[Elecraft] [OT] PCI Express sound card for digimodes

[Kok Chen]

On Jan 30, 2010, at 9:57 AM, N2TK, Tony wrote:

> Does anyone make a sound card, internal or external that has two separate
> inputs/outputs?

I believe stereo sound cards are actually more common than mono sound cards.  Edirol (I think) makes an inexpensive mono USB sound card, but almost everything else out there are multi-channel (both the E-MU 0404 (USB) and Edirol FA-66 (FireWire) have 4 channels, for example). 

However, some ham digital interfaces that include sound cards don't wire the right stereo channel, even though the chipsets in them are stereo; examples are the SignaLink USB and the microHAM USB Interface III. But many of the digital interfaces that come with sound cards do support two channel receive.  Some, like the microHAM digiKeyer and microKeyer II even have a pair of front panel pots to ride the gain for each channel independently.

The next issue is whether the software that you use allows you to select either the left or the right channel, even if the sound card has that capability.

> Right now I am using two sound cards for RTTY with my K3 -
> one for the main receiver and one for the sub-receiver. This way, when I
> turn on the sub-receiver I can tune around the band and decode the RTTY with
> the sub-receiver while I am decoding the RTTY on the main receiver. I am
> using two MMTTY programs at the same time.

With cocoaModem (a Mac OS X program), you won't need to run two copies to print from two receivers.  The principal RTTY interface in cocoaModem already has two independent channels (two waterfalls, two cross ellipse indicators, independent tone pairs, etc) within the same window (no window focus problems :-). See Fig. 11 here:

http://homepage.mac.com/chen/w7ay/cocoaModem/UsersManual/RTTYPage/WidebandRTTY/WidebandRTTY.html

A button on the bottom left selects if you want to transmit on the audio tone pair of the main receiver or the sub receiver. 

The two RTTY channels in that program can be set to take signals from two different sound cards, or different channels from the same sound card (the way I use it on a microKeyer II), or even the same channel on the same sound card (so you can use slightly different demodulation parameters on the same signal).   No, it doesn't have diversity RTTY yet, but it will come one day :-).

73
Chen, W7AY