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Old 05-04-2017, 15:01   #16
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Re: furuno FA-30 ais messages not being picked up by openCPN

Hi
it's a known issue, there's ascii null in Furuno data header (you can see them in your first screenshot, in the data hexa dump).

it currently doesn't work with opencpn.
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Old 05-04-2017, 15:22   #17
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Re: furuno FA-30 ais messages not being picked up by openCPN

Quote:
Originally Posted by did-g View Post
it's a known issue, there's ascii null in Furuno data header (you can see them in your first screenshot, in the data hexa dump).
Doh! How did I manage to miss post #9...
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Old 05-04-2017, 22:35   #18
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Re: furuno FA-30 ais messages not being picked up by openCPN

Yeah its a typo in my last posts. Sorry for that... 31.24 as memtiomed in initial message is the ipaddress everything is configured to.
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Old 05-04-2017, 23:47   #19
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Re: furuno FA-30 ais messages not being picked up by openCPN

@bcn as mentioned in the previous post 3 screenshots are published here
you should need to login to their site to see the images..

wireshark furuno - Album on Imgur

for some reason attching the files to the post didn't work.
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Old 06-04-2017, 03:58   #20
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Re: furuno FA-30 ais messages not being picked up by openCPN

@ bobby: can you PLS repost a complete one line of the relevant data line that contains the sentence?

@did-g: can you PLS post the part where the ascii null is and bold it out?

Thanks in advance.

I am considering if kplex could filter out or substitute the ascii null and solve the problem. But to test this I would need a file that contains a couple of such invalid ais sentences.

Cheers,
b.
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Old 06-04-2017, 07:04   #21
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Re: furuno FA-30 ais messages not being picked up by openCPN

So, interesting points from the wireshark screenshots:
1. You've got the wrong port. The AIS stuff is coming through on 10021, not 10033.
2. There's 3 examples posted. All 3 have a VDM sentence with a bunch of non-NMEA stuff in front of them including \000s. But the 3rd of these has a VDO sentence immediately following on from the \r\n for the preceding VDM which should show up I would have thought.

To answer Barnakiel's question yes kplex would filter the noise from the sentences, but the OP is using Windows so this would require a handy raspberry pi or similar on the network. I'm not very up on Windows but could something like NavmonPC be part of a workaround if this leading-NULL problem is indeed A Thing while it's being fixed in OpenCPN?
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Old 06-04-2017, 07:38   #22
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Re: furuno FA-30 ais messages not being picked up by openCPN

Thanks. Ill install navmonpc this evening and see what happens. Talker is at 2 do my pc cant have the same ipaddress so i set it to 1. The submask is important for that if i understood othet threads amd udp correctlyt. Submask is 255.255.0.0. Which means all ip addresses 172.31.*.* listening on 100021 should receive messages. I think.
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Old 06-04-2017, 07:41   #23
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Re: furuno FA-30 ais messages not being picked up by openCPN

Ive configured and tested opencpn on both 10021 and 10033 ports. It seems that mrssages containing aivdo showup in wireshark as being broadcast on port 10021 whilst packets of only aivdm messages arr picked up on port 10033 by witrshark.
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Old 06-04-2017, 07:43   #24
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Re: furuno FA-30 ais messages not being picked up by openCPN

Quote:
Originally Posted by barnakiel View Post
@ bobby: can you PLS repost a complete one line of the relevant data line that contains the sentence?

@did-g: can you PLS post the part where the ascii null is and bold it out?

Thanks in advance.

I am considering if kplex could filter out or substitute the ascii null and solve the problem. But to test this I would need a file that contains a couple of such invalid ais sentences.

Cheers,
b.
Yup will do when i get home. An rxample is visible in the third screemshot in my imgur link from previous reply.
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Old 06-04-2017, 09:00   #25
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Re: furuno FA-30 ais messages not being picked up by openCPN

Quote:
Originally Posted by muttnik View Post


To answer Barnakiel's question yes kplex would filter the noise from the sentences, but the OP is using Windows so this would require a handy raspberry pi or similar on the network.
So the problem is virtually solved:

- take an adsl router from the skip,
- upgrade its firmware to OpenWRT,
- add kplex,
- use kplex to filter the 'null thing' out,

The router can be powered from the Windows machine USB port. It can then also feed the data into the Windows USB port (if you use a router with USB port) or thru the wifi or the ethernet socket (if you use any other router).

Do / Can't Do?

