Add second GPS object to openCPN

[lsk]

Hi,
I'm in need of showing another object (in addition to my boat) in OpenCPN.
At the moment I wrote a little proxy server that translates GPGLL sentences in AIVDM, so I can plot the second object on the map as AIS target, but since I'm not a developer, it's painfully slow (one sentence every about 20 is translated, the other just lost...), and I'm quite sure there's a better method to achieve that.

Anyone has any idea?

Thank you

[Hakan]

lsk..
One method used for several similar purpose is to transfere the information from xxGLL to a xxTLL message.

OpenCPN will understand that as an ARPA target using the same functionality as for AIS targets.
You can have a general Target number, e.g. 01, and a name, e.g. "My target" and fill with the position from xxGLL on every update.
Set Status to "T" and nothing in the "Reference" field.

TLL - Target Latitude and Longitude
Target number, name, position and time tag for use in systems tracking targets.
$--TLL,xx,llll.ll,a,yyyyy.yy,a,c--c,hhmmss.ss,a,a*hh <CR><LF>

[rgleason]

I added that to FAQ


Is there any way that nmeaconverter would help with changing the GPS to TLL? Does it read connection priorities? Maybe not because it is a plugin of opencpn?

[rooiedirk]

Indeed translate your second GPGLL to xxTLL is much easier then translating to AIVDM.
Unfortunally I don't see a way to use the nmea-converter plugin to do the job.

[yachtvalhalla]

Originally Posted by lsk

Hi,
I'm in need of showing another object (in addition to my boat) in OpenCPN.
At the moment I wrote a little proxy server that translates GPGLL sentences in AIVDM, so I can plot the second object on the map as AIS target

Thank you

It might be my early morning brain not awake yet but are you trying to put AIS targets on the screen?


That's done with OpenCPN as a normal feature.


Terry

[rooiedirk]

Something comingup my mind.
If you can configure your 'first' GPS not to send a GLL sentence, and your 'other' does, then the only incomming GLL sentence would be from the 'other'.
Then if you tell OpenCPN not to use the GLL sentence for the ownship position by adding "UseNMEA_GLL=0" to the config/ini file.
Then you can use the nmeaconverter plugin to convert the GLL to TLL. No external programs and servers needed anymore.

[rgleason]

Dirk, I think your idea should be written up once, someone proves it works. I like it!

[sdowney717]

Except how many people will know how to configure a gps to not send a sentance? Or even change anything a GPS does send out, few and far between I think.

I could imagine since GPS has a Rx wire, it can be done if you have the right software and know the right command format. And how many people have that.

So IMO, for practicality reasons, that solution is vaporware, pipedreaming, frustration and I hate solutions like that where you have to be an insider technician.

[rgleason]

Sdowney
Is this a complaint?
If we show you how, would you do it?
If no, perhaps you ask for the moon?

[sdowney717]

Originally Posted by rgleason

Sdowney
Is this a complaint?
If we show you how, would you do it?
If no, perhaps you ask for the moon?

Sure, show me how, here is an example GPS for you to do that as it can be configured many ways.
I bought this one to connect for the radio.
I would like to know all the commands needed to change things like baud rate, update frequencies from 1 to 10, select which satellite systems to use, output ttl or rs232, leave out certain statements, etc...they mention all of this they can configure.

https://www.aliexpress.com/item/3291...4de64c4dzX7ecZ

And 90% of all DSC capable radios that dont have a gps attached still dont as most people cant figure out even a couple of wires.

And before the reg changed, 90% of all DSC distress calls had no gps information.
They changed it to you can not make a DSC call without gps info, and now they want all radios to have gps integrated, except it has to be on a wire, cause otherwise, it may not have a view of the sky and still wont work.

[barnakiel]

Originally Posted by sdowney717

And 90% of all DSC capable radios that dont have a gps attached still dont as most people cant figure out even a couple of wires.

And before the reg changed, 90% of all DSC distress calls had no gps information.


They changed it to you can not make a DSC call without gps info, and now they want all radios to have gps integrated, except it has to be on a wire, cause otherwise, it may not have a view of the sky and still wont work.

1) most people can figure out, those who do not hire a technician,
2) clear sky is not required. sirf IV and newer chipsets do well down below.


Over many years I have only seen one vhf dsc unit that should, but did not have, the input. ymmv, I am in the EU / Spain / France, mostly.



I know it is not required (clear sky) as our neolithic today garmin is mounted below a sandwich (grp/foam) roof and gets lock in 15 seconds and never once dropped it.


SH makes vhf with gps chip inside. Hurry get one.


b.

[barnakiel]

OpenCPN should be VERY


REPEAT VERY


carefull in if and how it enables seconday gps tracking.


I agree: this can be a fine tool for few specific users (e.g. for me) BUT it can be downright dangerous for some other, less experienced users.


So imho a superb functionality just needs to be very very well thought out in software application.


b.

[CarCode]

Up to now OpenCPN has no intuitiv function to add a GPS.
Imagine you have a car with navigation and have to install things like OpenCPN actually need to do. Imagine you buy a plotter for the boat and have to install things like OpenCPN actually need to do. Are there a lot of people doing this? Might be they ask the local vendor but nothing else.

So first do this better for OpenCPN before talking about connecting a second GPS. The average sailor is not a computer specialist.

[barnakiel]

Originally Posted by CarCode

Up to now OpenCPN has no intuitiv function to add a GPS.
Imagine you have a car with navigation and have to install things like OpenCPN actually need to do. Imagine you buy a plotter for the boat and have to install things like OpenCPN actually need to do. Are there a lot of people doing this? Might be they ask the local vendor but nothing else.

So first do this better for OpenCPN before talking about connecting a second GPS. The average sailor is not a computer specialist.

I do not think OpenCPN is designed to be used inside car nav systems.


In any case, it had zero problem finding and using the gps on my tablet.


And I have never ever had a single class of IT.



Which leads me to the conclusion that car owners have become somewhat removed from the mean of human IQ. Like three sigmas or something.



barnakiel

[bdbcat]

barnakiel...


What is your concern about seconday gps tracking?


Dave