NMEA0183, USB connection

[Techstyleuk]

I just ordered this device (Thanks Peter) and I am thinking about how I will set it up. I have ordered the NMEA0183 version and plan to connect the USB to the Openplotter running RPI and have the NMEA0183 connected to a VHF radio. I expect the VHF to read the info from Maiana and get AIS and GPS info from it. The messages the VHF will listen to are listed below under NMEA0183-HS input. In addition the VHF will output the DSC and DSE sentences - will Maiana pass these through to the USB or do I need to connect in a RS422/USB from the VHF to the Pi?

Thanks for the Great work, by the way!

[peterantypas]

MAIANA is a talker only, you’ll need to feed the Pi via some other adapter.

…

Sent from my iPhone

On Feb 15, 2022, at 8:30 PM, Techstyleuk ***@***.***> wrote:  I just ordered this device (Thanks Peter) and I am thinking about how I will set it up. I have ordered the NMEA0183 version and plan to connect the USB to the Openplotter running RPI and have the NMEA0183 connected to a VHF radio. I expect the VHF to read the info from Maiana and get AIS and GPS info from it. The messages the VHF will listen to are listed below under NMEA0183-HS input. In addition the VHF will output the DSC and DSE sentences - will Maiana pass these through to the USB or do I need to connect in a RS422/USB from the VHF to the Pi? Thanks for the Great work, by the way! — Reply to this email directly, view it on GitHub, or unsubscribe. Triage notifications on the go with GitHub Mobile for iOS or Android. You are receiving this because you are subscribed to this thread.

[muebau]

@Techstyleuk just out of curiosity, what do you with the DSC and DSE sentences.
I was in hope to find some cool GUI to see all the recent DSC calls in OpenCPN. I found nothing.

I thought it would be nice to have some kind of "recent radio" thing eg. in the browser.

If combined with some SDR (2 rtlsdr should be enough) there could be even a recording of all channels at the same time and have them on some multichannel timeline. If you would click on an item you hear the radio transmission and you see the ATIS (Europe) etc.

[peterantypas]

Yes, this is a hardware limitation. I'm not aware of any inexpensive and low-power silicon that can decode DSC. It will have to be some kind of SDR with a lot of post-processing.

[kagouraki]

Dead end then...

[Techstyleuk]

@muebau - it seems like some of this functionality is available. according to this page:
https://opencpn.org/wiki/dokuwiki/doku.php?id=opencpn:opencpn_user_manual:toolbar_buttons:ais:dsc_buddy_via_ais
DSC messages are treated similar to AIS and will appear in the AIS target list and will be highlighted on the screen.

[muebau]

Oh wow you are right. This is very cool.

[muebau]

Automated usage of the vhf is risky. But the option to "record" dsc calls is an interesting one.

Well some of the commercial plotter support the "automated usage" as I mean it. One can click on the screen (AIS etc.) and the VHF sends a DSC call request. This is not very risky.

The "record" is a nice thing and should be not to complicated to implement if 2 RTLSDR would be used to cover the complete VHF band.
There are ready to use GNU radio blocks to cut a band in several channels, make a power analysis on every channel and output just the currently "active" channels in one step.
From there every call on every channel could be stored in a separate file. I have seen GNU radio blocks for most of this. The question is if a Raspberry Pi has enough power to lift this.