FreeDV with SignaLink?

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Gary - K7EK

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Dec 13, 2012, 6:50:24 PM12/13/12
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I've read references to using SignaLink interfaces with FreeDV, WinDRM, etc. I wonder if someone would tell me how to that? I have a  SL-USB connected to the 8 pin din connector in the back of my Icom IC-756 Pro-II. I regularly work EasyPal, JT65A, and other digital modes with excellent success.  I haven't figured out how to do DV with the SL-USB. Constructive comments and suggestions are welcome. Thanks.

Best regards,

Gary, K7EK

Sent from my Verizon Droid-X

John Laur, KF5SAB

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Dec 14, 2012, 2:12:07 PM12/14/12
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Gary,

Using the SignaLink USB with FreeDV is almost exactly the same as with any of the other digital modes. Make sure you are using the latest Beta release of FreeDV (0.91 or later) and do not configure the PTT settings.

Under Audio Setup make sure you choose the signalink interface (USB audio CODEC) as the To Radio and From Radio interfaces. You would use another sound card for your speaker output and mic input. A USB headset with microphone is a good choice here. The sample rate should be 48000 for the signalink and ideally for the other device too.

Adjust the SignaLink's TX gain until you have little to no deflection on your ALC meter when transmitting (one or two dots is probably the max). For receiving just tune the RX gain until you have a waterfall that looks similar to the screenshot on FreeDV.org and your audio decodes.

You will have marked improvements if you are willing to modify your SignaLink USB to improve its audio quality. My notes on this have been posted at http://freedv.org/tiki-index.php?page=Tigertronics

Best regards,
John KF5SAB

Gary - K7EK

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Dec 15, 2012, 1:21:07 PM12/15/12
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Hi John,

Thanks for your message. I guess the real question is "Where do I plug in a speaker and microphone in order to transmit and receive DV?" In my standard configuration, the SLUSB is hard wired to the 8 pin DIN jack on the back of the Icom IC-756 Pro II, and a USB cable connects to the computer. For analog operation the station mic is plugged into the front panel of the radio, and the station speaker is built into the radio. When I invoke EasyPal or any other soundcard based digital program, incoming and outgoing audio moves through the SLUSB, which is hard wired. I guess a simple block diagram of the necessary connections for DV would prove most valuable. I find it kind of difficult to visualize the DV wiring requirements with my SLUSB being hard wired to the radio and computer. Maybe my difficulty has been due to a mental block.  In any case, thanks for your help.

Best regards,

Gary, K7EK

Sent from my Verizon Droid-X

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Bruce Perens

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Dec 15, 2012, 1:39:34 PM12/15/12
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On 12/15/2012 10:21 AM, Gary - K7EK wrote:
> Maybe my difficulty has been due to a mental block.
:-) No, we've just changed the rules.

You need a second sound interface.
bruce.vcf

Mel Whitten

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Dec 15, 2012, 2:06:52 PM12/15/12
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Gary,
 
The Quick Start Guide and video may be of help found on freedv.org .  You will need a second sound device (card/microphone or USB headset will work).  
 
 Probably will be using your existing set up/sound card just like you do with PSK31, RTTY or most other digital modes.  Add another device to encode/decode the actual digital voice.
 
 
Mel
k0pfx
PC to Radio interface.png

Frank or Barbara Rossi

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Dec 15, 2012, 1:46:06 PM12/15/12
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If your current setup brings audio to and from your radio to your computer, that part is good,
You then need second sound card and a mic and headphone to get your voice to and from the DV program.
The second sound card can be as simple as a usb device that headphone and mic plug into.
N3FLR - Frank


John Laur, KF5SAB

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Dec 16, 2012, 6:39:55 PM12/16/12
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Yes, Gary as others have suggested you will need a second interface for your computer. Since you are using a SignaLink USB, it's likely you already have one in fact. 

When FreeDV receives, the audio from your radio comes into your computer via the SignaLink and is decoded by FreeDV would play back on the computer speakers the same as any other program playing audio on your computer. For transmitting, you would attach a microphone to your computer sound card and FreeDV would encode that microphone input and send the encoded audio to your radio via the SignaLink. You may not have a microphone suitable to connect to your sound card though. Note that you cannot easily connect your station mic to your computer though without an adapter and power supply.

So as others have suggested also, the easiest thing to do is to purchase a simple USB headset -- this will show up as another sound card to your computer. It is probably cheaper than building or buying an interface box to use your station mic too.

John

Lewis Malgieri

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Sep 23, 2013, 5:02:28 PM9/23/13
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I have a similar problem.I need a wiring diagram not a block diagram.I have a IC 756pro MFJ sound card and Logitech USB. I still cant get it to work and I use PSK31 and JT 65 all the time.Please provide a wiring diagram. 73 Lew, W2PDY

Walter Holmes

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Sep 23, 2013, 8:56:07 PM9/23/13
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Lew,

 

If you have your setup working now on PSK etc..  then you have completed the HARD part.. J

 

That means you’re complete with the DATA side.

 

 

To use FreeDV, then all you need is the 2nd sound card device like the Logitech USB device.

 

Ie..  whatever device is managing your DATA side, (RADIO) use that for the Audio Config on the TOP screen Receive (FROM RADIO)

 

Lower box is the To Speaker/Headphone, select your Logitech USB

 

For the TRANSMIT side,

Top box is your Logitech

 

Bottom box in your TO Radio connection. Mic or Transmit connection for DATA

 

I hope that isn’t too confusing, but please let me know if it is, and I can spend a few minutes with you on the phone or Skype, and I’m sure we can get you going..

 

Walter/K5WH

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