How to Determine Fuse Settings I bought an arduino compatible board here: http://unsigned.io/projects/micromodem/
and am trying to flash new supported firmware onto it. The only instructions given to flash the board is to use the command avrdude -p m328p -c arduino -P /dev/ttyUSB0 -b 115200 -F -U flash:w:YourFirmwareFile.hex . 

I'm trying to follow the tutorial here using an Uno as a programmer: https://learn.sparkfun.com/tutorials/installing-an-arduino-bootloader#uploading-code---hard-way but I don't know what to use for the fuse settings. I've tried a few different fuse settings such as the one for the Uno, and default 328p ones using a fuse calculator but it seems like they all have unpredictable results. Some fuse settings make it so that I can't connect  to the COM port at all to monitor the traffic, and others let me connect, but send a message of . I'm expecting an introduction message from the firmware that is supposed to be built in.

Thanks for the help.
Normally you don't need to change the fuse settings, this configuration should be fine with the default arduino setting of 

lowfuse=0xff 

highfuse=0xde 

extendedfuse=0x05

Serial should work fine.