Moitessier HAT receives fewer targets than expected

 

To comment on questions or provide answers, please login first.
Register | Login

 

Questions and AnswersCategory: Moitessier HATMoitessier HAT receives fewer targets than expected
Christian Staff asked 2 years ago

The performance of the Moitessier AIS receiver is lower than expected. One would expect more targets and a higher reception range for AIS signals. Can the performance of the AIS receiver be improved?

6 Answers
Christian Staff answered 2 years ago

This can happen, due to low-quality converters of the Raspberry Pi’s power supply. Choosing a higher quality power supply for Raspberry Pi and Moitessier can improve the AIS performance significantly.
Find more information and a comparison of two different power supplies here:
https://www.rooco.eu/2018/08/07/improve-moitessier-ais-right-power-supply/

Mark Gensler replied 2 years ago

Do you have any examples of purchasable high quality power supplies? All I’ve found so far is DIY circuitboard examples, e.g. https://pihw.wordpress.com/meltwaters-pi-hardware-kits/power-supply-kit/ (no longer available)

Christian Staff replied 1 year ago

Hi Mark,

we are currently in the process of evaluating a number of different power supplies.
Afterwards, we will publish our researches here.
Stay tuned.

Mark Gensler replied 1 year ago

Great, thanks!

Roberto Cipriani answered 1 year ago

MarineTraffic supplied receiver

Roberto Cipriani answered 1 year ago

Moitessier

Roberto Cipriani replied 1 year ago

I also experience sensitivity problems as shown on previous attached images
https://www.dropbox.com/s/enchnk0dkier6wd/MarineTraffic.PDF?dl=0
https://www.dropbox.com/s/enchnk0dkier6wd/MarineTraffic.PDF?dl=0

One is MarineTraffic’s supplied receiver and the other is Moitessier.
Perhaps Moitessier is desensibilized?

I obtained the same results exchanging antennas and power supply.

Thank you for support.
Do not esitate to ask me for further testing.

Roberto

Thomas Staff replied 1 year ago

Hello Roberto,

I need some more information, to find a proper solution for your issue.
What do you mean with “MarineTraffic’s supplied receiver”? Do you mean the online view at marinetraffic.com?
Do you have any electronic equipment next to your HAT or reception antenna that might disturb your device? e.g. radio equipment, smartphone, Wi-Fi etc.
Do you have a transmitter on board (e.g. radio equipment)? How far away is the transmitter antenna to the HAT and the reception antenna?
How long was the system running before you created the screenshot?
Which power supply do you use for the Raspberry Pi?
Which antenna do you use?
How many meters above sea level is your antenna installed? May I get a picture of your installation?
Is your system installed on a ship or on the shore?

Please enable the range rings in OpenCPN and send me a new screenshot. Use 10 rings and a distance of 5NM in between of them.
Please show the AIS target list and send me a new screenshot. Set the range limit to > 500 NM.

Regards,
Thomas

Roberto Cipriani replied 1 year ago

> What do you mean with “MarineTraffic’s supplied receiver”? Do you mean the online view at
> marinetraffic.com?

I host a receiver obtained for free by MarineTraffic, the SLR350Ni, to send data to their server.
It look as a raspberry with a hat, receiving AIS.
Actually it is inside my home, hooked to one of my vhf antenna, waiting to install another antenna and connected to internet.

> Do you have any electronic equipment next to your HAT or reception antenna that might disturb your
> device? e.g. radio equipment, smartphone, Wi-Fi etc.

no; only the MarineTraffic (MT) one, but also switching off does not change the ship received by Moitessier.

> Do you have a transmitter on board (e.g. radio equipment)? How far away is the transmitter antenna
> to the HAT and the reception antenna?

Actually I don’t have any transmitter attached to an antenna.
The two antennas for AIS (one for Moitessier and the other for MT) are roughly separated by one meter and in the free air 3 meters over the flat roof.

> How long was the system running before you created the screenshot?

rougly one day

> Which power supply do you use for the Raspberry Pi?

A 2,5A 5V from the main.
I exchanged the two power supply (for MT is a Raspberry original one) with no difference.

> Which antenna do you use?

One collinear 144/432 Mhz and a GP for 144 Mhz; I am waiting to install a 162 Mhz collinear for AIS.
I exchanged also the two antennas with no difference in reception.

> How many meters above sea level is your antenna installed?

At 110 mt above see level.

> May I get a picture of your installation?

Yes:
https://www.dropbox.com/sh/vmeqrsiwed56ini/AABezx-eRS3XUFUUrM26zYL1a?dl=0

this is a folder with pictures of the antenna and visibility and a depliant of the MT receiver

> Is your system installed on a ship or on the shore?

For the moment at home, on the shore.

Christian Staff answered 1 year ago

GENERAL NOTE:
We are currently in the process of evaluating the issue.
Any updates on the subject will be published here, as soon as available.

thomas.nienkemper answered 1 month ago

Are there any updates on the matter? I might have the same problem.
Setup: 

  • Raspberry Pi3b+
  • Moitessier Hat 1 incl. Case

Error:

  • Have this error since I got the hat in mid 2019. Never worked. 
  • reception is 0.4 miles
  • no difference if antenna is attached or not
  • tried 2 different antennas directly connected, mounted on main and mizzen mast in 14 and 17m
  • tried different power adapters (1 low noise 3a converter, 1 high quality car charger 2.5a)
  • had all other electrical equipment nearby turned off, even the display (disconnected the breakers)

None of the measures had any effect at all. Receiving always the same 3 ships within 0.4nm (I know there are more).  
I am now out of ideas. Thought about wrapping the case in aluminium foil but I doubt this makes a difference. 

What can I do? 

Thomas Staff answered 1 month ago

Hello Thomas,
how do you verify that more than 3 ships are sending AIS?

Tips to improve reception performance:

  • Use low-noise and high-quality converters
  • Mount the antenna as high as possible above sea level
  • Avoid noisy sources next to the receiver
  • Use AIS antennas only
  • Keep antenna cables as short as possible and use low-loss cables
  • Place AIS antenna as far away as possible from other radio equipment

If you have already considered and tested the above mentioned suggestions, we could test your hardware in our lab. However, all of the HATs are tested prior shipping and it would be very strange if it never worked properly.
Please tell me the serial number of your HAT. Open a terminal and enter the following command:
~/moitessier/app/moitessier_ctrl/moitessier_ctrl /dev/moitessier.ctrl 1
Send me the complete output.
Regards
Thomas

 

To comment on questions or provide answers, please login first.
Register | Login