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

[Lake-Effect]

Wetduck, you da man!

(sorry for the gender assumption, but without it the pun falls flat)

Yours was the second mention I've seen in two days on using these guys for sdr, and the AIS idea is parfect.

[dougwm10]

I am a non technical person who like many others using O are very interested in this project.

I would very much appreciate information from anyone who has managed to set up this dongle and get it working with BOTH AIS and WEATHER SATELLITE inputs.

The main problem I see with the weather satellite transmissions is to find a good efficient high gain antenna and following a lot of investigation on the internet it seems that a suitable antenna is both hard to design and make or expensive to buy a commercial unit. The only type of antenna that seems to be recommended is a Quadrafilar Helix design ????

Does any one have experience or can recommend a suitable inexpensive antenna for this purpose that can be made easily or bought for a reasonable cost. ?

If anyone has managed to get this project working in both of these modes could they please detail HOW together with any ancillary bits and pieces are required and a circuit diagram would be very useful if it could also be included.

Hoping someone out there can help

[Lake-Effect]

Stay tuned here, and keep checking the links given in this thread. There's alot of current activity on these things and I'm sure there will shortly be solutions in abundance.

The thread compelled me to order one via Ebay yesterday, so I will have one to play with in short order, depending on mail from Hong Kong. (usually 7-10 days)

Everyone says the included antennas are junk, but things get better with just using TV rabbit ears. More directional antennas can be made, with patience. It will all depend on the band and the signal. Weather satellite might pose a challenge. Making ONE dongle serve both AIS and weather satellite might be a challenge, unless you manually change antennas and run different programs.

Remember, we're just a bunch of hackers playing with a $20 toy, and it may work as AIS or weather receiver, but it is no replacement for proper receivers. If you're unable to make DIY antennas, you will have to buy something, and at that point it might make more sense to just buy the proper receiver.

[sailias]

With regards to weather fax, thats simple, I use an Eton G5 with the wip antenna and fldigi as the software. Now the antenna is an issue as reception is poor from Boston in the Great White north, however a friend simply used a long wire with aligator clips at each end, one went to the antenna, the other to the backstay. Worked pretty good for daily weather reporting while cruising in the Rio Dulce area and waters.

On the AIS side, gotta get me one these babies and play....

The advise on getting proper equipment is well placed however. But for those who enjoy this kind of thing....its a lot of fun.

Best regards

/ch

[HappySeagull]

Listening to satellites? Satellite dishes come to mind...I'm not the first one to think of THAT, I bet!
and there's so many available as junk.

[PjotrC]

Originally Posted by dougwm10

Does any one have experience or can recommend a suitable inexpensive antenna for this purpose that can be made easily or bought for a reasonable cost. ?

Some years ago I made a QFH (Quadrifilar Helix antenna, which is the usually recommended one for wxSat reception; no dish needed), with some pieces of copper wire and plastic tubing. I never used it afloat, however... Attached is a sample obtained with an Icom R1500 receiver. The blurs are due to a passing car and a neigbour mowing his lawn, so hopefully offshore should be better... I would certainly be interested to hook it up to a dongle. To make the QFH was maybe a day of relaxed work. Can somebody confirm the reception of WFM mode on 137 MHz with any of these dongles... ?

[capn_billl]

I just gat a message from the seller of that item, that stated, TVB is not compatible with ATSC due to different bandwidth of signal. He didn't think I could program the TVB to receive the ATSC signal of the US because of bandwidth issues even though you could get the correct frequency.

[PjotrC]

Originally Posted by capn_billl

He didn't think I could program the TVB to receive the ATSC signal of the US because of bandwidth issues even though you could get the correct frequency.

Not exactly good news, but not a show stopper. I've seen lots of reports from people using regular FM receivers (NFM - Narrow FM, as opposed to Wide), who still obtained good pictures with QFH and home-made frequency converters. Still worth trying...

[HappySeagull]

Thanks for the tip, Pjotr. QFH looks better than trying to point a dish on a boat!...they're both big and awkward though - something like this
Sarantel Small Quadrafilar Helix GPS antenna SMA - CSG Shop
appeals to me! but I guess tuning might be a stretch...? making one for each wavelength might work?

[PjotrC]

QFH are frequency-specific indeed, and those for 137 MHz are not as small the GHz ones... but there are people saying that if they would have to settle for One source of weather information, they'd pick sat images...
I followed the instructions and sizing from Chris van Lint guide, and used the free version of WXtoImg software with a borrowed R1500. I am slowly considering a receiver now...

[conachair]

After spending ages messing around with hdsdr crashing I found this very easy way to get in if you are on windows..

Windows Software [rtlsdr.org wiki]

Use zadig to install the driver then run SDR#dev , doesn't even install.

Seems to work well.

[conachair]

Originally Posted by PjotrC

QFH are frequency-specific indeed, and those for 137 MHz are not as small the GHz ones... but there are people saying that if they would have to settle for One source of weather information, they'd pick sat images...
I followed the instructions and sizing from Chris van Lint guide, and used the free version of WXtoImg software with a borrowed R1500. I am slowly considering a receiver now...

Not sure if the bandwidth of the dongle would be wide enough for wxsats, I'll give it a go at some point soon. Need to figure out how to get the signal into wxtoimg, can't be that hard. I've had a just readable image before with an icom ic7000 and a backstay antenna, but not something to be relied on.

I've not met any of those people who would prefer a sat img to a wfax image though, gimme wfax any day, even over grib if there's no choice. Shame these little dongles don't go low enough for wfax, would have been a great way to get cheap weather updates.
Still it works well enough, atis airport weather reports were quite clear. Apparently it's raining lots of places, not just London

[conachair]

Update, Just had it tuned into NOAA17 weather satellite, which is bust, transmitting but no image . But it seemed to pick up enough of a signal to hint that it might just recieve an image if one was being transmitted. Easy to track the doppler shift using the mouse to tune.
Still need to figure out how to pipe the audio straight into wxtoimg, radio through the speakers and wxtoimg set to mic input works, but there must be a better way.

All good fun

[rgleason]

I've been reading and looking into this, and at this point it seems a little too iffy and tentative, involving getting the right DVB-T SDR with the right chips that support several alternative soffware interfaces, and getting a good antenna, and even then AIS does not seem to work that well from what I have seen so far. Does anyone actually have it working? As I understand it the software decodes to an AIS Nema stream, but I don't think this USB hardware is robust enough for good AIA reception.

Please advise and tell me I am wrong about that and let us know how you did it.

[Lake-Effect]

Without a doubt this is iffy. It's unlikely that the end result will be a dependable primary marine system. If you need/want dependable AIS on your boat, go out and buy the proper thing.

What this is, is cool and interesting. It's a chance to play with SDR (software-defined radio) which until now cost a few hundred dollars for hardware. With some small effort (better antenna, LNA, software tweaks) it holds the possibility of being a low-cost AIS receiver for use with OpenCPN. Among other uses.

If the right devices remain available, and with some community input... it's possible that anyone, regardless of technical chops, could follow some steps and get it working for OpenCPN. And that would be pretty cool for a $20 dongle.

Hope that's clear.