My Beginners Experience With DRM

[gccradioscience]

I do have issues with receiving normal broadcast DRM signals, one is that I do not have a decoder built into the radio, so basically the DRM signals are kinda private and hidden on the shortwave bands along with other utility shortwave signals. I try to look around at receivers and software, right now at this time there was 1 receiver was called the Di-Wave 100 and the RX-320D, but they were definitely out of my price range, so I put DRM on the back burner. I am still kinda disappointed that most shortwave portable receivers don't even have a IF out jack on them for at least a converter except there was 1 receiver that I am going to order that has one called the C Crane SW, but requires a converter to use with the Dream software which is an extra $80. I have been looking around for kits on how to buy and build my own DRM converter, not even Ramsey Electronics does not even have such a converter after all they are selling a bunch of AM mode receivers.

I am right now experimenting with DRM transmission and how it works, and right now I am just practicing with converting the simulated broadcast to a .wav fiie. I tried to hear the raspy burst sound on my shortwave receiver on the AM broadcast band, it sounded like the sound I heard on non decoded signals, and it's genuine. Today, I am trying to find a schematic or kit that I can build as long it does not require parts that are hard to find. Still if I cannot find anything I will just buy the $80 converter box to connect to the new portable SW radio next month. I hope that manufactuers can try to make it easy to make receivers with DRM decoding and deluxe receivers with HD and DRM decoding, and some cheap to moderate price receiver with at least one IF out jack to connect to a 455 kHz to 12 kHz converter box. I think many tuners on stereo systems especially in Europe need these output jacks to connect to a converter to digital decoder box to audio outputs. I would like support for both my experimental AM station and get at least one receiver to receive DRM reception of my station and shortwave. I have various radios such as the DX-398, DX-392, G5, G6, and S-350 DL, G4000A, and soon the C Crane SW and G3. How do I make an IF output jack from my receivers and converter box? I hope everyone understands that I am still new to this. I am glad to be here. :)

[dadalbinder]

Beginners experience with DRM

It is not so easy to go the first steps. Some hightec receivers have an IF-output jack.

Of the most popular receivers and not so expensive ones, is Roadsta ar TRA-2350P. I made a converter for it with a TA7358 circuit. This receiver has an output jack for 455 kHz.

Some experiments showed that the shape of this IF in mode WIDE is not ideal but it works.

A big advantage of the mentioned Roadstar receiver is the fact, that You are able to regulate the voltage of the incoming signal by handdriven potentiometer. Try to adjust it to a suitable level.

For taking a signal from a receiver with an IF 455 kHz is depending on qualifications of the receiver. Mainly the AGC is very influential. The AGC should be relatively slowly, because fast AGC disturbs a DRM-signal while it is just developping (it needs a certain time to be complete).

The procedure is even working with an IF of 10,7 Mhz. But not on the Roadstar.

You could have a look on sat-schneider.de for some converters for 455 kHz to 12 kHz or 10,7 Mhz to 12 kHz. The better ones are working with an xtal.

I build one with a Toshiba IC TA6358. You find the circuit in the appendix.

Decoding DRM-mode and others by DREAM software or SoDiRa software. Both solutions have some more modes as AM, SSB, FM, CW.

Connect the output of the converter to a soundcard input. Better would be the LINE-In Input because of the dimension of the signal

The circuit: It uses a 2-pole ceramic filter with a frequency of 470 kHz. In this configuration it works on a frequency of 464,5 kHz. The resulting signal – IF of 455 kHz is about 9,5 kHz. The two C-value besides the ceramical filter have a value of about 470 picoFarad. Try the best values. They influence the resulting frequency.

Wolfgang Hartmann, Nürnberg

[Siber]

I will try to add Mr.dadalbinder a little. As converter power supplies it is possible to use the block from two batteries 1,5 V, or USB of your computer. Battery plus is connected to the pin 9, minus to the pin 5. For USB the scheme added the filter from the diode and condensers. The diode can be any mark.
I used the resonator on 465 kHz. Its frequency moves to 467 kHz by condensers.

