WEBVTT

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So I was driving into work one morning along

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the Mississippi running that, you know, that

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stretch that's between Wisconsin and Minnesota.

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Normal commute radio on as usual, because, you

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know, I got to monitor the station I work for.

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And at some point I realized I wasn't listening

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to my my local station anymore. I was listening

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to KFAI out of Minneapolis 90 .3 FM about 180

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miles north it was on the same frequency KFAI

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was running in HD and the transmitter for my

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local 90 .3 had recently shut its HD down so

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the receiver found the only signal The only digital

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signal it could on that frequency It grabbed

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it and it played Minneapolis KFA I Now I'm a

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broadcast engineer. I knew about HD radio Hijacking,

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you know, I knew what it was before That event

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took place that morning. I heard about it, you

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know through presentations at the WBA broadcasters

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clinic. I understood how it works, the concept,

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and I still sat there in my car for a second

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going, wait, hang on, that's not right. The gap

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between knowing how something works and having

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it happen to you in real life is where this episode

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is going to live. This is the Tyler Woodward

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project. I'm Tyler Woodward and today I'm talking

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about HD radio the HD radio digital capture or

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HD radio Hijacking as some people call it, you

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know what it is why it actually happens and what

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it means for any station that doesn't have a

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digital signal defending its frequency Quick

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disclaimer as usual though everything here is

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from my own point of view Not the position of

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any station I work for or any organization that

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I'm affiliated with These are my opinions from

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my point of view For folks that don't work in

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the engineering side of radio or you know want

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to peek behind the curtain, this is how it works

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HD radio is a hybrid system. A radio station

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keeps its regular analog FM signal that it's

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always had, but it also transmits a set of digital

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carriers right alongside it, on the same channel,

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not a separate frequency, right there, on both

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sides of the analog signal. Like, parentheses,

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I guess is the best way I can put that, gives

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you a visual. The digital carriers run at a fraction

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of the analog power at standard levels roughly

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1 % of what the analog transmitter itself is

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putting out. The pitch when this system was designed

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was that the digital would be quiet enough to

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be invisible to receivers that couldn't read

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it. loud enough that HD capable receivers could

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lock on to that signal. An HD radio receiver

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is designed to prefer the digital signal over

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the analog signal. That preference is the feature.

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Digital obviously sounds a little better. It's

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cleaner, no static, no multi -path issues, and

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that's the whole argument for the system. So

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the receiver looks for Digital first over the

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analog Now if it finds the digital carrier on

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that frequency it locks on It doesn't check whether

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that digital signal is from your local station.

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It just latches on to it So when my local 90

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.3 had its HD running my receiver grabbed it

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from my local stations digital signal Fine, it

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worked as designed. That's how it's supposed

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to work the moment though that by 90 .3 shut

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its HD down while the local digital signal was

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gone and KFAI's HD1 signal 180 miles north on

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the same frequency was sitting right there waiting

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for someone to grab it. My receiver found it.

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It locked on and played me Minneapolis for the

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drive in. I knew the HD was off. I had not fully

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thought through what that meant for the morning

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commute until that happened that very morning.

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Let's talk about co -channel stations. Two stations

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on the same frequency in different cities. They're

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protected from each other by distance. The FCC

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spaces them out just far enough that in normal

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analog propagation, The weaker signal fades before

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it reaches the other station's listeners. That

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math, I mean, it's worked for decades. It's built

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for, lack of a better word, the analog era. An

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HD receiver, it's not comparing analog field

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strengths, it's looking for that digital carrier

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sitting out there in the open. And a digital

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carrier travels differently than the analog signal

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strength. a powerful station running HD can extend

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its digital influence further into the surrounding

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territory than the traditional co -channel protection

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distance assumes in the rule book, especially

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when the local station isn't running HD at all,

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which was in my case. No local digital signal

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means no competition to fight. fight off that

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intruding HD1. The receiver finds whatever digital

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signal it can reach on that frequency and that's

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what you're going to hear. Now, I should point

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out that in my vehicle, my Subaru Forester, when

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I lost my 90 .3 and locked on to 90 .3 Out of

