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DigiBC
04-09-2004, 05:32
Press Release by Coding Technologies:Coding Technologies introduces world's first USB receiver for Digital Radio Mondiale at IBC, hall 8, booth #8.484, September 10-14, 2004

Digital World Traveller to be on sale after the show

Nuremberg, September 1, 2004 - Coding Technologies, the leading provider of audio compression technology for digital broadcasting, mobile and Internet streaming, will showcase world's first USB receiver for Digital Radio Mondiale (DRM), the new standard for digital broadcasting in the long, medium/AM, and short-wave bands, at the International Broadcasting Convention IBC 2004 in Amsterdam. The handy little box branded "Digital World Traveller" is to be connected to the USB port of a PC or Notebook. The device comes with the Digital World Traveller Radio Software and is capable of receiving DRM, FM and AM radio programs. After the 1st and 2nd generation DRM receiver, the Digital World Traveller is the third DRM receiver from Coding Technologies and will be sold for a competitive price after the IBC show.

With the introduction of the Digital World Traveller, listeners can now easily enjoy Digital Radio Mondiale services in a convenient way by connecting it to a Notebook or standard PC without any additional power supply or battery. It is an ideal device for business and holiday travellers who want to stay in touch with their home countries by listening to first hand news and information in clear DRM broadcast quality. The included Digital World Traveller Radio Software supports decoding of all DRM modes and is compatible with Windows 2000, XP Home Edition and XP Professional.

"We are very excited about the introduction of the Digital World Traveller" Peter Senger, Chairman of the DRM consortium, said. "Just after one year of DRM being officially in service, it is a great achievement to offer such an innovative and affordable receiver to our listeners."

Added Stefan Meltzer, Vice President Business Development at Coding Technologies: "It has been a pleasure to work with our partners at AFG Engineering, FhG, Himalaya and Micronas to make the Digital World Traveller a reality. We are convinced that this ambitious project will contribute to the success of Digital Radio Mondiale by giving an easier access to the technology for a broader community."

The Digital World Traveller will be demonstrated at the booth of Digital Radio Mondiale in hall 8, booth # 8.484 and will be on sale after the IBC at a price of €199+VAT. The package includes the Digital World Traveller receiver box, the Digital World Traveller Radio Software and operation manual on CD, USB cable, and wire antenna.

For more information, visit www.codingtechnologies.com (http://www.codingtechnologies.com) and www.mp3prozone.com (http://www.mp3prozone.com)

dk8cb
04-09-2004, 08:26
Hi,

but there are still unanswered questions:

How much of the decoding is done in this external USB device?

Does it contain the long awaited DRM chipset?

The latest edition of the german magazine c't contains an article about DRM in which a "design study" of such a device, probably exactly this one, and a picture of the circuit board (unfortunately only one side of it) are shown.

Roland

Connor Walsh
05-09-2004, 01:27
A great price at least!
But is there any point in asking for a Mac version? :( Probably more than just drivers needed though.. If it was more than a software radio, wouldn't it cost more, and wouldn't they make a fuss about it?

Doctor Daemon
05-09-2004, 15:25
I hope too that there will be a Macintosh version. This thing would be the perfect mate for my iBook. For my Home PC it wouldnt make much sense, because I already have my TenTec connected to it.
Let's hope one of the deveolpers is reading this forum.

DigiBC
05-09-2004, 15:39
Hi!Originally posted by dk8cb
How much of the decoding is done in this external USB device?
Does it contain the long awaited DRM chipset?I don’t think so since they say:
The included Digital World Traveller Radio Software supports decoding of all DRM modes...I suppose the receiver will work conventionally: It'll probably send a 12 kHz IF signal to the computer, but not analogue via the soundcard but digital via the USB interface.
There have been some studies (by Sat-Service Schneider and others) using a Micronas USB sound chip for the A/D conversion of the IF signal right after the mixer unit. So no one would have to worry about the DRM capabilities of the build-in soundcard of a computer (laptop).
If Plug & Play recognizes the sound chip as an USB sound card other decoding software than the "Digital World Traveller Radio Software" (which perhaps will be based on the "DRM Software Radio") could be used too: "Dream", especially if the receiver is added to "Hamlib" ("Ham Radio Control Libraries"), and some decoder programs for analogue modes (AM, SSB, CW, RTTY...) should work then.

