Allows the GPS module to retain and output last known position in NMEA after losing GPS satellite fix

Overview
"Last Position Retention" customization is a convenient yet elegant solution that allows the GPS module to continue output its last known position in the event of losing GPS satellite fix (eg. when inside tunnels or when GPS signal is jammed by Solar flare or GPS jammers). This simple feature helps designer saves time and resources during GPS development.

Background
Even though GPS is tightly woven into the everyday lives, its function is still limited to those with partial view to the sky. GPS will cease to operate when travelling inside the tunnel, building or other structures that blocks the satellite signals from above. This is also true during periods of Solar Maximum, where the Sun shoots out huge jets of hot plasma known as solar flare that disrupt satellite signals.

Typically, the GPS module will output null or "blank" positions in NMEA when the fix to the GPS satellites is lost, but under special conditions and applications, such as AVL, the operators might actually want to know the whereabouts of the last known position.

Solution
BONAV can configure the GPS module so it retains and outputs the last known position in the NMEA sentence after the fix to GPS satellite is lost.