OpenCPN SIMRAD/LOWRANCE Radar Overlay PlugIn

[merrimac]

Originally Posted by BMD21

The Lowrance display I bought is specifically for North America and loses functionality outside of that area. I also understand they sell a Europe only model. I'm not sure what that impacts, since I'm staying in North America, but I'd check your needs vs what they're selling.

The Europe model is different from ROW (Rest Of World) only in which charts are supplied with the MFD, I believe. Note that this has also changed a few times. I -think- that the current state in Europe is that Lowrance models and touch versions from Simrad/B&G come with a Navionics Updates chart, which you can activate online with any chart region. NSE Simrad/B&G models used to come with Navionics Silver for all of europe on a hard drive, but they may have changed to this single-region-but-more-detail as well.

Originally Posted by BMD21

Another comment is that the latest Lowrance update (3.0) provides auto-routes, whatever that means. This doesn't work in North America. No explanation.

Laywers & liability issues seems the most obvious reason.

Even the EUR + ROW models won't auto-route within US waters.

You're not missing much, it doesn't work very well yet. I tried several routes and the only thing it really helps with is things that I could route myself very well, thank you.

What I personally would like is when I put in a route myself is that it would check for dangers, in particular overhead clearance. To see overhead cables you must zoom in way too far.

[muttnik]

Originally Posted by merrimac

There is exactly -one- disadvantage to multicast, and that is that "stupid/cheap" routers fall back to 1 Mbit/s when sending out multicast over WLAN

I am certainly no 802.11 expert and have a deep distrust of transmission paths which apparently use "magick" as their layer 1 but I did some reading around this yesterday and I am not left with the impression that high-rate multicast over wireless is generally now "fixed" for heterogeneous networks. 802.11aa seems to address it but doesn't seem to be widely implemented. Am I missing something or are you simply saying that clever/expensive routers should have the ability to specify the PHY used for multicast (which would be handy but I'm not aware that that is standard)? Happy to be educated here....

On a practical note, given that the receiving socket in the plugin binds to INADDR_ANY it should be possible to fire unicast UDP at the machine running OpenCPN assuming you know its address: the receiver won't care if the packet is multicast, broadcast or unicast as long as it's to the right port. Control messages from the plugin to the scanner shouldn't be a problem rate-wise. Probably a number of ways to go from multicast to unicast on the wired network (socat? packet mangling on the router?) and keeping the multicast off the wireless network (packet filtering? using the opencpn machine's firewall to block outbound igmp if the router supports igmp snooping?) but not really a trivial fix.

[RobbieW]

Originally Posted by merrimac

.....My opinion: do some research on which router (software) works well, and then publish that here. OpenCPN development has taken thousands of manhours, all contributed for free. See this as an opportunity to do something in return.

Based on research done so far; an ASUS RTN16 running Tomato (Version Shibby 1.28.0000 MIPSR2-117 K26 USB VPN) with some configuration changes to IGMP/Multicast will allow the multicast from the scanner through to OpenCPN over wireless. The router is configured to run 11N only for wireless connections, to give it a fighting chance of handling the data volume. It also has 4x100Mb ethernet ports.

Changes effected were:
Advanced>Firewall>Multicast - Enable "IGMProxy" & "LAN"
Advanced>Routing>Miscellaneous - Enable "Efficient Multicast Forwarding"
Advanced>Wireless - Set "Multicast Rate" to 54Mbps (the max allowed)
Advanced>Wireless - Set "Wireless Multicast Forwarding" to Enable

As I can see from the router throughput charts, the radar data load usually sits around 50-52Mbps but can increase to 70 or so. I expect that some packets are being dropped but have no way of proving that. Other wireless traffic continues, mostly internet connections for other devices, but is slowed by the multicast traffic (of course this could also be parts of the network external to mine as I'm connecting through the ASUS router via a WiFi extender into a local business as I tested and wrote this). The observed CPU load at the ASUS router has not exceeded 20% whilst carrying out these tests so it would appear to be well capable.

The NSS/Radar is connected to the ASUS router by putting a hub between the radome and the RI10 interface box, this tees the radome output into the RI10 and ASUS router. The NSS MFD picks up an address from the ASUS in the same way as any of my other devices do. By creating a connection in OCPN for the address of the NSS with a port of 10110 a plethora of NMEA data is being sent, including GPS messages, which OCPN picks up.

