This is one in a series about trends and best practices in codecs for radio.
Robbie Green is product manager, communications products for Telos Alliance. He is the former senior director, enterprise technology for Audacy and has held engineering management roles at Cumulus and Clear Channel, among other broadcast companies.
Radio World: Robbie what is the most important trend in the design or use of codecs for radio broadcasting?
Robbie Green: Hands down, it’s path redundancy. To ensure 100% uptime, you need to send your critical audio across more than one path. The good news is IP path redundancy is very cost-effective these days. You could pair two different wired ISPs, or an ISP and a low-cost IP radio option. As long as one link remains up, you are still on the air.
RW: More and more parts of the broadcast air chain now are performed in software rather than hardware. How has this affected broadcast codecs?
Green: If anything, it’s made codecs even more ubiquitous. As air chains have become increasingly virtualized and coding algorithms standardized, deploying codecs has become much easier.
Telos offers several virtual codec choices tailored to different tasks; all of them integrate into modern studio systems and AoIP networks quite nicely. Things have come a long way since the days of ISDN and 66 blocks!
RW: How well do today’s codecs integrate with today’s AoIP networks and infrastructures; what issues do they present?
Green: I’d say they integrate extremely well. As the people who invented AoIP for broadcast, we’d better have codec integration nailed down! Telos Zephyr Connect and iPort codecs integrate directly with Axia Livewire and AES67 networks. It’s very seamless.
RW: How widespread are IP-based systems for STL applications now?
Green: I’d say they’re very widespread. In many parts of the world, IP-based STLs are more the rule than the exception these days.
RW: What tools are available for sending audio to multiple locations at once?
Green: Telos Zephyr Connect and iPort are designed to send audio to over 64 locations using both a main and backup path for each link. As long as half the packets arrive on one path, and half the packets arrive on the other path, audio is seamless on the air. These paths could be two different internet connections, or a combination of some sort of wired or fiber path and an IP radio link.
RW: How are manufacturers assuring reliable transmission with low delay over marginal IP networks?
Green: The gold standard is really path diversity. When it comes to any RF or wired link, it’s not a matter of if the link will fail, but when. Eventually, a backhoe will cut the fiber, or some other radio in your vicinity will become spurious and disrupt your microwave link.
Fortunately, these days, there are very cost-effective options to achieve path redundancy. You can pair a business-class cable modem or fiber link with inexpensive IP radios to create an STL that won’t go down, even if you experience a fiber cut or interference issues with a microwave link.
RW: How can an engineer protect codecs and their related infrastructure from cyber attacks?
Green: Three words: “change the defaults.” These are crimes of opportunity, and factory logins are there to get you started, not for long-term use.
Changing usernames and passwords should be a routine part of any new equipment installation. There are lots of excellent password manager apps out there; pick one and let it generate unique secure passwords for your gear. It’s just good practice.
Ideally, you should also have any codec that is sending audio over the public internet behind a firewall, and sending the traffic through a VPN tunnel.
By creating a VPN, you can effectively create a link extension from location A to location B on the public internet that nobody else can access — think of it as a very long Ethernet cable. If cost and complexity are an issue, Ubiquiti offers inexpensive solutions like the Gateway Lite and Gateway Max that feature easy-to-use setup wizards
RW: Is availability of parts for legacy codecs a serious problem?
Green: Although many old hardware codecs soldier on reliably, there are units out there that are 10 to 15 years old, sometimes older. I don’t think parts availability for units this old is an issue, because advances in algorithms, connectivity and link reliability, plus the migration to software codecs for many applications, make replacing these old devices with new, modern solutions a wiser monetary choice than repairing them.
RW: What misconceptions do people have about codecs that you’d like to dispel?
Green: That the public internet isn’t ready for prime time when it comes to audio transport, and that 950 MHz STLs are the only way to guarantee reliability.
While 950 MHz links have traditionally performed well, they have several single points of failure — a dish can be damaged by falling ice or water intrusion over time, large coax cables are an attractive target for copper thieves, etc.
Inexpensive IP links offer transport redundancy that 950 MHz links just can’t beat.
Read more on this topic in the free ebook “Trends in Codecs 2026.”
