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HD2 & HD3 Bandwidth Throttling

T

TXengineer

Guest
Can you throttle the bandwidth of an HD3 to allow for more on HD2? (Like you can do with DTV?),
So if you have a music format on HD2, but a talk format on HD3 which needs less bandwidth, you can throttle down the bandwidth on HD3 for HD2?


You have to understand my background is mainly television transmission but I find this stuff very interesting.
 
> Can you throttle the bandwidth of an HD3 to allow for more
> on HD2? (Like you can do with DTV?),
> So if you have a music format on HD2, but a talk format on
> HD3 which needs less bandwidth, you can throttle down the
> bandwidth on HD3 for HD2?
>
>
> You have to understand my background is mainly television
> transmission but I find this stuff very interesting.
>

Yep, you can divide the pie any way you'd like!<P ID="signature">______________
</P>
 
> > You have to understand my background is mainly television
> > transmission but I find this stuff very interesting.
> >
>
> Yep, you can divide the pie any way you'd like!
>
Thanks Chris.

BTW, nice to see yours and K9EZ's sites on Scott Fybush's site of the week the last couple of weeks...
 
> > > You have to understand my background is mainly
> television
> > > transmission but I find this stuff very interesting.
> > >
> >
> > Yep, you can divide the pie any way you'd like!
> >
> Thanks Chris.
>
> BTW, nice to see yours and K9EZ's sites on Scott Fybush's
> site of the week the last couple of weeks...
>

Thanks!

If you want to see an HD install, click below...

One of my transmitter sites!

What is interesting here is the two switch design. This allows us to use the HD transmitter as an analog backup by switching it around the IBOC injector and connecting it directly into the antenna.

With one mouse click on AutoPilot, both transmitters shut down, the HD box switches from 2.1KW of HD to 11kw of analog, the antenna switch connects the HD TX directly to the antenna, and turns the HD TX back on. It takes about 15 seconds total. It turned out to be a great way to keep an analog backup available in a small transmitter suite.<P ID="signature">______________
</P>
 
> > > > You have to understand my background is mainly
> > television
> > > > transmission but I find this stuff very interesting.
> > > >
> > >
> > > Yep, you can divide the pie any way you'd like!
> > >
> > Thanks Chris.
> >
> > BTW, nice to see yours and K9EZ's sites on Scott Fybush's
> > site of the week the last couple of weeks...
> >
>
> Thanks!
>
> If you want to see an HD install, click below...
>
> One of my transmitter sites!
>
> What is interesting here is the two switch design. This
> allows us to use the HD transmitter as an analog backup by
> switching it around the IBOC injector and connecting it
> directly into the antenna.
>
> With one mouse click on AutoPilot, both transmitters shut
> down, the HD box switches from 2.1KW of HD to 11kw of
> analog, the antenna switch connects the HD TX directly to
> the antenna, and turns the HD TX back on. It takes about 15
> seconds total. It turned out to be a great way to keep an
> analog backup available in a small transmitter suite.
>

I am not familiar with the Nautel, but dont you haev to change bias in eh HD transmitter to go to analog, or does Nautel take care of that for you?
 
>
> I am not familiar with the Nautel, but dont you haev to
> change bias in eh HD transmitter to go to analog, or does
> Nautel take care of that for you?
>


Don't you remember the demo? ;)

It handles that for you. You can save any mode (HD, HD+FM, FM) at any frequency and any power level as a preset, and call it up with a remote closure. It literally takes about 1 second for the transmitter to switch modes and re-bias.

It's one of the reasons we went with the Nautel V10. Push one button, and it switches from 2.1KW HD to 11KW FM!<P ID="signature">______________
</P>
 
> Yep, you can divide the pie any way you'd like!

Yes, but you have to choose the dividing yourself and implement it manually (or program it via dayparting). The IBOC exciter can't manage the bitrate of each HD channel "on the fly" in response to the instantaneous audio content of each channel. That's what Sirius is doing, but this concept has yet to be implemented (or even planned) for HD Radio.

<P ID="signature">______________
It's a common mistake to not use punctuation in its proper form.
<a target="_blank" href=http://www.cgl.uwaterloo.ca/~csk/its.html>Be kind to your friend, the apostrophe.</a></P>
 
Hey K9EZ,

check your email, the one listed on your qrz.com profile.
 
> > Yep, you can divide the pie any way you'd like!
>
> Yes, but you have to choose the dividing yourself and
> implement it manually (or program it via dayparting). The
> IBOC exciter can't manage the bitrate of each HD channel "on
> the fly" in response to the instantaneous audio content of
> each channel. That's what Sirius is doing, but this concept
> has yet to be implemented (or even planned) for HD Radio.
>

Correct. Sirius has the "on-demand" type encoding (I believe DirecTV uses this as well) which allows a channel with temporary high-bandwidth demands to "borrow" bits from a channel that doesn't need them.

HD is static at 96kb/s. You set it manually for whatever you want, but that's where it stays. Commonly it's one of the following: 96, 48/48, 64/32 or 48/32/16

It would be interesting to see if it gets considered by iBiquity.
<P ID="signature">______________
</P><P ID="edit"><FONT class="small">Edited by RadioDoc on 04/11/06 02:21 AM.</FONT></P>
 
So does some DTV setups. A station I know is using two Harmonic encoders with a specialized device that Harmonic has to vary the rates "on the fly" for HD transmission , but Ive heard it can be buggy as well...
 
> It would be interesting to see if it gets considered by
> iBiquity.

At this point, I think anything which is incompatible with existing IBOC receivers is out of the question. They are already getting burned by the fact that first-generation receivers don't support HD Radio's most attractive feature (HD2/HD3 multicasting).
<P ID="signature">______________
It's a common mistake to not use punctuation in its proper form.
<a target="_blank" href=http://www.cgl.uwaterloo.ca/~csk/its.html>Be kind to your friend, the apostrophe.</a></P>
 
> > It would be interesting to see if it gets considered by
> > iBiquity.
>
> At this point, I think anything which is incompatible with
> existing IBOC receivers is out of the question. They are
> already getting burned by the fact that first-generation
> receivers don't support HD Radio's most attractive feature
> (HD2/HD3 multicasting).
>

Good point. The other problem, I imagine, is the fact that there are only a maximum of three streams. There really wouldn't be a whole lot of benefit going from, say, 64 to 75kb/s on the fly!

There just wouldn't be enough additional bits to make it real effective...<P ID="signature">______________
</P>
 
> Good point. The other problem, I imagine, is the fact that
> there are only a maximum of three streams. There really
> wouldn't be a whole lot of benefit going from, say, 64 to
> 75kb/s on the fly!
>
> There just wouldn't be enough additional bits to make it
> real effective...

It would really make sense for Eureka 147 DAB.... but the IBOC proponents have done their best to make sure that system won't see the light of day in the USA.
<P ID="signature">______________
It's a common mistake to not use punctuation in its proper form.
<a target="_blank" href=http://www.cgl.uwaterloo.ca/~csk/its.html>Be kind to your friend, the apostrophe.</a></P>
 
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