Steve - How long did it take FM to catch-on ?
So in 2015 we can then judge whether DRM may
indeed be the norm and an accepted form of
Shortwave Broadcasting or some idea that
never went anywhere over time. ~ RHF

In article .com,
wrote:
Why do you think DRM ultimately failed? I think it was simply an idea
that was behind its time, meaning it would have been successful 50
years ago, but is an anachronism today. It's neat that there are still
some DRM broadcasts around, but don't count on that to continue. In
particular, don't sink a lot of money into a DRM-capable receiver.

Huh? You're holding the funeral before the damn thing is even born.

Consumer grade receivers are just coming on the market in Europe now.

But, on the other hand, if whoever it was operates on 6095 at the
same time as I'm trying to get Radio New Zealand in the morning...

Mark Zenier
Googleproofaddress(account:mzenier provider:eskimo domain:com)

Yes, but FM sure did catch on eventually, and now it's everywhere. One
more thing that renders DRM obsolete. The writing is already on the
wall.

"Kristoff Bonne" wrote in message
...



Well, one of the things about technology is that sometimes "textbook
technology" which has existed for long only in books or in very
specialised applications (usually defence) just becomes mainstream. Take
COFDM or CDMA.


In the US, much of the pioneering work was done by commercial interests such
as RCA and AT&T. There was good money to be made trafficing messages around
the world!


[snip]


Now, I don't think there is anything in the specs for a situation where
you would put the same signal twice inside the same DRM transport-stream
(one delayed to the other) and give them both the same streamid, so I
don't know how a receiver would react to that. (some of them will
probably crash :-) )


Perhaps that's something to add in the specs.

But wouldn't a new radio crashing DRM spec make at least some of the new DRM
radios at least partially obselete? If so, that's bad marketing. Once the
radios start selling, they're pretty much stuck with whatever works with all
the DRM radios.


[snip]

True. My personal opinion is that -concidering the interest of quite a
lot of the big broadcasters- it will succeed, but we will see.


The real decision will be made by the public. In the US, the broadcasters
had a great amount of enthusisiam for AM stereo. There were some radios
offered, but, for the most part, the public didn't care. AM stereo just
never caught on, for whatever reason.

I suppose it's possible that DRM may also be an incomplete success. For
example, the public might find the occasional SW dropouts too annoying, but
they might very much like the improved signal to noise ratio on LW.

Frank Dresser

"Kristoff Bonne" wrote in message
...
c. Analog has sync detection, which eliminates most of the fading most of
the time. This is much better than drop outs.


AFAIK, sync detection is against partial-cochannel interference, not
against fading.

Perhaps its greatest benefit is improved immunity from distortion due to
selective fading, especially that which sucks out the carrier. Suppressing
one sideband also reduces fading distortion. The Dream software DRM decoder
also incorporates a synchronous AM, selectable sideband detector. The
improvement in listenability for a DSB AM signal in the presence of
selective fading is truly remarkable when it is used in synchronous ECSS
mode.

Broadcasters would free spectrum, reduce interference, be more energy
efficient, maintain compatability with the huge installed base of AM radios
by converting to SSBc mode. Radios manufactured with DSP capable of
synchronous AM selectable sideband would probably require less silicon than
DRM (read cheaper), be more energy efficient (read eat batteries more
slowly), be compatable with the huge installed base of DSBAM transmitters
and the then-growing number of SSBc transmitters. Why don't we hear more
about this alternative from broadcasters and manufacturers? Have I missed
something?

b. An analog radio with sync detection would sound better than a DRM
radio using the same radio spectrum bandwidth.

Do you actually have a DRM-radio? Can you compair?

While DRM might give the subjective impression of wider frequency response
and higher signal-to-noise ratio, to fit within a 10 or 20 kHz bandwidth, it
necessarily uses a very low bitrate lossy codec. I find that listening to
such codecs is aggravating, moreso than (and very different from) the
dynamic changes in spectral balance from an AM transmission in moderate
fades.

Moreover, the DRM spectrum is rectangular - even energy distribution. If we
take our 10 kHz channel and use SSBc to fill it (carrier at channel edge),
we will get nearly 10 kHz audio bandwidth. If we also use pre-emphasis (as
is done in FM), or one of the (ancient) Dolby or dBx type noise reduction
systems to lift the treble energy in the sideband, we will get a much
improved S/N. Still very listenable on a conventional DSBAM radio with
typical IF and AF passbands.

Why don't we hear about this approach? It sounds so easy I think I should
build a transmitter and experiment with it! There must be a catch...

