PDA

View Full Version : beginner about DRM


Janis
31-05-2008, 00:16
Hi everyone!

'please tell me-Where I can find technical requirements for DRM tuner?

maxpower
01-06-2008, 08:42
Hi Janis!

If you are a developer and want to develop DRM Radio Sets, the best would be to go to www.drm.org and look/ask for the specifications.

If you are more the DRM-Amateur listener type (as most of us), this thread http://www.drmrx.org/forum/showthread.php?s=&postid=17419#post17419 gives you maybe a good start which receivers are good to modify for DRM Reception. Its very important for DRM reception to use a receiver with very clean signals. So the RX's with a high reception SNR are very good to use with drm.

Last not least if you are more the "just want to listen" type of listener, the maybe best way to receiver DRM transmissions is a Morphy Richards or HImalaya 2009 All-Mode Receiver. These radios can receive AM, FM, DAB and DRM and you can get them from the T-Online Internet-Shop in Germany.


Stephan

Janis
01-06-2008, 13:11
Hi Stephan and all!
I'm student and I need to known DRM receiver technical characteristics for calculation of the receiver. Where I can find information about:
Intermodulation attenuation
In-Band IMD
IMDDR3
Spurious response attenuation
Blocking Dynamic range
Co-channel suppression
Adjacent channel selectivity
Distortion factor
I looked all specification from http://www.drm.org/ but I can't find this characteristics.

dadalbinder
02-06-2008, 07:22
Hi Janis,

I try a simple solution:

DDS-Generator for tuning by – mainly – serial connection to the computer.

1.First mixer with NE/SA602 or TA7358

2.IF 455 kHz or better 10,7 Mhz with a ceramic filter or Xtal-filter (10,7 Mhz) both a little more than 10 kHz bandwidth

3.Second mixer with the same type ICs from 455 kHZ/10,7 Mhz to 12 kHz Output. For this secon mixer, You need a very stable xtal or ceramic filter, to get a stable output frequency.

4.Soundcard input


There is no need of AGC because the software as DREAM manages AGC and is FILTERING with a very sharp form-factor.

Extend to an IF of 45 Mhz is a very hard task. But seems to be possible. The stability of the xtal or ceramic element in the second VFO is a very main one.

This for 12 kHz solutions. Not for I/Q receivers and principle.

Wolfgang

Janis
02-06-2008, 10:59
Hi Wolfgang!

Thank you for your explanations! schema with IF1-10.7
Mhz and IF2-12kHz I have never met before. Could you show me a pair of examples of realization?
But the receiver with a direct principle, is not interesting to me.
Actually this time I more interested about figures for calculation.

dadalbinder
02-06-2008, 11:28
Hallo Janis,

in the appendix I give You the circuit, I developed parallell to a super working with 455 kHz if.

I hope You are able to translate the data.

Have a look on the www.b-kainka.de pages of Burkhard Kainka.

Wolfgang

maxpower
02-06-2008, 12:01
Burkhart Kainka is a very good start for Building Receivers for DRM. He has written a book in german about Software Defined Radios, too.

Threre are some very important things with building a SDR-DRM Receiver Board:

1. VCO stability and - very important- low noise and very low jitter (best ist to use either a fixed crystal oszillator or a DDS, some PLL Chips are good enough for building a drm-receiver, but most aren't)

2. don't use agc if you don't need it because it can compress the drm signal so it can't be decoded any more

3. Use a outside antenna if you can, because computer made noise can be very high, depending on the machine you use

4. for the most sdr's a good soundcard is essential for good reception. Please take a look at the soundcard test thread here at the board.


You can get some ready "naked" boards or kits to build receivers on your own at a good price: Elektor (www.elektor.de ) is a good start for that and at the Funkamateur onlineshop you can get some very cheap fixed frequency sdr-kits.
http://www.box73.de/catalog/product_info.php?cPath=112_113&products_id=1219&osCsid=e9ec6ae18b4c884d45b9220590ce2670


For technical Specifications please write to drm.org, they can help you further.

Janis
02-06-2008, 20:41
Hi Wolfgang! thank you for responsiveness.
unfortunately I can't to take advantage from this link. I have no time to translate it. And for me is difficult to understand attached scheme.

Hello Stephan! important aspects in DRM are very interesting for me.
especially characteristics differences between DRM receiver and AM receiver.

Janis
03-06-2008, 19:36
to Wolfgan
where I can find more information about attached circuit?

dadalbinder
04-06-2008, 08:16
Hallo Janis,

I bought a DDS-generator by www.ak-modulbus.de.

The ad9835 datasheet can be found in the net or on the pages of AK-Modul-Bus. It corresponds with receiver remoting of Elektor-DRM receiver from the year 2004. You can easily use it, while activating Elektor-DRM receiver by open software as DREAM, G8JCFSDR and others.

There are several more types of DDS-generators at Modul-Bus. Have a look on the pages.

Wolfgang

PP5AZF-Ataliba
08-06-2008, 03:11
Um bom exemplo de SDR é o projeto SDRZero brasileiro por João K. de Marco, PY2WM, Edson Pereira, PU1JTE, N1VTN. Já está sendo criado um transmissor chamado SDRZero G2 com transmissão também. No momento estão desenvolvendo um VFO digital que inclui o circuito integrado Si570 como oscilador local para o SDRZero. Vale a pena conhecer este projeto e o site de PY4ZBZ que ensina como adaptar um rádio IC-725 para recepção de sinal DRM. Esta adaptação é a que eu utilizo neste momento: IC-725 + SDRZero + Dream.
http://ewpereira.info/SDRZero/
http://paginas.terra.com.br/lazer/py4zbz/

Translation: "Google"
A good example of SDR is the Brazilian project SDRZero by John K. of March, PY2WM, Edson Pereira, PU1JTE, N1VTN. Already being set up a transmitter called SDRZero with G2 transmission as well. Currently VFO are developing a digital integrated circuit that includes the Si570 as local oscillator for the SDRZero. Good to know about this and the site of PY4ZBZ project that teaches how to adjust a radio IC-725 for receipt of the signal DRM. This adaptation is that I use now: CI-725 + SDRZero + Dream.