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Power Up Hybrid Radio With RadioDNS

Learn new tech and save money by doing it yourself

How RadioDNS works graphic
RadioDNS pulls unique station identifiers from RDS. It rewrites these into a format that looks like a domain name. This gets passed to the nearest DNS server. The receiver then makes a direct connection to a station’s stream using the IP address.

Hybrid radio is just around the corner. Is your station ready?

Audi and BMW are selling vehicles with hybrid radios in the United States and Canada. This technology enables both over-the-air and internet radio reception in cars.

Impressive as that is, these receivers will also be able to display a station’s logo as well as station information such as “now playing” and other metadata from the web stream as part of a vehicle’s on-screen station guide.

RadioDNS display
A small web icon for KITS at the right indicates that the station, along with its associated metadata, is being received via the web stream rather than over the air.

Additionally, the Audi radios will offer service following, which means they will be able to switch from the FM signal to streaming audio when radio reception becomes iffy, effectively extending your station’s coverage area.

The receiver will enable the most seamless transition possible, matching timing and levels between the two signals, so long as the time difference is 30 seconds or less.

Audi hybrid radio service following option screen
Audi radios offer “service following,” and the driver is given the option of switching to a station’s stream when the FM signal becomes marginal.

In order for stations to reap the benefits of hybrid radio, they must first create an XML file with station information, host it on a publicly-accessible web server, create some DNS records and register with RadioDNS.

Any number of service providers can do this for you, but in these challenging economic times, you can save some cash by doing it yourself. It’s not difficult, but like most things, it takes some study, advance planning and organization to ensure a happy outcome.

Founded in October 2009, RadioDNS is a non-profit organization based in the U.K. that promotes the global use of open technology standards to enable hybrid radio. In addition to HD Radio, the standard supports VHF/FM, DAB, DRM and AMSS. RadioDNS manages the internet-based technologies that can connect hybrid radios to radio stations providing internet content like streaming audio URLs.


To assist the do-it-yourselfers, NAB PILOT offers a free on-demand webinar that walks you through the process. It’s hosted by David Layer, vice president, advanced engineering in NAB’s Technology Department. Panelists include Christian Winter, development engineer, radio, media at Audi AG; Nick Piggott, project director and co-founder RadioDNS Hybrid Radio; and Andy Buckingham, creative technologist at Togglebit.

Help is also available on the RadioDNS website. There you can find step-by-step guides to implementing RadioDNS functionality, as well as presentations from technical conferences explaining how to manage RadioDNS hybrid radio application systems. There are also discussion boards where you can post your questions.

This fall’s Radio Show virtual event, co-produced by NAB and RAB, featured a session on “How Radio Broadcasters Can Support RadioDNS.” It was hosted by Layer with panelists Piggott; Jason Ornellas, regional director of engineering, Bonneville International; and Mark McConnell, system administrator and digital content manager, Bonneville International.

Layer began the Radio Show session by noting a September press release from Audi, announcing a collaboration with iHeart Radio, which is making more than 600 of its radio stations hybrid radio capable during its initial integration phase.

The release, according to Layer, underscored an important point. “Auto manufacturers are going to great lengths to introduce hybrid radio-equipped cars, and now the onus is on radio broadcasters to do their part by making their stations capable of utilizing this new service.”

Layer adds that no fees are collected for registering your station with RadioDNS; it is a free service. However, there are costs involved in setting up radio stations to make use of RadioDNS technology.

RadioDNS is supported financially by its members worldwide, of whom NAB is one, as are several broadcast groups in the U.S. Broadcasters who want to help move this technology forward should consider joining RadioDNS.

The XML file with station information previously mentioned is called the Service Information (SI) file, and is the main resource for conveying basic information about radio stations to the hybrid radio receiver.  To create this, you’ll need a database containing the station metadata from all stations being supported. For each station that should include call sign, name, description, genre, logo URLs and audio stream URL. Also needed is information on the station’s RDS PI code (for analog FM stations) or the facility ID (for HD Radio stations).

NAB PILOT has created a way to automate the collection of the PI code/facility ID and other “bearer” information. It’s called the “Radio Call-signs API.” For more information, contact David Layer via Station logos as well as a web hosting service to put the SI and logo files on are also required.

Next, you’ll need to create the XML file to make it all work. Most of the examples on the NAB webinar are created using the PHP scripting language, but other languages can also be used.

Preparation is key

The first step is to collect all the station information from the database. Next, all the images need to be prepared.

RadioDNS specified five different resolutions to support different receiver display resolutions, including 32 X 32 PX, 112 X 32 PX, 128 X 128 PX, 320 X 240 PX, and 600 X 600 PX. This step is really a matter of converting your one large image file into these smaller sizes. Then, you’ll need to ping the Radio Call-signs API to get back your broadcast station details. Finally, you must build the SI file document and save it.

