ABOUT - Digital Radio Mondiale (DRM) = http://www.drm.org/
 

"Frank Dresser" wrote in message
...

"Tom Holden" wrote in message
...

[snip]


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.

They do use premphasis with AM radio transmissions, at least in the US.
The
NRSC has come up with a suggested premphasis scheme:

http://www.nrscstandards.org/Standards/nrsc-1.pdf

This is NRSC 1. As I understand it, NRSC 2 is similiar, but with a a cut
off to the treble boost above some frequency to reduce adjacent channel
interference.

Frank Dresser

Seems like a good starting point - they obviously were seeking a
pre-/de-emphasis curve that would be a workable compromise between the ideal
for best S/N that could be achieved with new radios and listenability on
typical radios. Of course, with a new standard implemented in new radios,
one could use double-ended multi-band companding for greater benefit.

Tom

ABOUT - Digital Radio Mondiale (DRM) = http://www.drm.org/
 

"Kristoff Bonne" wrote in message
...
Tom Holden schreef:
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?

Well, I was more thinking in term of ASICs then "generic" DSP-processors.

Whether general-purpose DSP or ASIC DSP or software DSP running on a general
purpose CPU, it's still DSP.


When I left school (in 1993), I saw the first ASIC-chips (a V21/V23
decoder) which where based on DSP-technology; so I guess these things must
be pretty commonplace now.
If that is the case, a AM-decoder which is also able to do "detect" a
AM-signal is infact SBBc and decode it correct (and not as a "normal"
DSB-AM signal).

It's called a synchronous AM detector. While not commonplace, it is included
in several 'better' receivers. AM Stereo receivers used sync AM detectors.
The Sony IC-2010 has a highly reputed sync AM IC - analog. The WinRadio line
looks to include both sync AM and conventional envelope detectors in the
software DSP that runs on the PC to demodulate the 12 kHz IF output fed into
the PC sound system. Any sync AM detector is capable of demodulating both
DSB-AM with carrier and SSBc AM. As it is a product detector with a
synchronised BFO, the same detector may also be used for SSB suppressed
carrier and other modes, especially by defeating the synchroniser.

Concerning the DRM-chips, if you look at the specification from TI (see
link below, they say that this one chipset can do DAB, DRM, FM, RDS and AM
(plus mp2, mp3 and wma-playback).

So this does look like a SDR but I don't know if it is actually possible
to "flash" the device and upload new DSP-code into it.

The Radioscape module based on this chipset can be programmed via USB. It
looks to incorporate AM envelope detection as standard.

Regards,

Tom

DRM vs SSBc
 

"Kristoff Bonne" wrote in message
...

It can image that a AM-decoder can decode this correctly for CHU, but I
don't know if this would apply for a broadcasting-signal.

Why not? CHU contains human voice announcements in USBc so why would a SSBc
broadcast signal be any different as far as an envelope detector is
concerned?

I wonder what would happen if you would have a situation like this:
- Say that you have a radio-station in 5 Khz USB SSBc at (say) 7200 Khz
(hence, taking up 7310 to 7315 Khz; just a random frequency)

(you mean the 5 kHz USBc carrier is at 7310, not 7200)

- and you have a second signal just below (either a SSBc from 7305 to
7310, or a DSB-AM from 7300 to 7310).

(i.e. a USBc or a DSBC at 7305)


How would a AM-decoder react if it was tuned to 7310Khz. Wouldn't he think
this is a DSB-AM station from 7305 to 7315 Khz and completely decode this
incorrectly?

If the IF shifts the 7310 to the centre of its 5 kHz passband, then both an
envelope detector or a sync AM detector centred in the passband are going to
see the upper 2.5k of the upper sideband of the lower adjacent freq. As you
tune the receiver higher in frequency, less of the undesired sideband and
more of the desired will be seen, thus improving the S/I. A correctly
designed selectable sideband synch AM receiver would correctly align the
passband on the selected sideband and with the synchronous BFO.

A DSP/ASIC based signal might be programmed to see that the signal at
7305-7310 Khz is completely different then 7310-7315 KHz and switch to
SSBc because of that, but how would an "analog" AM-decoder react to this?

