, the geographic location of a failure along with the explicit information on the nature of the event.
Remote monitoring systems can also show the location of a failed component — for example, a distribution amplifier that has reported its own demise to the monitoring system — both as text information as well as the rack layout and the explicit frame and slot at risk. Systems can be programmed to bring up schematics that show how the component is used in the system, making a workaround plan easier to formulate.
I first saw such a system in the late '80s in London at ITN News. The system would flag a problem and then bring up a graphic, showing perhaps the failed frame synchronizer and how it was routed in the system. By dragging a replacement from a pool in the corner of the display on top of the failed unit, the system commanded the house router to switch the failed synchronizer out of the path and replace it with a spare. The operator did not need to know input and output numbers, or even use a router panel. The monitoring system and the control overlay allowed simple analysis and effective repair without complicated actions.
This should be the goal of all monitoring and control systems. However, simplification of complex environments is increasingly difficult without using a system that can interact with IT systems. As we integrate more IT components into broadcast infrastructures, we need to increasingly look to systems that converge on common platforms, or at the very least allow the display of data collected from SNMP and other monitoring systems.
Evaluating signal monitoring
Today, with centralized operations and other WAN systems, it is often important to bring data and control, as well as the monitoring of the signals themselves, back to a central location for evaluation. Using a scope, a broadcaster can digitize the waveform and transmit that data over a network. But this process is bandwidth-intensive if the data is to be even close to real time.
Another approach is to probe the signal, catching a snapshot of the signal and transmitting both a thumbnail and a representation of the waveform in low bandwidth. This is often enough, especially if failure conditions, such as loss-of-signal or out-of-range parameters, trigger a remote alarm of more intensity.
If desired, a streaming copy of the signal can be forwarded at whatever bandwidth necessary to allow adequate analysis of picture or audio errors or content verification. System latency can complicate such monitoring because streaming engines can take many frames to deliver encoded content. Monitoring of closed captions, MPEG stream analysis, PSIP data and a host of other information gathered routinely from content is possible and highly useful.
Lastly, in some cases, small and inexpensive remote monitoring devices can provide highly useful information. A solution can be deployed to cable headends that remotely monitors a station's signal, verifying that the signal integrity is good without delays while operators find phone numbers and chase down their counterparts.
Security cameras and remote monitoring systems can be combined to permit lights-out facilities to be monitored almost as if an operator has been dispatched to a location where trouble is suspected, such as to an unattended transmitter building.
With such technology, we now can determine when failures happen and often repair the affected system using remotely monitored and controlled routing systems. The largest broadcast remote monitoring systems are the network distribution systems used by most of the large networks. These not only monitor the health of the network signal, but also switch receivers and, like E.T., phone home for further instructions.
John Luff is a broadcast technology consultant.
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