Eye on IBOC

[Carmine5]

Interesting series of factoids from Radio Magazine on the state of DAB.

http://radiomagonline.com/digital_radio_update/digital-radio-update-030409/#studies

Note particularly the author's "A Tale of Two Studies" which is an analysis of the Jacobs Media survey on behalf of Public Radio.

Quote:

"I expected the study...to say some positive things about HD Radio adoption and how it is becoming a factor in shaping how listeners use public radio. But what I found was something quite different."

"...only about 3 percent of respondents reporting access to an HD Radio receiver, the technology was succinctly defined as remaining in the embryonic stage."

Quoting from the Jacobs report itself:

"the HD Radio initiative's impact is miniscule, and fraught with several practical barriers that may hamper future growth."

To quote the author: Ouch!

C5

 

[Play Freebird]

On this Radio Magazine webpage, there's also a list of Pennsylvania IBOC stations which was provided by iBiquity. However, I know that one of them, WZXM in Harrisburg, is no longer on the air with HD Radio -- in fact, WZXM no longer has a digital transmitter.

The current owner acquired the station in a swap with a public broadcaster and asked that the IBOC rig be removed to reduce electric consumption and waste heat.

 

[Savage]

Shocking. iBiquity claiming that a station is operating with HD which clearly no longer is? Who'd have thunk it?

Kind of puts the often-touted "HD Scoreboard" which appears in RW in proper perspective.

As well as their claims for "receiver sales." Oh, wait - I sit corrected. Even iBiquity isn't comfortable about lying publicly about THAT sensitive little issue. So they finesse it with "SKU numbers for HD products" and "chipsets manufactured."

You know - anything but the truth.

 

[nd2023]

The HD transmitter uses only 2% more electricity.

 

[Reaper]

The HD transmitter uses only 2% more electricity.

And creates 1000% more interference....

 

[Play Freebird]

The HD transmitter uses only 2% more electricity.

Citation needed.

Seriously, where did you read that?

 

[w9wi]

The HD transmitter uses only 2% more electricity.

Citation needed.

Seriously, where did you read that?

That's probably not an entirely unreasonable estimate for a station running 1% IBOC from a new transmitter. (i.e., one that didn't retrofit IBOC to an existing rig)

Agreed, that it's at least an order of magnitude too low for a station that retrofit IBOC to an analog transmitter. (i.e., the vast majority of stations)

 

[Play Freebird]

That's probably not an entirely unreasonable estimate for a station running 1% IBOC from a new transmitter. (i.e., one that didn't retrofit IBOC to an existing rig)

Agreed, that it's at least an order of magnitude too low for a station that retrofit IBOC to an analog transmitter. (i.e., the vast majority of stations)

If the new transmitter uses common amplification (low level combining), which was the case with WZXM's now-removed digital transmitter, a linear PA would be required-- and as you know, these are significantly less efficient than the Class C final stages in FM analog-only transmitters. I would assume at least a 30% decrease in PA efficiency. Add in the cost of additional air conditioning and the operating expense goes even higher.

High level combining wastes about 90% the digital power in a reject load, as well as 10% of analog power, so we're way over the 2% figure there.

The only situation I can think of where IBOC (at -20 dB injection) could be added for only a 2% increase in electric consumption would be through the technique of "space combining", but the digital transmitter would need to feed an auxiliary antenna with somewhat higher gain than the main (analog) antenna. But how many stations have the opportunity to install a second antenna of this size economically?

 

[w9wi]

If the new transmitter uses common amplification (low level combining), which was the case with WZXM's now-removed digital transmitter, a linear PA would be required-- and as you know, these are significantly less efficient than the Class C final stages in FM analog-only transmitters. I would assume at least a 30% decrease in PA efficiency. Add in the cost of additional air conditioning and the operating expense goes even higher.

High level combining wastes about 90% the digital power in a reject load, as well as 10% of analog power, so we're way over the 2% figure there.

The only situation I can think of where IBOC (at -20 dB injection) could be added for only a 2% increase in electric consumption would be through the technique of "space combining", but the digital transmitter would need to feed an auxiliary antenna with somewhat higher gain than the main (analog) antenna. But how many stations have the opportunity to install a second antenna of this size economically?

I forgot all about the need for linear amplification. More accurately, I forgot that FM transmitters *don't* need linear amplification if they aren't running common-amplified IBOC. (I'm a TV type and tend to forget you FM types can get away with Class C PAs!)

The "order of magnitude" comment was meant to apply to high level combining, which is of course what most stations use.