The NMEA data is useful because it provides a backup for the instances of kPlex that also run on the router. The kPlex instances take inputs from Serial/USB connections from the older instrumentation on the boat giving both GPS and AIS messages into an OCPN connection. kPlex also has an outbound instance that takes autopilot data from a separate OCPN connection back to one of the Serial/USB connections, overcoming the limitation OCPN had until recently with input and output through the same connection ( I havent been able to test muttnik's changes for this yet).

Since the ASUS is my main existing router, my research has focussed on whether that (and its firmware) are capable of running the functions I desire. It acts as the hub for onboard comms so handles external internet as well as intranet function, does some processing to packetise NMEA data into IP and handles VPN centrally for all connected devices when needed.

One limitation I'm aware of is that it uses a Broadcom SOC, the drivers for the wireless parts of the Broadcom chip are proprietary hence the 2.6 kernel used by Tomato. In turn this means that IGMP snooping is not part of the kernel and I risk swamping wireless devices because the multicast implementation on Linux based routers has limitations. This may be resolved if I change to the current development OpenWRT branch (around 3.10 I believe), which I've been looking at. That would upgrade the Linux kernel and may fix some other problems I've seen but at the risk of it bricking the router on installation - not something I want to do whilst cruising. So thats a project that is under consideration for risk!

There may well be a better router, but as I've found, the criteria governing that choice is going to be rather individual. My choices suit my usage so far, but I'm open to change. So far as researching multicast use goes, most references I've found are from people trying to use IPTV which is sort of relevant to this but not complete. As muttnik points out, this seems to be a grey area for standards.

I cant so far find reference to any router firmware with a > 54Mbps setting for multicast over wireless, they must be there given the number of ISPs with IPTV offerings. If I find one it will also need to have USB ports, ethernet, wireless, WAN, VPN; the processing power to run all that and the ability to recompile kPlex for it - oh and run off 12V!

[merrimac]

Originally Posted by muttnik

Am I missing something or are you simply saying that clever/expensive routers should have the ability to specify the PHY used for multicast (which would be handy but I'm not aware that that is standard)?

Correct. For instance: Advanced Wireless Settings - TomatoUSB

Originally Posted by muttnik

On a practical note, given that the receiving socket in the plugin binds to INADDR_ANY it should be possible to fire unicast UDP at the machine running OpenCPN assuming you know its address: the receiver won't care if the packet is multicast, broadcast or unicast as long as it's to the right port. Control messages from the plugin to the scanner shouldn't be a problem rate-wise. Probably a number of ways to go from multicast to unicast on the wired network (socat? packet mangling on the router?) and keeping the multicast off the wireless network (packet filtering? using the opencpn machine's firewall to block outbound igmp if the router supports igmp snooping?) but not really a trivial fix.

Good luck.

[Douwe Fokkema]

I just received my Lowrance 4G radar. I put it on the breakfast table, plugged the ethernet cable into the hub on which my Win7 laptop is connected and added 12 V on the cable. On the laptop there is OpenCPN 1824 with BR24Radar 0.40529. After enabling the plugin with the tools menu the radar icon appears in the bar. Clicking on the radar icon switches the radar on. It works straight away! Of course there is no GPS, no HDT at home. Right mouse button gives radar control buttons. Of course lots of strange echos inside the room. Some questions however:

- in the button bar, after enabling the radar plugin there are 2 radar buttons in the bar. One of these disappears when disabling the radar in the tools-plugin menu. The other one appears again after enabling and is functional.

- is there a command to use the target separation feature of the 4G?

- After setting a circular guard zone, the radar menu still shows Guard zone off. Some further adjustment required?

On a second computer however I can't get the plugin to work. When I enable the plugin (tools-plugins) the "preferences" button remains dimmed. One icon appears in the bar but is not functional.

Next step is to install on board, but haven't got the mast support yet. looks good! Thanks a lot for all the work so far.

Douwe Fokkema

[Douwe Fokkema]

Hi again,

Played around with the alarm. It works and sounds an alarm for zone type arc. However in the radar menu the Guard Zone 1 (or 2) button still shows off. Can the sound be changed? Which file is used for the sound?

regards, Douwe

[BMD21]

The only comment I can make is regarding your problems with the second computer. Helmsmatt, on the companion thread, describes how to conquer the Windows firewall. I used his advice and everything started to work.

