Fast cheap AIS using $20 rtl-sdr DVB-T SDR Dongles !

[Lake-Effect]

Thanks for the ARS TECHNICA link, conachair. I think that article is great background and lays out the potential of SDR reasonably well. The comments are an education as well (if you skip the Apple bunfights)

I do think that it underscores the fact that SDR right now is mainly a development tool and (not counting military use) that new devices, protocols and uses will eventually come out of work started now. But it's also important to note that it would take hundreds to thousands of dollars and often bulky SDR and computer hardware to duplicate today the functionality of a $200 VHF transceiver, or a $120 GPS, or a $100 AIS receiver... and the SDR versions would not be as robust, dependable or efficient as the lower-priced dedicated units. I mention this only because this is a cruising forum, and our electronic aids must work in our conditions. A boat isn't a lab bench or backyard shed.

Originally Posted by sailias

LakeEffect. In discussion with taiwanese suppliers the cost to waterproof a tablet is around 90 dollars US. The reason that they are not doing it is that there is little demand as of yet. So a top of the line tablet with an additional waterproofing package would last you how long on the hardware side. Once the thing is configured there is no software upgrades required other then for security reasons of application updates for new features. So I see a tremendous opportunity here in a designated market the given the current economy is declining. Not to be concerned, the higher end customers need integration efforts and that level of business will remain. A good waterproof tablet with say linux or android which the end customer never sees anyways is a very viable integration platform. Comments most welcomed as I love this stuff..

Me too

The rugged unit will eventually appear. I've often toyed with picking up something like a Panasonic Toughbook to have as a go-anywhere test bed, but my "research" budget can't yet accomodate the price, even for a used one. I make do with some ASUS eee netbooks which are reasonably durable (so far) and good value, but certainly not marine-survivable platforms.

I wouldn't be surprised to find that the Raymarines of the world are already working on a "marinized" tablet display or similar, together with a rugged dedicated central processor, that would be the platform for the next generation of marine instruments.

[sailias]

Originally Posted by Lake-Effect

Me too

The rugged unit will eventually appear. I've often toyed with picking up something like a Panasonic Toughbook to have as a go-anywhere test bed, but my "research" budget can't yet accomodate the price, even for a used one. I make do with some ASUS eee netbooks which are reasonably durable (so far) and good value, but certainly not marine-survivable platforms.

I wouldn't be surprised to find that the Raymarines of the world are already working on a "marinized" tablet display or similar, together with a rugged dedicated central processor, that would be the platform for the next generation of marine instruments.

That was my thinking as well. And there is lots to choose from I like the quad processor board I mentioned in another thread. At 250 its not cheap but it can easily be marinized to handle all the data inputs and outputs as well as other processing requirements. Live converting DVD's, lets be honest hear. Everyone likes their movies...Running 'nix you have the option of dedicating processes to processors as you well know. A case is not a hard thing to do.

Best regards

/ch

[sailias]

As said cheap and proven watertight boxes are not an issue. Nice little unit as well.

Field Tracker 1000 - Solara Remote Data Delivery

[sailias]

The full monty....with a price. These guys cater to the expedition crowd. Interesting stuff that can be replicated to a degree on lower end equipment.

ExplorersWeb Inc. :: Laptops

[Lake-Effect]

Originally Posted by sailias

The full monty....with a price.

Except it isn't what's really required. It's a laptop in a baggie condom pelican case. If you have to stick a USB thingie in it, there goes your environmental protection. And it's still a conventional laptop, built by companies who expect you to buy something snazzier in three years.

No, the suitable marine platform does not yet exist.

[kiwiradical]

Just for those interested in a cheap AIS receiver to experiment with that works pretty much straight from the box - I've had good success with a cheap Puxing 888 VHF handheld, about $70 from China, It has a discriminator takeoff point marked on the PC board, just input from that + battey negative via the PC mic input to AISMON (freeware)and from AISMON to O. Works surprisingly well, even on the handheld antenna.

[ebaugh]

If you want a computer based receiver for US digital TV, we used HD HomeRun before we left the states. It connects via Ethernet not USB. Unfortunately it's not 20 bucks, more like 120 US. We use the same 27 inch LCD monitor for our Chartplotter, TV and DVDs....

[ami keren]

Originally Posted by kiwiradical

Just for those interested in a cheap AIS receiver to experiment with that works pretty much straight from the box - I've had good success with a cheap Puxing 888 VHF handheld, about $70 from China, It has a discriminator takeoff point marked on the PC board, just input from that + battey negative via the PC mic input to AISMON (freeware)and from AISMON to O. Works surprisingly well, even on the handheld antenna.

hey,
sounds interesting!
could you please describe in detayls what you did?
what range of AIS targets did you mannage to get?
Ami

[Tashtego]

Just for information, waterproof USB connectors are available (see for example ASSMANN WSW components USA :: 1-877-277-6266 Tempe, Arizona) as are waterproof RJ45 i.e., ethernet connectors (see for example CAT5 RJ45 Waterproof Connector IP67 weatherproof outdoor ethernet) and Panasonic is now making both large and small toughpads (see Panasonic Toughpad Android Tablet - Best Rugged Android Tablet) which should be good enough to use at sea. But they are pricey. Since the necessary parts are available it doesn't seem to hard for some manufacturer(wake up Panasonic) to get to work and make the waterproof marine tablet, AIS, VHF radio etc. box.

[rgleason]

From the Ars Technica link:
Ettus Research News: NAVSYS Releases the GNSS Signal Architect Test Set with USRP N210
Ettus Research - Ettus Research News

Also
http://www.gpsworld.com/gnss-system/...-signals-12972

[kiwiradical]

Originally Posted by ami keren

hey,
sounds interesting!
could you please describe in detayls what you did?
what range of AIS targets did you mannage to get?
Ami

It's a while since I used this, but it's not hard to set up. Just connect an audio shielded cable - centre to the discriminator output (If I remember correctly it's maked 'E' on the PC board) and shield to the battery negative, then connect to an 1/8" jack plug centre connector to tip, shield to ring- easiest to use a jack plug to jack plug cable with one plug cut off. Some relatively easy soldering is required. Then plug into PC sound input. Use AISMon
and configure to input from sound card, and output to a virtual serial port (use VSPE from here Eterlogic - create a device 'virtual' )

Then configure OpenCPN to receive the AIS stream from the serial port.

Obviously the receiver has to be set to one of the AIS channel frequencies.

Range depends on antenna height and size, but should be much the same as any AIS unit. Using the handheld antenna I saw signals from as much as 20miles away when inland at home in a noisy electrical environment.

[ami keren]

Thanks
Ami

[deandavis1]

I have the two following (probably dumb) questions:

1. What VHF channel does AIS operate on?

2. If using a discriminator takeoff on a VHF Radio works for receiving AIS and then using something like AISMon then why has there not been any work done to transmit AIS the same way?

Thanks.

[JesperWe]

1. AIS transponders use two different frequencies, VHF maritime channels 87B (161.975 MHz) and 88B (162.025 MHz)

2. It is much more complex.

[Viking Sailor]

Originally Posted by deandavis1

I have the two following (probably dumb) questions:

1. What VHF channel does AIS operate on?

2. If using a discriminator takeoff on a VHF Radio works for receiving AIS and then using something like AISMon then why has there not been any work done to transmit AIS the same way?

Thanks.

Because transmitting an AIS signal using unapproved equipment is highly illegal!