Why is HD’s power so much lower?

[djl]

I understand that the HD signals must run at lower power so they do not interfere with their analog station, but a full power New York FM Station that transmits from the Empire State Building gets 6,000 Watts for Analog and only 293 Watts for their HD signal.

That power difference must be huge. The HD signal does not even come remotely close to its analog coverage. Those full power stations have an Analog service area of approximately 50 miles (they often go further), but their HD counterparts become unstable around 35 miles from NYC (on Long Island).

Are there any plans to ever boost the power on the digital signal?

On another note, how come the only AM HD stations in the area are WCBS and WINS? Wouldn’t some of the other AM stations (WHLI) want to provide higher fidelity music? Of course WHLI’s FM counterpart WKJY 98.3 and WBZO 103.1 do not have HD either. WKJY and WBZO are practically the only stations in the area that do not have HD. I E-Mailed WBZO in the past and they totally dodged the question as to why they don’t have HD.

 

[PTBoardOp94]

Are there any plans to ever boost the power on the digital signal?

Any such change would require action by the FCC. It seems unlikely they will act, and honestly most broadcasters would have limited interest in throwing more electricity into an HD service that few listen to.

On another note, how come the only AM HD stations in the area are WCBS and WINS? Wouldn’t some of the other AM stations (WHLI) want to provide higher fidelity music? Of course WHLI’s FM counterpart WKJY 98.3 and WBZO 103.1 do not have HD either. WKJY and WBZO are practically the only stations in the area that do not have HD. I E-Mailed WBZO in the past and they totally dodged the question as to why they don’t have HD.

AM HD requires cutting down the analog audio bandwidth substantially. Therefore it is a terrible combination with music on AM, because most listeners do not use AM HD receivers. Worsening the audio for 90% of listeners for the benefit of the 10% who use HD receivers is a bad compromise. Also, some AM directional arrays cannot be made to work with AM HD due to bandwidth limitations without major reconstruction.

As far as why some FM stations do not use HD: Some of the big broadcast groups were and are major boosters of HD as a technology. The former CBS, former Clear Channel and Emmis launched FM HD on all their New York stations the same week in 2006.

Many smaller broadcasters have never seen the point - it's a technology which has high installation costs, adds to the utility bills, requires a licensing fee in perpetuity, and additional programming costs if you offer any sub-channels. And oh by the way, zero revenue.

 

[TheBigA]

Any such change would require action by the FCC. It seems unlikely they will act

I remember they increased the power maybe 8 years ago, and it was like they were throwing the folks a bone. They didn't want to, but were sort of pressured into it. The increase was for between 6 and 10db. I haven't read any recent mentions of it.

https://www.pillsburylaw.com/en/new...power-increase-for-most-fm-iboc-stations.html

 

[semoochie]

Part of the issue is that it's only intended to cover the protected contour. It can do pretty well under the right circumstances. I can hear a Portland OR C2 all the way to Salem, about 45 miles, which is well beyond the 60dbu.

 

[WJPYFM]

Digital does not require as much power to re-construct the signal as analog. However, the way the iboc signal gets to the antenna makes a big difference in the final output. Many FM stations share the same antenna and the digital signal power can be lost in the combiner which is often the case. New transmitters have options to combine at a less loss location in the transmitter with options to have side band powers different in case of short spacing interference. Some stations have dedicated directional antenna for just the HD so coverage would be much different.
AM iboc HD is much different than FM. IMO, it should just go all digital without analog carriers. The band is just a mess with poor audio quality that less & less people want to listen to.

 

[TheBigA]

The band is just a mess with poor audio quality that less & less people want to listen to.

BTST only a small number of people want to buy new radios, and that's what they'd have to do for all-digital AM.

If anyone wants to hear all-digital AM, they just stream it on their phone.

 

[rbc]

AM iboc HD is much different than FM. IMO, it should just go all digital without analog carriers. The band is just a mess with poor audio quality that less & less people want to listen to.

I totally agree! There is just too little power and bandwidth in the budget to split it between analog and digital. FM translators can be used for analog listeners.

 

[Ai4i]

The reason for the directional HD antennæ is to protect first adjacent channel stations.
I believe that when a station goes all digital, they will be able to transmit with their full licensed power...maybe.
Currently, any grandfathered superpower station that is overpowered can only transmit the greater of 1% of their licensed power or what their maximum would be if they were licensed today.
The commission apparently wants to emasculate those overpowered monsters from a bygone era.