nwts connects to your clock's GPS port and simulates a NMEA GPS signal to synchronize time. Using Wi-Fi and then connecting to a Network Time Protocol (NTP) source, your clock no longer needs to be next to a window for proper time synchronization within second precision - just needs Wi-Fi.
nwts supports TTL or RS232 serial signalling and it's configurable for compatibility with products from many manufacturers.
documentation and firmware upgrades are also available in the support section
nwts advanced settings are also configurable through a web page.
You can buy nwts here