Implementing GPS on a VHF-DSC radio without GPS

[smac999]

return the vhf and buy one with the built in gps....

[CarinaPDX]

@francois.lavoie:

The version of GPSd that you linked to in the repository is far too old - v3.11 - so uninstall it and install 3.22 from the tarball. IIRC UBXTOOL was added in 3.18 and you are really going to want that for modifying configurations. (Be sure to get a module with flash so that configurations are persistent.) CGPS and XGPS (included in GPSD) should check for baud and encoding (binary, NMEA) automatically and self-configure, but it is slow so give it time (minutes).

uCenter can do just about anything but it is incredibly difficult to use. You really have to get down to the bits and bytes to accomplish anything, and getting there takes a lot of time. My brother wrote UBXTOOL, and he had to invest a lot of time to understand uCenter and how to configure uBlox modules. He made UBXTOOL as an orders-of-magnitude easier way to configure uBlox modules, although it still requires some thought and understanding. With a current install of GPSd and a uBlox module with flash memory you should be able to configure it to work (of course if you are willing to reconfigure on boot every time then flash isn't needed.)

So very many people have played fast and loose with the NMEA 0183 spec, and as a result GPSd has had to create drivers to deal with the different (non-standard) interpretations. Fortunately if you use GPSd the output will be in a correct, standard-observing format. FWIW NMEA 0183 is only specified at 4800 baud, and High Speed NMEA 0183 is at 34800 baud; all other baud rates are non-conforming to NMEA 0183 - and very common. With GPSd you can determine the default baud rate, and change it for the session, but as I said before you need flash for persistence.

GPSd should work with the uBlox 6 module. It may have defaulted to an unexpected baud rate or it could have defaulted to uBlox binary, and either one would cause your problem. Once communication is established you can change the session config. BTW UBXTOOL has to go into binary mode to program the module and then return to NMEA to operate. Being in the wrong encryption mode is easy to do...

I have to agree with @smac999: it is infinitely easier to go back and buy a VHF with internal GPS, but I do appreciate the desire to do a little hacking.

Greg

[francois.lavoie]

Hello jonathanx,
This would be quite appreciated. Just click on my name on the precedent post. This will give you access to a private message.
Thanks so much. : P

[JonathanX]

Here is the file François. On the private message there is no place to attach a file except on the Post Reply which I did.

[francois.lavoie]

@jonathanx:
I have send you my email address.
Thanks.

[francois.lavoie]

CarinaPDX
Thanks for the precisions on gpsd and its tools. I will get with git the most recent version. Hail to your brother and its devotion to the gnu community.

[francois.lavoie]

@ all:
I am learning the hard way. My first GPS the NEO 6M seemed to be inoperable from the begining. By contrast, I could get satellite localization with xgps, the graphic version of gpsd with the Grove air 530. At least, until I interchanged accidentally the VCC or positive pole and the ground. It seems to be dead now. So maybe that the NEO 6M was good when it came in, its just that my manipulations did it some wrong.

Yet I have worked only with pins and their plastic female counterpart to plug a ttl to usb (cp2102) to these GPS modules. I will have to learn soldering skills and find some enclosure box to protect the electronic components.

l am looking for the antenna aspect of the GPS. The very small plate antenna does not seem ideal. But if it works, there no reason to go overkill. Alternatively, if I will have to provide a better antenna or to displace the GPS on some pole up outside the boat Thinking about it, maybe I could put the GPS in an abs tube with a cap, which with a cable long enough could connect to the Arduino and then to the VHS radio. Unless a wifi chip could spare me the cable connection. Otherwise, I could keep the GPS module inside the boat and provide an antenna. I am studying the antennae types, my first guess would be the helicoidal type, the j-pole type and the ground plane antenna. These should be designed according to the desired wavelength range.

I am expecting in the next few days or weeks, some components coming from china, additional GPS modules, a max485 ttl to rs485 connection, arduino nano, and wifi and rs485 shields and a raspberry pi 4 8gb to complete testings and implementation of my navigational and sensors electronic setup.
I will need to practice electronic soldering and familiarizing some more with arduino use and programmation.

I will come back and report. Thanks.

[Kelkara]

Originally Posted by francois.lavoie

l am looking for the antenna aspect of the GPS. The very small plate antenna does not seem ideal. But if it works, there no reason to go overkill.

I don't know what kind of boat you have, but on my little fiberglass boat, I keep mine below decks ... the little square antenna works just fine. Wire it up on a breadboard to test it before you start soldering things, then you can always change your plan if you have trouble getting a GPS fix.

[francois.lavoie]

@jonathanx or others:
You were mentioning the use of a radar for the fog in the: Bas du fleuve. That piece of equipment is not given. Maybe the best thing to do is to stay at the marina on the foggy days. : P



Follow-up. I should receive additional hardware this week. My ICOM M330 VHF-DSC radio is has now an helicoïdal antenna on my front balcony and is connected to the 12 V battery. I have registered to get the MMIS number with the goverment of Canada which will idenify my boat as a radio station. Otherwise the VHF radio would not work.

[emilecantin]

Salut François,

Have you succeeded in your project? I found this post through the search, so I realize it's a bit old, but I succeeded in interfacing that exact same radio (Icom M-330) relatively easily.

I used this RS-422 adapter: https://www.amazon.ca/gp/product/B01...e?ie=UTF8&th=1

And this USB GPS: https://www.amazon.ca/gp/product/B01...?ie=UTF8&psc=1

Both connected through USB to a Raspberry Pi running OpenPlotter. It's relatively easy to setup serial connections through the OpenPlotter tools, and the data was multiplexed using SignalK (included in OpenPlotter). You can choose relatively easily what data you want to output to the radio; everything is handled via "connections".

I just used the small "breakout board" that came with the RS422 adapter to connect the wires from the radio to the adapter, no soldering required.

Of course, all this might be a bit overkill if you only want to get GPS position on the radio, but in my case I wanted to setup OpenPlotter as my navigation system (with an AIS receiver too), so the only additional expense was the RS422 cable.