Because sync AM has a lock-in time or latency, it might be desirable to use
envelope detection for rapid and coarse tuning with an optional automatic
switch to sync AM mode. Of course, a DXer would want to exercise manual
control. I have no idea whether such auto switching is realisable in any
practical way.

I'm replying in digestible chunks - more later!

73, Tom

The Future and Fate of DRM and IBOC - "The Market Makers" Will Decide !
 

In article ,
"Tom Holden" wrote:

"Telamon" wrote in message
...
[snip]
I've lost count of how many times I have posted - the one I showed you
is the ONLY DEMONSTRATION SW DRM RADIO IN ANY OF THE LINKS.

1. http://www.mayah.com/products/products-drm.htm
2.
http://www.himalaya.com.hk/index.php...id=14&Itemi d
=28&lang=en

Both above are short-wave. Of course, SW could mean software and that adds a
few more.

I thought the discussion on performance, technology, market, motivators,
politics was most interesting - thanks to Kristoff for initiating it. It
would be nice to continue the discussion, respectfully.

Yeah Tom I post the links. Both links are the same radio. This is the
one DRM SW radio I have been able to find. This is the ONE concept radio
by two of the companies involved in the DRM consortium.

--
Telamon
Ventura, California

The Future and Fate of DRM and IBOC - "The Market Makers" Will Decide !
 

In article ,
craigm wrote:

Telamon wrote:
In article ,
craigm wrote:


Telamon wrote:


The statements that I have seen before about DRM being an open standard
are as far as I see false because the software is not in the public
domain.

The software does not have to be in the public domain for the standard
to be open. The standard is one thing, the software is an implementation
of the standard. I can write software that complies with an open
standard and sell it without putting the source in the public domain.

The DRM standard in part uses proprietary code licensed by several
companies depend on the mode you operate in. That does not meet the open
requirement.

Like this one?
http://sourceforge.net/projects/drm/


No I don't like it. This is another computer - radio. You do realize
that most of these units need a computer to operate? These are not stand
alone radios. The link I provided is the one stand alone SW radio that I
know about.


The reply was in response to your statement that the software was not in
public domain. Source code is available so your argument fails.


You do not have the rights to the software, those rights are reserved.
For the time being you can down load and compile it on a local machine
for your own use. If the rights holder tell you to stop using it then
that's it.

If you follow the requirements of the GPL, then the rights holder won't
tell you to stop using it.


If money is demanded then you will have to pay it.
Per the GPL, any money is for distribution costs. Since the links were
for a free download site, there is no cost, now or in the furute.


There are
many ways this can be enforced.

Yes, but you would have to violate the terms of the GPL.

I don't know what you are talking about here. This software is being
sold and is not free. If there is a free DRM radio decoder I did not
know about it. I don't understand how this could be because some of the
encoding/decoding algorithms are not free. Please point to the free DRM
decoding software.

There is one stand alone demonstration radio. I provided the link to it.
The others are multi kilo buck professional rack mount units that
consumers are not going to buy. All the other links by the DRM Troll
point to AMBCB and FM NOT SW RADIOS or computer assisted radios.

So the argument that "DRM consumer penetration into SW" is false.


Just because the software runs on a computer today, doesn't mean it must
always run on a computer. Initially MP3 encosded music only ran on a
computer. Now you can easily find battery operated MP3 players.


So what.

You argue that DRM is primarily limited to computers and that is an
issue for you. I provided an example of a technology that was initially
limited to computers and is now available in low cost devices that fit
in a pocket. The point being, the same can happen with DRM.



There are some that run 70 hours on a single AAA battery. Battery life
does not need to be an issue either.


Again so what.

You argue that the technology to turn a digital stream to audio is too
power hungry for portable devices. Again, MP3 players show that this
does not have to be so.



The other links are not SW radios or they need computers to operate or
they are rack mount units that are and will continue to be very
expensive. The rack mounts are not consumer units.



Once a semiconductor manufacturer produces an ASIC for DRM it will be
possible to produce battery operated radios with DRM. A receiver
manufacturer could also create a custom ASIC.


Yeah that's the no brainer requirement it will take to create a radio
that will operate on batteries. Make no mistake about this, battery life
will be shorter than the current generation radios.

