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

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 31.25 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

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

PSK-31 Basic transceiver to computer soundcard interface

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)

PSK-31 on 7035KHz using DigiPan

Adjust your equipment properly

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

A good PSK-31 signal PSK-31 audio clip

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

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 MT63-1000, and 200 wpm for MT63-2000

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 MT63-2000 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

MT-63 MT63-1000 signal on 20m MT63-2000 audio clip To fit within the audio pass band of an SSB transmitter, an MT63-2000 signal uses tones from 500 Hz to 2500 Hz

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

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.

Where to get the software Download FLdigi and associated modules FLmsg and FLwrap from: http://www.w1hkj.com/download.html

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