[simone]

In this document (http://www.drmrx.org/mods/AOR_7030_german_high_res3.pdf) we also have an example of how to build a 455/12 kHz converter, instead of the crystal oscillator you can scrap a ceramic resonator from some old TV remote controls.
Simone

[gccradioscience]

In this document (http://www.drmrx.org/mods/AOR_7030_german_high_res3.pdf) we also have an example of how to build a 455/12 kHz converter, instead of the crystal oscillator you can scrap a ceramic resonator from some old TV remote controls.
Simone

Simone,

Sorry, but I cannot read german, I speak english. Is there a way to get this in the english language, I got the schematic diagram, but the description is in german. :(

[gccradioscience]

Beginners experience with DRM

It is not so easy to go the first steps. Some hightec receivers have an IF-output jack.

Of the most popular receivers and not so expensive ones, is Roadsta ar TRA-2350P. I made a converter for it with a TA7358 circuit. This receiver has an output jack for 455 kHz.

Some experiments showed that the shape of this IF in mode WIDE is not ideal but it works.

A big advantage of the mentioned Roadstar receiver is the fact, that You are able to regulate the voltage of the incoming signal by handdriven potentiometer. Try to adjust it to a suitable level.

For taking a signal from a receiver with an IF 455 kHz is depending on qualifications of the receiver. Mainly the AGC is very influential. The AGC should be relatively slowly, because fast AGC disturbs a DRM-signal while it is just developping (it needs a certain time to be complete).

The procedure is even working with an IF of 10,7 Mhz. But not on the Roadstar.

You could have a look on sat-schneider.de for some converters for 455 kHz to 12 kHz or 10,7 Mhz to 12 kHz. The better ones are working with an xtal.

I build one with a Toshiba IC TA6358. You find the circuit in the appendix.

Decoding DRM-mode and others by DREAM software or SoDiRa software. Both solutions have some more modes as AM, SSB, FM, CW.

Connect the output of the converter to a soundcard input. Better would be the LINE-In Input because of the dimension of the signal

The circuit: It uses a 2-pole ceramic filter with a frequency of 470 kHz. In this configuration it works on a frequency of 464,5 kHz. The resulting signal – IF of 455 kHz is about 9,5 kHz. The two C-value besides the ceramical filter have a value of about 470 picoFarad. Try the best values. They influence the resulting frequency.

Wolfgang Hartmann, Nürnberg


I tried to read the schematic, but the diagram looks scribbled and the part numbers are hard to read. Also I tried to find the IC for the schematic diagram, still no luck. Someone here needs to come up with a kit version and a assembled version of the circuit for people on the go.

[simone]

Simone,

Sorry, but I cannot read german, I speak english. Is there a way to get this in the english language, I got the schematic diagram, but the description is in german. :(

I can translate and email you the most important things.
Simone

[Brendan1]

A partial kit for converting a 455kHz to 12kHz audio signal for DRM decoding is available from FAR Circuits in Illinois. This kit is based on an article in QST from October 2003, and they have a reprint available at extra charge. This includes the board and two components, a NE602 and an 78L05. Only $9.00 plus s&h and so on.

See http://www.farcircuits.net/convert2.htm#9convert for further info.

If you are so inclined, please join us at the DRM North American group at the following address: http://groups.yahoo.com/group/drmna/

This group is primarily for DRM listeners, experimenters, and anyone interested in the mode. We are SWL's, hams, techs, broadcasters, and others who are intent on dragging the U.S. into the world digital radio era in spite of itself. We do have members from around the world, and we welcome any and all to join us, but the focus is primarily on North American DRM broadcasting and reception.

[gccradioscience]

A partial kit for converting a 455kHz to 12kHz audio signal for DRM decoding is available from FAR Circuits in Illinois. This kit is based on an article in QST from October 2003, and they have a reprint available at extra charge. This includes the board and two components, a NE602 and an 78L05. Only $9.00 plus s&h and so on.

See http://www.farcircuits.net/convert2.htm#9convert for further info.

If you are so inclined, please join us at the DRM North American group at the following address: http://groups.yahoo.com/group/drmna/

This group is primarily for DRM listeners, experimenters, and anyone interested in the mode. We are SWL's, hams, techs, broadcasters, and others who are intent on dragging the U.S. into the world digital radio era in spite of itself. We do have members from around the world, and we welcome any and all to join us, but the focus is primarily on North American DRM broadcasting and reception.

