On Sat, 13 Oct 2007 10:05:11 -0700, "David Eduardo"
wrote:


"SFTV_troy" wrote in message
ups.com...

RHF wrote:
On Oct 12, 8:52 am, SFTV_troy wrote:
RHF wrote:
On Oct 11, 5:48 am, SFTV_troy

- There's no real difference between DRM's version
- (sitting next-to the AM signal) and HD's version
- (also sitting next-to the AM signal).

IBOC AM/MW "HD" Radio - Hybrid Mode
http://www.dallas.net/~jvpoll/rfi/AM...BOC_Mask10.gif
- Lower Digital Sidebands {Co-SideBand}
* Analog Host Signal (Mono) {Nested}
+ Upper Digital Sidebands {Co-SideBand}

- Thanks for proving my point. HD sits *next to* the AM signal (+/-

- 10 kHz). Same as DRM sits *next to* the AM signal (+/- 10 kHz).



DRM = Simulcast without Specification {Sans-Mask}
x x x Does Not Equal x x x
IBOC = Intrinsic {Mask} : Nested Analog + Two Digital Co-Sidebands



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. He may elect to place it next to his AM transmitter or the
regulator may force him to place it there so any interference will be
to his own service. Whatever, the signal will appear at only one point
in the spectrum. It is not a sideband of the AM.

HD, on the other hand is an actual sideband of the AM carrier. There
are two digital channels available, the primary and the secondary.
Each of them occupies 5kHz either side of the AM carrier, the primary
from 10 to 15kHz, and the secondary from 5 to 10kHz. The HD signal is
irrevocably combined with its host AM service.

d

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