Versatility in Modems The 9600/1200 bps PK-96 comes with 1200 bps AFSK tone signaling, as well as 9600 bps K9NG and G3RUH compatible direct frequency modulation, making it a truly high performance data controller. There is even a modem disconnect header for installing other modems.. The modem uses changes between the tones to indicate a zero and no change to indicate a one. So a low tone followed by a low tone would be no a zero, but so too would a high tone followed by a high tone. ... Note: AFSK is the modulation method used for common 1200 baud packet on the VHF frequencies. Different baud rates and modulation methods. "/>Afsk modem