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the cities that was broadcasting HD1, one option

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I do have in my vehicle is I can turn HD radio

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off. There is a button to disable HD radio. So

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I could turn it off and go right back to my local

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90 .3. But think of this coming from a, you know,

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a regular everyday person who just wants to listen

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to the radio on their way in to work on their

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commute. They may not know that and now you've

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accidentally lost the listener that latched on

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to someone else's HD1. A broadcast consultant

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did modeling on this for NPR labs. He worked

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out the field strength threshold at which a distant

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co -channel station's digital signal crosses

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into capture territory, the hijacking territory

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around You know he estimated around 35 to 40

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micro volts per meter that really gets into the

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nerdy stuff that I'm not really gonna get into

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on this episode But if a listener is inside that

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window and a local station isn't running HD the

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distance station gets the listener So my drive

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along the Mississippi that morning put me squarely

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in that window And we should point out, my situation

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is not unusual. There's a small community FM

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in Asheville, North Carolina, WPVM. It's 100

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watts at 103 .7 that has been getting captured

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by WSOC out of Charlotte for years. Some, the

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same frequency, WSOC is 100 ,000 watts, about

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100 miles away. The WPVM general manager found

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out about it in 2021 when she bought a new car

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with an HD radio tuner. Her screen was showing

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WSOC's call letters and album art, Charlotte's

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music, Charlotte's branding on her receiver inside

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her city. She reported it to radio world. Xpery,

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the company that owns the HD radio technology

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said they had received no official report and

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couldn't comment without one. The Buffalo case

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is different and maybe more instructive about

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the mechanics of this whole thing. WDCX is a

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big station running HD around Christmas 2022.

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Their own HD carrier failed. When it did, listeners

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started picking up a Canadian co -channel station

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instead. WDCX's own digital signal was the only

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thing holding the territory against the Canadian

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station. When the carrier went down, even just

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briefly, the ground was open for the taken. That's

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what I was dealing with on a smaller scale on

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my drive in that chilly fall morning. The moment

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the local HD went dark, the frequency was up

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for grabs, digitally. In KFAI, a legitimate well

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-run station 180 miles away didn't do anything

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wrong. Their signal was just there. The receiver

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found it and locked onto it exactly what it was

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supposed to be doing. The problem here is more

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to do with the math. The WSOC's digital sidebands

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at let's say standard injection levels are putting

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out roughly maybe a thousand watts of digital

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energy. That is 10 times WPVM's entire transmitter

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output. And my local situation is not, you know,

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not that extreme compared to that. KFAI is it's

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a community station, not a clear channel giant,

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but the principle behind this is the same. A

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station with more transmitter power has more

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digital territory. A station with no HD has zilch,

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nothing, nada. The FCC has been moving in one

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direction on this. In 2010, they... they raised

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the allowed HD digital power ceiling. In late

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2024, they approved asymmetric sideband operation,

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which let stations run more digital power on

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one side of their channel than the other. Every

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one of these decisions benefits stations with

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the capital to upgrade their transmission system

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and equipment over to digital. Now let's talk

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about the low power FM's the LP FM's they can't

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run HD Most community stations can't run HD the

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equipment costs. I mean, that's a struggle the

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engineering requirements and the know -how to

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operate it is real so they show up to the frequency

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without a digital signal and Literally have no

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protection against the station that does the

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FCC They've received hundreds of I Bach interference

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complaints since HD radio launched They have

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never acted on a single one that I could find

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Now here's what I keep coming back to KFA I They

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didn't do anything wrong. All right, so let me

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set the record straight. They didn't do anything

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wrong my car It didn't malfunction The receiver

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did exactly what it was designed to do nobody

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in this story is the bad guy What the story is

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about is what happens when you design a standard

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around the broadcasters funding its development

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Approve it without competitive evaluation and

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then slowly expand its power ceiling for decades

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while the secondary services it disadvantages

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have no regulatory path to complain or object.

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HD radio was selected by the FCC back in 2002

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as the de facto U .S. digital radio standard.

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One company's proprietary system, iBiquity, now

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Xpery, backed by the major broadcast groups.

