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

[rgleason]

Also this type of dongle would give you access to TV and Radio, perhaps weather radar via weather channel, which is not so bad either.

[rgleason]

Antennas - Some interesting links and examples.

infinite balun Archimedes spiral antennas
Miniture sprial http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA425105
Sprial Balun Spiral Antenna
Dodgy plans to make Archimedean spiral antenna for RTLSDR (software defined radio receiver) Archimedean Spiral Antenna w/RTLSDR
Good practical information about antennaes High Gain Collinear AIS (162MHz) Receiving Aerial
Good recep V/UHF STATION ANTENNA/DIAMOND ANTENNA CORPORATION

1. Amateur 2m aerial F22: 144 to 174MHz Length:3.2m Gain:6.7dB / Max.power rating:200W / Impedance:50ohms
2. VSWR:Less than 1.5:1 / Rated wind velocity:50m/sec. --Whereas AIS is AIS is 162Mhz ,V/UHF STATION ANTENNA/DIAMOND ANTENNA CORPORATION
3. Mk1 - 5 element Collinear 25 miles High Gain Collinear AIS (162MHz) Receiving Aerial - SHOWS HOW TO MAKE 3 meters long
4. Greg Kunkles version of Mk1 Greg Kunkel's Construction of 5 Element Collinearhe says " I have written a program in Delphi 5 to plot the AIS positions in real time on my local charts and on Google Earth"
5. Slim Jim antennae http://web.arundale.co.uk/docs/ais/slimjim.jpg

[HappySeagull]

...or a piece of bare wire stuck into the jack....that'll be my first protoype. MarkII will be an old extendable antenna off a transistor radio...

[capn_billl]

Well I just ordered a couple from Hong Kong. I'll let averyone know how well they work. The word must be out on the street, I had a hard time finding someone who had some.

[Lake-Effect]

Well I got my "SDR" USB stick last week (I bought this one) it came in just over 2 weeks and it works so far using the very nice SDRSharp on Windows XP.

One thing I've observed, which may impact the usefulness of this widget as a cheap receiver for AIS or weather fax - the SDR software puts a fairly heavy processing demand on your computer, because your PC is the digital signal processor that does the decoding and processing work. (well, duh, that's the 'S' in SDR). The software works fine on my desktop (a 6 year-old P4), but it was glitchy on a 2-year-old ASUS netbook running Win7 Starter. So, this means a serious computer is required, and it suggests that running both OpenCPN and an SDR for AIS on the same machine might be problematic.

I haven't yet tried the SDR in Linux, and it's possible that a well-written AIS-only driver might lighten the PC's load for that use.

Regardless, for this geek, the $20 TV-B thing is an unqualified hit, and will be a great toy for radio and RF spectrum experiments.

[sailias]

Looking forward too your report on linux. Should be much less of a burden on the processor due to process controls not available in windows I would suspect. Best of luck and do keep us posted.

/ch

[rgleason]

Dear Lake-Effect, Thanks for the information on
DVB-T Tunner Receiver for XP Vista Win7 Freeview RTL2832 RTL2832U E400 P160 P335 with IC Realtek RTL2832U E4000 SDR GNU Radio GPS GSM

There is a note at the bottom about this device not supporting TV for the US.
"It does not support US, Canada, Japan,Israel,Singapore users due to different digital standard"


What has your experience been? Do you know if we can get a device that will do AIS and USA Digital TV? Thanks

[rgleason]

To get USA and Canada Digital TV reception we would need "ATSC Digital TV (HDTV) USB" and I am not so sure those use the necessary IC chip Realtek RTL2832U and are compatible with the software. Does anyone know the answer? Perhaps we'd have to buy two dongles: One for USA ATSC Digital TV and another to get AIS.

[Lake-Effect]

Originally Posted by rgleason

Do you know if we can get a device that will do AIS and USA Digital TV?

Hi,

As you've noted, the SDR-capable devices don't support US/Canada digital TV standards.

When you add a laptop to the mix, it makes for a pretty expensive, power-hungry TV set anyway, in my opinion. If TV's a requirement on your boat, your best choice is an inexpensive 12V LCD TV.

[rgleason]

Thanks, excellent point about using a 12vdc LCD TV (which can also serve as a monitor for an on board computer with OpenCPN.

Interesting point about the added CPU load of running AIS and the digital signal software and OpenCPN.