I hope we'll get some technical information and pictures after the start of the IBC next weekend because I consider the receiver a very interesting concept (and a cheap alternative to the announced external WiNRADiOs). :)

Regards - DigiBC

dk8cb
05-09-2004, 18:08
and a cheap alternative to the announced external WiNRADiOs

Sorry, it may be cheaper than the WinRadio, but if it is just a dumb receiver, I don't consider it really cheap at 199 EUR + VAT.
Compare e.g. to a stand-alone WorldSpace receiver, which you can get for less than half the price.

OK, compared to the heavily overprized Elektor receiver, it may be considered to be a cheap device.


Roland

markp
06-09-2004, 09:43
Originally posted by Connor Walsh
A great price at least!
But is there any point in asking for a Mac version? :( Probably more than just drivers needed though.. If it was more than a software radio, wouldn't it cost more, and wouldn't they make a fuss about it?

Sadly, it seems often too much to ask for in the world of radio - almost all devices are always firmly fixed to the realm of Wintel.:mad:

Connor Walsh
06-09-2004, 09:59
All too true Markp! Someone at the DReaM forums said a few times he was working on a port of that for Mac OS X, and I think I heard somewhere Apple is working on an AAC+ update for iTunes... So maybe there will be frameworks in place for developers to use (that'a total speculation as I don't understand programming at all).
But there is still the dilemma of convincing someone to actually write the software for us!

DigiBC
06-09-2004, 17:27
Hi,

I've received a product sheet from Coding Technologies with some additional information:
The Digital World Traveller is a small, universal and easy to use mobile radio receiver for reception of Digital Radio Mondiale (DRM) broadcasts, the new standard for digital broadcasting below 30 MHz, as well as for analogue broadcasts in the FM and AM bands.
The Digital World Traveller consists of a receiver box, which is connected to a Notebook/PC over USB, and a software to control the receiver box and to perform the decoding of the DRM broadcasts. The software controls all functions of the Digital World Traveller and allows the storage of up to 10 stations for each frequency band. In the DRM mode, the software indicates the available service components and text messages of a DRM broadcast. An expert mode window provides additional information about the service components and also displays the spectrum of the received signal.
The receiver box is powered over the USB interface, so no external power supply is required.The supported DRM modes are well known from the "DRM Software Radio" (so no support for 18 / 20 kHz wide DRM signals).

A picture of the PCB of a prototype was published by German computer magazine c't today (see attached file).
It's not good enough to read the markings on the chips but I think the left one is a Micronas UAC355xB sound chip (with a separate EEPROM and a 12 MHz crystal). The other 32 pin chip seems to be an integrated PLL AM/FM receiver circuit.
I've got no idea what reception quality to expect from it, but since it doesn't look like a DDS circuit I wouldn't assume high SNR levels.

The receiver appears to be build for common consumers, who feel attracted to DRM, but not for enthusiasts like us. ;)
Perhaps we'll know more as soon as the first tests will be coming in. (But I'd agree with Roland that it won't be a competitor to the WiNRADiOs...)

@ markp / Connor:
I'm sure that there would be a Mac version of "Dream" if someone with knowledge in Mac OS programming would join the "Dream Team"...

Regards - DigiBC

Garf
06-09-2004, 18:17
Originally posted by Connor Walsh
All too true Markp! Someone at the DReaM forums said a few times he was working on a port of that for Mac OS X, and I think I heard somewhere Apple is working on an AAC+ update for iTunes...

You can just use FAAD2 on Mac OS X, which is the decoder that Dream uses for HE-AAC, no need for iTunes.

Connor Walsh
06-09-2004, 21:49
You can just use FAAD2 on Mac OS X, which is the decoder that Dream uses for HE-AAC, no need for iTunes.
So why can't they just give us Mac OS support for Winradio, this new radio, the official software radio ? :(
Garf, do you have experience of making Dream work on Mac OS X? I might ask you for some help if that's ok, as it didn't work out the few times I tried.
Like DigiBC says, I guess it is kind of a chicken and egg situation, with few applications and developers making them for Mac OS X? I've realised this is going off topic, perhaps we should start a separate Mac OS thread?

