Remote control systems: Push the button and hope
You can bet on it. It will happen on a dark and stormy night. The telephone will ring and a strange, mechanical-sounding voice will advise you that the transmitter is off the air — or the tower lights are out — or that the power is off and the generator won't start, or some other problem. You enter the magic numbers into the telephone and push the button for “raise” or “on” and wait to see what strange numbers the mechanical voice will repeat next, if any. It is at that time that the true character of the remote control system, either the hardware or your installation, will be known.
Over the years, remote control systems have changed significantly, just as everything else about the transmitting plant has. When this author started in the business, the standard remote control had 10 channels, selectable with a telephone dial that caused a stepping switch at the transmitter to be advanced in a strange and often variable fashion. The unit required a dedicated telephone line and the meter readings would usually give a reasonable indication of the transmitter parameters. It didn't have to be overly accurate as it was only used on non-directional AM or FM stations. Directional AM and TV stations could not be operated by remote control. Now, the era of deregulation allows all stations to be operated by either remote control or be unmanned if certain criteria are met. One of the arguments for such operation is that equipment is much more reliable than it was years ago. As most equipment is now solid state, with the possible exception of RF output devices, that probably is a true statement.
The kicker is that the rules concerning the operation of the physical plant haven't changed. In fact, they are even tighter than in past years in some areas. For example, the remote meters have a required accuracy of ±2 percent and the station is required to maintain the calibration to meet that accuracy. To examine those rules further, it is advisable to review Sections 73.1300 and 73.1350 of the Rules and Regulations.
Section 73.1300 simply says that the station can be operated by remote control or unattended if it can comply with the EAS requirements. In other words, the way the station is operated is largely up to the individual licensee, but the response to emergency messages is an absolute requirement. While that may seem to some like an unnecessary burden, the events of Sept. 11 have shown the justification for that requirement.
Section 73.1350 (a) is the one with the wide-reaching requirement. It states that each licensee is responsible for maintaining and operating its broadcast station in a manner that complies with the technical rules set forth elsewhere in this section in accordance with the terms of the station authorization. In other words, you can get your meter readings by semaphore flags as long as that method results in accurate indication of, primarily, the power output and the tower lights. It is also necessary to be able to turn the transmitter off. Of course, that particular method would require a line-of-sight path and two operators so it probably wouldn't be too practical. The point here is that the individual station is given a great deal of latitude to install a system of their choosing, but the results have to be correct within the required level of accuracy.
Remote control systems went through a great metamorphosis a number of years ago when they first started using microprocessors. A number of new units appeared at the conventions offering differing levels of complexity and capability. The usual shakedown has occurred over the years, resulting in a smaller number of systems being offered. The units currently on the market have been field proven to be reliable and stable.
This author has long argued that remote control systems should be standardized in accordance with some yet-to-be-written guidelines. All remote control systems should have the same plugs on the back — one per transmitter with one for the building systems. Then, all transmitters could have one plug, enabling them to be connected to the remote control. Since that hasn't been done, and probably never will be, the installation of a new remote control system should be started with a great deal of planning. First, it is necessary to determine just what parameters need to be measured on each piece of equipment as well as the building systems. The sum of all of that, plus a healthy margin for future additions, determines the number of measurement channels for the system. The same action is then taken with regard to the number of command channels. Depending upon the system, the larger measurement or command channels will usually determine the actual configuration of the remote control system. Then, some decisions need to be made to further identify the system to be installed. Is access by modem desired or necessary? How many sites are involved in the system? What type of link will be used between the control point and the transmitter site(s)?
When all of this information is on hand, the next move is to contact the manufacturers of choice to actually configure a system that will meet the anticipated station requirements. One little point should be carefully considered in selecting a system. Adjusting a system using digital metering is always more awkward than with analog metering. It is frustrating to make a minor adjustment and then have to wait to see what that adjustment did. In selecting a remote control system, determine from the manufacturer exactly what the delay will be between when a parameter changes and when the new value appears on the monitor screen at the control point. A delay of a second or two is acceptable. Having to wait for 10 or 15 seconds to see the results of an adjustment is an unbelievable pain and should be avoided if at all possible.
As a last point, be advised that a well-configured and reliable remote control system for multiple transmitters isn't going to be cheap. On the other hand, today's crop of remote controls is stable and extremely reliable. They are flexible and allow a far greater degree of control over the transmitting plant than was available twenty years ago.
Don Markley is president of D.L. Markley and Associates, Peoria, IL.
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