[BC] Balancing the processing from analog to digital

[Robert Orban]

At 06:22 AM 12/22/2006, Jim Tonne wrote:

>>I agree completely that processing on the road is absolutely necessary. 
>>Most Classical stations process more aggressively during drive time than 
>>the rest of the day.
>
>It seems to me the answer is not to process at the transmitter end,
>which affects everyone, but in the automobile receiver, where it is
>actually needed.

This is a good idea for digital channels. Dolby implemented it in AC3 and 
there is provision for Dynamic Range Control metadata in Eureka147. (I 
don't know if Digital Radio Mondiale also has this provision, although I'd 
be surprised if they left it out.)

The problem is getting consumers to understand it. Almost no one 
understands what is sometimes called "Night Mode" that turns on AC3 dynamic 
range compression at the receiver. And there are squirrelley 
implementations. On my Denon AVR-4806 receiver, night mode is not "sticky" 
and the receiver will drop out of night mode each time I fast-forward the 
TiVo. IIRC, it will also drop out of night mode in commercial breaks if the 
commercials are not broadcast in "Dolby Digital" mode, as opposed to "Pro 
Logic" mode. Evidently, the receiver has to see a continuous "Dolby 
Digital" bitstream in order to remain in night mode.

Regarding dynamic range compression of analog FM at the receiver side, the 
problem here is that in moving vehicles, the noise floor is all over the 
place and compression can suck up noise to objectionable levels.

Bob ORban