Returning to the topic (!) a more general purpose receiver is a big step forward. I saw the recent figure that the consortium wants to have millions of receivers here in China in 2005, and this trend of straight forward USB radios with an antenna is definitely a way to make that more possible!

dk8cb
06-09-2004, 22:16
Originally posted by DigiBC
The other 32 pin chip seems to be an integrated PLL AM/FM receiver circuit.

Hi,

I don't think it is an RF chip, it looks more like an Atmel microcontroller. I think I can recognize the Atmel logo (I'm not looking at the scan, but at the respective magazine page). It's my opinion, that the RF tuner is either on the lower side of the pcb or not yet installed. Could well be that the tuner fits into the large empty space in the right half.

Roland

Garf
07-09-2004, 11:15
Originally posted by Connor Walsh
So why can't they just give us Mac OS support for Winradio, this new radio, the official software radio ? :(


I think those softwares were simply not written with portability in mind and Windows is still the largest market.


Garf, do you have experience of making Dream work on Mac OS X? I might ask you for some help if that's ok, as it didn't work out the few times I tried.


Sure, you can contact me at gcp at sjeng dot org.

I am pretty sure (>99% :)) Dream works on Mac. The GUI it uses is totally crossplatform and supported on Mac, and FAAD2 should work as well. Maybe only the sound input/output needs some small adjustments, and perhaps some other small fixes.
The problem is just that none of the Dream developers or I have a Mac :-/

Connor Walsh
07-09-2004, 13:24
Thanks so much Garf! I'll give it another go and get back to you when things don't work ;)

DigiBC
07-09-2004, 21:13
This thread is getting a bit mixed up since two different topics are discussed. :confused:
So please don't mind if I suggest to open an new thread if you want to discuss "Dream" for Mac OS. Maybe it would be even better to start a thread at the "Dream Forum":
http://sourceforge.net/forum/forum.php?forum_id=242204

Getting back to our interesting speculations about the PCB:
You may be right, Roland. The logo on the second chip really looks much like "Atmel" but I don't think it's a microcontroller because of all the (ceramic) filters around it. (Maybe it's an AM/FM front-end circuit like Atmel's T4258N.)
I'd also agree that there could be a small, shielded RF tuner unit containing a PLL chip (not shown in the picture). That might explain the 6 pin socket.

If I take a look at a reference design board by MicronasNIT (see attached file) it could still be a single chip receiver solution too.

Regards - DigiBC

DRM-Fan
16-09-2004, 22:12
Image and specs in attached pdf file...

BofH
17-09-2004, 13:20
This new receiver from Coding Technologies is a joke!

Last time I checked, the standard contained 18 kHz and 20 kHz "double bandwidth" modes which support a bitrate up to 72kbps.

However there appears to be no minimum requirement set by the DRM Consortium for a production DRM receiver to support these 18 kHz and 20 kHz modes!

The Mayah 2010 does contain these modes:
http://www.mayah.com/content/download/pdfs/drm/DRM2010_e.pdf

However this new "Digital World Traveller" from Coding Technologies omits these important modes - and as this is supposedly the first high volume "production" consumer receiver, it is extremely worrying!

It seems to me we have another "AM Stereo" debacle on our hands, where lack of enforcement of certain minimum standards for receiver manufacturers (such as supporting decoding all DRM RF bandwidths) will lead to a situation whereby most consumer DRM radios will not support 18 kHz and 20 kHz because it is cheaper to make narrow banded radios!

Coding Technologies - it's not too late to recall the product and make it truly compatible with the DRM standard! Shame on you!

I certainly won't be buying a product that doesn't support all DRM transmission modes!

Connor Walsh
17-09-2004, 13:31
Well said BofH! You hit the nail on the head I think. Though 20KHz may require some changes from the ITU or HFCC?

BofH
17-09-2004, 13:40
Originally posted by Connor Walsh
Well said BofH! You hit the nail on the head I think. Though 20KHz may require some changes from the ITU or HFCC?

In Europe most likely however other countries such as Canada and the US would be able to use the 20 kHz mode.

