Newbie GPS mouse and DSC radio question.

[ThereAndBack]

I have a Simrad RD68 DSC radio which currently gets its GPS position from a Raymarine RN300. This means that whenever the RN300 is not swithced-on there is no postition at the radio.

Can anyone tell me if it is possible to connect a GPS mouse (of the eBay variety) directly to the radio so that it always has a GPS position?

Particularly, will the mouse need a power supply and, if so, can I take this directly from the radio.

Answers in layman's terms will be much appreciated.

Alan

 

[fluffc]

No. The types you describe are invariably USB ones, which is totally incompatible with NMEA wiring.

 

[ThereAndBack]

[ QUOTE ]
No. The types you describe are invariably USB ones, which is totally incompatible with NMEA wiring.

[/ QUOTE ]

If this is so, what does my GPS mouse manual mean by the following:

The protocol of G-MR is designed base on NMEA(National Marine Electronics Association) 0183
ASCII format. The full protocol is defined in “NMEA 0183, Version 3.01”.
A.1、NMEA Transmitted Message
G-MR GPS receiver use MediaTek as the core, and output NMEA-0183 standard format message.
The default communication parameters for NMEA output are 9600 baud, 8 data bits, stop bit, and no
parity.

Please excuse me for now being even more confused.

Alan

 

[alan]

I think the easiest way would be to connect a "GPS antenna" which already has a serial NMEA output. The type that comes with most plotters/GPS receivers (these "antennas" are actually the antenna and receiver in one 'mushroom').
You would need to feed the "antenna" with 12 volts from somewhere and then feed the NMEA output from the antenna to your radio. This "antenna" could most probably be mounted in the cabin near your radio, most will work inside the boat with no problem (depending on boat construction, location of antenna e.t.c.).

If you want to use a GPS mouse use then you will need to feed it with the same power as the USB port on a computer provides (5 volts I think!); identify the serial wires and then wire them to USB to serial converter using the correct terminal plug (probably arrange power for the converter, 12 volts I think) and then take the NMEA serial output from the converter to the radio. This means a lot of messing with wires and power .......... and as you asked for answers in layman terms, then I would suspect that you would find it difficult to achieve this.

There are two things involved here: the NMEA protocol and the physical layer which carries it; RS232C (serial comms protocol) can carry NMEA sentences, also USB which has its own protocol can carry NMEA sentences but the physical layers (volts, range of volts, handshaking e.t.c.) are not the same.

Hence my suggestion above.

Alan.

 

[fluffc]

[ QUOTE ]
[ QUOTE ]
No. The types you describe are invariably USB ones, which is totally incompatible with NMEA wiring.

[/ QUOTE ]

If this is so, what does my GPS mouse manual mean by the following:

The protocol of G-MR is designed base on NMEA(National Marine Electronics Association) 0183
ASCII format. The full protocol is defined in “NMEA 0183, Version 3.01”.
A.1、NMEA Transmitted Message
G-MR GPS receiver use MediaTek as the core, and output NMEA-0183 standard format message.
The default communication parameters for NMEA output are 9600 baud, 8 data bits, stop bit, and no
parity.

Please excuse me for now being even more confused.

Alan

[/ QUOTE ]

The USB Mice would typically emulate a COM port on the host computer, so that any software accessing that COM port 'sees' a virtual RS232 (ie NMEA) signal.

 

[Birdseye]

The NMEA bit is simply the format that the info is sent in.

The GPS mice are designed to run off the 5 v or so that is provided by the usb socket on your lappy. As far as I am aware there is no 5 v power output on an RD68, just the 2 wires which take the NMEA signal. so the two are incompatible without a lot of work.

however there are stand alone GPS engines that can be powered by the 12v you have available - CDA-3 GPS Antenna at http://www.gpsw.co.uk/details/prod2766.html is one example and there probably are others.

 

[Avocet]

I did exactly this with a Haicom USB GPS mouse and an XM DSC radio. It works absolutely fine! I just cut the USB connector off the mouse and played about with the wires (using the manual downloaded off the internet which gives the wire designations). For power, I have a holder with 4 AA batteries giving 6V and this lasts plenty long enough for my kind of cruising. Only thing to watch is that the mice often have magnets in the bottom to stick to a car roof so make sure it's well away from the compass.