> Anybody have any experience with the SR161 AIS receiver from Milltech > marine? > Seems reasonably priced. > Gordon
I just got one, and it is running on my desk as I type. It is in a metal box, similar to the NASA plastic box unit (or maybe a little smaller), and it seems to have similar sensitivity. My location is on a ridgetop a few miles from the ocean, at about 1000ft elevation, and with an 8ft VHF whip antenna I can receive out to about 40 miles max. I haven't taken the box apart yet.
The unit has two status LEDs, which are very nice -- one for RFdata received, another for serial NMEA data sent. It has a strange locking power connector, but they provide a mate with a pigtail. It has a BNC antenna connector. The current drain is about 90mA with the LEDs lit. The power-supply range is spec'd at 9-15V, but I have only run it at 12V.
The NASA unit sends each AIS message in an NMEA string, but the SR161 breaks the longer AIS messages into two parts. I understand that the NMEA spec doesn't allow the long messages, so the SR161 appears to comply with this and the NASA unit doesn't. Both units are understood by the programs I'm using to evaluate these boxes: Yacht-AIS and SeaClear II. The NMEA multiplexers from ShipModul don't handle the long (illegal) NMEA messages from the NASA unit, but I understand that Meindert is looking into this.
> "Gordon" <gaz...@localnet.com> wrote in message > news:120m6blmek3a93b@corp.supernews.com... >> Anybody have any experience with the SR161 AIS receiver from Milltech >> marine?
> I just got one, and it is running on my desk as I type. It is in a metal > box, similar to the NASA plastic box unit (or maybe a little smaller), and > it seems to have similar sensitivity. My location is on a ridgetop a few > miles from the ocean, at about 1000ft elevation, and with an 8ft VHF whip > antenna I can receive out to about 40 miles max. I haven't taken the box > apart yet. > [etc]
The range is actually better than 40 miles, I discovered. My computer is pretty close to the antenna, and must be putting out significant R.F. noise. I've been able to receive beyond 60 miles when the computer is off. This is hardly a scientific sensitivity test, though. I'm using a PocketPC to decode the NMEA data from the SR161, and the PPC puts out less noise than the PC. -Paul
>>> Anybody have any experience with the SR161 AIS receiver from Milltech >>>marine?
>>I just got one, and it is running on my desk as I type. It is in a metal >>box, similar to the NASA plastic box unit (or maybe a little smaller), and >>it seems to have similar sensitivity. My location is on a ridgetop a few >>miles from the ocean, at about 1000ft elevation, and with an 8ft VHF whip >>antenna I can receive out to about 40 miles max. I haven't taken the box >>apart yet. >>[etc]
> The range is actually better than 40 miles, I discovered. My computer is > pretty close to the antenna, and must be putting out significant R.F. noise. > I've been able to receive beyond 60 miles when the computer is off. This is > hardly a scientific sensitivity test, though. I'm using a PocketPC to > decode the NMEA data from the SR161, and the PPC puts out less noise than > the PC. > -Paul
I am quite interested in this topic but I have a question: isn't the AIS system meant to rely on transponders, i.e. on Transmitters/Responders? If so, a plain receiver like the one you write about is bound to receive the information only from the vessels that were "excited" by someone else. Is it so?
On Mon, 13 Mar 2006 16:36:32 GMT, Daniele Fua <daniele....@unimib.it> wrote:
>I am quite interested in this topic but I have a question: isn't the AIS >system meant to rely on transponders, i.e. on Transmitters/Responders? >If so, a plain receiver like the one you write about is bound to receive >the information only from the vessels that were "excited" by someone >else. Is it so?
>Daniel
Vessels underway transmit their position, heading and speed every second or so, depending on speed, and full data every six minutes.
> On Mon, 13 Mar 2006 16:36:32 GMT, Daniele Fua <daniele....@unimib.it> > wrote:
>>I am quite interested in this topic but I have a question: isn't the AIS >>system meant to rely on transponders, i.e. on Transmitters/Responders? >>If so, a plain receiver like the one you write about is bound to receive >>the information only from the vessels that were "excited" by someone >>else. Is it so?
>>Daniel
> Vessels underway transmit their position, heading and speed every > second or so, depending on speed, and full data every six minutes.
> They do not wait until interrogated.
