Jump to content

[POTM] dAISy - A Simple AIS Receiver

Recommended Posts

  • 1 month later...
  • Replies 327
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Popular Posts

Overview dAISy (do AIS yourself) is a very simple AIS receiver that I developed from scratch. It is built around the Silicon Labs EZRadioPRO Si4362 receiver, using a Texas Instruments MSP430G2553 MC

Ain't she pretty?    

Good news for everyone having difficulties sourcing the Si4362 radio IC.   I verified that the transceiver Si4463 works with dAISy. This probably also applies to Si4460 and Si4461. Besides being mor

Posted Images

Progress is slow in dAISy land, mostly due to lack of time. But I finally got time to unpack and test the first production batch of the 2-channel dAISy HAT for Raspberry Pi.



I've used MacroFab for the first time, which worked out great. Because they don't have NRE, it's the perfect solution for slowly ramping up volumes while still tweaking the design.


I even built a little jig for programming and testing.



Even though I included a Tag-connect footprint, I decided to use pogo pins and a F5529 LaunchPad for programming. As communication with the Raspberry Pi is only via UART, I can also fully test the board via the LaunchPad. Saves a ton of time compared to using a real RPi.


I will have to write some useful documentation before putting them up for sale on Tindie. I'm a little scared of the potential support nightmare to help non-IT people configure their RPis. :unsure:


PM me if you can't wait and don't need no stinkin' documentation.


Edit: Now available on Tindie https://www.tindie.com/products/astuder/daisy-hat-ais-receiver-for-raspberry-pi/

Link to post
Share on other sites

It's a modified aquarium pump with an improvised foot pedal (piece of wood with a hole to cover with your toe to enable the suction action). The airflow is not sufficient for larger parts, but 0603 works great. I got it off eBay two years ago for $20 or so.


You should try some larger needle tips. My pickup tool is a small DC motor pump + PVC tubing and Luer-loc syringes, I've found switching to larger diameter tip enables me to pickup larger parts TSSOP and 32 pin TQFP.

Link to post
Share on other sites

Hi everone!
It's my first post on this forum. I'm following this thread with great interest. I come back every now and then to check the progress. I'm also a boating enthusiast and have built a few electronic devices.
The reason I'm writing is becasue a while ago I was searching for a way to connect two receivers on the same antenna. The idea was to use a resistive splitter with 6db loss and an amplifier to compensate for the loss.
I've noticed you have built a device with two receivers so I was wondering if you can explain how you designed the splitter. I see on the picture you have two baluns (without the 220pF capacitor) and a bandpass filter (green boxes), but I can't figure out the central arrangement of passive components (in blue box). Can you please explain how you realised the splitter and what are it's losses?
Additionally what is D41 for?


Thanks for your reply and keep up the good work.


Link to post
Share on other sites

Hi @@matkar


Very good analysis of the PCB.


The components in the blue box form a Wilkinson divider tuned to 162 MHz. It has an insertion loss of about 3 dBm. Surprisingly I didn't notice any impact in real-world performance compared to the single-channel dAISy. Not sure why, but I suspect a combination of better noise management (e.g. noise filtering on power rail, radios further away from MCU) and the signal being limited by environmental noise.


D41 is for diodes to protect the radios from RF overload. But I struggle to find the right part and am unsure how much it really helps. E.g. I doubt it will handle the situation where the receiver gets connected to the same antenna as a transmitting VHF radio.


The missing components in the baluns are a inductors. The application note for the radio IC offers two configurations with 3 and 4 components. I did go with 3 as the 4-component configuration didn't improve real-world performance.

Link to post
Share on other sites
  • 2 weeks later...

Hi all,


Is there a bandpass filter on board the dAISy HAT? I've build a couple of these:




It is a wide range LNA, suitable from 100MHz to 1+ GHz, but I'm a little afraid to overpower the dAISy input... I'm using these LNA's on my ADS-B receiver and I'm using a bandpass filter there too.

Link to post
Share on other sites

Hi Polyphemus,


Yes, dAISy includes a bandpass filter.


I experimented with external LNAs a few times, but didn't see any benefit. Though I never was very systematic about my experiments.


The max input must not exceed 10 dBm. Even -50 dBm is more than enough to reliably decode a signal. A LNA would only be useful if it pulls very weak signals (say below -100 dBm) out of the noise.

Link to post
Share on other sites
  • 5 weeks later...

@@StrangerM just tried with a MSP430F5529 LaunchPad and it works for me.


I tried both ways entering the bootloader, either pressing the BSL button when plugging in or the B command in the debug menu.


I can see two potential issues:


1) Make sure your firmware file is not corrupted. Some browsers seem to save HTML code instead of plain text when downloading a .txt from Github. I just uploaded them to Github as ZIP file to avoid that issue.


2) On my LaunchPad, only the GND, 5V and 3.3V jumpers are in. The other jumpers on the debug connection are empty.




Link to post
Share on other sites
  • 2 weeks later...

I have made a simple  test generator for dAISy on RasPi 2 and USB sound blaster. I used the programm PiFm with command "arecord -fS16_LE -r 48000 -Dplughw:1,0 - | sudo ./pifm - 162.025 48000 (or arecord -fS16_LE -r 48000 -Dplughw:1,0 - | sudo ./pifm - 161.975 48000)". I played the sound file AIStest.wav on a laptop. I connected an audio output of the laptop with an audio input of the sound blaster. It works perfectly well with dAISy and AIS ENGINE3.   








Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...