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Old 01-11-2016, 04:24   #16
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Re: OpenCPN not seeing dAISy output

I assume you are following Adrians instructioms? I I always determune which com prt. the driver has selected and I always use the same usb port and have it labeled (it matters), What OS?
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Old 01-11-2016, 08:03   #17
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Re: OpenCPN not seeing dAISy output

You might try

fuser /dev/ttyACM*

to identify the processes owning the port(s) in this moment.
Will give you the PIDs and with TOP you should know the process name.

Hubert
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Old 01-11-2016, 08:20   #18
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Re: OpenCPN not seeing dAISy output

This morning I wasn't able to get any AIS targets when I connected to my VHF radio antenna. Without the proper connectors the connection is pretty poor, but I got targets yesterday. I still get more 1/4 second green flashes with the VHF antenna than with the 3' whip, but I get a lot of red flashes, too. No matter what I do I don't see any messages in the NMEA debug window in OpenCPN.

Running

Code:
screen /dev/ttyACM0 38400
I see the occasional AIS message and, of course, I can produce test messages, but other than demonstrating the dAISy is capable of generating test messages I don't see what that does for me. I still can't see any NMEA messages from the dAISy in OpenCPN.

When I toggled on debug messages I got a lot of failed AIS messages, either CRC errors, wrong stuff bits, or invalid message types. RSSI noise levels were running around 100db. All that seems consistent with an inadequate antenna.

Based on my experience yesterday I think the dAISy is working fine but needs a better antenna. I'll try it again when my antenna and adapters arrive next week.

If I can reliably see AIS targets with the new antenna I'll be satisfied, but I'm still curious about the missing AIS messages in the NMEA debug window. Does anyone running AIS with OpenCPN see those messages?

Fabbian
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Old 01-11-2016, 09:41   #19
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Re: OpenCPN not seeing dAISy output

Is the 'control checksum' enabled or disabled in the connections window ?


Quote:
Originally Posted by fgd3 View Post
This morning I wasn't able to get any AIS targets when I connected to my VHF radio antenna. Without the proper connectors the connection is pretty poor, but I got targets yesterday. I still get more 1/4 second green flashes with the VHF antenna than with the 3' whip, but I get a lot of red flashes, too. No matter what I do I don't see any messages in the NMEA debug window in OpenCPN.

Running

Code:
screen /dev/ttyACM0 38400
I see the occasional AIS message and, of course, I can produce test messages, but other than demonstrating the dAISy is capable of generating test messages I don't see what that does for me. I still can't see any NMEA messages from the dAISy in OpenCPN.

When I toggled on debug messages I got a lot of failed AIS messages, either CRC errors, wrong stuff bits, or invalid message types. RSSI noise levels were running around 100db. All that seems consistent with an inadequate antenna.

Based on my experience yesterday I think the dAISy is working fine but needs a better antenna. I'll try it again when my antenna and adapters arrive next week.

If I can reliably see AIS targets with the new antenna I'll be satisfied, but I'm still curious about the missing AIS messages in the NMEA debug window. Does anyone running AIS with OpenCPN see those messages?

Fabbian
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Old 01-11-2016, 21:02   #20
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Re: OpenCPN not seeing dAISy output

Quote:
Originally Posted by petter5 View Post
Is the 'control checksum' enabled or disabled in the connections window ?
Yes, both "Control checksum" and "Receive input from this port" are checked.

Fabbian
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Old 02-11-2016, 01:23   #21
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Re: OpenCPN not seeing dAISy output

Just try with checksum unchecked to see if you see any change in behaviour.

If you see any AIS messages in the nmea debug window then, your problem is mostly the antenna.

Quote:
Originally Posted by fgd3 View Post
Yes, both "Control checksum" and "Receive input from this port" are checked.

Fabbian
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Old 07-11-2016, 03:30   #22
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Re: OpenCPN not seeing dAISy output

My antenna and adapter arrived. I connected it to the dAISy and I had AIS targets and NMEA messages from /dev/ttyACM0 in the debug window. The notion that you can get AIS messages with a simple wire is going to lead you to frustration. VHF signals are not real powerful, there's a lot of noise out there, and the dAISy isn't a super sensitive receiver. You need a good antenna. Mine cost $28.63 (with free shipping) on eBay.

I installed it below deck on an internal bulkhead. I saw targets 8 miles away. If more range is important it can easily be achieved by mounting the antenna higher.

Fabbian
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Old 07-11-2016, 04:46   #23
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Re: OpenCPN not seeing dAISy output

AIS Aerial Performance Comparisons

Interesting page comparing different recieve antennas from a land based site.
Also, instructions for a diy antenna..

High Gain Collinear AIS (162MHz) Receiving Aerial
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Old 07-11-2016, 12:18   #24
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Angry Re: OpenCPN not seeing dAISy output

AIS is very sensitive to loss in coax cable due to coax length and quality. Always use RG214 or better coax, and always keep the coax length as short as possible.

