Channel 6 LPTV Aural Power Level

[NECRAT]

OK So we know that analog 6, the aural power level is typically 10% of the visual power level.

However recently in New York City, a LPTV is operating as a "FM" station on 87.75, with a digital license.
Supposidly, the digital bandwidth is reduced to allow for the analog FM aural carrier.

The question I have, is with a digital LPTV, the power level is reduced by license. How does the FCC handle the aural power level?
Is it 10% of the equivelant visual "analog" power?
do they allow it to be at the maximum of the digital power level?
is it 10% of the digital license power? (yikes!)

I've been curious about this for a while now and hope one of the braintrust here has an idea for me.

[eadler]

I have read somewhere that when applying for the license/change, Ch.6s are explicitly stating their plans for this analog audio. That said, there is no more visual carrier so I do not see what it could be... One such Ch.6 is applying for authority to make it's effective visual carrier level higher than it was before but not having an actual visual carrier (or something of the like).

[w9wi]

OK So we know that analog 6, the aural power level is typically 10% of the visual power level.

However recently in New York City, a LPTV is operating as a "FM" station on 87.75, with a digital license.
Supposidly, the digital bandwidth is reduced to allow for the analog FM aural carrier.

The question I have, is with a digital LPTV, the power level is reduced by license. How does the FCC handle the aural power level?
Is it 10% of the equivelant visual "analog" power?
do they allow it to be at the maximum of the digital power level?
is it 10% of the digital license power? (yikes!)

I've been curious about this for a while now and hope one of the braintrust here has an idea for me.

I want to know how they're getting their DTV to work properly with the bandwidth reduced.

[eadler]

I want to know how they're getting their DTV to work properly with the bandwidth reduced.

Likely simply less bits, in a similar manner to how ATSC M/H gets introduced, but with a true void instead.

[w9wi]

I want to know how they're getting their DTV to work properly with the bandwidth reduced.

Likely simply less bits, in a similar manner to how ATSC M/H gets introduced, but with a true void instead.

Maybe I'm misunderstanding but it's my belief the ATSC datarate is fixed at 19.2MBPS. You *have* to transmit 19.2MBPS -- if you don't have enough "payload" to fill it, you have to fill with null packets. The same number of bits move from transmitter to receiver regardless of what you're sending; it's just that if you don't need the full 19.2M, the receiver discards the nulls.

Or maybe I'm wrong?

[NECRAT]

I want to know how they're getting their DTV to work properly with the bandwidth reduced.

Likely simply less bits, in a similar manner to how ATSC M/H gets introduced, but with a true void instead.

Maybe I'm misunderstanding but it's my belief the ATSC datarate is fixed at 19.2MBPS. You *have* to transmit 19.2MBPS -- if you don't have enough "payload" to fill it, you have to fill with null packets. The same number of bits move from transmitter to receiver regardless of what you're sending; it's just that if you don't need the full 19.2M, the receiver discards the nulls.

Or maybe I'm wrong?

Maybe the CSTBs are set to auto detect the overall transport rate, like how some sat receivers can do that.
By having them auto detect the rate then youre not prone to issues with variances in the ota stream and/or muxing equipment.

[eadler]

Maybe I'm misunderstanding but it's my belief the ATSC datarate is fixed at 19.2MBPS. You *have* to transmit 19.2MBPS -- if you don't have enough "payload" to fill it, you have to fill with null packets. The same number of bits move from transmitter to receiver regardless of what you're sending; it's just that if you don't need the full 19.2M, the receiver discards the nulls.

Or maybe I'm wrong?

Exactly. But you don't have to fill it with null packets, you just have to say that there are null packets there, the receiver *should* ignore them.... Again, not sure on the exact specifics of how they do it, but I'd guess it's just like ATSC M/H which there are plenty of whitepapers available on from the OMVC among others.