So who do you think is going to spend hundreds of thousands of dollars
to make ASIC's to do this?

Sony could. TI could. Philips could. Analog Devices could. If you could
sell tens of thousands of them, why not. Many companies are making ASICs.

DRM uses MPEG4 AAC audio coding as one of its choices. The Apple IPOD
supports MPEG4 AAC audio coding. Perhaps half the ASIC work is already done.

You are missing about every point in the thread. The DRM Troll started
out saying that the DRM SW was imminent because consumer radios existed.
There is one that I can find no thanks to the Troll. I don't know if
this one radio is actually being sold since it is described as a
"concept radio." He kept posting links of the same radios that are not
SW radios but are AMBCB or FM. The radios that did receive SW need a
computer to operate or they were very expensive professional rack mount
units. Basically the radios that need a computer are science experiments
for early adopters. There is no analog equivalent DRM SW radio being
manufactured today as far as I can tell.

Of course there could be a DRM SW equivalent tomorrow. Of course any
company with the resources could spend the money to produce ASIC's to do
the job. It is just that they haven't done it yet contrary to what the
DRM Troll is espousing.

A DRM radio needs to perform many functions compared to what an MP3
player needs to do. Additional functions over what an analog radio
requires so even if a well financed company decided to build a high
order of integration with several ASIC's a DRM radio would still draw
much more power than a analog radio. Standard batteries many not be able
to handle the power requirements and when DRM SW portables show up they
will probably use lithium ion rechargeable batteries.

There is nothing magical about DRM technology. Everything used by the
DRM scheme is used someplace else. Nothing new here and that might be
part of the problem of a technology not well matched to the SW
propagation environment.

--
Telamon
Ventura, California

The Future and Fate of DRM and IBOC - "The Market Makers" WillDecide !
 

Telamon wrote:

You are missing about every point in the thread. The DRM Troll started
out saying that the DRM SW was imminent because consumer radios existed.
There is one that I can find no thanks to the Troll. I don't know if
this one radio is actually being sold since it is described as a
"concept radio." He kept posting links of the same radios that are not
SW radios but are AMBCB or FM. The radios that did receive SW need a
computer to operate or they were very expensive professional rack mount
units. Basically the radios that need a computer are science experiments
for early adopters. There is no analog equivalent DRM SW radio being
manufactured today as far as I can tell.

--
Telamon
Ventura, California


A "Concept" unit is usually something that was built to take to trade
shows to see if there is a market for a product. With radios its not
uncommon for the "Concept" device to only have a computer board and
software to let you operate the controls. I saw one that cost a company
over $1,000,000 US dollars. It had a laptop inside, and a bunch of 50
Ohm 2 Watt carbon resistors across all of the BNC connectors, in case
someone actually tried to hook it up. The real prototype DSP based
telemetry receiver was still on the designers bench, not working.

--
?

Michael A. Terrell
Central Florida

The Future and Fate of DRM and IBOC - "The Market Makers" WillDecide !
 

Telamon wrote:

The software does not have to be in the public domain for the standard
to be open. The standard is one thing, the software is an implementation
of the standard. I can write software that complies with an open
standard and sell it without putting the source in the public domain.


The DRM standard in part uses proprietary code licensed by several
companies depend on the mode you operate in. That does not meet the open
requirement.



I think the difference in our opinion revolve around the definition of
an open standard. There is enough information on the net that someone
can develop the code to receive DRM.





There are

many ways this can be enforced.

Yes, but you would have to violate the terms of the GPL.


I don't know what you are talking about here. This software is being
sold and is not free. If there is a free DRM radio decoder I did not
know about it. I don't understand how this could be because some of the
encoding/decoding algorithms are not free. Please point to the free DRM
decoding software.


You haven't looked at http://sourceforge.net/projects/drm/

You download for free, compile and use. If you don't like something
about the code, change it, recompile and use.





You are missing about every point in the thread. The DRM Troll started
out saying that the DRM SW was imminent because consumer radios existed.
There is one that I can find no thanks to the Troll. I don't know if
this one radio is actually being sold since it is described as a
"concept radio." He kept posting links of the same radios that are not
SW radios but are AMBCB or FM. The radios that did receive SW need a
computer to operate or they were very expensive professional rack mount
units. Basically the radios that need a computer are science experiments
for early adopters. There is no analog equivalent DRM SW radio being
manufactured today as far as I can tell.