Tom

In article ,
Kristoff Bonne wrote:

Gegroet,


Oeps. I am a bit behind scedule replying to this one.

No problem.

Telamon schreef:
Nope. I'm talking about Deception Radio Mondiale.
Didn't know this one. :-)

Nice!!!

You know why it's nice? Because it true.

DRM might bring people back to LW/MW/SW and they might not even know
it.
LW and MW are around 24/7 but SW stations change frequencies all
the time. It takes a little more effort to find a SW station.

That's what "AF" is for. (Alternative Frequency information inserted
into the DRM stream, just like on FM/RDS).

The problem is that you have to get a decent signal to get the
information.

One of the things with DRM (and especially with the DAB/DRM chipset
now available) is that the user will just be presented with a list of
stations and he will just have to pick the one from the list. She
will not know if she is listening to a DAB broadcast at 1.4 Ghz or
long-wave at below 200 Khz.

Most women are clueless about technology but what about us guys?

Great. Do I write "she" to say "hey, let's not be sexist and say that
only men know about technology and radio", and you reply "women don't
know anything about radio".
:-)

You could have written the same thing without he or she. Why bring sex
into it.

But seriously what station is going to broadcast the whole SW station
schedule in the background data stream. Do you have any idea how big
that is? You would need to do this because schedules (times and
frequencies) change all the time.

First of all, that's not such a big issue, as there do exist things like
the "EPG". It broadcasting-technology neutral so it can be used in
DAB, DVB and DRM.

What is "EPG"? If it's another digital stream then you have to able to
pick up the signal to get the information and that is a lot of
information for a low bit rate signal that can, lets face it, have drop
outs.

Second, the only thing the radio will do is scan all frequencies it can
receive and compose a list based on that. That's how DAB radios work
nowdays too.

I can do that right now so who needs DRM?

DRM has two major advantages: - it does away with fading, which is
one of the things people find most annoying about LW/MW/SW. The
"audio-quality" aspect is a bit mood as it all depends on what mode
you are using and I think for most people is not the most important
element. But if you produce a stable signal without fading, this
would make LW/MW/SW broadcasts quite acceptable by most people.

1. Fading
a. Fading is replaced with dropouts. I fail to understand how that can
even be considered an improvement.
Only if the signal goes below a certain S/N threshold.

Which it will.

b. I don't find it the most annoying thing.

Well, last year I was in Northern Italy and I was listening to the
worldservice of the public broadcaster of Flanders (dutch-speaking
belgium) on shortwave; and -to be honest- my wife was pretty anoyed by
the fading-element.


Somebody who just "hears" a radio (so, who is not really "listening") is
used to have a radio with a more-or-less constant quality-signal. They
are not really used to have a radio sound good, then get all kind of
noice, then sound good again, and then with noice again.

It attacks their attention and this annoys them. Radio should be a
"background noice" thing and this means that is should be more-or-less
constant.

It looks to me that you have not used a good analog radio with sync
detection and an adjustable AGC. With those two functions at your
disposal you won't have that problem.

c. Analog has sync detection, which eliminates most of the fading most
of the time. This is much better than drop outs.


AFAIK, sync detection is against partial-cochannel interference, not
against fading.

This tells me that you have never used a radio with sync detection. A
sync detector helps with selective fading and a good one will give weak
signals a boost. This together with a properly adjusted AGC will give
you constant quality audio.

2. Audio quality.
a. I have several analog radios that during real SW reception sound much
better than the audio demonstration files on the DRM website.

True, but there are stations who also sound worse.

So what that got to do with it. The DRM "sound" sucks with a good signal
and analog station with a good signal sounds much better. A DRM signal
that was weak would be dropping out and would get turned off.

b. An analog radio with sync detection would sound better than a DRM
radio using the same radio spectrum bandwidth.

Do you actually have a DRM-radio? Can you compair?

No I don't. I told you I listened to the samples on the DRM website and
besides that there are plenty of examples on the web of low bit rate
audio encoded files that don't sound very good.

c. No LW broadcast in NA ...
Correct, but I read somewhere that Australia is thinking of restarting
broadcasts on LW (because of DRM).

Most NDBs have disappeared from that band overthere.


... but I find that MW and SW are quite acceptable.
Are there domestic SW-broadcasts in the NA? CBC/RC?

Yes there are quite a few SW broadcasters and broadcast sites in NA but
I spend little time listening to them.

(The term "near-FM" is marketing talk, just ignore it).