Can you invite me to the Yahoo! Group? my screen name for Yahoo! Groups is gccengineering I will try to join. I am interested. Thank you. Wait I was already a member of the group, I did not know that I joined. Welcome me back.

[Brendan1]

Welcome back! If you would like a PDF copy of the circuit from QST I was able to download the article, so I can send it to you. Let me know.

[Digger]

Of the most popular receivers and not so expensive ones, is Roadsta ar TRA-2350P. This receiver has an output jack for 455 kHz.


Hi all,

My converter for the Roadstar is here:

http://www.omnirep.ch/drm/roadstar.html

It is a great receiver and good value for money!

[Siber]

My variant of the converter on S042P

I did not use an additional filter IF as I consider that for suppression of the mirror channel from carrying over 455 to 12 kHz it is enough of the internal filter IF of the receiver.

[mvs sarma]

My variant of the converter on S042P

I did not use an additional filter IF as I consider that for suppression of the mirror channel from carrying over 455 to 12 kHz it is enough of the internal filter IF of the receiver.
Hi, Please check the USB pin numbering
I think pin1 is Vcc and pin4 is ground. As such the components are to be changed.

[Siber]

Dear Sarma.
Thanks big for your remark. I have already corrected the error.
At installation of USB jack it is necessary to be attentive, as at a sight from backside of it these pins will be upside-down

Regards,Vladimir

[mvs sarma]

Dear Sarma.
Thanks big for your remark. I have already corrected the error.
At installation of USB jack it is necessary to be attentive, as at a sight from backside of it these pins will be upside-down

Regards,Vladimir
I saw that the chip was numbered otherwise.
but i was only thinking it would not matter as perhaps it was manually made with paint software.
you may perhaps replace it with a suitable eagle sch and brd.
Nice work. you may perhaps replace S042 with any later version chips as S042 may not be available.

we get cheaply Toshiba's TA7358AP, a 9 pin SIP
Though used as FM front end, it also works as general purpose mixer with inbuilt osc transistor.
All the best and hope to see many more designs from you.

[Digger]

S042P DIP: I have hundreds of them here. I'll be more than happy to give them away for free. . .

[Siber]

I made converters on various microcircuits : S042P, SA612, TA7358 etc. Appreciable difference in their work I have not found. The TA7358 advantage is that it does not demand from 5 Volt and above. My favourite scheme works from 1,5 Volts. A batterie is enough on half a year.:)

[mvs sarma]

@Digger,
It is Great that you have hundreds and willing to give off. but on the international scenario, the courier charges become too much. Hope that you can help some close in & around Swis.

@Siber,
It is interesting to see your ring modulator. May i have a suggestion. I saw R4 being substituted by a voltage ref like two schottkie diodes.
this helps a constant voltage bias irrespective of battery upto a major life of battery. the same bias could also be used for oscillator transistor. A Nice design, in fact.

[Siber]

Dear Sarma,
Thanks for Your advice.
I used there germanium diodes. But schottkie diodes have better characteristics. It will be better to use them instead of R4 and ring diodes.
When I made the circuit I had not of them.
However ,as it seems to me, it will not give benefit in the oscillator scheme.

[dadalbinder]

Hello,

a nice bunch of solutions I saw in the forum.

For the mentioned Roadstar receiver there is a very stable output jack. And everything works instantly.

The problem with other receivers, one should find a suitabel place for taking the signal for the converter. The only thing necessary is a suitable solution for taking out the signal without disturbing the circuit of the receiver.

In such cases, one should take a FET-preamplifier with high impedance and connect it with a classical converter.

A nice and forwarding discussion.

Wolfgang Hartmann, Nürnberg

[dadalbinder]

Hello,

I found two screens on my computer.

Narrow and wide filtering by the Roadstar receiver.

One could easily see some difference. Use WIDE for DRM-decoding.

Wolfgang Hartmann, Nürnberg

[gccradioscience]

Still waiting for to buy my Sangean CC Crane SW and then I have to get a DRM converter box for the computer connection. I still hear 9800 kHz from Sacksville, Canada, but I cannot decode it yet. If no one cannot help me for with alternatives to DRM, then I am going to drop the project until I can get the money to buy the equipment.