NASA repeater problem

[tolhurstorganic]

I have a NASA Clipper GPS repeater in cockpit connected to a Standard Horizon CP300, down below in nav. Area. The repeater has never worked properly and am just getting around to finding out why.
So GPS is switched on with a waypoint selected. When switched to POSN the repeater shows current co-ordinates. Select STEER and it shows SOG and CTE but no sign of any road with track distance or waypoint bearing. If DEST is selected the screen shows “No GPS dest” despite having selected a waypoint on GPS.
I have checked wiring all seems to be OK. The repeater manual makes reference to setting GPS unit up to send NMEA version 2.0 or later at 4800 Baud. None of this I understand at all. The Standard Horizon manual does not appear to tell me if the unit is set up for this. How do I check? Can anybody enlighten we as to what the problem may be?

 

[aslabend]

The Nasa manual is carp for the gps repeater but it's a simple bit of kit so doesn't need much more. The problem you have sounds like not all the NMEA sentences the repeater needs are being sent out by the plotter. You should find somewhere in the plotter menu system an option to set up nmea and there you make sure that it is sending out GLL (lat and long) and RMC + RMB data (navigation information). On mine (Lowrance plotter) the CGA, (time, position, fix related data) GSV, (Fix mode, sats in view) are also selected for when plugged into the PC plotter.

see here for more about nmea sentences http://aprs.gids.nl/nmea/