chicken

[POTM] dAISy - A Simple AIS Receiver

262 posts in this topic

I looked at your layout and it looks like your traces for the radio are not 50 ohms but ~65. How I did this is using AWR tx-line calculator(its free) , its really helpful when dealing with trace impedances.  When doing RF stuff you always need to be conscious of impedance.  Also using an SMA connector will help because it is designed for 50ohm impedance the pins you have right now are probably also messing with your signal because the impedance is probably greater than 50ohms. 

chicken likes this

Share this post


Link to post
Share on other sites

@@KwaiChang nice little tool, thanks for pointing it out!

 

So plugging the numbers from OSHPark into the CPW Ground calculator, with 10 mil spacing to the ground fill-in, my signal traces should by approx. 50 mils wide. Or 35 mil traces if I push spacing all the way down to the 6 mil limit. Does that sound about right?
 

Share this post


Link to post
Share on other sites

Yup that sounds right.  Also since its a technically a mixed signal maybe isolating the digital and analog parts may help? maxim has a pretty good mixed signal layout [here] . It may not be necessary because it is such a simple system.  I don't know too much about mixed signal stuff so dont take my word for it.

Share this post


Link to post
Share on other sites

dAISy USB is alive!

 

Before reflow - can you spot the DOH! moment I had shortly after reflow? :blush:

post-9974-0-07140200-1393641552_thumb.jpg

 

And flashing LED after programming via F5529 LaunchPad

post-9974-0-45824000-1393641570_thumb.jpg

 

Pretty jazzed that it worked at first try! :smile2:

Next up, migrating the dAISy project to the MSP430F5508. Already have it working on the MSP430F5529.

greeeg, Druzyek, gmtii and 2 others like this

Share this post


Link to post
Share on other sites

@bluehash: serial over USB, once I get USB working that is :-\

At some point I will also give Bluetooth a try via the serial lines on the programming header.

bluehash likes this

Share this post


Link to post
Share on other sites

Time for a status update.

 

post-9974-0-05208700-1397943883_thumb.jpg

 

I was busy with a lot of business travel over the last few months. On the upside, I stayed at some places close to busy ports giving me the opportunity to debug the software issues that plagued the standalone version of dAISy. So dAISy USB is finally alive and kicking.

 

Back home, I did a field trip to Seattle and recorded this short video to show it in action.

 

I'm currently reworking the USB side of the PCB as I missed a few crucial things. As discussed in another thread, I had to patch in a few resistors to make it work.

 

I'm also contemplating to add a shield on top of the radio IC in the hopes to increase sensitivity. Does anyone know if that's worthwhile?

 

Next up is a proper case. Does anyone know a finger-sized case with holes for a USB plug on one end and BNC or SMA on the other?

 

reaper7, spirilis and Maddox675 like this

Share this post


Link to post
Share on other sites

How about run a USB pigtail out the side of an Altoid's tin and SMA connector / pigtail on the lid?

Share this post


Link to post
Share on other sites

How about run a USB pigtail out the side of an Altoid's tin and SMA connector / pigtail on the lid?

 

Well, I was thinking about something a bit more "professional" than that B)

Share this post


Link to post
Share on other sites

Yeah, I was half joking.

Maybe a little overkill but what about a 2.5" USB hard drive enclosure?

Or maybe this project enclosure?

Share this post


Link to post
Share on other sites

For $4, it's probably worth the experimentation considering it's aluminum and would probably help the shielding you mentioned. Maybe go to an SMA bulkhead type connector for an external antenna, but BNC might be a fit too; either may be doable with a slight tweak to the board dimensions.

 

If I wasn't over the hill from Newport, Laguna and other marinas I'd probably ask to buy one from you for the novelty factor alone. ;)

Share this post


Link to post
Share on other sites

As a sophomore in Electrical Engineering and and avid sailor, this thread is just awesome.  Do you plan on releasing the project source code and schematics for your new design?  This would be such a fun summer project to try to add to my boat. :smile:

Maddox675 likes this

Share this post


Link to post
Share on other sites

Do you plan on releasing the project source code and schematics for your new design?

 

Not sure yet, whether I'll also make the USB version open source as I'm contemplating making this an actual product.

 

But happy to share individually. Send me a PM.

Share this post


Link to post
Share on other sites

very interesting, have already my boards from osh and I'm now wating on a reply from my local distributor for the si4362, Mouser wanted $39 for postage.

I have been in research mode for an AIS receiver for a few weeks when I finally stumbled into this project.