I see no DRM radios similar to a Sony 7600, yet. (If that is what you
mean.) That does not mean it can't happen.


Of course there could be a DRM SW equivalent tomorrow. Of course any
company with the resources could spend the money to produce ASIC's to do
the job. It is just that they haven't done it yet contrary to what the
DRM Troll is espousing.


The other links in the thread refer to a TI part.
http://focus.ti.com/docs/apps/catalo...dio_digrad_drm
Check this link where it is being used.
http://www.radioscape.com/downloads/...500_Doc_02.pdf
or,
http://www.radioscape.com/



A DRM radio needs to perform many functions compared to what an MP3
player needs to do. Additional functions over what an analog radio
requires so even if a well financed company decided to build a high
order of integration with several ASIC's a DRM radio would still draw
much more power than a analog radio. Standard batteries many not be able
to handle the power requirements and when DRM SW portables show up they
will probably use lithium ion rechargeable batteries.

You are missing my point about the advances in technology. What has
happened with MP3 players, PDAs, cell phones, and computers has lead to
portable devices that are battery operated. The same concepts applied to
DRM can yield similar results.

Yes, it will use more power than an analog radio. However, we are not
talking about the same performance as a radio with no digital circuitry.



There is nothing magical about DRM technology. Everything used by the
DRM scheme is used someplace else. Nothing new here and that might be
part of the problem of a technology not well matched to the SW
propagation environment.


Time will tell.

I think there is good potential.

craigm

DRM vs SSBc
 

"Kristoff Bonne" wrote in message
...
My question is what happens if you tune a normal DSB-AM decoder to a SSBc
signal (say in USB), where there happens to be another signal at the 5 Khz
below.

Actually, there is a good test for that. 7335 khz is in the middle of a
broadcasting-band.
Can you still hear CHU at that frequency (SSBc USB, carrier at 7335 Khz,
signal from 7335 to 7340 Khz) with a normal DSB-AM radio if there is a
station broadcasting at 7330 Khz in DSB-AM (i.e. signal from 7325 to 7335
Khz)?

Yes, answered before and below...

If the IF shifts the 7310 to the centre of its 5 kHz passband, then both
an envelope detector or a sync AM detector centred in the passband are
going to see the upper 2.5k of the upper sideband of the lower adjacent
freq. As you tune the receiver higher in frequency, less of the undesired
sideband and more of the desired will be seen, thus improving the S/I.

That is saying that you would tune the conventional envelope detector
receiver to the upper side of the USBc carrier in order to suppress
interference from the lower adjacent channel, just as you would if the
desired signal was DSB and there was interference from the lower adjacent
channel. The more difficult and potentially untenable situation for even the
most sophisticated receiver is if the interferer is DSB on the upper
adjacent channel of a USBc signal.


But I do think the situation in different parts of the world:
- here in Europe SW is used to beam news and information from "home" to
holidays-destinations
- in the US -as there are no "domestic" SW-broadcasts- (at least, that's
what I read somewhere) SW is probably more a "hobby" thing.
- in other parts of the world, SW is also used for "domestic"
broadcasting.

I think you are correct that the US FCC does not license SW broadcasters for
domestic coverage but many supposedly international US broadcasters have
their largest audiences within its borders. I am in Canada - we have a few
SW transmitters for domestic coverage.

But, as I already said, the question is to what degree this really
matters. The way I see it, we're asking ourself the wrong question here.
The first question would be "who are we aiming this service for and what
kind of equipement do they have now"?


I see two possibilities:
- either you direct this at a target-group which already owns a shortwave
radio, and -then- backwards compatibility with DSB-AM is important.

And that is my point - the already huge installed base, not only of SW but
also MW and LW radios....

- either you are looking at a group of people who currently do not have a
SW-radio, and they will have to buy a new one anyway, so -at that moment-
backwards compatibility of your service to existing DSB-AM receivers is
not important!

