🚀 go-pugleaf

On Mon, 15 Oct 2007 07:20:19 -0700, SFTV_troy <SFTV_troy@yahoo.com>
wrote:

>
>Don Pearce wrote:
>> On Sat, 13 Oct 2007 10:05:11 -0700, "David Eduardo"
>> >"SFTV_troy"
>> >>
>> >>
>> >> I still don't see the difference.  Both standards are using
>> >> sidebands, adjacent to the analog AM signal.
>> >
>> >DRM is not using a sideband; to do analog and digital requires a separate
>> >transmitter for each on a separate carrier frequency. HD is a combined
>> >analog and digital signal on the same carrier frequency. DRM is digital
>> >only... if you want analog, you have to have a separate channel, close to or
>> >not to the DRM one.
>> >
>>
>> Exactly. DRM is a separate signal that can go wherever the operator
>> chooses. ..... It is not a sideband of the AM.
>> HD, on the other hand is an actual sideband of the AM carrier.
>
>
>
>
>I see your point, but that seems a trivial difference.  Especially
>since HD also uses a separate signal (exciter), separate from the
>analog signal.  "As with AM, FM stations may use separate exciters to
>modulate the very different signals." - wikipedia.
>
>Sounds like simulcast of two signals.
>
>Not just one.

An exciter is simply a source of a signal which can be modulated onto
a carrier.

If you want an analogy, HD is a little like the stereo subcarrier on
an FM signal - not the same as the baseband signal, but an integral
part of the overall signal. DRM would be like transmitting the stereo
signal on another channel entirely, with its own transmitter.

The difference is far from trivial.

d

-- 
Pearce Consulting
http://www.pearce.uk.com