And I installed Wireshark to see what was on the network. That gave me some insight. I have read that the 4G has a different ethernet protocol that the 3G.

Good luck and maybe someone who really knows will chime in. Leaving for Canada next week. We can only pray that everything will work.

Boris

[Douwe Fokkema]

Regarding this second computer (Win-7): I don't think it has anything to do with the Windows firewall. Firstly it is off and secondly the "preferences" button in the options-plugins-BR24radar should be active even with no radar connected.

This morning I was testing on a 10 year old Win-XP laptop. Basicly works fine (still without heading input). I still got 2 radar buttons in the menu bar, but one of them disappeared non-reproducible. Alarms work fine here! The low performance of this system in not a problem.

Installation on-board is planned for next week.

Good winds!
Douwe Fokkema

[Douwe Fokkema]

Re question on the sound of the Guard Zone alarm: found the answer, the alarm sound is in Windows\Media\Windows XP Ding.wav , at least on Win-XP So it is easy to change the alarm sound.

[Douwe Fokkema]

On the second Win-7 computer where the radar plug in does not work there is the following lines in the opencpn.log

3:24:50 PM: PlugInManager: Initializing PlugIn: C:\Program Files (x86)\OpenCPN 3.3.1731\plugins\br24radar_pi.dll
3:24:50 PM: Error: BR24radar_pi: Unable to create UDP sending socket

[Hakan]

Originally Posted by Douwe Fokkema

On the second Win-7 computer where the radar plug in does not work there is the following lines in the opencpn.log

3:24:50 PM: PlugInManager: Initializing PlugIn: C:\Program Files (x86)\OpenCPN 3.3.1731\plugins\br24radar_pi.dll
3:24:50 PM: Error: BR24radar_pi: Unable to create UDP sending socket

Douwe.....
-Win7 not connected: Are you sure both internal and external firewalls are disabled? For Win 7 the radar UDP connection is external.
-The double icons: Yes that's a Windows bug to be corrected. My work around is to: 1; Have the radar powered and establish its network. (Win7 says "unknown network", that's ok.) 2; Then start OCPN. (Check if the radar plugin is activated. If not, activate it and restart OCPN.)
-I'm using the "old" BR24 and don't have any 4G experience.
Håkan

[Douwe Fokkema]

For some reason Alarm Zones work fine now also on the Win-7 laptop (where I earlier reported a problem with the circle).

According to the Windows taskmanager network LAN utilization is on 3% of 100 Mbps, so much lower than I find in other posts.

[RobbieW]

Originally Posted by Douwe Fokkema

...According to the Windows taskmanager network LAN utilization is on 3% of 100 Mbps, so much lower than I find in other posts.

Mea culpa, had another look and I clearly cant do mental arithmetic or read properly! My router gives data in kbits/sec, it was recording a peak of 1500 kbits/sec with a 3G radar on 1/2 mile range just now. If I have the math right this time, thats about 190 Kb/sec. I'm pretty sure I've seen peaks of 6000 kbits/sec previously but even that comes in under 1 Mb/sec.

Thanks for the double check

[Douwe Fokkema]

I was wandering how to apply the radar setup, as I did not find any menu for that. My boat is PC-only, I do not use a dedicated card plotter.
According to the manual several items have to be adjusted when commissioning the radar.

- Bearing alignment. I seems this can be done be adapting the value of HeadingCorrection in the opencpn.ini [PlugIns/BR24Radar] section. Changing this value rotates the radar image.

- Adjust antenna height. I suspect this is a value in the radar control register. As this is a one time setting it may not be worth putting it in the plug-in. If I knew the register values this could be written to the radar with a small standalone program (I could do this in Java).

- The other settings: "Adjust local interference rejection" and "Sidelobe suppression" seem less important to me.

As "target separation" is one of the main features of the 4G, it would be nice to have this feature available in the command structure. If the command codes for "target separation" are known, I could try them out with a stand alone program. I looked at the plug in sources, but my C++ knowledge is insufficient to work on these.

[Douwe Fokkema]

Correction: heading alignment can be done from the preferences window after enabling the pi (options-plugins).