This article is from the free ebook “Optimize Your Air Chain.”
As we explore ways to optimize and improve the efficiency of our air chains, allow me to share a few thoughts and experiences around the idea of simplification.
Demands on a radio station air chain have changed a lot over the past couple of decades. It used to be that getting stereo audio to the listeners was all that was required. While it sometimes took a surprising number of boxes to accomplish this, the end product was relatively simple.
Then along came RDS, HD Radio, diversity delay adjustments, live traffic data, album art, remote studios, voice tracking, and a slew of other complications that, if we aren’t paying attention, can create rather complex air chains with many failure points.
New technologies and the demands from our audiences require us engineers to think in a much more strategic manner when both planning and working with the modern air chain.
For me, one priority remains the same: Keep It Simple (Smarty?).
Simplicity begins by considering what’s truly most important. That goes back to the basics in radio: delivering audio to the listeners. Everything else is anchored to this foundation.
Many years ago, I was working a project in Los Angeles. My goal was to get as close as reasonably possible to “five nines” uptime. A noble aim, one that I thought I could achieve by over-engineering each system.
I designed a web of interconnected and layered devices so that if any failed, the backup could be routed remotely or automatically into the air chain without a site visit.
What a great idea on the whiteboard.
What a mess in real life.
It quickly became very difficult to determine what was actually on the air and what was in standby. The need for numerous tallies, monitoring points and alarm triggers quickly grew to the point where the wiring was far more complicated than any other site I oversaw.
After months of headaches and plenty of downtime, we went back to isolated main and backup air chains with a simple A/B switch between diverse paths. The station seldom had another notable outage due to equipment failure.
This was a hard and expensive lesson, but a valuable one. It taught me to look at the air chain differently.
I began removing all unnecessary appliances from the on-air path. Eventually this got down to audio source, EAS and processing. It was literally a couple boxes in a rack that kept stations on the air, with all other systems wired in a way that prevented them from taking out FM audio.
Auxiliary sites were built around same barebones equipment necessary to keep the music playing.
From this core K.I.S.S. foundation we can begin adding features.
For example, RDS is inserted into the processor, and if it fails, no one will die. Diversity delay equipment, if required, is in the HD path, not the FM path, because, while important, if HD1 goes down fewer people will miss it than if FM is silent.
Inline audio switchers were removed in favor of multiple discrete paths. And so on.
To achieve a more robust backup to both the primary and backup chains, I prefer to have two diverse audio paths to the audio processor(s). If the facility is using AES67, this is often primary, but an old-fashioned AES3 or even analog lane from the source audio is valuable, especially if a switch on the AES67 network fails.
And while many processors have an automatic fallback to the second input when the main is lost, I favor manual switching to ensure I’m aware the main path is down and can more effectively troubleshoot the system.
Most modern consoles use AoIP, and some are entirely virtual, which unfortunately means they lack meaningful AES3 or analog input and output options. This is where I find taking an old-school approach helpful.
As mentioned, getting audio to the listeners is the most important task, so consider the simplest ways to do it. A CD player wired to the STL or standby audio processor’s second input can buy you an hour to swap gear or get a prod studio ready to become the main.
Better yet, a cheap Windows PC with a Focusrite USB sound card and freeware automation system, such as RadioDJ or Playout One Standard, can provide endless hours of content to keep listeners happy while repairs are made.
If your automation system supports running a standalone machine without a connection to a remote database or server, that’s a great option.
If these offline emergency audio backups are implemented, I recommend you set recurring reminders to have your PDs update their playlist and liners so things aren’t too out of date when needed.
If physical space allows, consider outfitting an office or production studio with an inexpensive “classic” console, mic and playout system.
STL paths should also be viewed from a what-matters-most perspective. With many stations moving to IP STLs, we are now dealing with large corporations that own the circuits we rely on. Even with contracted SLAs, repairs may take hours.
A backup RF STL or unlicensed 5.8GHz link that you own is more than enough to survive “backhoe fades” on the local fiber circuit. Cellular and satellite backups are also great, but again we’re dealing with big companies in the middle, and a local disaster may overwhelm their capacities quickly. Point-to-point is arguably the simplest and most reliable option.
If you implement automated switching to backup feeds and sources, add alarming on the links to ensure you’re notified when failure occurs.
Finally, considering our transmitter sites, this is another great opportunity to simplify and streamline the air chain.
I prefer to have both the primary and backup audio paths going to both the main and backup transmitters. This gives more options than simply having the backup audio lane (say, your RF STL) land only at the backup transmitter.
This works best if you can remotely access your exciter to switch inputs. A composite or audio switcher can be helpful, but these are points of failure especially if they are not passive, so I lean toward leaving them out and wiring direct whenever possible. Less is more.
There are a thousand ways to optimize and improve the air chains at the stations we maintain. From my experience, great gain has come through removing unnecessary complexity and minimizing failure points.
Thankfully, our industry has moved away from cart machines and miles of analog wiring in studios. But we’ve replaced those with servers, managed switches and cloud-based applications.
Failures in these systems are often more technically challenging to troubleshoot than a loose ground connection on a 66-block. So I personally am always looking for ways to bring the K.I.S.S. principle back into the radio facility so that the music never stops playing.
Jeremy Preece, CPBE, DRB, is president of Wavelength Technical Solutions LLC.
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