Nobody is being forced to buy a new method of reception, unless the
regulators shut down the current methods, as is intended for TV broadcast.
For radio, the US and Canadian regulators seem to be more inclined to let
market forces decide. Canada was an early adopter of Eureka 147 in a new
slice of spectrum for broadcast - the L-band. The number of receivers sold
over the course of nearly 6 years since its launch is probably numbered in
the high hundreds, certainly less than a few thousand, despite claiming
coverage of over 10 million people. The number being used is probably a tiny
fraction of that. They were not forced to buy and certainly not induced by
the supposed attractions of Program Associated Data, AF interchange with FM,
multiple services, and the claims of 'CD quality', etc. So all that
investment in DAB transmission has been wasted. Anybody mounting an
advertising-based service solely on DAB would have been foolish.

So, what is our goal?

- more robust reception?
- better audio quality.
- a better user-interface
- additional services
- reduced broadcasting-power

AND

- low transition cost, for both broadcasters and listeners
- rapid reach to a large potential audience
- economical receivers, in cost, weight and power consumption
- interference mitigation

I think the most usefull approach is to put the two techologies next to
each other and see how well they score for every element.

Of course. But it's not easy. Real-world A-B comparisons are the right way
to do some of these things, double-blind tests, controlled conditions,
etc...

We can then try to "map" these to what we think is important for the
listener, but that will also vary on the kind of listener you're aiming
this at.
And this will different for somebody who is interested to learn about
foreign countries and who also has access to the internet, then for
somebody whos SW-radio is the only way to get news, information and music
from the central island of the archipel.

Sure, the weight one puts on each criterion will be influenced by context.

73,

Tom

The Future and Fate of DRM and IBOC - "The Market Makers" Will Decide !
 

"Telamon" wrote in message
...
In article ,
"Tom Holden" wrote:

"Telamon" wrote in message
...
[snip]
I've lost count of how many times I have posted - the one I showed you
is the ONLY DEMONSTRATION SW DRM RADIO IN ANY OF THE LINKS.

1. http://www.mayah.com/products/products-drm.htm
2.
http://www.himalaya.com.hk/index.php...id=14&Itemi d
=28&lang=en

Yeah Tom I post the links. Both links are the same radio. This is the
one DRM SW radio I have been able to find. This is the ONE concept radio
by two of the companies involved in the DRM consortium.

Check again if you think both links point to the same radio. #1 is the Mayah
DRM-2010, #2 is the Himalaya with twin speakers and a star of David pattern
set of controls and is unmistakeably different from #1. The Himalaya is
based on the Analog Devices Blackfin processor, the 2010 on some unnamed
module. Mayah has nothing to do with #2 but the Himalaya company is involved
in both.

Anyway, what's the point if there is or was only one at some point in time -
there will be more soon, if not already. Two hairs or split hairs - it's
only hair! ;-)

73, Tom

The Future and Fate of DRM and IBOC - "The Market Makers" Will Decide !
 

In article ,
"Tom Holden" wrote:

"Telamon" wrote in message
...
In article ,
"Tom Holden" wrote:

"Telamon" wrote in message
.
..
[snip]
I've lost count of how many times I have posted - the one I showed you
is the ONLY DEMONSTRATION SW DRM RADIO IN ANY OF THE LINKS.

1. http://www.mayah.com/products/products-drm.htm
2.
http://www.himalaya.com.hk/index.php...view&id=14&Ite
mid
=28&lang=en

Yeah Tom I post the links. Both links are the same radio. This is the
one DRM SW radio I have been able to find. This is the ONE concept radio
by two of the companies involved in the DRM consortium.

Check again if you think both links point to the same radio. #1 is the Mayah
DRM-2010, #2 is the Himalaya with twin speakers and a star of David pattern
set of controls and is unmistakeably different from #1. The Himalaya is
based on the Analog Devices Blackfin processor, the 2010 on some unnamed
module. Mayah has nothing to do with #2 but the Himalaya company is involved
in both.

Anyway, what's the point if there is or was only one at some point in time -
there will be more soon, if not already. Two hairs or split hairs - it's
only hair! ;-)

Sorry about that, I looked at the first one and not the second. The
second one (himalaya) in the past needed a computer for processing the
audio. Looks like it might be a stand alone radio now.

--
Telamon
Ventura, California