1. PSK-31 and MT-63 Digital Modes
Al Duncan VE3RRD

2. PSK-31 Was created by Peter Martinez G3PLX
Based on RTTY style of communications, and is useful for keyboard-to-keyboard QSO’s
Data rate of baud or about 50 wpm
Total bandwidth of about 50 Hz (with proper equipment setup and adjustment)
Can fit at least fifteen PSK-31 QSO’s into the bandwidth occupied by one SSB QSO
Uses an SSB transceiver connected to a computer soundcard and free software

3. PSK-31
The PSK31 station consists of a combination of Software, PC, Sound Card, SSB transceiver & interface hardware
Software: DigiPan, FLdigi, Ham Radio Deluxe, or many other free programs
- Encodes and Decodes PSK signal tones
- Controls TX PTT via the serial port
PC:
Laptop or desktop preferably running Windows 2000 or later operating system

4. PSK-31
Basic transceiver to computer soundcard interface

5. PSK-31 Many commercially made interfaces are available
One of the best is the SignaLink USB which includes its own soundcard and transceiver keying and only needs a USB cable to the computer (powered by the USB cable)

6. PSK-31 on 7035KHz using DigiPan

7. Adjust your equipment properly

8. Don’t overdrive the transmitter
Signal at 1000 is overdriven with multiples of 31 Hz on either side of center – about 185 Hz wide
Waterfall screen shot  below is an example of a badly overdriven sound card. Notice that you can count out to the 15th harmonic and it is splattering over 500Hz taking out at least 6 PSK31 QSO's

9. A good PSK-31 signal
PSK-31 audio clip

10. PSK-31 QRP
The Small Wonder Labs PSK80 Warbler is a small 3W 80m QRP transceiver that covers 3580 to 3581 KHz uses computer soundcard, and serial port to key TX

11. MT-63 Uses up to 64 separate tones
Uses FEC (Forward Error Correction) giving it an advantage in poor signal conditions
Not really useful for a keyboard-to-keyboard QSO due to long FEC decode time (several seconds)
Three bandwidths used: 500 Hz for HF, 1000 Hz for HF under excellent conditions, 2000 Hz often used for VHF/UHF FM
Speeds vary: 50 wpm for MT63-500, 100 wpm for MT , and 200 wpm for MT

12. MT-63
Computer and audio interface requirements are the same as mentioned for PSK-31
Best free software for MT-63 use is FLdigi
FLdigi includes additional modules optimized for the error free transfer of text message files
Error free message transfer ability makes it an excellent choice for emergency communications
MT works very well over 2m FM simplex and also through a repeater
FM radio interfacing can be done acoustically!! A real bonus for emergency communications

13. MT-63
MT signal on 20m
MT audio clip
To fit within the audio pass band of an SSB transmitter, an MT signal uses tones from 500 Hz to 2500 Hz

14. MT63-2000 received via a microphone
The “wrap” function includes a checksum for the message enclosed by commands that allow FLdigi to recognize the message and automatically save it

15. ICS-213 message received in the previous slide using a microphone held close to the speaker
FLmsg is used to open the received message. It puts all the text back into the proper fields so that the received message is a duplicate of the message created by the originator who also used FLmsg.

16. Where to get the software
Download FLdigi and associated modules
FLmsg and FLwrap from:

17. And now for a demonstration of PSK-31 and MT-63