low modulation

Olivia - The Olivia transmission system is constructed of two layers: the lower, modulation layer is an (almost) classical Multi-Frequency Shift Keying (MFSK) and the higher layer is a Forward Error-Correcting (FEC) code based on Walsh functions.

PocketPacket Mac OS - PocketPacket started as an APRS client for iPhone/iPod Touch/iPad devices, but is also available for the Mac desktop or laptop. PocketPacket incorporates a software-based TNC, allowing you to directly capture and visualize, or encode and transmit 1200 baud packets (AFSK modulation) using a VHF radio transceiver.