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Old 12-06-2007, 08:50   #31
dadalbinder
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Simple Soundcards

Hallo Maxpower,

aus den Anfangszeiten der DRM-Dekodierung gab es ja die Empfehlung, möglichst einfache Soundkarten zu benutzen. Ich denke, das hat den gleichen Grund.

Das scheint das gleiche Phänomen zu sein, was uns jetzt auch bei I/Q beschäftigt eben nur auf der Stereo-Ebene.

Hinter allen Sound-Applikationen im Rechner steht eine Menge von bisher nicht so dokumentierten Faktoren. Direkt zugreifen auf alle Faktoren einer Soundapplikation scheint bisher nur indirekt möglich.

Es gibt unter www.Audiotester.de eine Software, die es ermöglicht im OSZI dort, die Parameter einzustellen.

Weitere Hilfe könnte Virtual Audio Cable sein. Aber etwas schwierig. Lohnt sich trotzdem reinzuschauen.

Wolfgang 49N28, 11E00
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Old 14-06-2007, 09:53   #32
mvs sarma
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Quote:
Originally Posted by dadalbinder
Hallo,

as far as I see, the calibration of Your soundcard is extremly able for driving the I/Q-receiver, Elektor_USB. The difference between signal and mirror signal after calibration seems to be extremly high (and suitable).

SDR, Software Defined Receivers in general do not need a soundcard capable to work with I/Q-receiving.

Wolfgang H., 49N28, 11E00

Thanks Mr. Wolfgang for your comments.
for the time being i can only try to receive genral AM shortwave .

I observed that with and internal loop ant , it was not possible to receive anything and perhaps may beed an amplifier.
i will have to give a try again.
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Elektor SDR 5/07- Elektor Preselektor - Miniwhip Antenna of PA0RDT
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Old 14-06-2007, 11:43   #33
maxpower
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Hello Sama!

If you want to use your receiver for AM listening, i would recommend to use the G8JCF-SDR Software Radio. http://www.g8jcf.dyndns.org/
Its free to use.

It supports the Elektor SDR direct. You only have to setup some things like model (in this case the elektor sdr) and the soundcard input/output device and you will be able to listen to AM, SSB, FM... transmissions from 150 kHz to 30 MHz.

I use it with the old Elektor DRM and its working very well as a very comfortably Receiver. So you can easy test out your antenna and the rest of your equipment.

Btw: You can simply try to use some meters of wire to feed the antenna-input. maybe that gives you more input-gain?!

Regards, Stephan
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Old 14-06-2007, 13:07   #34
dadalbinder
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Impedance at the input of the Elektor_USB

Hallo Sarma,

for testing the receiver You should know, that the receiver has a relatively high impedance at its entrance. Main factor is an inductivity of 220 MikroHenry. Because of that one should engage an hf-transformator from a 50 Ohm-line to the entrance of the receiver.

In general there is no need of a preamplifier.

Wolfgang Hartmann, 49N28, 11E00
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Old 14-06-2007, 20:06   #35
mvs sarma
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@Stephan and Wolfgang Hartmann,

Thanks for the suggstions. i have PCBs on hand ,for elektor SW radio with DDS and DRM(Dec06). I have to develop the software myself and a friend of mine agreed to collaborate in the development.

meantime, i had assembled the SDR model with crystal oscillator on a prototype board,employing 74HC4053 and HC74, and ne5532. Trying this assembly with SDradio ver1.00 software.

added a single stage aerial amplifier expecting to work it on internal whip ant. Now i plan to go for a SW loop ANT with a gain block and mount it in my second floor balcony and try out.

i shall get back with my observations shortly.

Thanks again,
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Last edited by mvs sarma : 17-06-2007 at 05:22.
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Old 20-06-2007, 16:11   #36
andimik
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I hope this is the right topic ...

I'm using my onboard Realtek soundcard with 48 kHz sampling frequency. It's a MSI motherboard for AMD CPUs. Here my results using In8 of USB Elektor (05/2007).

Link to the motherboard: http://www.msi-computer.de/produkte/...hp?Prod_id=228
Attached Images
File Type: png sdradio.png (43.4 KB, 797 views)

Last edited by andimik : 20-06-2007 at 16:13.
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Old 01-07-2007, 21:29   #37
mjn
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Hi All,

New member here. Been strugling to modify a Drake TR-7 for DRM reception, and finally have it. But, the main problem appears to have been the sound card. I started out with an AOpen AW-850, which has a C-Media CM8738/C3DX chip. I built up the NE555 Tester, and it showed spurs just like the other guy saw on the CM9738 chip. Maybe a little worse!

