[Flexradio] PSK & RTTY setup

Joe - AB1DO ab1do at optonline.net
Thu Jun 22 11:57:34 CDT 2006


At the risk of being too expansive, let me see if I can answer your

First, just to make sure that everything is clear in your mind, N8VB's vCOM
utility enables the creation of virtual COM port pairs and is used to
connect from 3rd party software to PowerSDR for CAT control and/or PTT
control. As far as the third party program is concerned, it is just
connecting to a COM port, as it would for any other radio. Select one side
of a vCOM port pair in the third party program and the other side of the
same vCOM port pair in PowerSDR

VAC is indeed the (not free) program designed by Eugene Muzychenko. Any of
the versions 3.09 through 3.12 (the latest of release 3) will work. Do not
buy version 4.x at this stage as it still does not yet work properly with
PowerSDR. In essence, VAC enables a virtual sound card connection between a
third party program and PowerSDR. As far as the third party program is
concerned, it is just connecting to a sound card, as it would for any other
radio. Create 2 cables in VAC as per the instructions of N4HY. One cable is
used to connect the sound card input of the third party program to the VAC
output of PowerSDR, the other to connect the sound card output of the third
party program to the VAC input of PowerSDR. It doesn't matter which cable is
used for which connection, as long as one end of a VAC cable goes from an
input to an output or vv. The actual selections of input/output are made in
the third party program and PowerSDR setup form>audio>VAC sub tab

These are the only software connection utilities you will need.

The delta-44 needs to be setup and connected as per the Delta44 setup guide
you already referenced and is no different than for voice. If you can
receive SSB using your Delta-44 you're good to go. Ideally you would want 
the smallest buffers (Delta-44 Control Panel > Hardware Settings Tab DMA 
Buffer Size and PowerSDR setup form > audio tab > sound card sub-tab Buffer 
Size)  you can get away with without distorting the audio (clicks/pops). 
However, don't worry about optimal
settings at this stage - you can always adjust them later once everything is 
working correctly to fine tune. Although optimal settings depend on your 
system, 512 is usually a good starting point.

To configure the COM port connection and sound card selection in Digipan,
you can essentially follow N4HYs instructions for MixW. PTT is up to you,
but I usually just use CAT to control PTT. Play around with it. The ultimate
test will be whether clicking on TX /RX on Digipan will switch PowerSDR to
TX /RX respectively.

To configure VAC for Digipan, follow the instructions for MixW. Make sure
the sample rates between Digipan and PowerSDR (setup form > Audio > VAC)
match and that on the VAC sub-tab stereo is unchecked. Enable VAC (or select
auto enable and select either DIGU or DIGL on the Front Console of

To configure the COM port for MMTY, follow the instructions in N4HY's guide.

To configure VAC for MMTTY, follow the instructions in N4HY's guide. It
might help to know, that MMTTY will only allow selection of sound cards by
device ID. Unless you feel adventurous, by far the easiest is to select the
default windows sound card ID (-1) in MMTTY. In this case, you will need to
set the VAC audio cables as the default windows sound card devices for
playback and record . This you do using windows control panel > sounds and
audio devices as per the directions of N4HY.

To fine tune the audio settings, on the VAC sub-tab use the RX and TX boxes
to adjust the audio levels from and to PowerSDR respectively. The RX should
be set at the correct receive level for DigiPan/MMTTY and the TX box should
be used to adjust the volume to PowerSDR from DigiPan/MMTTY. In the latter
case, set the TX Meter on the PowerSDR Front Console to ALC and adjust for
0dB (peaks).

To reduce latency, adjust the buffer on setup form>audio tab>VAC sub-tab as 
low as you can get away with without distorting audio, just like the Delta 
44. A setting of 512 usually works well, but will depend on your computer 
system and concurrently running applications.

Finally, the easiest way to run Digipan/MMTTY with your Jupiter from time to
time, is to leave VAC, vCOM and PowerSDR untouched. Connect the Jupiter to a
hardware COMport and asecond hardware soundcard. In
DigiPan/MMTTY configure the appropriate hardware COMport and CAT
settings. In DigiPan simply select the approriate (2nd sound card). For
MMTTY, use the windows control panel>sounds and audio devices to select the
2nd sound card as playback and record device.
That way you can leave all hardware connections (SDR-1000 to Delta-44 and
Jupiter to 2nd sound card/hardware COM port) untouched.

Hope this helps,
73 de Joe - AB1DO

Bob Lusby wrote:

>    I am a fairly new subscriber and SDR1K owner seeking guidance on
> setting up Digipan PSK-31 and MMTTY.  I am getting a bit confused with the
> various VAC program downloads and settings for the Delta 44.  My system
> is:
> SDR-100 with 100PA and internal tuner.
> AMD Sempron Processorat 1.61ghz w/1gb RAM computer.
> Windows XP Home edition.
> Sound board on the motherboard with nothing connected to the in/out/mic or
> speaker jacks.
> N8VB serial port driver installed.
> Delta 44 sound card installed with breakout box connected as per Delta 44
> Quick Start Guide instructions.
>    I have the N8VB configured for Com 2 & 3, 6 & 8 and am using Com 8 as
> the PTT line.  PTT works fine with the MMTTY and Digipan program.  The VAC
> 2 & 3 works fine with my logging program, including passing the SDR
> frequency to the WIN-EQF logging program.
>    The SDR CAT control is setup for Enble CAT Com 2 and PTT Com 6 and ID
> as TS-2000.
>    At this point I'm not sure if I have the optimum settings for the sound
> card.  For Digipan the sound card settings I have are Type computer sound
> card as Input & Output preferred sound card.  The MMTTY program is Misc:
> Sound Loopback off, TX Port: Sound, and XMIT PTT Com 8 and Radio Command:
> None.
>    Power SDR setup is VAC enble.  Driver Windows Direct Sound.  Input
> Delta 44 mixer.  Output Delta 44 multi.  I have clean signals
> send/receive.
>    I am not sure if I have the best settings or if I should be using one
> more program with N8VB.  The "How to Setup VAC with PowerSDR" by McGwier,
> N4HY, says that Virtual Audio Cable (VAC 3.09) is needed, but doesn't give
> a source.  My questions are:
> 1.  I found a program by Eugene Muzychenko and would like to know if I
> should add it to my programs to run with N4VB's program.
> 2.  What are the optimum settings for the Delta 44 for my system (if I
> have given enough info)?
> 3.  What is the best way to run the sound card, either the Delta 44 or the
> on-board sound card with a non-SDR radio?  I.e., have my Jupiter able to
> run PSK & RTTY.
>    Thanks in advance for the help.
> Bob Lusby, k9foh
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