By convention, amateur RTTY uses the lower sideband, with the Mark frequency 170 hz higher than the Space frequency. The generation of Mark and Space frequencies required for Amateur Radio RTTY transmission is commonly accomplished in one of two ways:

Also by convention, a RTTY QSO's frequency is that of its Mark frequency. Thus accurate DX spots for RTTY stations specify the station's Mark frequency.


FSK requires a transceiver support in the form of a RTTY or FSK mode in which the transmitter frequency switches between RTTY Mark and Space frequencies as dictated by the signal driving the transmitter's RTTY input. FSK's advantages include

However, only a few transceivers provide RTTY output waveshaping.


AFSK is accomplished by placing the transceiver in LSB mode (some transceivers provide an LSB DATA or PKT mode for use with AFSK) and directing the PC soundcard to generate Mark and Space tones that are fed to the transmitter's audio input to produce Mark and Space frequencies at the transmitter's output. AFSK's advantages include

Setting up CW, Phone, PSK, and RTTY Operation

Getting Started with CW, Phone, PSK, and RTTY Operation

Getting Started with DXLab

AFSKFSK (last edited 2018-03-23 06:41:34 by AA6YQ)