Output GPS to DSC VHF

[Leigh]

Hi,

I have a RPi3-Sensehat setup with a USB GPS (see bragboard)

I'd now like to export GPS to my VHF radio (NAVMAN 7100EU)

Page 36 in the manual in the link above says the Navman has GPS/NMEA input (I know this since at the moment I have the VHF wired up to an old Garmin Etrex)

It also says Comm. Port: 4800 baud NMEA on page 36.

How could I do this, physically and in terms of software setup

Please 

Leigh