New adventures in remote control

Remote control systems have evolved to an incredibly level of complexity and functionality
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Figure 1. This remote control system base screen provides access to control (left side), monitoring (center) and metering (right side) functionality. Base Recon screen courtesy Harris.

Those of us who are becoming more gray and feeble will remember the days when remote control systems were limited in capacity and function. They normally required a metallic pair between studio and transmitter with no transformers as DC voltages. They provided a limited number of controls and metering channels (usually 10) and were only used for nondirectional radio transmitters.

The regulatory feeling was that directional radio stations were so unstable that a first-class radio/telephone operator had to be on-site at all times. This wonderful situation put many technical types through college (including your author). There was absolutely nothing to do, so you could do homework on the job. As for TV stations, the commission fully realized that the operation of one of those monsters was roughly like flying a helicopter — one hand on video and the other on black level at all times. How could that possibly be controlled remotely?

Remote control systems in those days depended on stepping relays that, hopefully, would step synchronously at both ends of the system. The samples of the measured parameters were connected much as they are today, except that some transmitters had control circuits that didn't match well with anything. Stations often had to design and construct a relay panel to provide an isolating interface to avoid certain system destruction. Oh, how that has all changed.

Today, not only has the commission determined that directional AM antennas are stable and removed the requirement for a licensed operator to be at the transmitter site, it has eliminated all testing for operators. In addition, TV transmitters have been judged sufficiently stable that they don't need on-site operators either. The result is that remote control systems have become unbelievably complex and capable.

Now, the Internet can provide broadcasters with a high-speed, reasonably secure path for multiple uses. Broadcasters were quick to take advantage of this capability for their transmitter control systems. Earlier systems provided for access to transmitter monitoring and control of a single site from any location through the Internet. That meant the chief operator could access his equipment from the office, home or on the road simply by dialing in with a modem.

Next, systems appeared that allowed technicians to measure the performance of DTV systems and to remotely adjust the necessary precorrection circuitry to maintain proper operation. The ability of those early systems to modify the operating parameters by phone has been carried over into use of the Internet.

Today's control functionality

Now, operators can use a single control system to access essentially any number of transmitter sites in any location. All they need is an Internet access point. They can use almost any hardware — from a master monitoring system with tons of logging and trend-spotting recording features, to a wireless PDA or cellular browser. This is a bit much for those of us who have only recently convinced our mates that a flashing 12:00 on the VCR means that the diagnostics are working properly.

The new control systems present the data in just about any format desired. Not only do metered parameters actually appear to be on meters, their values can also be shown in bar graphs and on digital readouts. Towers are actually shown as tower-shaped icons with the lights shown in their proper location, indicating whether they are operating properly. Operators can adjust adaptive correction circuitry remotely and simply download software upgrades from the manufacturer. Transmitters are shown in block diagram form, so alarms or out-of-tolerance conditions appear where they exist in the actual system. Figure 1 shows the base screen of one of these remote control systems.

Not everything in the new systems depends on staff input. For example, staff can be notified of fault conditions by e-mail, pager, cell phone messages or good old-fashioned alarms going off in the studio. Systems can route alarms to more than one person, and alarms can vary with the severity of the fault. For example, switching an STL to the hot standby might be cause to notify the local maintenance technician but not rise to the level of notifying the group director of engineering. On the other hand, a full-blown off-the-air fault would lead to notification of several people to ensure the quickest possible response.

Multiple access levels with different passwords are common. One password can allow the engineer full access to monitor and control everything at the transmitter plant. At the same time, a separate password could limit the operator on duty at the studio to normal monitoring and basic corrective procedures. A third level might allow monitoring only, with no control access at all. Furthermore, many of these systems allow more than one staff member to be in the system at the same time without interfering with the others. Obviously, these systems are protected to a high degree by firewalls and passwords — especially those levels permitting control actions.

The password-protected systems available from some companies will also allow the transmitter manufacturer access to install system upgrades, perform diagnostics when problems exist and make some corrective adjustments. This sometimes leads to snivels from technicians that they don't want anyone else having access to “their” transmitters. Those comments are usually from operators that really don't have much of an idea about how the equipment works in the first place. A good operator is always open to help from the manufacturer — in fact, they probably need such help periodically when new challenges arise.

The new generation of control and monitoring systems offers the ability to monitor and operate all the transmitter plants in a large network from a single control location. These systems allow operators, technicians and supervisory personnel access on an as-needed basis, while blocking others' access. Perhaps more importantly, access to the systems is convenient and fast. Those who need to know what is going on, or think they do, can check on any transmitter in the system using a PDA, even while having dinner. Of course, your guests might consider that rude.

Don Markley is president of D.L. Markley and Associates, Peoria, IL.

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