I'm not an engineer....

[AMRocks]

So I'll ask this question to someone who may know:
Could a station, in theory, broadcast only in HD? Meaning, they would NOT have their analog signal.
(Not that anyone would want to do this....but could they do it.....)

Thanks

 

[frankberry]

It's possible but not legal at this time.
There is not an analog carrier. It's actually a single carrier with digital sidebands.

 

[tomservo]

I've actually heard a station doing this. I don't know if the analog transmitter was taken down for routine maintenance and they left the HD up, or it was some sort of glitch in the system, but our local country station WKSJ in Mobile has done this a few times in the wee hours of the morning. When the station is tuned with an HD radio, there's static on the main channel, but the HD light flashes until it syncs, and then music out of the ether. Of course on analog radios all I heard was HD fuzz on the side channels and static on the main channel.

Very strange.

 

[diymedia]

Sounds like they're using the dual-antenna configuration for HD.

 

[tomservo]

That was my thought, too, diymedia. I don't see evidence of a second antenna at their analog site, but it's a really tall tower so something small could be hiding out at a weird angle. They are also the only commercial station in our market that appears to be running higher HD power, as their digital is dropout free for a good 30 miles and easy to receive for 50 or more.

I forgot I had this, but here's a quick video showing the station's HD decoding while the analog is off air:

https://www.youtube.com/watch?v=pV5r3gnGJlg

 

[jras20]

I do remember one time when I had my HD radio's hooked up when a storm around, the analog was off, but the HD was on broadcasting.