I see the si4362 is a transceiver chip so it should be possible , with a GPS module, to make a AIS transponder.

What size is the crystal , just looking at the board it looks like 7mm x5mm.

Share this post


Link to post
Share on other sites

very interesting, have already my boards from osh and I'm now wating on a reply from my local distributor for the si4362, Mouser wanted $39 for postage.

I have been in research mode for an AIS receiver for a few weeks when I finally stumbled into this project.

I see the si4362 is a transceiver chip so it should be possible , with a GPS module, to make a AIS transponder. Whoops saw this mentioned in an article, just checked definately receive only.

What size is the crystal , just looking at the board it looks like 7mm x5mm.

Share this post


Link to post
Share on other sites

very interesting, have already my boards from osh and I'm now wating on a reply from my local distributor for the si4362, Mouser wanted $39 for postage.

I have been in research mode for an AIS receiver for a few weeks when I finally stumbled into this project.

I see the si4362 is a transceiver chip so it should be possible , with a GPS module, to make a AIS transponder.

What size is the crystal , just looking at the board it looks like 7mm x5mm.

 

The Si4362 is only a receiver. For a transponder, you will have to look into the Si446x family.

http://www.silabs.com/products/wireless/EZRadioPRO/Pages/Si446x.aspx

 

However note, that GMSK encoding is only supported indirectly, which is fine for receivers but might not be up to spec for transponders. See this discussion: http://www.eevblog.com/forum/beginners/need-some-help-with-si4362-%28gfsk-vs-gmsk%29/

 

As for alternative sources for the IC, it looks like Farnell/Element14 has some in stock:

http://www.findchips.com/search/si4362

 

I currently use two kind of crystals, the larger footprint (5x3.2mm) is for this one:

http://www.mouser.com/Search/ProductDetail.aspx?R=7B-30.000MEEQ-Tvirtualkey57230000virtualkey717-7B-30.000MEEQ-T

 

I also use this smaller crystal (3.2x2.5mm) which is a bit out of spec as per Silabs application note (to large load capacitance), but works just fine for me:

http://www.mouser.com/Search/ProductDetail.aspx?R=AM-30.000MAGE-Tvirtualkey57230000virtualkey717-AM-30.000MAGE-T

PaulTech likes this

Share this post


Link to post
Share on other sites

Element14 and RS don't seem to be stocking this if yet, shows up in the list but no stock. Thanks for the sizes now get on with ordering.

An article did mention it was also for TX but they may have been confused with the TX/RX ready bit in the intro, it really meant it was suitable to go on a TX as the receiver. And of course I did get a bit excited until I re-read the app sheet again,, trying to figure out how it was possible to do that on so few I/Os

Share this post


Link to post
Share on other sites

Element14 and RS don't seem to be stocking this if yet, shows up in the list but no stock.

 

Well, at least Element14 Australia says under availability "75 deliver in 6 - 7 working days from our UK warehouse"

http://au.element14.com/jsp/displayProduct.jsp?sku=2414377&action=view&CMP=GRHB-FINDCHIPSAP1-1004809

 

Good luck, let me know if you have any questions or issues.

Share this post


Link to post
Share on other sites

For those struggling finding the radio IC: The Si446x (60/61/63/64) transceivers seem to be software and pin-compatible with the receive-only Si4362 that I used.

http://www.silabs.com/products/wireless/ezradiopro/pages/si446x.aspx

 

I saw that for example Digikey has a few Si4460 in stock.

http://www.digikey.com/product-search/en/rf-if-and-rfid/rf-transceivers/?k=si4460

Share this post


Link to post
Share on other sites

So.. dAISy looks like just what I'm looking for. I live within minutes of the sea, and have been looking at a non-sdr way of receiving AIS signals. I know you're toying with making this a commercial product, but whilst this is going on, would you be prepared to provide me with a pre-release version for a suitable 'donation'? I would happily beta test, helping improve the device - the ultimate goal will be to use the AIS feed to know when something interesting is heading out across the Solent, so I can take our little one out to see it sail past (and there's something cool about having the receiving equipment rather than just using marinetraffic.com or something else similar).

Share this post


Link to post
Share on other sites

@@jimeney @@petertux @@bluehash and others, due to recurring requests I added a poll to this thread.

 

What's the interest in buying dAISy and in what shape?

 

dAISy USB in its current form for US $50, tested & shipped, no antenna ($16 extra), no case.

 

post-9974-0-33358800-1400644211_thumb.jpg

 

dAISy BoosterPack (to be designed) for US $20, tested & shipped, basically a tidied up version of the original POTM entry.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now