[million440]

I for one don't mind playing with my toy. Whilst I conditionally accept part of the comments about buying the correct gear, I believe that what we are doing with OpenCPN, Gnu radio, RTL dongles and like is to explore new ways of utilising technology. It will eventually place pressure on manufacturers to come up with lower priced solutions that will aid navigation and safety at sea. Rather than being held to ransom by Raymarine and like with their overpriced pseudo proprietary electronics, our work is important in developing new markets and new solutions for the benefit of all.

[capn_billl]

Well the long and the short of it is the bandwidth of US standard digital TV is much larger than UK's due to UK using Quadrature amplitude modulation. It may be possible to program a way around this limitation, but to my knowledge no one has done it yet.

One big downer is the Elonics chip company is a UK based company,...so they have no motivation to develop a chip that supports USA TV. And so far no one that has built a US chip had included the programmability the the UK chip has.

........OR no one has figured out how to Hack the registers to reprogram it.......YET.

The key to this technology is not that, Yes; watching TV on a 8" laptop screen is better than watching it on a 40inch widescreen.

It is the fact that you are watching it on a device that has no TV tuner, no extra hardware, no fist sized bundle of coils, capacitors, and crystals tacked onto the side to demodulate the RF signals.

It is the fact that now you can duplicate ANY radio device, by popping in a CD, and uploading the correct software. This technology is in it's infancy, so ecpect a few speed bumps along the road.

Eventually you will no more go out and buy a new TV or radio, or GPS, or weather Fax, or any other radio device, any more than you now drive downtown to the local bookstore to buy a paperback book, or to the local record store to buy a LP record.

You just click on Paypal to download it, and run the correct program. Newer computers will have no problem running several of these programs at the same time.

This is the dawning of a new era, no less significant than the invention of the computer, or the Kindle.

[Lake-Effect]

Originally Posted by million440

I believe that what we are doing with OpenCPN, Gnu radio, RTL dongles and like is to explore new ways of utilising technology. It will eventually place pressure on manufacturers to come up with lower priced solutions that will aid navigation and safety at sea.....our work is important in developing new markets and new solutions for the benefit of all.

Originally Posted by capn_bill

Eventually you will no more go out and buy a new TV or radio, or GPS, or weather Fax, or any other radio device, any more than you now drive downtown to the local bookstore to buy a paperback book, or to the local record store to buy a LP record.

You just click on Paypal to download it, and run the correct program. Newer computers will have no problem running several of these programs at the same time.

This is the dawning of a new era, no less significant than the invention of the computer, or the Kindle.

Hmmm.

I agree that in general, more and more of an electronic device's functionality will come from software (or firmware).

I don't necessarily see our TV-B USB dongles as being a significant part of that transition; the dongles are a happy accident, that rare occurrence where a cheap mass-produced unit is shown to have sophisticated behaviour that can be easily exploited. So, if anything, it's put a neat little experimental SDR platform into the hands of thousands who otherwise might not have bothered because of cost. Increased awareness, in other words.

I don't believe we are quite on the threshold of a world of software-only upgrades. My house is littered with proof of that - functioning electronic devices between 2 and 10 years old that are essentially worthless in the market because they are no longer supported, while flyers proclaim laptops with the power of last-year's top-line unit at the price of last-year's entry-level unit. Besides processing power, there are still refinements going on in display and input technology. So you can still expect to replace much hardware every 2 years.

What we do need to move this marine vision forward is an energy-efficient, waterproof and shock-resistant, sunlight-visible 10" tablet that is usable in any condition. But, this would probably cost $600 to a grand, and it would still be obsolete in 2+ years.

I want to say a word in defense of the Raymarines and Furunos of the world. They've been producing dependable hardware that can last years, for a fairly small market. Moreover, if something cracks or breaks, it's usually repairable, for less than the cost of replacement. They're not cheap, but if they have a service life of 10-20 years or more, it's good value. This sort of reliability won't be achieved by low-cost generic hardware that is only expected to last 5 years, because it would be thrown out in 3 years anyways. It's no secret that much modern hardware (even hard goods like tools, refrigerators) fails sooner than their ancestors did.

(Electronics and software are my fields; I could talk for days on this stuff. You may have noticed. )

[conachair]

How software-defined radio could revolutionize wireless | Ars Technica

Interesting.

[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..

/ch