AIS receiver

I was going through a major overhaul on my navigation system and decided to install an AIS receiver. There are only a few of them out there, and some of them are way overpriced for the featureset. After reviewing a bunch of online reviews, I choose the Smart Radio SR162 and the Smart Radio VHF Antenna Splitter both sold by Milltech Marine in the U.S. After a few questions to the folks at Milltech, who answered same-day with detailed technical information, and copies of the newest manuals, plus some tips, I ordered it direct.I chose the SR162 over the SR161 since I sail and motor in a congested, busy area, and want the assurance of both A and B channels used for AIS being caught by my systems. The SR161 only listens to the A channel, which limits the amount of boats it “hears” in busy areas.

The manual online is slightly better than the printed one that comes with the unit. There are a few confusing things in it, but overall if you know NMEA 0183 and basic VHF antennas, you can set this up. First was the VHF splitter – I opted to use this since I have a single VHF antenna on the top of my mast, and I didn’t want to add a second antenna dedicated to the AIS system. The splitter installs upstream of your other VHF devices, in my case my VHF radio, and allows the AIS receiver to use an existing antenna, while still allowing you to use the antenna for other things such as VHF radios, and VHF broadcasts. The splitter was easy to install, and required power as well as re-routing my existing VHF cable. Once that was installed, the resulting cables coming from it went to my VHF radio, and to the AIS unit.

Install of the AIS unit went pretty smoothly too. It required power, the input from the splitter, and output to my chartplotter. Initially I wanted to send the AIS output to my Shipmodul NMEA multiplexer, but after extensive testing, the high speed 38,400 baud rate of the AIS receiver added too much traffic to the rest of the data going back and forth, and caused overflows. