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-   -   Virtual Audio Cable (http://www.drmrx.org/forum/showthread.php?t=2164)

FritzWue 07-11-2009 17:43

Virtual Audio Cable
Today I gave up using Virtual Audio Cable 4.09.
No use testing the trial version as it injects announcements into the audio stream, so I purchased it almost a year ago as I thought it was a brilliant idea to avoid cables and hardware audio distortion.
Nevertheless I always got dropouts when connecting the Flex-5000A output to DREAM input via VAC.
Tried a lot of things but never got it working without dropouts.
Today I changed my setup using the onboard Realtek ALC1200 HD sound for decoding DRM.
Hope to get better % CDA results now although the SNR [Maximum] may suffer.

Did anybody else try it, any experience?

dadalbinder 07-11-2009 20:24

Virtual Audio Cable

ich benutze VAC an 2 Rechnern mit je 2 Soundkarten. In einem Fall an einer I/Q fähigen Soundkarte neben einer Audigy-Karte, die für I/Q nur sehr bedingt geeignet scheint. Der andere Rechner besitzt eine USB-Soundkarte und eine Onboard-Karte.

Bei mir sind keine Probleme aufgetreten. Zusätzlich kann man ja auch Parameter für die Audioströme ändern.

Ähnliche Erfahrungen mit WAVE CLONE.

Das einzige "Ärgernis" ist, daß beide Programme bei Aktivierung von Strömen das Herunterfahren des Rechners beachtlich verlängern. Das kann Minuten dauern bis das in dieser Einstellung passiert.

Erfahrungen zeigen, daß diese Programme dazu dienen können, etwa den Eingang eines Dekodierungsprogramms über Soundkarte 1 zu empfangen, an Soundkarte 2 auszugeben und von einem dritten Kanal eines dieser PRogramme im Input aus dem Output von 2 zu nehmen, um dieses Signal einer speziellen Dekodierungssoftware für Sondermodi beginnend etwa mit CW wiederum zuzuführen.

Das Ganze ist aber doch etwas anspruchsvoll abstrakt, weil man sich erst einmal einarbeiten muß, bevor man das alles beherrscht. Keine Notwendigkeit in bestimmten Rechnerkonfigurationen eine dritte, ... Soundkarte zu implementieren.

Ich grüße

Wolfgang Hartmann, Nürnberg

FritzWue 08-11-2009 08:54

Hello Wolfgang,

thanks for the feedback.

I used VAC in various setups for different purposes and generally have no problems with it.
With the Flex-5000A, PowerSDR software and the Realtek HD1200 onboard sound I tested all possible parameters and configurations but it did not work without frequent resyncs.
You hardly notice that when listening as it occurs only once or twice per hour or so, but it simply looks bad in the statistics of DRMcalc.

I am just checking SNR from Bolshakovo on 7325 kHz.
With VAC I had 42.5dB some days ago and now via line in cable the SNR is very close to that today. So no problem, I'll stay with the cable for now. :)

FritzWue 03-12-2009 18:29

1 Attachment(s)
Just an info:
Today I installed my Fraunhofer DRM Software Radio to test this combination with the Flex-5000A and the Virtual Audio Cable Software.
The FhG DRM Software Radio 2.0.38 detects the virtual audio cable and works with it without problems. :)
A reminder:
You have to buy VAC as a voice is talking into the audiostream regularly in the testversion. :o

FritzWue 26-02-2010 17:36

VAC 4.10 with multi cpu support is available since some days.
I have to set milliseconds per interrupt to its minimum 1 to get no buffer problems with the Flex5k.
Works fine.

F1BJB 20-07-2015 21:04

An alternative to VAC can be found here:
Not all the SDR programs allow an audio output at 192Khz sampling frequency
as is needed for RDS or DRM+ decoding .
HDSDR is my favorite.
PS new link

F1BJB 17-08-2016 19:01

As creative labs and Windows 10 have decided that my
EMU 104 192Khz 24bits USB sound card was too old :mad:
I had to use the VB audio trick with my SDRplay USB SDR.
There is one point that was not mentioned before and that may be important:
Disabling any kind of AGC from the analogue software used to feed Dream.
SDRsharper in my case.
Strange behaviour can happen if you don't do that.
On the other hand setting the RF gain correctly can be tricky mainly
if you have only 8 bits resolution as with RTLSDR.
Results are almost as good as those from my old setup.

F1BJB 31-01-2019 07:02

I came across this web page that may be useful:

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