AIS receiver only, not responder: diy with openplotter

[francois.lavoie]

My goal is to prepare a hardware setup to be able to get AIS and GPS information on my boat available to android tablets or phones so to facilitate navigation with the ais of opencpn or navionics. This post is about the AIS portion of the project.

AIS definition:
https://artes.esa.int/sat-ais/overview
AIS communication takes place using two VHF frequencies, 161.975 MHz and 162.025 MHz, using a bandwidth of 25 kHz.

Materials:
raspberry pi 3B or higher (I have already a 3B, but I could use it for other usage)
NESDR nano 2+
0.1-2000MHz RF Wideband Amplifier,Wide Frequency Range, High Gain,30dB Low-noise Amplifier LNA Board
Rationale
http://www.radioforeveryone.com/2016...-external.html

https://www.rtl-sdr.com/tag/lna/page/3/
The LNA (Low noise amplication module)

RF Wideband Amplifier,Wide Frequency Range, High Gain,30dB Low-noise Amplifier LNA Board Module

Links to the information to do the AIS project:
Simple
https://www.sarcnet.org/ais-receiver.html
More complicated
https://www.forward.com.au/pfod/Chea...dge/index.html

DIY antenna:
Helicoidal type (the only one designed for AIS specifically)
https://www.sarcnet.org/ais-receiver.html
Other types of antenna, would need some work as to suit the AIS range (161.975 MHz and 162.025 MHz)
Spider antenna
ADSB Ground Plane Antenna – Fuzz The Pi Guy

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

J-pole, very practical but needs a balun:
https://jeroen.steeman.org/ADSB/Ante...mparison-Tests
Making antennas in general but not for 161.975 MHz and 162.025 MHz:
https://lucsmall.com/2017/02/06/maki...raft-tracking/

I am trying to get my noelec NESDR nano 2+ to get going on my desktop computer and/or on my raspberry pi 3B. My first results were rather negative, I would get very few channel captation with the Kalibrate sofware.

I imagine that some people on this forum have already done something like that. With the given information in the above, suggestions or comments would be appreciated. I will communicate my results as soon as I get the materials and get some better results.

Thanks so much.

[Reefmagnet]

Have you considered using an AIS receiver hat like the daisyHat? Makes set up and configuration so much easier.

[francois.lavoie]

Good idea! I have considered it. Sorry if I am scarring the crowds with my list of reference. I thought that I had to do my homework before posting.
I think that both are set up with openplotter and are operated with opencpn. As I did not made the setup already, I dunno. Maybe you know.

The difference in term of budget before shipping costs is:
$77 CAN daisy hat receiver
vs
$34 CAN NESDR nano 2+
$18 CAN Wideband Amplifier,Wide Frequency Range, High Gain,30dB LNA
$52 CAN TOTAL

Is there an amplifier on the daisy hat?
Really, I don't know if I am right this is why I did the posting.
Cordially.

[ka4wja]

Francois,
Forgive me if I'm wrong here, but it appears that you have some computer knowledge (primarily software?), and are trying to "build" an AIS receiver in order to save money?

And, also it appears that you have little RF (radio) knowledge?

So, I'm not surprised that you're having difficulties here...

Please conform my assumptions here....

Until then, please remember a few things:
a) Radio receivers generally have "distributed gain", but yes SDR's are a bit different...
b) using a "wideband" front-end (like that wideband LNA and such a wide-band SDR) can be a very bad thing!
c) too much RF Gain (such as from a "30db gain LNA") can be VERY bad!

And, of course....
d) you can buy an AIS receiver (either just the receiver on a chip, or a whole standalone receiver) for less money that what you're trying to design/build yourself....[but, if you're just looking for a fun project, and are trying to learn by experimenting, then I understand]


Please explain your knowledge of all of this, and give details of your exact reasoning here / what is your actual end-result desired.

Fair winds.

John

[ebc81]

Hi,
There is also a DIY Android solution possible for the receiver part.

See my blog
https://www.ebctech.eu/rtl-sdr-ais-receiver/

[francois.lavoie]

Hello John,


You understood well, I have almost no knowledge about radio frequencies. I am only trying to get hands on so to understand what is going on. Nice to you to intervene with such diplomacy.

Saving money maybe, after experimentation and purchasing the wrong electronic parts or modules maybe not, but clearly not saving time. I thought it could be interesting or fun as you say. But the goal is to be on the water by the end of may with or without AIS.

To put you in to context, my first move was to to buy a VHF-DSC radio without GPS an ICOM M330, my old RAY45 had no DSC function. There I thought that I could save some money by simply plugging a GPS like the GY-GPS6MV2 or the Grove GPS AIR530 directly to the radio or thru an arduino board to adjust the baud rate to 4800 NMEA 0138.



I just got those GPS modules. You get them at a cheap price ($12). I am not even sure that I have to reduce the baud rates thru the arduino board. I am trying to sort that out. In a first step I would just like to plug one of the GPS into the NMEA 0138 plug of my radio.



My first intent was to buy the following equipment to get GPS to my ICOM M330 and at the same time to be able to connect opencpn or navionics to my android tablet and phone:
- QUARK-ELEC AIS-GPS-SeaTalk (QK-A027)-NMEA-0183 message output through WiFi,USB and RS422 ($245CAN)
- VHS splitter glomex RA201 ($ 72CAN)



But to come back on the topic, putting aside the LNA device, you mean that a DTL-SDR dongle would not be suited for marine navigation? Do you mean that there will not be the needed accuracy?

[Bill O]

Originally Posted by Reefmagnet

Have you considered using an AIS receiver hat like the daisyHat? Makes set up and configuration so much easier.

Agree, there are much easier ways to get this project done successfully.

A HAT would work as well as an AIS dongle or a VHF radio (Standard Horizon) w/built in AIS GPS receivers.
We set up our VHF to send AIS to OCPN and discuss how we did it here.

[francois.lavoie]

@ebc81:
You provide an even simpler setup of achieving an AIS receiver with a RTL-SDR stick and the installation procedure could be no more KISS (keep it simple and stupid). There is no need to go thru the openplotter interface install software and set serial devices.
Would there be some way to install the app on a raspberry pi instead?
As I can see on the opencpn charts on your youtube demonstration you do not seem to have the GPS data which would be quite useful at the same time (there is no little green bars on the opencpn GPS icon). The GPS information would also be quite useful to save data cost on the android devices.
Also, installing on a pi which comes with wifi, you could go around the boat with your Android devices (tablet or phone) without being connected directly to the dongle.

At 3.49$ CAN, is this yearly or life fee?

Great setup!

[francois.lavoie]

@Bill:
My radio is VHS-DSC without GPS. But your pi setup might help me disantangle some practical aspects of computer on board.
Thanks for the link!

[ebc81]

GPS output is also supported.
Have a look at
https://www.ebctech.eu/is-app-xy-com...ith-ais-share/ on Chapter 04-02

3.49$ CAN, is life fee and you can use it on every device which is connected with your Google play store account.

But please test your equipment with the free app before.
https://www.ebctech.eu/installation-rtl-ais-driver/

[ebc81]

My android app can't installed on pi. Or so far i would not know how.


The Pi solution has benifits , but of course you have to deal with a lot of configuration stuff.

Android TV box