Radar plugin v5.0.0 released

[Hakan]

Sorry, "inside" wording. But the result is that OCPN/Radar plugin is occupying the (Windows) system memory until W can no longer run. (A "borrowed" memory would normally be payed back when used. Here it's just kept forever and that's a serious bug)

[Baikal]

checked for more than two hours on the recorded nmea log
no departures due to AIS
build latest alfa from master

[bdbcat]

Baikal...
Memory leak bug on radar_pi has been corrected in current github master branch of opencpn.
Thanks for testing.


Dave

[Carryonsailing]

Just a quick note to say thank you for all your efforts in relation to this. The world is certainly a better place for it. I for one am learning so much more. Perhaps some day I will be able to assimilate your skill and knowledge.
I my videos on the youtube channel I will be covering a lot about your work and conveying my debt of gratitude. Kind regards James

[volksbar]

What difference/benefit between halo 20 and halo 20+?

sorry if this question has been raised before - yet I could not find an answer using the forum search function.

Having a functioning old radar, we want now to add a radar that works with open cpn. Why? To include the radar function that warns if other vessels approach.

As I understand the halo 20 and halo 20+ are recommended often.
allong following info:

halo 20 being slightly cheaper, spinning with less RPM (does less RPM mean longer durability?)

halo 20+ spinning with faster RPM and allowing to get additional info via doppler effect

Not born as a radar expert, it is difficult to judge which of the two works best and most reliable with opencpn. And whether the additional 20+ attributes can be integrated into openCPN.

If anybody could provide some further recommendation, which radar to choose for such use case scenario, and which brand of the halo to choose - would be highly appreciated

thanks in advance

Volk

[Hakan]

Volk..
If I understand it correct the Halo 20 is comparable with the previous 4G and the doppler function is not available.
The Halo 20+ though has the doppler function. Ref: this issue

For any radar type supported by the Radar plugin you can always set up a watch zone and get an alarm if any target is detected inside the watched area. For the same or a second area you can also use the automatic ARPA function and take advantage of OCPN's AIS CPA functions for such a radar target.

You may want to read the manual for more general info.

[volksbar]

Thanks a lot, Harkan! That was clarifying and very helpful.

Somewhere I read that the largest adventage of 20+ against 20 would be to be able to detect approaching weather fronts, thanks to the Doppler . But only read this once.

Of course this sounds nice of being able to identify a fast approaching front from 20 mile distance.
Is this a true feature of halo20+ in connection with open cpn or rather a wishful thinking and myth?

And is there any difference between the different branded halos, like Lowrence, etc? Or are they all Navicos under the hood?


Volk

[Hakan]

Volk..
Navico is the maker, correct. Simrad, Lowrence or B&G is the brand/label on the hood.

I don't have a Halo (but a 3G) so I can't say how the doppler function can be used. If the Halo will detect a weather front as a moving target and thus send doppler info to the radar plugin I don't know. Others may have more experience to share.


I can't though resist mention a basic comment. All electronics are aid to navigation. Don't trust them to the "bitter end". The reality and skipper's mind are always the first hand.

[volksbar]

Again, much appreciated, Hakan! Including your advice.
Thanks again!

Nevertheless, there is a video trying to show the weather mode (and bird mode, to detect diving sea birds as indicator for abundance of fish)

https://www.youtube.com/watch?v=BUPpP9dhPmI

yet such functions might be something else and only indirectly readable by open cpn, while connected to the simrad software. just guessing

[Hakan]

The radar plugin can control and use all functions of the connected radar. No MFD needed.
Well... Except update firmware. For that you need a MFD.

[fabrice]

Hi,
I am new to your forum and plan to buy a HALO20+ antenne with a B&G Vulcan MFD.
Your plug-in seems great. Well done!

I read carefully your Wiki specially the operation page.
I have a question regarding the MARPA/ARPA feature.

