DRM 3995
 

The past few evenings I've tuned up to the top of the 75 meter band to see what
effect DRM on 3995 has on the band and it's atrocious.

DRM = QRM

dxAce
Michigan
USA

In article , dxAce
wrote:

The past few evenings I've tuned up to the top of the 75 meter band to see
what
effect DRM on 3995 has on the band and it's atrocious.

DRM = QRM

That's one of the neat things about technology is predictability.

DRM claims about better audio in the same bandwidth is BS as are the non
adjacent channel interference clams.

--
Telamon
Ventura, California

Telamon wrote:

In article , dxAce
wrote:

The past few evenings I've tuned up to the top of the 75 meter band to see
what
effect DRM on 3995 has on the band and it's atrocious.

DRM = QRM

That's one of the neat things about technology is predictability.

DRM claims about better audio in the same bandwidth is BS as are the non
adjacent channel interference clams.

Yep, I just checked the signal a few minutes ago on 3995 and it wipes out at
least the top 10 kHz of the band.

dxAce
Michigan
USA

In article , dxAce
wrote:

Telamon wrote:

In article , dxAce
wrote:

The past few evenings I've tuned up to the top of the 75 meter band to see
what
effect DRM on 3995 has on the band and it's atrocious.

DRM = QRM

That's one of the neat things about technology is predictability.

DRM claims about better audio in the same bandwidth is BS as are the non
adjacent channel interference clams.

Yep, I just checked the signal a few minutes ago on 3995 and it wipes out at
least the top 10 kHz of the band.

How about below? The upper harmonics are a sure thing but I expect the
DRM signal to spread out as far below the frequency transmitted on.

Digital signals spread out above and below the frequency they are on.
Upper frequency spread is from multiple carrier mixing products and
higher frequency harmonics of the fast switching edges and phase noise
or random jitter. The low frequency spread is from data dependent
effects or data dependent jitter and the data mixing with the carriers.

--
Telamon
Ventura, California

Telamon wrote:

In article , dxAce
wrote:

Telamon wrote:

In article , dxAce
wrote:

The past few evenings I've tuned up to the top of the 75 meter band to see
what
effect DRM on 3995 has on the band and it's atrocious.

DRM = QRM

That's one of the neat things about technology is predictability.

DRM claims about better audio in the same bandwidth is BS as are the non
adjacent channel interference clams.

Yep, I just checked the signal a few minutes ago on 3995 and it wipes out at
least the top 10 kHz of the band.

How about below? The upper harmonics are a sure thing but I expect the
DRM signal to spread out as far below the frequency transmitted on.

Digital signals spread out above and below the frequency they are on.
Upper frequency spread is from multiple carrier mixing products and
higher frequency harmonics of the fast switching edges and phase noise
or random jitter. The low frequency spread is from data dependent
effects or data dependent jitter and the data mixing with the carriers.

Well I did mention the top 10 kHz of the band. Apparently the signal is centered on
3995, and it is certainly audible both above and below that point.

In the few times I've checked recently I've not noticed any amateur use of that
range when the DRM signal is on.

It's a mess!

dxAce
Michigan
USA

In article ,
Telamon wrote:

How about below? The upper harmonics are a sure thing but I expect the
DRM signal to spread out as far below the frequency transmitted on.

Digital signals spread out above and below the frequency they are on.
Upper frequency spread is from multiple carrier mixing products and
higher frequency harmonics of the fast switching edges and phase noise
or random jitter. The low frequency spread is from data dependent
effects or data dependent jitter and the data mixing with the carriers.

Huh? There're no fast edges. It's a COFDM signal that consists of
hundreds of closely spaced subcarriers modulated as some slow baud rate
(around 30-50 Hz). It shouldn't slop over much, but it'll fill up all
the spectrum it's using. It's very similar to a FDM telegraph (Droning
DC-3) signal, only about 5-20 times as wide.

Mark Zenier Washington State resident

In article ,
(Mark Zenier) wrote:

In article
,
Telamon wrote:

How about below? The upper harmonics are a sure thing but I expect the
DRM signal to spread out as far below the frequency transmitted on.

Digital signals spread out above and below the frequency they are on.
Upper frequency spread is from multiple carrier mixing products and
higher frequency harmonics of the fast switching edges and phase noise
or random jitter. The low frequency spread is from data dependent
effects or data dependent jitter and the data mixing with the carriers.

Huh? There're no fast edges. It's a COFDM signal that consists of
hundreds of closely spaced subcarriers modulated as some slow baud rate
(around 30-50 Hz). It shouldn't slop over much, but it'll fill up all
the spectrum it's using. It's very similar to a FDM telegraph (Droning
DC-3) signal, only about 5-20 times as wide.

Mark Zenier Washington State resident

There are not hundreds of carriers. I believe the number is sixteen.

It is not the rate that they are switched at but how fast they actually
turn on and off. Think dV/dT.

--
Telamon
Ventura, California

dxAce wrote in message ...
The past few evenings I've tuned up to the top of the 75 meter band to see what
effect DRM on 3995 has on the band and it's atrocious.

DRM = QRM

dxAce
Michigan
USA

What is DRM?? Some kind of digital communications??

Steve

P.S. sorry if this is a dumn question.

Steve wrote:

dxAce wrote in message ...
The past few evenings I've tuned up to the top of the 75 meter band to see what
effect DRM on 3995 has on the band and it's atrocious.

DRM = QRM

dxAce
Michigan
USA

What is DRM?? Some kind of digital communications??

Yes, it is radio transmitted digitally. Give a listen up on 3995 in our North
American evenings and listen to the QRM.

And then try and imagine what that sort of thing will do to the other shortwave
broadcasting bands.

dxAce
Michigan
USA

Screw DRM,




If I want to listen to digital radio I'll just buy an XM radio or
listen to internet radio.

For me, I like my shortwave analogue since it's an escape from all the
digital stuff.