Naming Different Connections for Tracking other Vessels (Buddy)

[sea_rescue]

Hi,
I am having a play with it, but it is telling me line 16, in <module>
import bitstring
Import error: No module named Bitstring

Sorry for this hassle....

Python 2.7.7 on Windows 7

[nohal]

sea_rescue...
Install pip, the python package managing tool (https://pip.pypa.io/en/latest/installing.html)
and then do

python -m pip install bitstring

Pavel

[sea_rescue]

Ahhhh got it working..... thanks

Will play with it for a while and see where I get....

Thanks all

[PjotrC]

sea_rescue...

Glad you are progressing. Some remarks:

I think there was a dependence on Python 3.3 somewhere. Not sure.

This little Python tool is OK if you have just a couple of vessels to track. But the manual configuration and management is not really suitable for a live, mission-critical operation.

Back in 2010, at your request, I have implemented into OCPN the code to handle Franssen GPSGate protocol. However, to my knowledge, it has never been tested with real data, since I never had access to a live stream. I implemented only what I found in the documentation, and no one came forward to test...

I am sure this is a better way to go, but I have no idea how to obtain the live $FRPOS sentences...

Probably looking at the GPSGate Server will eventually lead to a better solution.

[PjotrC]

Just refreshing my memory on GPSGate...

When I looked at it some years ago, it was a very interesting and promising concept. Maybe cheap AIS did overtake it a bit on the water, but it has been well worth some attention. However, I do not know the current status of Franson software and services offering.

Briefly, it works as follows:

Many targets can report their position via multiple channels to some organization, hosting a GPSGate Server. It can be over Internet apps and - most notably - from a mobile phone over SMS service.

The server keeps a database of position reports.

The database can be interrogated by a client in two basic ways.

One type of request addresses a specific target. The response then takes form of a single RMS sentence, without identification, because this is already well known from the query context.

Another type of request addresses a "Buddy Group" - a predefined set of targets. The response then takes form of a series of FRPOS statements, similar to RMS, but extended with target identification and other details, not present in NMEA RMS.

So, depending on whether one makes an individual or a group query, the stream of responses contains just RMS or just FRPOS sentences.

GPSGate Server and Client is not free, so I was not in a position to comfortably set up a test site. I just implemented the obvious: handling of FRPOS sentences, piggybacking on the existing AIS subsystem. I left out the login/authentication and active interrogation part until having a real test bed and gaining some experience. (That was in 2010...)

GPSGate targets differ from AIS targets, mainly because they do not age so easily. The position reports may come irregularly, and not so often - even once per day or so ... Some of the reports, I am not sure which, indicate only positions that had changed since the last interrogation. So directly translating FRPOS into AIVDM is not always right.

Tracking GPSGate Buddies has been fully implemented in some chartplotters. One example is SOBvMAX from Digiboat.

I do not think now that there is a need to put more effort into this. However, there would be 3 ways to move forward:

1. Implement full GPSGate Client into OCPN or a Plugin.

2. Write a small connector program to perform the login and interrogation, passing back the FRPOS responses to OCPN.

3. Find a way to use existing GPSGate software to perform these tasks.

If I were an actual user, I would start from investigating choice #3.
Choice #2. is still a possibility.
I feel it is still too early for choice #1.

Notably, many users use GPSGate Client software just as a connectivity tool, not using the Server protocol at all, just routing NMEA between various transports ...