How to use GPS data from SeaTalkng for DSC VHF radio via NMEA 0183

Which NMEA 0183 Sentences Are Sent?

The SeaTalk to SeaTalkng Converter transmits the following NMEA 0183 v4.10 sentences at 4800 BAUD:

• GGA: Time, date, position (if L/L available).
• RMC: Time, date, course, speed (if L/L available).
• VTG: Course and speed over ground (if valid data available).

How Does Sense Mode Work?

After the update, the converter operates in Sense Mode during the first 20 seconds:

• If SeaTalk packets are detected → the converter works as a SeaTalk to STng Converter.
• If no SeaTalk packets are detected → the converter works as a one-way data bridge and transmits NMEA 0183 GPS sentences with $GP Talker ID at 4800 BAUD.

Wiring Diagram – Example Installation

The diagram below shows how a SeaTalk to SeaTalkng Converter can deliver GPS data from an a67 MFD to a DSC VHF radio that requires NMEA 0183 data. The same solution works with Raystar 130 or other STng/NMEA 2000 GPS sources.

Important Notes

• DSC VHF radio must always have a GPS data source according to international regulations. Without GPS data, the radio issues a NO FIX alarm.
• Manual position entry is for emergencies only.
• The solution also applies to Axiom MFDs and Element displays. Use adapter cable A06075 DeviceNet (F) to STng Spur for connection.

Best Practices for Low Power Consumption

Many want to monitor DSC VHF radio at anchor without powering an MFD. Recommended solution:

• Install an external GPS sensor, e.g., Raystar 150.
• Power the STng/NMEA 2000 backbone and VHF radio from separate circuits for minimal consumption.