Saturday, April 19, 2008

Amateur PSK31 and Mac

I've been a dormant ham for a while now, but with some encouragement from my wife, I've recently got back on the air. Back in the day, I managed to work all the states on 20 meter AMTOR. Since then, the new AMTOR is a mode called PSK31. It's a digital mode optimized for keyboard-to-keyboard QSOs.

You have to use computer software to work PSK31. It converts your typing into audio, then converts the tones it hears from your transceiver back into text. It does the latter by listening for signals throughout the audio passband of your rig, showing them all in a waterfall display that you click on to choose either a blank spot to call CQ or on a signal to decode it and set up your transmitter to reply to.

So to make it work, you need to do three things:

1. Get the receiver's audio into the computer
2. Get the program's transmit audio into your transceiver
3. Allow the program to control your radio's PTT button

The grand plan was to buy a TigerTronics SignalLink USB. It looks to me to be the best possible solution. It connects to your computer only via a USB cable. It has an internal USB audio device and the signal isolation transformers necessary to keep the two apart. It uses VOX to key the radio (that is, when audio comes out of the audio device, it keys the radio automatically). All in all, it seems ideal. Unfortunately, however, they're 4-6 weeks backordered, since it appears that I'm not the only one who thinks it's an ideal solution.

The next best thing is a RigBlaster Plug-n-Play. It makes 3 connections to your computer - audio in, audio out and a USB connection. The USB connection is for a USB-to-serial adapter that is used for PTT and for an (optional) radio control serial port interface. The port's RTS line is connected directly to the radio's PTT actuator. There is a software download on West Mountain Radio's site that contains an unsupported MacOS X driver. From what I can tell, it works just fine.

On the software end, there is a program called MultiMode, but the interface seems awfully primitive to me. Plus it costs almost $90. Instead, I went with cocoaModem. It has an auxiliary helper program called cocoaPTT that will do the serial port RTS for PTT thing on behalf of cocoaModem. You just have to make sure that the rigBlaster is plugged in, then start cocoaPTT, then start cocoaModem.

3 comments:

Anonymous said...

Thanks for the info.
Just getting into PSK with a mac

Anonymous said...

Hi!
Now available on Apple Store I-PSK31 for IPHONE and IPOD TOUCH!!!!

steve said...

I've seen the comments for the iPhone app and I've downloaded it. People say it works with an iTouch but how do you get audio out to transmit? I'm thinking you make a cable and do a 'Y' split into the mic and headphone jack. Does iPSK take of the PTT?

Tnx N2XC