The 18 kHz mode is usable in much of the world, eg Australia and New Zealand amongst others have this channel width.

I'm not sure what the situation is with Shortwave channels however - it would be fairly easy to find two adjacent channels to allow use of 18 / 20 kHz bandwidth?

G8JQW
17-09-2004, 13:54
Hi

I noticed that the USB receiver does not support 18/20 kHz but it has the DRM logo on it. To use this logo it seems that a receiver does not have to conform to the DRM ETSI standard only that the company producing the receiver is a consortium member (or am I being a bit cynical?).


73s, Roger

DigiBC
17-09-2004, 15:10
Sorry, but I don't think that the lack of both wide modes is of any real significance.

There are no such transmissions now and I rather doubt that there'll be some in the future. In most regions there's a shortage of frequencies in the AM bands so that the occupation of two channels won't be allowed. (Not to mention that smaller bandwidth modes are more reliable for sky wave propagation.)
The 11 m band might be the only place for 20 kHz mode transmissions if it will be used by local radio stations...

Regards - DigiBC

DRM-Fan
17-09-2004, 18:29
Would'nt double bandweidth just be a simple software upgrade via the USB port of this receiver ?

Though who will use this mode and when ? Surely this is not possible on MW ?

G8JQW
20-09-2004, 08:56
Hi All

I believe that medium wave DRM stations will want go to double channel for two reasons.

There isn't the pressure on medium wave frequencies (at least in the UK) as suggested. All of the radio networks currently broadcasting on medium wave are also broadcasting on DAB and/or Freeview (Digital Terrestrial Television). So there is no incentive for them to spend money to switch from AM to DRM unless it can provide better quality than DAB or provide other services like multi-media, and this means DRM at 18 kHz.

Also DRM is more efficient in terms of spectrum occupancy because it can support Single Frequency Networks (SFN), which means using only one frequency irrespective of the number of transmitters or coverage area.


73s, Roger

DRM-Fan
20-09-2004, 10:21
So does this mean we could have HQ stereo on MW with double bandwidth, left ch on one, right ch on the other ?

Do you really think ofcom would allow this 'standard' to be used ? Surely they would think it was a waste of spectrum ?

G8JQW
20-09-2004, 11:17
Originally posted by DRM-Fan
So does this mean we could have HQ stereo on MW with double bandwidth, left ch on one, right ch on the other ?

Do you really think ofcom would allow this 'standard' to be used ? Surely they would think it was a waste of spectrum ?
That's not how DRM works. DRM is a multi-carrier system, there is little correlation between the spectrum that the DRM signal occupies and the bandwidth of the received audio.

By allocating a double channel allows doubles the 'normal' number of OFDM carriers, which in turn (almost) doubles the available bit-rate. For example from 26.6 kbps (9 kHz spectrum bandwidth 64-QAM) to 49.1 kbps (18 kHz spectrum bandwidth 64-QAM). How this bit-rate is allocated is up to the broadcaster.

73s, Roger

DRM-Fan
20-09-2004, 22:49
Originally posted by G8JQW

That's not how DRM works. DRM is a multi-carrier system, there is little correlation between the spectrum that the DRM signal occupies and the bandwidth of the received audio.

By allocating a double channel allows doubles the 'normal' number of OFDM carriers, which in turn (almost) doubles the available bit-rate. For example from 26.6 kbps (9 kHz spectrum bandwidth 64-QAM) to 49.1 kbps (18 kHz spectrum bandwidth 64-QAM). How this bit-rate is allocated is up to the broadcaster.

73s, Roger

OK thanks for info and excuse my total ignorance about all this. I hope it comes about then esp as we never had analogue am stereo...

www.amstereoradio.tk

BofH
24-10-2004, 00:34
So has anyone bought one of these Coding Technologies USB DRM Receivers yet? Or even know where they are available?

Would be good to see a review?

simone
24-10-2004, 09:12
Hi BofH,
it is available in Germany from Charly Hardt (http://www.charly-hardt.de) , price is 230.85 Euro including taxes, plus 6 Euros for shipping to other countries than Germany. I saw a demonstration of the receiver at IBC this year, but I am not sure if it was already the final version, so no comment about the performance.
73, Simone

Per
04-11-2004, 18:27
Originally posted by BofH
So has anyone bought one of these Coding Technologies USB DRM Receivers yet? Or even know where they are available?