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The major broadcast groups, they ran pilots.

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The system got built around their infrastructure

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and their power levels. LP FM stations are considered

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secondary services. That is a specific regulatory

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category that means basically you get what's

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left over and you don't get the file complaints

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against the primary services. The interference

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rules in this area were written for analog to

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analog scenarios. And I mean, they don't cross

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over onto the digital capture slash hijacking,

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which is an interference in the traditional sense,

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I guess. The receiver is working correctly, but

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that also is exactly the problem. I knew that

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morning that our HD was off. That wasn't a me

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decision. That was a company decision was to

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shut the HD radio service down. What I didn't

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think about, but you know, I heard at you know,

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conferences like WBA and through trade magazines

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and publications that HD radio hijacking was

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real. But I hadn't thought through what it meant

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for that little Minneapolis community station

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that was going to be sitting on that frequency

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digitally for anyone in my position driving along

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the river. And maybe we should have. I mean,

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we know this stuff. We just didn't think that

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morning with ducting or whatever that KFAI would

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come in to interfere with my local 90 .3. It

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really caught me off guard because I had heard

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of the concept. I have heard of hijacking, but

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never experienced it. The listeners who don't

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think about this at all have no idea what's happening

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to them. They're wondering where their local

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public radio station went. The WPVM general manager

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Found out because she bought a new car. Most

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LPFM managers didn't get that prompt. There's

00:16:09.620 --> 00:16:12.340
people in Asheville right now hearing Charlotte

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and not knowing it. There's no form to file for

00:16:17.120 --> 00:16:19.480
them though. Nothing goes anywhere. The system

00:16:19.480 --> 00:16:22.360
is doing exactly what it was supposed to do.

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So what all clothes on is this? for the LPFMs

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who can't do digital. Unfortunately, there's

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not a whole lot you can do right now, but advocate

00:16:36.429 --> 00:16:42.610
for turning on digital. But for full power primary

00:16:42.610 --> 00:16:49.669
stations who are not at least running an HD1,

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I would reconsider that. If anything, if you

00:16:54.330 --> 00:16:58.230
have no desire, no plan, no thoughts on ever

00:16:58.230 --> 00:17:01.330
running any additional content channels in HD2

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or in HD3. I mean, at least having HD1 on your

00:17:06.869 --> 00:17:11.769
primary station protects you from this HD radio

00:17:11.769 --> 00:17:15.970
hijacking slash HD radio capturing. It protects

00:17:15.970 --> 00:17:22.369
your contour from unfortunate digital quote unquote

00:17:22.369 --> 00:17:25.849
digital interference. So if anything, I would

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look into at least putting HD1 on the primary.

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If for no other reason other than it sounds better,

00:17:33.509 --> 00:17:37.970
it looks better in your listener's dash and well,

00:17:38.049 --> 00:17:41.869
protects you from the HD radio hijack. Make sure

00:17:41.869 --> 00:17:44.529
you subscribe over on Apple Podcasts, Spotify,

00:17:44.809 --> 00:17:48.029
or even iHeartRadio, rate and review the show.

00:17:48.170 --> 00:17:50.490
Follow me on Facebook and YouTube at The Tyler

00:17:50.490 --> 00:17:54.089
Woodward Project, Instagram, threads, blue sky.

00:17:54.210 --> 00:17:56.329
I'm over there too, at Tyler Woodward dot me,

00:17:56.410 --> 00:17:59.230
reach out and say, Hey, hit me up with any ideas

00:17:59.230 --> 00:18:02.970
on some content. And, uh, well also subscribe

00:18:02.970 --> 00:18:06.309
to the sub stack at sub stack dot Tyler Woodward

00:18:06.309 --> 00:18:09.309
dot me. I'm all independent. This is my thing.

00:18:09.589 --> 00:18:11.829
I don't have any sponsors. So if you like the

00:18:11.829 --> 00:18:14.890
show, show some love or just share it and subscribe

00:18:14.890 --> 00:18:18.390
to the podcast as well. That's it for me this

00:18:18.390 --> 00:18:20.930
week. I will catch you guys on the next one.