SailNet Community banner

1 - 8 of 8 Posts

·
ASA and PSIA Instructor
Joined
·
4,121 Posts
Discussion Starter #1
Following up on the two prior threads http://www.sailnet.com/forums/gear-maintenance/43139-gps-dsc-round-2-a.html, after several more debug rounds with Garmin support I got my 182 GPS updated to the latest firmware version. Restarting the GPS I entered the new DSC pages, turned on DSC and low and behold I find my new ICOM 402 still reads "no position". So after rechecking everything done to date, I have discovered that the ICOM 402 requires NMEA 0183 ver. 3.01 while the Garmin firmware supports NMEA ver. 3.0 My seventh call to Garmin support got someone whose best advice was "call ICOM"...

So there will be at least a Round 4 to this story.

But the morale to date is, that if you want to have a DSC radio, you may need to buy more than just a new radio...even if your existing gps supports NMEA and DSC and the vendors are Garmin and ICOM.
 

·
Registered
Joined
·
2,283 Posts
Ain't technology great? I'm spending my first weekend on my new to me Catalina 36 working through the survey punch list and finding a few others headaches to address. One of which was that the Loran, yes Loran, was interfaced to my DSC radio. Further, the postion shown was no were near where my Seaclear showed me being. After a 1/2 hour of button pushing and head scratching I found I had no signal so started tracing the coax out to the antenna. Guess what, it was cut off at a fitting on the transom. I retermininated the connection and the unit works fine with a postion very close to the GPS lat/lon, only problem is the coax is about 3 feet too short so I have to run new coax. If it were any more complicated I'll scrap to loran but sense it seems to funtion fine and is already interfaced I think I'll keep it. Pilots like redundancy!

Oh yeah, the folks in the slip next to me sold their C28 and bought a brand spankin' new C350. So much for keeping up with the Jone's.
 

·
Telstar 28
Joined
·
1,000 Posts
SF-

The problem probably isn't either the Garmin or the Icom...it's the weird wiring that the Garmin uses. Attach the Icom's NMEA In - line to the DC system ground. Garmin doesn't have a signal ground IIRC, and if you don't have the In - line connected to the ground, you won't get any DSC data.

Hope this helps. :)

SD
 

·
Registered
Joined
·
476 Posts
SF, both should accept DSC sentences as 3.01 changes has not to do with position sentences (as of 2002). Dog is probably correct, ICOM uses differential input (current loop) for data ports, much more resilient to electrical noise, so the NMEA (-) is not grounded. Your GPS has traditional i/o based on GROUND. So, connect your NMEA (-) on ICOM to the DC GND. Then connect ICOM NMEA (+) to GPS NMEA TX (Green cable). But 402 only receive information, as it's not capable to transmit an incoming DSC call to your GPS. Another check is yor GPS baudrate, not mentioned by ICOM, the 402 is set to 4.800.
 

·
Telstar 28
Joined
·
1,000 Posts
BTW, the standard for the NMEA 0183 protocol is 4800 baud, No Parity, 8 bits, 1 Stop Bit, or 4800, N, 8, 1. It also doesn't use any handshaking. Some newer NMEA hardware will let you set a higher baud rate...but I doubt your 402 is one of them.

For the geeks out there—the real problem is that the real NMEA 0183 specification is an RS422 protocol, while most manufacturers have implemented it as an RS232 serial protocol, which is much more common and not as resilient.
 

·
ASA and PSIA Instructor
Joined
·
4,121 Posts
Discussion Starter #6
SF, both should accept DSC sentences as 3.01 changes has not to do with position sentences (as of 2002). Dog is probably correct, ICOM uses differential input (current loop) for data ports, much more resilient to electrical noise, so the NMEA (-) is not grounded. Your GPS has traditional i/o based on GROUND. So, connect your NMEA (-) on ICOM to the DC GND. Then connect ICOM NMEA (+) to GPS NMEA TX (Green cable). But 402 only receive information, as it's not capable to transmit an incoming DSC call to your GPS. Another check is yor GPS baudrate, not mentioned by ICOM, the 402 is set to 4.800.
Way cool info, Negrini, thanks to you and SD for this advice. In reviewing the ICOM 402 manual, although it shows the NMEA (-) connection to be meade, the instructions don't speak to whether the unit USES that connection to deliver position info to the GPS, so I suspect you are correct. I will move that connection from the Garmin NMAE (+) to ground and see if I get success. Beers are on me if this works!
 

·
Registered
Joined
·
109 Posts
Don't know if this applies, but we have a handheld Garmin and an Icom DSC cobbled together. Works fine as long as I have lots of batteries on hand. Garmin uses a common ground for signal and for powering and our ICOM does not like that, once the ground for powering is cut, all works flawlessly, have spent lots of time with both Garmin and ICOM and at the end of the day (after trying all the things they suggest) they end up blaming each other. Aside from spending a small fortune on batteries it works very well, especially with the WHAM handset. (1 touch distress calling doesn't help if you can't reach the radio.)
 

·
Registered
Joined
·
1,000 Posts
Sailingdog,

Thank you.
I have been working on the Garmin and Uniden DSC think for 2 days, the in to ground work. now my DSC is working and im safer for it.
 
1 - 8 of 8 Posts
Top