I did not find any mention ARPA vectors display modes that are common to commercial grade radars and very usefull to graphically appraise colission risks in restricted visibility:
Relative, True Sea Stabilised or (less used)True Ground Stabilised.
Has the user the option to change vector display modes?

[Hakan]

fabrice..
The radar plugin does produce the (M)ARPA function with any connected radar scanner.
It's mentioned in the manual. If you like I illustrated it here.

[fabrice]

Hi Hakan,
Thanks for your response.
I did understand that you have implemented the (M)ARPA feature for any connect radar.
My question is more about the way course and speed of a targets may be displayed.
Let me try to explain more in details:

AIS usually displays a vector wich shows the course and speed over ground of each target.
On a SOLAS Radar this is called True Ground Stabilised Vector display.

Theses radars offers 2 more display types of the same ARPA data:
1) Relative Vectors which shows course and speed of targets relative to our boat (very usefull to see targets presenting a risk of collision because their relative vector will then point to our boat, in this case CPA is graphically obvious to evaluate)

2) True sea stabilised vectors which show course and speed relative to the sea eg what we usually true bearing and boat speed over the sea (this shows the aspects if the targets. That is very usefull to apply COLREGS rules)

Finally the length of the vectors displayed can also be adjusted in term of minutes of navigation.

Vector display mode and vector length are usually global setting of the Arpa subsystem of the radar.

I would like to know if this display customisation capabilities are already implemented the Arpa feature of your Plug-in.

If this feature is not yet availlable or in developpement, I am interested in contributing to specify the feature in detail and to implement it because it would substantially increase the value of the ARPA feature by easing graphical interpretation for collision avoidance when sea mens are under high work load.
Best Regards
Fabrice

[Douwe Fokkema]

The radar_pi is using GPS positions for the ARPA. That means that all target positions and speeds are are relative to ground. The ARPA targets are passed to OpenCPN with TTM messages. OpenCPN handles the ARPA targets just like AIS targets, all based on GPS positions and speed and heading relative to ground. In this way OpenCPN performs the CPA calculations and provides corresponding vector diagrams. Normally OpenCPN is not aware of any currents, though currents (and speed and direction though water) could be calculated if speed through water is known.

Before your question I have not seen any request for this, so I do not think that your requirements will get a high priority.

[fabrice]

Hi Douwe,
Thanks for your detailled response. First of all sorry for my late reply. I did not receive any notification for your message.

I think I understand your point about the data your plug in provides to OpenCpn to display the ARPA targets but this sounds weird to me because of the nature of Automatic Radar Plotting Aid feature.

Firstly this feature is used in merchant marine as the primary the tool to aid mariners to avoid collisions in restricted visibility conditions as oppposed to AIS which does rely on GPS.
The beauty of the radar is that plotting (that not long ago was done manually on radar screen) is not dependent on GPS.
Motion vector of a target (relative to my ship) is directly the motion of a target on the screen between measured between delta time. Then CPA is minimum the distance between the line formed by this relative motion vector and my ship. This bring to seamen an obvious graphical view the dangerous targets.
This is very well illustrated by the video found on your plug-in manual pages teaching radar plotting: https://youtu.be/plunSlYEbUc?si=zJRj890QxzHPu_IF
I found a big disadvantage in term of reliability to depend on GPS for collision avoidance with the radar.


Secondly I read in your manual :
The plugin has class leading ARPA and MARPA support, supporting 50 ARPA and MARPA targets independent of used scanner type.

RATTM message can natively provide relative course and speed of targets:
see attached screen copy

Most of professional seamen advice not to display AIS and ARPA on the same screen because with high traffic this is confusing.

To provide AIS and Radar independancy and enable users to use an instance of Opencpn as an independent, fully fonctional radar display I believe that it would be very useful to able to display ARPA relative vectors (bearing and course of tracked targets) on the radar screen.

That would be a matter of extending the AIS target display to be able to select
1/ display of AIS targets and/ or ARPA targets
2/ relative or true target motion vectors

Best Regards
Fabrice