Ned Soseman /
03.04.2011 12:54 PM
Web-based transmitter remote control

Back in the day when you had to wind up your TV to watch it, licensed broadcasters were required to log transmitter meter readings every half hour, and only an FCC-licensed engineer could do it. Today, manual transmitter readings and transmitter log clipboards have become as rare as First Class FCC licenses, but that doesn’t mean that closely monitoring transmitter metrics has lost any importance.

In fact, transmitters have become so sophisticated and digital circuitry so precise that monitoring and controlling a transmitter can be done at microscopic levels never dreamed of by yesterday’s meter readers and maintenance engineers. Digital electronics gives transmitter engineers powerful new tools to predict and prevent failures and has rendered traditional analog meters nearly as obsolete as a green Xcelite screwdriver.

Transmitter remote controls are nothing new. At one time, they were crude but effective parallel devices. Readings were taken and sent to the station using a frequency-shifted teletype-type protocol over dedicated phone lines or microwave, and printed logs were automatically created on a teletype machine or modified electric typewriter. Simple transmitter remote control commands were usually accomplished using a rotary telephone-type dial. Eventually, the rotary dial was replaced and capabilities were multiplied by DTMF control tones or dedicated buttons.

About the time the first TRS-80 was set up on a broadcast engineer’s bench, it didn’t take long for some engineers to begin thinking of ways a computer could be used for remote transmitter monitoring and control. Thanks to the Internet, it’s a reality today. For that matter, nearly every modern transmission or broadcast infrastructure product with rack ears comes with an IP port, offering more precise and sophisticated control than ever before.

It’s one thing to take and track a dozen or so basic transmitter meter readings, but there’s a host of other transmitter, exciter and facility details worthy of tracking and monitoring using IP. Monitoring and tracking details, such as monitoring the RPMs each PA cooling fan is turning, can help engineers spot minor trouble or prevent catastrophic failures later.

There are several new ways to look into what’s occurring at a transmitter plant. Most remote DTV transmitters include some form of IP-based remote control that allows operators and the chief operator to monitor key parameters, make power adjustments and perhaps switch from one exciter or transmitter to a standby unit.

A remote eyeball

If your transmitter doesn’t provide an IP connection, the least expensive and most effective upgrade to monitoring an unattended transmitter plant is a webcam. A wide variety of reasonably inexpensive webcams are available: Some use WiFi, while others are hardwired with USB or FireWire; some see in the dark, while others provide remote pan and tilt. A strategically placed webcam or two can enable easy monitoring of status lights, power meters, video input, demodulator monitors, ambient building temperature or activity in the parking lot. Some webcams can be set to detect and record motion, providing additional unattended facility security. At the least, a webcam is a surprisingly useful and inexpensive tool for operators and managers to visually verify all is well at the remote location, or not.

Most new AM, analog and digital FM and DTV transmitters include a TCP/IP interface, and many provide a view of circuitry performance, electronic minutia and troubleshooting aids far more powerful than the meters analog systems offer. Data can include test values, status information, presets, fault indication and diagnostics to the component level. Additionally, an interface often includes fault logging describing the fault stamped with the time and date of the occurrence. In many new transmitters, this capability is built into a LCD screen mounted in the front of the cabinet. The TCP/IP connection usually offers identical capabilities from any Web connection. Many, but not all, offer these capabilities with a standard Web browser, while others require product-specific software.

Within limits

This new, nearly universal form of IP access may raise new concern among managers: After all, not everyone needs access to every function. Fortunately, most systems offer several levels of access. These levels have different names among manufacturers, but nearly all have similar steps. The basic level usually provides access to basic equipment monitoring functions. The next level offers control of the equipment, such as commands to switch off, switch on, reset or change from exciter “A” to exciter “B,” for example. The next higher level is authorized to configure the equipment. Parameters such as modulation, warning threshold adjustments and various other settings, which are not typical transmitter commands, are usually included at this level of access. The highest level of access, not unlike most computers, is administrative. As the name implies, this level is designated to allow the administrator to configure the network and user profiles, set passwords and user access rights, and add or edit e-mail addresses and perhaps telephone numbers for those who get notifications when a parameter goes out of tolerance. In addition, at one or more levels of the GUI, logbook events can be viewed and downloaded for archive and processing.

That late-night phone call

It’s one thing to get a 3 a.m. phone call from an employee too ill to make it to his early-morning shift; it’s another to be awoken in the middle of the night by your GM calling to report that the station is off the air. The first comes with the territory; the latter is something you would rather never happen.

Some add-on IP remote control equipment has the capability to call your telephone and report to you by synthesized voice that your transmitter or facility has a specific failure or that a parameter has exceeded a programmed tolerance value. Users can set the remote-control equipment to e-mail or call your phone as specified by the event and its severity, all with adjustable tolerance limit settings. Some even have the ability let you set what times not to call you, instead perhaps calling someone else in the middle of the night.

Another benefit of add-on remote controls is the ability to connect to equipment other than a transmitter and exciter. For example, you can monitor AC voltage, building ambient temperature, stack temperature or be notified if an intrusion sensor has been tripped. You could choose to be notified when a generator has been automatically started unexpectedly, when a temperature is too high or, by using a macro, when a transfer switch was used to switch to a standby exciter or transmitter. In some cases, STL gear or satellite receiver control can be included in an add-on remote control. Some add-on units offer up to 256 channels of metering status and control.

In short, there’s not much you can’t do with the right remote control from the comfort of your office, home or even smart phone. Set up your remote monitoring, control and notification system correctly, and you and your GM can expect to get a good night’s sleep.



Comments
Post New Comment
If you are already a member, or would like to receive email alerts as new comments are
made, please login or register.

Enter the code shown above:

(Note: If you cannot read the numbers in the above
image, reload the page to generate a new one.)

No Comments Found




Thursday 10:05 AM
NAB Requests Expedited Review of Spectrum Auction Lawsuit
“Broadcasters assigned to new channels following the auction could be forced to accept reductions in their coverage area and population served, with no practical remedy.” ~NAB


 
Featured Articles
Research & Standards
Discover TV Technology