No I won't ignore it. The better sound quality hype is just another
example of the sales deception that surrounds the DRM technology.

No, I meant that the term "near FM" is just marketing-talk. It allows
for better audio then AM, that is for sure but it all depends on what
mode you use.

I know what you meant. You are missing my point that this is not the
extent of the hype and I strongly disagree that DRM sounds better than
analog AM. It clearly sounds worse. You would have to increase the
bandwidth DRM currently uses for it to sound better.

If you listen to a very-low bitrate auxilairy channel (e.g. one used for
broadcasting traffic-messages) it will sound much worse then FM.
If you use it in the 20 KHz mode in the 11 meter broadcasting-band, it
will probably sound better then FM.

And just how do you think analog would sound using the same bandwidth?

The audio-quality-issue is technically much more complex then this, but
-marketing-wize- "near FM" is probably the simplest thing to say.


It allows broadcasters to break into certain markets by broadcasting
from abroad. BCE (RTL's broadcasting arm) plan to use it to broadcast
using DRM on LW, MW and SW towards different countries.

I don't know about this. What exactly does the DRM technology have to do
with enabling markets?

It allows them to broadcast with a "accepable" signal across the borders
so that -using their Luxembourg license- they can "break into" other
markets.

So your argument for DRM here is change the technology to overcome a
political problem?

The new frequencies on LW and MW they have requested at the ITU are
279 Khz (Junglinster towards Germany), 567 Khz (Clervoux towards the
Netherlands), 783 Khz (Beidweiler towards France) and 1098 Khz
(Clervoux towards Belgium).

I'm happy this is not in my part of the world.

Why not. The more channels, the better.

Just the opposite. One low bit rate crappie sounding DRM signal wastes
three channels. A good sounding DRM signal would waste twice as many.

Anycase, the biggest user of DRM will probably be not in Europe, but
will be in China. (for a very different reason, but that's a different
discussion).

Actually besides sounding like crap DRM biggest problem is that
broadcasters can start controlling who can listen. DRM would also be
easier to jam. Small wonder China would go for it.

For SW, they have asked the HFCC for coordination for two
frequencies: 5990 and 6095 Khz.
I would prefer that the DRM transmissions stay out of the international
broadcast bands and stick to the digital utility frequencies.

Why is that. If they are general-public broadcasts, that's where they
belong, isn't it?

No they are a digital mode that interferes with the analog signals I
want to listen too. They should stick to the part of the spectrum for
digital mode signals.

What does a x. KW high-power general-public broadcasting-station do in
the same band as medium-power utility-broadcasts?

Why should a digital mode signal be sitting in the middle of a analog AM
broadcast band?

If these broadcasts are analog or digital are IMHO of no importance.

I don't know why you would say this. Usage and mode of transmission
determine what frequency you transmit on. Why should DRM be an exception?

Cheerio! Kr. Bonne.

Yeah, cheerio to you too.

--
Telamon
Ventura, California

Well, my impression is that DRM is essentally stillborn. It's inspired
by the dream of making SW reception and audio sound just like FM.
However, it's not quite as good as FM on either count and it's a
bandwidth hog....oh, and there's that pesky problem of drop outs, which
is ultimately far more objectionable than fading. So, DRM is this
exciting new addition to the scene--that's not really quite as good as
either regular shortwave or FM in any of the respects that count.

I think the question is whether DRM even deserves a proper burial.

Kristoff Bonne wrote:
Gegroet,

schreef:
Well, my impression is that DRM is essentally stillborn. ...

A funny thing to say about something that hasn't even started yet and
you already declare it death.


Well, some ideas are just that bad.



I think the question is whether DRM even deserves a proper burial.
Concidering the fact that DRM will be used for MW/LW, local broadcasts
in the 11 meter, long-distance broadcasting on SW and possible also in
band I or band II; you'll have a difficult job buring it. :-)


DRM would leap headlong into the hole. Five years from now we won't
even remember what it was.

I don't make such predictions either about new technologies of any
consequence. However, I'm not worried about it in this case.

"Kristoff Bonne" wrote in message
...
Gegroet,

Just interested. Does anybody know if the AM-decoding in a "normal price"
SW-receiver is done in hardware or in software (ASIC/DSP)?

I'm not aware of any radios at any price that do AM decoding by DSP. I
suspect they exist in some form - after all, that is what one would expect
from Software Defined Radio technology. What about these new DRM radios - do
they also do AM and FM demodulation via DSP?

I might have missed something but AFAIK you cannot decode SSBc with a
standard AM-radio, can you?