Hi all,

Look at http://www.codingtechnologies.com/products/digtrav.htm
There is also an order form on the home page. But I think the product sheet contains very little information. There isn' t any information of covered frequency bands.

DRM-Fan
04-11-2004, 18:34
Originally posted by Per


Hi all,

Look at http://www.codingtechnologies.com/products/digtrav.htm
There is also an order form on the home page. But I think the product sheet contains very little information. There isn' t any information of covered frequency bands.

• Reception of Digital Radio Mondiale, analogue AM and FM

FM on SW so good for 10m FM ham band then ?! Unless it's 88 - 108 Mhz which I doubt or is it a mistake ?

A bit over priced I think half that and I may buy one

jbriggs
08-11-2004, 17:45
;)
We have just received 8 of these receivers from Coding Technologies today. Unfortunately I can't install the software yet as I need the permission of my company IT section, and my home "PC" is an Apple ibook. I hope there will be some software for this device and OSX at some point.
In the meantime if anyone wants the manual or some photos of it please contact me at james dot briggs at merlincommunications (com). The manual is a pdf 12 pages long and 1.8Mb in size.
The production version is much heavier (110 grams) than the version on display at IBC, I think this is due to extra metal shielding. I am sure the FM option is for 88-108 MHz, but this is not specified in the manual, so I will report again on this once I have tried it out.
I will e mail a picture to Simone, strangely I can not post attachments although I am an administrator on the forum!
James

dk8cb
08-11-2004, 18:06
Hi James,

concerning pictures: I guess we are not so much interested in its outside view but rather a lot more in its inside views so that we can have a close look at it. :cool:

Roland

DigiBC
08-11-2004, 18:26
Hi!

There are many people out there who seem to have problems with the installation of the receiver:
Software installation is successful but Windows refuses to detect the receiver when it is connected to the USB port. (There could be incompatibilities between different USB chipsets, although Micronas USB chips have a very good reputation.) :(

I've heard that Coding Technologies is taking care of that now.

Attached a picture of the DRM decoding window (not really exciting...).

Regards - DigiBC


PS: Hopefully I'm going to have more luck with the new WR-G303e USB receiver arriving here tomorrow...

simone
08-11-2004, 18:39
Hi all,
here is the picture of the CT receiver, just the outside :(
I personally would be interested in any reports about the performance on MW.
73, Simone

dk8cb
08-11-2004, 19:01
Originally posted by simone
...
here is the picture of the CT receiver, just the outside ...

Sorry, but the picture reminds me of a soap box. :D

Roland

Ager
11-11-2004, 14:18
I, too, got the receiver today. Under the current difficult propagation I did not manage to get a sound out of Wertachtal at 6130 kHz with Dream but with Digital Traveller and the same outdoors wire I did, the S/N is about 5 higher.

Easy and enjoyable. But I wonder if making logs is possible?

dk8cb
11-11-2004, 15:40
Originally posted by Ager
I did not manage to get a sound out of Wertachtal at 6130 kHz with Dream but with Digital Traveller and the same outdoors wire I did, the S/N is about 5 higher.


Can you specify which receiver and which version (current CVS or perhaps older) of Dream you were using as a comparison?

Roland

simone
11-11-2004, 15:44
Hi Ager,
what OS are you using on your computer? I am asking because I have heard of several people having trouble with the USB using Win XP.
73, Simone

Ager
11-11-2004, 16:26
Hi sirs ;-)

The Dream version is 1.1.4c, and receiver is Grundig Yacht Boy 400 with win2000.

With Digital Traveller I use XP Pro. No problem with USB there, just mr. Gates made some gloomy warning when installing, but I was not very interested in his opinion.

My "test" was just some 10 minutes, and not simultaneous. I hope to share the antenna tomorrow with both receivers at the same time to make a more competent comparison. At least the propagation is challenging for that.

dk8cb
11-11-2004, 17:17
Originally posted by Ager
The Dream version is 1.1.4c, ...

Does that mean that it is the latest CVS? I ask, because recently, there have been changes that are not deducible from the version number.

