NMEA Interface on IC-M802

[duncan_ellison]

Hi all.

Can anyone confirm that the only GPS sentence that the IC-802 will respond to is 'GGA'.

I have both an IC-M504 and an IC-M802. The NEMA feed from my nav set up drives both the IC-M504 and a handheld (HX471) perfectly, but it's a no go on the SSB.

I read somewhere that it insists on a GGA input, but the manual seems to be silent on this matter.

Duncan
S/Y TALISA

[fairbank56]

Yes, I can confirm this for you. GGA only for the 802.

Eric

[duncan_ellison]

Thanks Eric.

The 802 is a wonderful bit of kit, but correct installation seems to be by word of mouth rather than following the instructions !

Duncan

[SoonerSailor]

Not only does it require GGA, it needs $GPGGA i.e. a GGA sentence from a GPS.

That shouldn't be any problem under normal circumstances, but I did try a $STGGA and $IIGGA from a Seatalk conversion, and my M802 did not like those sentences.

[duncan_ellison]

Soonersailor,

Thanks for that further clarification, I wouldn't have looked for that.

The NMEA GGA sentence was going to be derived from a ST stream via a multiplexer, so that probably wouldn't have worked.

Why do I feel the installation of yet another GPS receiver on the boat coming on ??? Good job they are relatively small and cheap these days.

... and whilst I'm at it, whatever possesed ICOM to use a BNC connector for NMEA ??? Ever tried wiring twisted pair cable to a BNC plug ??

Duncan

[Wotname]

Originally Posted by duncan_ellison

Soonersailor,

Thanks for that further clarification, I wouldn't have looked for that.

The NMEA GGA sentence was going to be derived from a ST stream via a multiplexer, so that probably wouldn't have worked.

Why do I feel the installation of yet another GPS receiver on the boat coming on ??? Good job they are relatively small and cheap these days.

... and whilst I'm at it, whatever possesed ICOM to use a BNC connector for NMEA ??? Ever tried wiring twisted pair cable to a BNC plug ??

Duncan

Yes and why did Icom design the M402 NOT to need GGA. I ended up getting self-contained GPS antenna/receiver just for my M802.

See also http://www.cruisersforum.com/forums/...ems-27992.html

[richardhula]

Originally Posted by duncan_ellison

Soonersailor,

Thanks for that further clarification, I wouldn't have looked for that.

The NMEA GGA sentence was going to be derived from a ST stream via a multiplexer, so that probably wouldn't have worked.

Why do I feel the installation of yet another GPS receiver on the boat coming on ??? Good job they are relatively small and cheap these days.

... and whilst I'm at it, whatever possesed ICOM to use a BNC connector for NMEA ??? Ever tried wiring twisted pair cable to a BNC plug ??

Duncan

Why not feed the M802 directly from the GPS receiver. You can attach several devices to same output. I appreciate this may mean less convenient cable run but we are only talking about simple coax cable run (easier than messing with two wires to BNC). You will have GPS feed as soon as it's switched on without extra links in the chain.

See my installation below

[SoonerSailor]

I agree with Richard. I have an old Garmin GPS60c in a RAM mount in the Nav station. The serial output from it goes to the M802, M502, and Brookhouse MUX all in parallel. All get the needed data, and the little Garmin also functions as a backup display to the main navigation system and backup GPS data to the MUX.

[duncan_ellison]

Richardhula, Soonersailor,

... because my main GPS is a Raystar 125 in Seatalk mode and my back up GPS is integral to my AIS tranceiver and talks to my Raymarine E80/120 at 38,400bps.

It seems like the easiest way is just going to be a cheap GPS dedicated to the SSB. Actually not such a bad plan as its likely to still operate even if my main instrument busses are shot to hell and I'm trying to get an emergency DSC call out.

I even have a couple of 32 channel SIRFStar receivers lying around and they are quite incredible, they don't even need a clear sky view to get a fix, so would probably work just fine stuck to the inside of the coachroof with some velcro.

BTW, Richard. Nice diagram, I can see why might feel the need to commit this to paper, but I think you've got the GGA and RMC sentences going to the wrong radios (!)

[richardhula]

Originally Posted by duncan_ellison

BTW, Richard. Nice diagram, I can see why might feel the need to commit this to paper, but I think you've got the GGA and RMC sentences going to the wrong radios (!)

Thanks you may be right as I created the diagram some time ago using CorelDraw. In any case I now have a M-504 VHF although wiring unchanged. The manual mentions:

When connecting GPS receiver is compatible with several sentence formatters, the order of input precedence is ‘RMC,’ ‘GGA,’ ‘GNS’, ‘GLL’ and ‘VTG.’

So mine takes the RMC sentence as priority & displays only UTC time.