GPS signal to icom M302

[CarinaPDX]

Here is the manual for the GlobalSat BR-355S4:

https://www.globalsat.com.tw/ftp/dow...Guide-V1.0.pdf

It does output in MNEA 0183 v3.0 protocol so no problem using it out of the box.

It is an older GPS module; others could have been bought for the same or less price that are newer. Newer would have got you faster first fixes, more sensitive reception (better for below deck operation) and positioning using other GNSS signals (Russian GLONASS, Chinese Bei Dou, European Galileo) but little accuracy improvement. It will get the job done just fine.

Greg

[CarinaPDX]

Correction: The BR-355S4 supposedly uses the same module (SiRFstarIV GSD4e) as the older BR-353S4 but the hot start time to first fix has been reduced from 8s to 1s - a competitive number - and there must have been an upgrade to the same model of the module. The available sensitivity is also way up, depending on the LNA used, so again very contemporary performance. The only "improvement" could be the reception of other GNSS signals; in practice GPS is the most accurate so not really an issue unless something happens to GPS. Qualcomm (who bought SiRF) was a little naughty in not using a new model name for the upgraded module, but it is definitely upgraded.

Greg

[Steven UK]

Originally Posted by CarinaPDX

Correction: The BR-355S4 supposedly uses the same module (SiRFstarIV GSD4e) as the older BR-353S4 but the hot start time to first fix has been reduced from 8s to 1s - a competitive number - and there must have been an upgrade to the same model of the module. The available sensitivity is also way up, depending on the LNA used, so again very contemporary performance. The only "improvement" could be the reception of other GNSS signals; in practice GPS is the most accurate so not really an issue unless something happens to GPS. Qualcomm (who bought SiRF) was a little naughty in not using a new model name for the upgraded module, but it is definitely upgraded.

Greg

Wooshhh... right over my head..! I’ll read the manual and digest first, but the m506 does have NMEA 2000 & 0183 inputs. Prepare for more stupid questions...

Regards Steven

[atoll]

normally if you use the nmea output from a gps chart plotter to the vhf it is just a case of connecting 2 wires

[Steven UK]

After a quick google... the TX and Rex -wires can be grounded to the power supply puck ( not sure why the radio needs to talk to the puck). I’m thinking three wires for the puck:-
+5v
-5v
Puck talker + to radio gps receive

[atoll]

Originally Posted by Steven UK

After a quick google... the TX and Rex -wires can be grounded to the power supply puck ( not sure why the radio needs to talk to the puck). I’m thinking three wires for the puck:-
+5v
-5v
Puck talker + to radio gps receive

the rx wire and ground would be for software input to the puck via usb cable from a computer.

the radio only needs the tx + and ground - from the puck
to its nmea rx+ input and ground-,only 2 wires ie green- and yellow+ on the radio

puck power input would be the common ground and pos input

radio talker wires brown -and white+ go to either a chartplotter or can be connected to a usb adapter cable to a pc for dsc data on the respective plotters

[Steven UK]

Originally Posted by atoll

the rx wire and ground would be for software input to the puck via usb cable from a computer.

the radio only needs the tx + and ground - from the puck
to its nmea rx+ input and ground-,only 2 wires ie green- and yellow+ on the radio

puck power input would be the common ground and pos input

radio talker wires brown -and white+ go to either a chartplotter or can be connected to a usb adapter cable to a pc for dsc data on the respective plotters

Got it...
I’m assuming that two radios can share the same feed from the puck, I.e. two radios in parallel with the puck TX and ground wire. I may just leave my old radio in place....
Regards Steven

[CarinaPDX]

IIRC the NMEA standard is, or at least used to be, that one talker could drive up to 4 listeners but that would not necessarily apply as these GPS pucks aren't NMEA approved. You should be on safe ground with 2, and even if 4 or more were a problem it shouldn't damage anything.


Greg

[atoll]

Originally Posted by Steven UK

Got it...
I’m assuming that two radios can share the same feed from the puck, I.e. two radios in parallel with the puck TX and ground wire. I may just leave my old radio in place....
Regards Steven

not really any point in that as then you would need 2 vhf antennas or a vhf antenna splitter if you wanted them both to operate,keep it as a spare in a locker or ebay the old one

also for some reason on some radios if the gps data does not show up ,swapping the pos and neg TX inputs rectifies the problem
you might also need to set the nmea settings on the radio in the menu for in/out tx/rx 4800 baud in com1 and or com2

[Steven UK]

Just closing the loop here, I ended up buying a M506 with AIS but still needed the GPS input, the below suggestion worked perfectly. The GPS info is on the screen about a second after the radio boots up and the collision function works great. Many thanks all that helped here.

Regards Steven

Originally Posted by CarinaPDX

The OP asked for an economical solution. For $20 he can buy a new, marine GPS receiver with NMEA i/f and 12V power, from China:
https://www.aliexpress.com/item/12V-...807433645.html

For $6 more he can buy a unit that also receives GLONASS, and if he wants to do a little extra work, Galileo. Or GPS+Galileo+(Beidou or GLONASS): https://www.aliexpress.com/item/NEW-...971734254.html
The only downside is that it takes 1-2 months to receive.

Greg