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FM Stereo: At What Cost Letter

R

rbrucecarter

Guest
Interesting letter in Radio World Feb. 1 issue - concerning the signal parity of FM Mono and FM Stereo stations.

I haven't applied the calculations to IBOC - but any way you do it, it would explain the loss in coverage some of us have observed when a station adds IBOC.
 
Anytime you add anything in the way of a subcarrier it will reduce the coverage..stereo a little bit, an SCA a little more and more than likely IBOC would do that. It's imperceptible to the average listener. Remember most stations lost coverage area due to all the influx of Docket 80/90 stations.
 
> Interesting letter in Radio World Feb. 1 issue - concerning
> the signal parity of FM Mono and FM Stereo stations.
>
> I haven't applied the calculations to IBOC - but any way you
> do it, it would explain the loss in coverage some of us have
> observed when a station adds IBOC.
>

We have been over this before. Let really deal with facts here.

There is no way an analog FM station can lose coverage due to the addition of HD Radio. Most installs utilize and seperate transmitter for HD and doesnt change the analog transmitter. The only thing that could happen is that the engineer may not have considered injector losses (10%). At 10% power we are not talking about much loss in range and may not even be precptible.

I have listned to about 40 different stations that have added HD and not one has lost any coverage.
 
> Interesting letter in Radio World Feb. 1 issue - concerning
> the signal parity of FM Mono and FM Stereo stations.
>

It is customary to include a <a target="_blank" href=http://www.radio-info.com/mods/board?Board=hd&Post=657001>link</a> so we can all read it before we reply.<P ID="signature">______________
Proud 2 B a pioneering satellite radio subs¢riber
Ai4i is always on the trailing edge of technology
______________</P>
 
> There is no way an analog FM station can lose coverage due
> to the addition of HD Radio. Most installs utilize and
> seperate transmitter for HD and doesnt change the analog
> transmitter.

Is there no analog loss in the high level combiner or is the loss strictly digital?

Do you simply increase the power and use the extra heat to warm a small city? I think I've found a use for all those old TV studio air conditioners now that lighting doesn't need so much.

Rich
 
> > There is no way an analog FM station can lose coverage due
>
> > to the addition of HD Radio. Most installs utilize and
> > seperate transmitter for HD and doesnt change the analog
> > transmitter.
>
> Is there no analog loss in the high level combiner or is the
> loss strictly digital?
>
> Do you simply increase the power and use the extra heat to
> warm a small city? I think I've found a use for all those
> old TV studio air conditioners now that lighting doesn't
> need so much.
>
> Rich
>

With high level combining, yes! To overcome the loss, you increase the analog power by 10%. The lost power goes into a big ol' heater.<P ID="signature">______________
</P>
 
> With high level combining, yes! To overcome the loss, you
> increase the analog power by 10%. The lost power goes into
> a big ol' heater.

It was a cold day on my transmitter visit. Inside the transmitter building it was about 80 degrees. Toasty warm, thanks to the heat given off by the combiner. I want the air conditioning concession during the Summer.

Rich
 
> > With high level combining, yes! To overcome the loss, you
>
> > increase the analog power by 10%. The lost power goes
> into
> > a big ol' heater.
>
> It was a cold day on my transmitter visit. Inside the
> transmitter building it was about 80 degrees. Toasty warm,
> thanks to the heat given off by the combiner. I want the air
> conditioning concession during the Summer.
>
> Rich
>

In some parts of the country that could be quite nice. Especially when the road is not passable and you have to hike in the snow. Then you open the door and warm right back up!<P ID="signature">______________
If you put your mind to it, you can accomplish anything...</P>
 
Mono FMs, changing the subject a bit

There was a Mono FM in the Tampa area that (illegaly? I presume so, to it was not a pirate, it was licensed) was running audio up to the full 20khz--in analog.

Simple: no Stereo pilot, no need to run anything other than audio where the 19khz. pilot 'stood'.

I made a couple of airchecks, took an Eico tube tuner from the early 60s that 'took' the response all the way up to "20,000cps" as the promotional literature said..My friend was getting married in that area and I was some distance away from the TX, but those highs really were there, analyzed them on a scope and all.

Here's another question, now with HD Radio....Simple here, in iTunes, when you take a file and convert it Mono, it only uses half the bitrate...So then, if I were to broadcast in HD Radio in Mono (OK, an FM at 96kbps in Mono), couldn't I theoretically further split the channels since all I needed was half for one channel??
 
Re: Mono FMs, changing the subject a bit

> There was a Mono FM in the Tampa area ...
> I made a couple of airchecks, took an Eico tube tuner from
> the early 60s that 'took' the response all the way up to
> "20,000cps" as the promotional literature said..My friend
> was getting married in that area and I was some distance
> away from the TX, but those highs really were there,
> analyzed them on a scope and all.
_______________

FM stereo broadcast transmitters can have flat audio response to ~16 kHz or so. If all other things were equal, it would take some really "golden ears" to hear the difference that audio response flat to 20 kHz would add to normal program material.

//
 
Re: Mono FMs, changing the subject a bit

> Here's another question, now with HD Radio....Simple here,
> in iTunes, when you take a file and convert it Mono, it only
> uses half the bitrate...So then, if I were to broadcast in
> HD Radio in Mono (OK, an FM at 96kbps in Mono), couldn't I
> theoretically further split the channels since all I needed
> was half for one channel??
>

AFAIK, HD Radio just gives each station, AM or FM, a certain number of kbps (obviously less for AM), and they can divide it up any way they want. Mono channels, stereo channels, 5.1 surround sound.
 
Re: Mono FMs, changing the subject a bit

> There was a Mono FM in the Tampa area that (illegaly? I
> presume so, to it was not a pirate, it was licensed) was
> running audio up to the full 20khz--in analog.
>
> Simple: no Stereo pilot, no need to run anything other than
> audio where the 19khz. pilot 'stood'.
>
> I made a couple of airchecks, took an Eico tube tuner from
> the early 60s that 'took' the response all the way up to
> "20,000cps" as the promotional literature said..My friend
> was getting married in that area and I was some distance
> away from the TX, but those highs really were there,
> analyzed them on a scope and all.
>
> Here's another question, now with HD Radio....Simple here,
> in iTunes, when you take a file and convert it Mono, it only
> uses half the bitrate...So then, if I were to broadcast in
> HD Radio in Mono (OK, an FM at 96kbps in Mono), couldn't I
> theoretically further split the channels since all I needed
> was half for one channel??
>


From what I understand, there were no provisions made for mono on HD. You have to run two channels of the same thing.
 
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