This is correct. The transmitters are indeed transponders, though, since they have the capability of responding to a specific interrogation, and they participate in the coordination of the timeslotted transmissions from all local transmitters.
The receive-only units are much simpler, as they only have to listen.
> This is correct. The transmitters are indeed transponders, though, > since they have the capability of responding to a specific > interrogation, and they participate in the coordination of the > timeslotted transmissions from all local transmitters.
> The receive-only units are much simpler, as they only have to listen.
Hell, vessels at the Charleston container piers are all sending out their beacons on AIS all the time, too! They don't have to be underway. There is no "transponders". AIS beacons continuously, even when noone is listening.
While an AIS receiver is a great toy at this time, I'd wait until the yachtie versions of the full AIS transmitter/receiver/display units come down in price to something reasonable and buy that, instead. Just receiving will do you no good when you're at sea and the containership is bearing down on you at 15 knots. Having the transmitter makes you stand out just as big as the next 950' containership!
Everyone will have them very shortly, I suspect. This is just too good a working system (probably because it has nothing to do with NMEA or the ITU) to not be on every yacht. Ship radars way up high can't see your little plastic boat's metal rigging in the swells. Ship AIS is not effected by this malady if we can just get YOU to install the AIS transmitter!
Have you seen the SR260/SR261 from Smart Radio? It is a receiver/transmiter, but not a "full AIS Class A/B" and do not have oifical homologation yet, but can save lives.. I am waiting the AIS support on Garmin chart ploters (pheraps this month?) to buy a complete package (AIS receiver/transmiter, user friendly low 12V consumer, color Gps/Chart/Ploter, not a laptop PC).
On Mon, 13 Mar 2006 18:49:59 -0500, Larry <no...@home.com> wrote: >While an AIS receiver is a great toy at this time, I'd wait until the >yachtie versions of the full AIS transmitter/receiver/display units come >down in price to something reasonable and buy that, instead. Just >receiving will do you no good when you're at sea and the containership is >bearing down on you at 15 knots. Having the transmitter makes you stand >out just as big as the next 950' containership!
Don't be foolish. Although future affordable class-B transponders will be great, currently available cheap receive-only units are still great assets. Detecting the big ships 20-40 miles out, and having accurate collision warning is very valuable. Not to mention the ship name and MMSI number making radio contact easier and more likely to be successful.
-- BRENT - The Usenet typo king. :) *** Free account sponsored by SecureIX.com *** *** Encrypt your Internet usage with a free VPN account from http://www.SecureIX.com ***
> On Mon, 13 Mar 2006 18:49:59 -0500, Larry <no...@home.com> wrote:
>>While an AIS receiver is a great toy at this time, I'd wait until the >>yachtie versions of the full AIS transmitter/receiver/display units come >>down in price to something reasonable and buy that, instead. Just >>receiving will do you no good when you're at sea and the containership is >>bearing down on you at 15 knots. Having the transmitter makes you stand >>out just as big as the next 950' containership!
> Don't be foolish. Although future affordable class-B transponders > will be great, currently available cheap receive-only units are still > great assets. Detecting the big ships 20-40 miles out, and having > accurate collision warning is very valuable. Not to mention the ship > name and MMSI number making radio contact easier and more likely to be > successful.
Agreed, a receive-only collision alarm is *much* better than nothing. Even though the big ships will be much more likely to notice you by AIS than by radar (if you have an AIS transponder), my plan is to assume they don't see me and stay out of their way. For the other smaller boats with receive-only units, having a transponder is obviously a better choice. Of course, many smaller boats will have no AIS at all.
While I am waiting for the class-B "yacht" transponder, I will definitely have the receive-only unit on-board. Regardless, you still need to keep a visual/radar watch going.
The SeaLinks RADARPLUS SL162B transponder may be the ticket, but I don't think it has been released for sale yet.
"Pascal" <pasc...@uol.com.br> wrote in news:1142294909.882724.90990 @p10g2000cwp.googlegroups.com:
> Have you seen the SR260/SR261 from Smart Radio? It is a > receiver/transmiter, but not a "full AIS Class A/B" and do not have > oifical homologation yet, but can save lives.. I am waiting the AIS > support on Garmin chart ploters (pheraps this month?) to buy a complete > package (AIS receiver/transmiter, user friendly low 12V consumer, color > Gps/Chart/Ploter, not a laptop PC).
No, haven't investigated that one. Got a webpage address?
