Rf solutions zulu 868mhz wireless serial data radio modem modules rf solutions zulu m868 so the zulu m868 so modem module is a highly integrated rf modem and intelligent controller with a simple interface that achieves a wireless serial data link for data up to 38k4bps over a 2km range its range may be further extended by using a suitable antenna the user interface is standard rs232 style control operating at low voltageall rf operation is automatically controlled with error checking