When trying to receive DRM, the USB edge of the signal stair-stepped down. It was worse for higher frequencies. Could not decode anything with the signal centered at 12 KHz. Was a little successful with the DRM signal at 1 to 11 KHz. Then even more successful using the undersampling - tuned the BFO so that the signal out of the detector was around 50 KHz.

Then came across your test circuit, and the SDRadio program, and gave it a try. So. Pretty much gave up on the AOpen sound card, and took it out of the computer.

The computer then reverted to the apparently excellent Analog Devices (no affiliation!) SoundMAX integrated audio. Too bad its not a 5.1 system in this computer. Which is why I put the AOpen card in the computer in the first places. So, below is the tuned up response of the SoundMAX integrated audio in this HP computer.

ADSoundMaxIntegratedAudio.JPG

The TR-7 has a 48 MHz two-monolythic crystal can filter that is working well for DRM, although its a little narrow. About 9.5 KHz at 3 dB down. I have the resistor network mod in the IF Selectivity board for position C, leaving only the 48 MHz filter for the real selectivity.


73, Don ...
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Old 02-07-2007, 10:04   #38
dadalbinder
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Soundcards

Hallo Don,

You need not to remove any soundcard from the computer.

One has only to switch between soundcard1 and soundcard2 on Your machine. In RECORD and PLAY menus or in the decoding software.

Sometimes it is usefull to have a second card for phoning and other purposes.

If Your computer has a high working frequency, You will be able to compare two cards, while the receiver is working or to engage to receivers - maybee on one antenna - to compare. In such cases change the soundcard from one receiver to the other one and vice versa.

Wolfgang Hartmann, 49N28, 11E00
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Old 02-07-2007, 17:19   #39
mjn
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Hi Wolfgang,

Thank you for the comments. But for some reason, the only sound card available was the AW-850 after it was installed. It would have been very handy to test as you suggest.

I have since obtained a SB Live! USB and after installing it, I find the SoundMAX is still available and working similarly to before installing the SB Live! USB.

The AW-850 is a PCI card sound card. Maybe that has something to do with it?

In the DReaM setup, I now have the input from the SoundMAX and the output to the SB Live! USB. This would not have been possible with the AW-850 installation, as the SoundMAX was not in the menu. Or even in the Control Panel System Hardware configuration. It just disappeared!
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Old 02-07-2007, 18:40   #40
dadalbinder
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Soundcard Issues, VAC

Hallo Don,

nice information about soundcards. I had partly the same behaviour, that a certain soundcards makes a second card not to be seen on the machine.

There is a very special software called VAC, Virtual Audio Cable.

It gives the possibility to see all installed audio channels and gives the feature, to install some virtual audio cables which enables to let communicate all these installed audio-devices even with given or changing parameters.

It is a little bit abstract, but sometimes it seems to be helpful.

Wolfgang
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Old 05-07-2007, 18:00   #41
deltaar
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Sound card test - Realtek High Definition Audio

Hi.

My sound card is a Realtek High Definition Audio, inside a ACER laptop with Intel Pentium M 760, running at 2.0 GHz.

Here is a photo of the circuit mounted in a breadboard:

SoundCardTester.jpg

SDRadio test:

sound_board_test.PNG

Cheers!

Last edited by deltaar : 05-07-2007 at 19:57.
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Old 07-07-2007, 08:16   #42
FritzWue
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Creative SB0350 Audigy 2ZS

A little off topic, no IQ test, but perhaps also important:

I tried the Creative Audigy 2ZS for pure DRM decoding with 12 kHz input.
There is a problem with it I read about before somewhere in the help files of my WinRadio G303i.
The drm decoding is ok but muting the line input does not work.
That means you hear the decoded drm signal plus the hissing sound of the 12kHz input all the time.
Replaced it with a SB0060 SoundBlaster Live! 5.1 and that works like it should.
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Old 12-01-2009, 22:24   #43
dadalbinder
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Speedlink SL 8850

Hallo,

who has experience with a not USB card of this type?

Is this model useable for I/Q-purpose?

Wolfgang Hartmann, Nürnberg
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Old 13-01-2009, 08:30   #44
maxpower
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Hi Wolfgang!

The chances are probably not very good for this model to work good as I/Q Line In, because it works with a C-Media Chip.
Until now I found no chip from this manufacturer that works well for this propose.
But the device seems to be very cheap (about 10 €) so maybe you want to give it a try anyway?!


Stephan
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Old 13-01-2009, 18:55   #45
dadalbinder
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SL 8850

Hallo Stephan and all readers,

I asked for a friend, who owns a computer with this soundcard, and is willing to start with SDR and especially I/Q-SDRs.

Thank You for the help

Wolfgang
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