[BC] IBOC not working (was Noise Floor...)

[Robert Meuser]

You have touched on an interesting point.This ties into recent posts 
about the complaints some people have with the Boston Acoutics Receptor 
not hearing digital well enough.  It has occured to me that there were 
never really indoor real world tests performed with IBOC transmission. 
To date there is only one table top indoor receiver on the market.

 We are all familiar with how FM has a great noise advantage above it's 
threshold, which is primarily determined by the modulation index.  Many 
fail to consider that the digital IBOC component is for all intents and 
purposes an AM signal and requires around a 17 db signal to noise to 
function. This noise floor you discuss is usually higher inside 
buildings than outdoors. It is not hard to see how digital carriers, 
already at a disadvantage power wise, could be buried in noise not heard 
by an analog FM receiver.

There is some more interesting research to be done as more products 
reach the home market.  That uncontrolled noise floor could become an issue.

In a similar vein, it is interesting that the FCC just fined Behringer 1 
million dollars for not certifying their digital products. Maybe more of 
that should happen in the future.

R





Burt I. Weiner wrote:

> Until the FCC decides to enforce the part 15 rules, all of them, then 
> the noise floor will continue to climb and the best of receivers will 
> only hear noise where there is noise.
>
> I remember years ago, using only a simple table model receiver, I was 
> able to hear AM stations across the country at night.  Now all I can 
> hear are noise from computers, light dimmers, soda-vapor street lights 
> as well as a myriad of other devices.  I have yet to be convinced that 
> digital communications is going to be immune from the same or similar 
> levels of "noise".
>
> Burt
>
> At 08:47 PM 2/17/2006, you wrote:
>
>> From: "Dave Dunsmoor" <mrfixit at min.midco.net>
>> Subject: Re: [BC] Satellite sensitivity...
>> To: "Broadcasters' Mailing List" <broadcast at radiolists.net>
>> Message-ID: <00e701c6341d$caff9040$0200a8c0 at cd2176218a>
>> Content-Type: text/plain;       charset="iso-8859-1"
>>
>> Oh, certainly it is. But food for thought...
>>
>> Dave
>>
>> > Keep in mind that where satellites are located the noise floor from
>> > man-made noise is much lower than it is down hear on the "flats".
>> >
>> > Burt
>> >
>> > At 10:00 PM 2/15/2006, you wrote:
>> > >     Now if that satellite can hear such a extremely small signal 
>> from
>> > >however high up they orbit, why doesn't IBUZ use something like 5 
>> watts
>> and
>> > >have the receiver manufacturers come up the rest of the gain and 
>> noise
>> > >floor? That in itself would be a superb incentive to move over to 
>> IBUZ.
>> > >Similar (or even better than) to moving to SS from a tube 
>> transmitter.
>> > >
>> > >
>> > >Dave Dunsmoor
>
>
> Burt I. Weiner Associates
> Broadcast Technical Services
> Glendale, California  U.S.A.
> biwa at earthlink.net
> K6OQK
>
>
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