Roland

jbriggs
11-11-2004, 20:23
Just to confirm that the Digital World Traveler does indeed receive FM 88-108 MHz. Quite a useful little device if you have to carry a laptop anyway on a trip.

DRM-Fan
11-11-2004, 20:31
Originally posted by jbriggs
Just to confirm that the Digital World Traveler does indeed receive FM 88-108 MHz. Quite a useful little device if you have to carry a laptop anyway on a trip.

Yes add RDS for FM and DAB also and it would really sell!

Ager
15-11-2004, 09:26
I did a very small photoshop-helped comparison between YB 400 and Digital Traveller with the same outdoors wire though reception has not became normal yet. (At the moment is is getting just better .)

DT seems to produce audio also with lower S/N than my normal reception combination. There were just a few very brief dropouts with DT while YB got muted for longer periods.

dk8cb
15-11-2004, 09:58
@Ager:

Hi,

are you running the YB-400 from batteries or from a power supply? In case of the latter, is it the original power supply that came with the set?

I ask, because this may have considerable influence on the result obtainable. See my thread on homemade interference in the 'Receiver Modifications' section.

Furthermore, does your YB-400 show any signs of frontend overload if tuned to a clear frequency, ie do you hear a mix of stations then?

Roland

Ager
15-11-2004, 10:38
Hi Roland,

I am running YB from a power supply, original one. I have read your previous information about using batteries, but I forgot it :-(. I shall test batteries in days to come.

About the frontend overload problem, I have not noticed such. I have not listened to AM with YB, there is another receiver for that. Have to do some checking still.

Anyway, I must use YB "local" knob, not "dx", the antenna is rather effective.

carknue
20-11-2004, 10:03
I have just received my DWT. No Problems with the installation. It runs perfectly. But reception with connected power supply is not possible with the wire antenna. Currently I'm listening to TDP on 7240 khz...more later.

byrnefm
20-11-2004, 12:19
Having had a look at the manual yesterday, I was surprised to find that you can only set a total of 8 stations for each band. Surely for a PC, one shouldn't be limited to such a small number of stations to be saved, especially when you consider how many stations are available on SW alone! The user interface doesn't seem to be expandable in that regard as all eight saved stations are displayed on screen at once.

Not sure how WinRadio handles saving stations but I think it would be a useful feature for a future version of the DWT software - especially when the number of DRM stations grow.

Just my 2c ;)

carknue
20-11-2004, 20:29
I played a little bit with the DWT and found a big bug in MW reception. I hope the the right people of Coding Technologies are still reading here.

Bug:
DRM reception on mediumwave is not possible!

There must be an IF ofset error or someting like that. I tuned to the mighty 1296 khz, waited and waited... even no label could be decoded. The signal looked quite OK in the expert screen. Then I started die DRM Software Radio and feed it with the signal from the DWT. The spectrum window now showed the reason for this. The DRM singnal is not in the middle. Then I started Dream and feed it also with the signal from the DWT. It displayed an DC frequency of 10860 hz. The offset to 12khz is too big for the DWT Software and the DRM Software Radio, Dream has no problems with the 1 khz offset and decoded the DRM signal just fine. See attachted screenhot. I only wonder why the DRM signal is in the middle of the DWT expert screen? But I think that this bug can be fixed quickly with a new Software release.

It does not help to tune to 1297 or 1295. IF will not go to 12 khz center frequency!

Ager
20-11-2004, 20:43
I, too noticed that, and wondered and wondered...

simone
20-11-2004, 20:53
Hi Carsten,
quoting from my own post some days ago:
Originally posted by simone
Hi all,
here is the picture of the CT receiver, just the outside :(
I personally would be interested in any reports about the performance on MW.
73, Simone

I asked for reports on MW because at the demonstration at IBC back in September we could not get audio decoding on 1296 kHz with the DWT, strange that they did not fix it till the official release.
73, Simone

VE3MEO
21-11-2004, 03:13
Maybe the DDS only tunes in 5kHz steps. That could explain the nearly 1kHz error on 1296 kHz. Was the error the same when set to 1295 and 1297 kHz?