Yes. I might have the acronym wrong - I mean SSB with reduced carrier, not
suppressed. The Canadian time signal transmissions from CHU on 3330 and 7335
kHz use this mode - easily received on the cheapest SW radios.

DRM has two advantages of this:
- it's a digital system. This means it includes features like auxilairy
content, "Alternative frequency" information, station identification,
multiple streams (e.g. two audio-streams in one DRM transport-stream),
variable bandwidth from 4.5 to 20 Khz, variable modulation-sceme and
error-correction mechanism based on channel quality, easier support for
time- and frequency diversity, single-frequency networking.

I'm aware of this but it's incompatible with the huge installed base......
I'm not sure about your "easier support for" statement - it's true for time
diversity but I can't quite imagine how and why one would need this for an
analog transmission mode so it seems a specious point. Frequency diversity
and SFN is done with AM. One's sense of hearing does a wonderful job of
"error correction" as part of an analog system - the digital system can't
work without its own. Seems like many of the purported advantages are born
out of necessity.

Auxiliary content, AF, station ID's, multiple streams and various bandwidths
and bitrates in DAB surely did not excite the public in this country. Now,
satellite radio with terrestrial fill-ins may be a different matter, and
cable and satellite DTH audio services with images and text certainly are.
The takeup has been pretty good.

It's easier to integrate into combined DAB/DRM chipsets which allows for
an one "integrated" chipset for both systems. It also allows
cross-platform services; e.g. does the "AF"-service work between DAB, DRM
and FM/RDS.

This may be of interest in those markets that Eureka 147 DAB was adopted
with fair market success (where is that other than the UK?) and maybe where
FM/RDS is likewise deployed but both require that the broadcaster has
multiple transmitters carrying the same program in multiple modes for the
listener to realize the benefit of cross-platform AF service. This may be
more theoretical than practical. The time delay for lockup to DRM or DAB is
so large that AF service using either of them would require dual receivers
so that the alternate frequency is already tuned and locked before the
current
frequency goes unlocked, rather than blindly chasing the AF list.



- it's one technology for LW/MW, for SW, for 11 meter "local" broadcasting
and, with the extension of DRM+, for band I and band II.

So could SSBc and maybe NBFM


This creates an enormous market for this, and -therefor- cheaper chipsets.

Likewise for any mode common to all bands/markets...


- And it allows you to lower the transmission-power (and hence the
electrivity-bill).

My observations of DRM on shortwave has been that high transmitter power is
still needed - maybe less than for DSBAM. SSBc also saves power.

Interest idea. Just interested to know how 10 Khz SSBc would react to
selective fading. As you said in the beginning, the problem is when the
carrier is gone. Wouldn't you have the same problem as with a
DSBAM-receiver?

When selective fade knocks out the carrier, you lose lock but not the
modulation, with a "true" synchronous AM detector. There will be an error
distortion, as in asynchronous ECSS, which could be very small for some
considerable time. DRM is not immune to selective fading - the cause is
multipath which causes jitter or spreading of the digital stream and when it
is big enough - no decoding and then wait for re-lock after the jitter has
fallen below the acceptable threshold.

BTW. AFAIK (correct me if I am wrong) a DSBAM-decoder will completely
chocke on such a signal, so I kind-of miss the reason why you say this is
compatible with a convensional DSBAM-radio.

An envelope detector will demodulate as long as there is carrier. There is
increasing distortion as the carrier is reduced relative to sideband below
some level. There would have to be a tradeoff between power savings and
receiver distortion.

Well, how would such a system react in a situation of two half co-channel
stations. (i.e. one station at 9.900 - 9.910 Khz, and another channel at
9.905 - 9.915 Khz).

(What is the exact jargon-word for this? co-channel? semi co-channel?)

With DSP IF brickwall filtering as in the Dream and SDRadio softwares, I
think it should work very well indeed by setting the filter to less than
5kHz - for the lower of the pair if we assume USB mode for both. The higher
would experience crosstalk from the first for program content whose audio
spectrum extends well above 5 kHz. Conventional AM radios could also be
tuned to minimise interference from the adjacent channel.

How does DRM react to overlapping spectrum from an adjacent or co-DRM? Not
likely very well given its poor performance in the presence of DSBAM or SSB
overlapping its spectrum. DRM SFN's may be another matter but jitter due to
path differences will cause problems somewhere - maybe synchronous SSBc
transmitters could form equally effective SFN's that work with the huge
installed base....

Cheers, Kristoffe. You lead a good discussion.

Tom