George,
I'll take this one. While it is true that the channels are 10 kHz apart, in any
one geographical area you never have two stations with adjacent channel
allocations because the AM signal is wider than the 4.5 kHz you mentioned and
the FCC needs to protect stations. So, for example, here in Los Angeles, I
don't believe there are any two stations closer than 30 kHz. Most, including
all of the high power stations, are at least 40 kHz away from each other.
I did my senior project on a related topic and in doing the research called all
of the radio stations here in Los Angeles, and they all told me that they went
out to between 12 and 15 kHz audio bandwidth. (This was before the regulatory
change mentioned by Paul.) Even my advisor was skeptical; he was the one who
forced me to call and speak to the chief engineers themselves before he
believed me.
Regards,
Al W6LX
> -----Original Message-----
> From: George, W5YR [mailto:w5yr@att.net]
> Sent: Friday, 18 April 2003 2:54 PM
> To: tentec@contesting.com; geraldj@isunet.net; w8au@sssnet.com
> Subject: Re: [TenTec] Enhanced SSB
>
>
> Paul, are not AM broadcast stations still assigned
> frequencies on a 10 KHz
> spacing?
>
> If so, that would appear to limit the upper end of audio
> response to about
> 4500Hz, leaving a small amount of guard band between adjacent
> stations.
>
> Straighten me out on this one, please! <:}
>
> 73/72, George
> Amateur Radio W5YR - the Yellow Rose of Texas
> Fairview, TX 30 mi NE of Dallas in Collin county EM13QE
> "In the 57th year and it just keeps getting better!"
> <mailto:w5yr@att.net>
>
>
>
>
>
> ----- Original Message -----
> From: "Paul Christensen, Esq." <w9ac@arrl.net>
> To: <geraldj@isunet.net>; <tentec@contesting.com>; <w8au@sssnet.com>
> Sent: Friday, April 18, 2003 2:16 PM
> Subject: Re: [TenTec] Enhanced SSB
>
>
> > > damping to let the microphone hear only the "golden
> tones" of the ham
> > > transmitting. AM broadcast doesn't even allow going to 15 KHz.
> >
> > Prior to the implementation of NRSC mask in the early '90s,
> AM Broadcast
> stations had no upper limit. The NRSC mask now effectively
> > limits the audio passband to approximately 9.5 kHz....and
> the service
> still sounds poor despite attempts by broadcast stations and
> > receiver manufacturers to improve the quality.
> >
> > WOR in New York has been experimenting (yes, even
> broadcasters are allowed
> to experiment just like hams once were) with digital IBOC
> > but the jury is still out on whether it can be a viable
> mode given sky
> wave propagation, fading, noise & interference, etc. The
> > IBOC receiver goes into an analog "blend" mode when the BER
> reaches a
> pre-determined threshold. I haven't heard it, but I can only
> > imagine...
> >
> > -Paul, W9AC
> >
> > _______________________________________________
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> > TenTec@contesting.com
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>
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