73, Tom

DRM-Fan
21-11-2004, 12:06
I thought this USB radio got the power from the USB connection itself ?

Dave

dk8cb
21-11-2004, 14:10
Originally posted by VE3MEO
Maybe the DDS only tunes in 5kHz steps. That could explain the nearly 1kHz error on 1296 kHz.

No. In case the LO would only be tunable in 5 kHz steps, this would mean that the nominal receive frequency is 1295 kHz. With the first LO and the downmixer usually being above the intermediate frequency, the net result is no spectrum inversion and a signal on 1296 kHz would then appear at around 13 kHz, not at 11 kHz.

If however, the downmixer's LO works below the intermediate frequency, then the effect described could happen with 5 kHz tuning steps. But then, Dream would have to be adjusted to flip the input spectrum, which doesn't seem to be necessary.

I have received information, that a TDA 7512 from ST is used as the tuner chip. A short glance at the data sheeet reveals that it has a built-in PLL, also the chip's IF frequency is programmable. I guess that the PLL is just being wrongly programmed by the software driver.

Roland

carknue
21-11-2004, 15:17
I just tested the MW Bug with the 1611khz from Radio Vatican. DWT tuned to 1611 khz no decoding possible, spectrum in center of Expert screen. Dream showed a DC frequency of 10860 Hz and decoded the signal. DWT tuned to 1610 khz, DWT started decoding, but spectrum not in center of expert screen. Dream displayed a DC frequency of 12560 Hz and decoded as well. DWT tuned to 1612 khz, both DWT and Deam couldn't decode anything. Dream showed 10860 hz DC frequency. First 3 LEDs went green and then everything went red and started again.

BBC also works on 1295 khz with DWT Software. So what is the reason of the problem?

dk8cb
21-11-2004, 15:55
Originally posted by carknue
So what is the reason of the problem?

Let me suggest that you connect a second receiver's antenna input to the antenna input of the DWT, there should be some oscillator feedthrough and you can then determine on which frequency the DWT's LO is really running.
Check the datasheet (http://www.ortodoxism.ro/datasheets/stmicroelectronics/9300.pdf) and note that in AM mode, the device is normally operated as a double conversion receiver with a first IF of 10.7 MHz, and a second IF of 450 kHz using a down conversion oscillator of 10.25 MHz.

Roland

carknue
20-08-2005, 22:34
I wonder if all DWTs have a loss of up to 10 dB on the left side of the snr spectrum like mine that you can see in the attached screenshot? Can other DWT users confirm this lower snr on the left side?

Owdjim
21-08-2005, 03:00
Hi Carsten

If only there were some DRM signals for my DWT to receive....

I've had a look back through some of the screen captures I took when RNZ were testing on 657 kHz, and it does look like the SNR is worse on one side than the other, as with your example.

I'll have a look this evening if any of the 49m band DRM signals are strong enough.

Cheers, Chris

FritzWue
21-08-2005, 05:35
Hello Carsten and Chris,

I wonder why there is such a slope in the IF output noise baseline, please see picture.
There is a 40 dB difference from 0 to 24 kHz.
This seems to be the reason for the decreasing SNR on the left side.
Would be interesting to know if the DWT output noise is really increasing so much, if the 12kHz audio cable's capacity/ lowpass characteristic causes this (if there is any), or if the soundcard is the problem.
Carsten, did you check your soundcard with another 12kHz IF signal?
If the output noise of the DWT is varying so much it could be a noise problem of the internal frequency synthesizer.

simone
21-08-2005, 06:10
Hi Carsten,
to answer your question, all DWT´s that I have seen showed this behaviour, so there is probably nothing wrong with yours.
73, Simone

dk8cb
21-08-2005, 13:45
Originally posted by simone
... all DWT´s that I have seen showed this behaviour, so there is probably nothing wrong with yours.


Looks like there isn't a particular fault with Carsten's DWT but a design fault with the DWT's circuit as such.

Roland

simone
21-08-2005, 16:07
Originally posted by dk8cb
Looks like there isn't a particular fault with Carsten's DWT but a design fault with the DWT's circuit as such.


...that´s what I tried to say, but this does not seem to have a big effect on the results, the main problem that I have with the DWT is the antenna input.
73, Simone