BTW I believe a smart tinkerer could actually fire up the kplex in a virtualbox on the Windows machine and then simply configure the ports accordingly.

barnakiel
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Old 06-04-2017, 09:44   #26
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Re: furuno FA-30 ais messages not being picked up by openCPN

Tje examples posted are all the one packet. I just cpuldnt open all the information in wireshark window and have it fit on the one screenshot. So i took 3 to display all the information that witesgark hason that one packet.
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Old 06-04-2017, 10:39   #27
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Re: furuno FA-30 ais messages not being picked up by openCPN

Hi dig-d,

i
"it's a known issue, there's ascii null in Furuno data header (you can see them in your first screenshot, in the data hexa dump).

it currently doesn't work with opencpn."

Which part of the hexidecimal packet is ascii null?

This is the full hexidecimal of the message in the example

ff ff ff ff ff ff 00 d0 1d 04 e8 85 08 00 45 00 00 85 53 eb 00 00 20 11 d6 3c ac 1f 18 02 ac 1f ff ff 27 25 27 25 00 71 19 49 01 12 00 01 00 00 00 00 21 41 49 56 44 4d 2c 31 2c 31 2c 2c 42 2c 31 33 60 65 3f 35 50 50 31 3a 50 46 77 35 54 4d 73 3f 4b 57 30 67 77 32 52 36 49 38 2c 30 2a 33 39 0d 0a 21 41 49 56 44 4f 2c 31 2c 31 2c 2c 2c 31 3e 71 63 36 36 3f 50 3f 77 3c 74 53 46 30 6c 34 51 40 3e 34 3f 77 70 30 50 30 30 2c 30 2a 32 39 0d 0a

what are the ascii nulls?

I've just written java method to translate hex to ascii, need to know what I need to strip out of the packet.
Appreciate your help!

thanks
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Old 06-04-2017, 10:41   #28
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Re: furuno FA-30 ais messages not being picked up by openCPN

Quote:
Originally Posted by barnakiel View Post
So the problem is virtually solved:

- take an adsl router from the skip,
- upgrade its firmware to OpenWRT,
- add kplex,
- use kplex to filter the 'null thing' out,

The router can be powered from the Windows machine USB port. It can then also feed the data into the Windows USB port (if you use a router with USB port) or thru the wifi or the ethernet socket (if you use any other router).

Do / Can't Do?

BTW I believe a smart tinkerer could actually fire up the kplex in a virtualbox on the Windows machine and then simply configure the ports accordingly.

barnakiel
what's Kplex exactly?
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Old 06-04-2017, 10:57   #29
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Re: furuno FA-30 ais messages not being picked up by openCPN

Quote:
Originally Posted by bobbylockes View Post
Hi dig-d,

i
"it's a known issue, there's ascii null in Furuno data header (you can see them in your first screenshot, in the data hexa dump).

it currently doesn't work with opencpn."

Which part of the hexidecimal packet is ascii null?

This is the full hexidecimal of the message in the example

ff ff ff ff ff ff 00 d0 1d 04 e8 85 08 00 45 00 00 85 53 eb 00 00 20 11 d6 3c ac 1f 18 02 ac 1f ff ff 27 25 27 25 00 71 19 49 01 12 00 01 00 00 00 00 21 41 49 56 44 4d 2c 31 2c 31 2c 2c 42 2c 31 33 60 65 3f 35 50 50 31 3a 50 46 77 35 54 4d 73 3f 4b 57 30 67 77 32 52 36 49 38 2c 30 2a 33 39 0d 0a 21 41 49 56 44 4f 2c 31 2c 31 2c 2c 2c 31 3e 71 63 36 36 3f 50 3f 77 3c 74 53 46 30 6c 34 51 40 3e 34 3f 77 70 30 50 30 30 2c 30 2a 32 39 0d 0a

what are the ascii nulls?

I've just written java method to translate hex to ascii, need to know what I need to strip out of the packet.
Appreciate your help!

thanks
Every 00 in your payload. look at the data in wireshark second pane or highlight it in the third one.
In most C like string functions 0 is end of string, here there's 0 before the AIS data and nothing is forwarded.
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Old 06-04-2017, 11:11   #30
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Re: furuno FA-30 ais messages not being picked up by openCPN

Quote:
Originally Posted by did-g View Post
Every 00 in your payload. look at the data in wireshark second pane or highlight it in the third one.
In most C like string functions 0 is end of string, here there's 0 before the AIS data and nothing is forwarded.
I've written short java program that filters the packet and only prints out ASCII AFTER the last 00.

But now I just need to get my receiver to pick up the packets from from so I can send the packet through my filter and then forward on to opencpn.

By my receiver code (see previous post) didn't pick up anything. Assume its something to do with the 00's or not? if so any idea why a simple udp receiver does not pick up udp containing 00 (byte nulls) but wireshark does?

many thanks!
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