Using RG58 cable with a length of more than a few meters is a safe way to get bad AIS reception,,,,,,

For more info:https://digitalyacht.net/2014/10/03/...ais-reception/


Quote:
Originally Posted by fgd3 View Post
My antenna and adapter arrived. I connected it to the dAISy and I had AIS targets and NMEA messages from /dev/ttyACM0 in the debug window. The notion that you can get AIS messages with a simple wire is going to lead you to frustration. VHF signals are not real powerful, there's a lot of noise out there, and the dAISy isn't a super sensitive receiver. You need a good antenna. Mine cost $28.63 (with free shipping) on eBay.

I installed it below deck on an internal bulkhead. I saw targets 8 miles away. If more range is important it can easily be achieved by mounting the antenna higher.

Fabbian
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Old 07-11-2016, 13:03   #25
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Re: OpenCPN not seeing dAISy output

Quote:
Originally Posted by petter5 View Post
AIS is very sensitive to loss in coax cable due to coax length and quality. Always use RG214 or better coax, and always keep the coax length as short as possible.

Using RG58 cable with a length of more than a few meters is a safe way to get bad AIS reception,,,,,,

For more info:https://digitalyacht.net/2014/10/03/...ais-reception/
I cannot confirm that. Okay, you should not have rotted cables and connectors but RG58 is good and I receive AIS signals from about 100 miles with RG58 cables. For sure the signals from more than 100 miles (up to 500 miles) are from the basis mirror "Montagna Grande" 83 miles away from here at Pantelleria. But usually the radius of 100 miles is OK for me.
You should not believe everything what is written on the internet. There are too much people proud of writing something even when it is ********.

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Old 07-11-2016, 13:36   #26
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Re: OpenCPN not seeing dAISy output

Loss in rg58 coax is very well known, and the reason for better quality and more expensive coax being manufactured.

With your long range AIS targets in mind, I assume that you have an high placed antenna with a good quality AIS receiver and a short rg58 cable. Yes, a rg58 will work even with some meters length, but a better quality cable will always give better performance when the length of the coax is increasing. Better coax = less signal loss in the coax.

Quote:
Originally Posted by CarCode View Post
I cannot confirm that. Okay, you should not have rotted cables and connectors but RG58 is good and I receive AIS signals from about 100 miles with RG58 cables. For sure the signals from more than 100 miles (up to 500 miles) are from the basis mirror "Montagna Grande" 83 miles away from here at Pantelleria. But usually the radius of 100 miles is OK for me.
You should not believe everything what is written on the internet. There are too much people proud of writing something even when it is ********.

Gerhard
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Old 07-11-2016, 14:12   #27
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Re: OpenCPN not seeing dAISy output

Quote:
Originally Posted by petter5 View Post
Loss in rg58 coax is very well known, and the reason for better quality and more expensive coax being manufactured.

With your long range AIS targets in mind, I assume that you have an high placed antenna with a good quality AIS receiver and a short rg58 cable. Yes, a rg58 will work even with some meters length, but a better quality cable will always give better performance when the length of the coax is increasing. Better coax = less signal loss in the coax.
Do you see for yourself the error, please?
A high placed antenna will need a long cable, right?
So it's wrong what you write.
I have 16 meters RG58 cable between antenna and the device.

Once again: Don't believe any ******** in the internet.

Gerhard
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Old 07-11-2016, 14:21   #28
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Re: OpenCPN not seeing dAISy output

And you would have seen even more class B ais at larger distance targets with a better coax :-) - END

If you need more technical background information, pleaser try to gather information from for example coax manufacturers, scientific research papers etcetera.

If the ais receiver itself it placed high ( like mine at home ) you does not need a long coax.

Quote:
Originally Posted by CarCode View Post
Do you see for yourself the error, please?
A high placed antenna will need a long cable, right?
So it's wrong what you write.
I have 16 meters RG58 cable between antenna and the device.

Once again: Don't believe any ******** in the internet.

Gerhard
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Old 07-11-2016, 14:29   #29
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Re: OpenCPN not seeing dAISy output

Gerhard,

from your screenshot you have one target at 20 something miles. Complete normal. Will get everybody with an antenna at 10-15m.

And you will have correct connectors and cables.

What Petter is pointing out that he knows from the installations he is putting on vessels how important these "details" are.

As you say the rest of the targets you observe are relayed. From our station at Barcelona we see as well a lot of relayed Atons or MRCCs at several hundred miles. So what..
With ducting we get targets at the north coast of your Tunesia or at the Alboran. But completely useless. Nice to observe, ok...

And don't tell people that the working range of AIS is 80 miles. 10, 15, perhaps 25..
And yes, receiver, cables and antennas count.
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Old 07-11-2016, 17:34   #30
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Re: OpenCPN not seeing dAISy output

Just out of curiosity I just connected to my highly elaborated $8 radio rig
and received this within 20 seconds


The most distant targets are Class A, of course. The "antenna" is something between 50 and 100 meters above sea level and there is an almost unobstructed line of sight and way bellow average radio pollution here. But still I'm pretty impressed
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