After the coding is complete, you need to register your station with RadioDNS. A bit of preparation is necessary. You’ll need to gather some information about the parameters in your signal. In order to get into the RadioDNS hybrid radio registry, analog FM stations must be transmitting RDS, including the PI (Program Identifier) code.

It is further recommended that you transmit the ECC (Extended Country Code). This can help improve the accuracy of locating your DNS entry. For the United States, the ECC is A0.

The DNS utilizes a GCC (Global Country Code), which comprises the first digit of your RDS PI code followed by your ECC code. For U.S. stations, PI codes begin with A, B, D and E, so valid GCCs would be AA0, BA0, DA0 or EA0.

When you register, RadioDNS will create a DNS entry for each of your frequencies. If your group has numerous channels, you may be able to register with a wildcard (*) entry, and you won’t need to list them all. Otherwise, frequencies need to be entered as a five-digit number, i.e. 08850 for 88.5 MHz, or 10790 for 107.9 MHz.

In summary, each FM channel will information entered in the form frequency.pi.gcc, for example 08850.pi.BA0.

If you’re operating with HD Radio, you need to be transmitting your FCC Facility Identifier (ID) in hexadecimal format, padding with leading 0s to create a five-digit number. This should be followed by the country identifier (CC), which is 292 for the USA. And if you’re transmitting multicast, all of this needs to be preceded by MC.

An example of a multicast HD Radio entry would be, for example MC.10C21.292.

Completed applications should be e-mailed to [email protected]. These should include your fully qualified domain name (FQDN) and your broadcast parameters for FM and HD for each station being registered, your .zone file as an attachment (if you have created one), your name and telephone contact number, the registered name of the radio station(s), and finally the name of the authority that issued the broadcast license(s). RadioDNS will acknowledge the change request via email, within 48 working hours. New and changed entries take up to 24 hours to propagate through the Domain Name Service.

On the air

Some stations have already taken the plunge into this new technology.

As soon as Ornellas and McConnell heard about hybrid radio, they knew they wanted to make Bonneville International an early adopter in the six markets the company serves. Their journey took them to places they never expected.

Ornellas said, “Initially, we just wanted to be a part of it. Then Mark began looking online and realized we can do so much more than just have an online presence. The Capital FM example inspired us to put all the extra information out there for our listeners.”

McConnell adds, “The two big things that jumped out for us were their use of the PI content code, as well as their use of an electronic program guide which had links to their social media. But the entire structure is XML-based, so there’s a lot of flexibility to add what you want.”

The second big discovery for Ornellas and McConnell was how much data could be gleaned once the server logs are combined with owner data from car dealers.

“These can be used to create some powerful real-time analytics,” says Ornellas. “The age and sex of the driver, for example, can be combined with where and when they tune in, how long they listen, and what station they eventually switch to.

“There’s probably more to be discovered. The challenge for us is to take this wealth of data, which is already parsed out by station, and create a dashboard where it can be easily accessed and understood by sales, promotion and management.”

McConnell began the process by using a PI code look-up tool, which obtained the PI codes necessary for analog FM stations. A few things were left to be added by hand, including the ETSI content CS codes and electronic program guide links, including social media, website and studio line links.

The result was the overarching framework for the Bonneville station’s SI files, and it was left to station engineers to fill it in, using the Sacramento station as an example. All of the completed files reside in the Bonneville International corporate server.

Piggott said getting hybrid radio to work involves teamwork.

“The implementation of hybrid radio brings people from two sides of the business together. It’s the intersection of broadcast engineering skills, such as making sure PI codes are being transmitted on RDS encoders, but also knowledge of how to set up DNS records and put files on web servers.”

Ornellas added, “You need to have that collaboration with digital and engineering to really streamline this, especially the artwork and stream URLs. Some engineers have access to that, others rely on the digital folks. We’re unique at Bonneville in that we already work together so closely that this was a seamless process. Moving forward, I believe digital and engineering are going to become very integrated, and hybrid radio is a perfect example.”

Radio never stands still, nor should your SI file. Stations change logos, formats, call signs and even ownership, often with little advance notice. It’s best to think of creating the SI file, as well as your other digital assets as a process rather than a one-time event. This may be another reason to learn how to create and manage them yourself, rather than relying on a service provider.

The solution at Bonneville is a virtual machine located at company headquarters. When new logos or other graphics are created, they are immediately uploaded. Station engineers also keep backups of their SI files and other engineering data there.

Tom Vernon is a longtime contributor to Radio World.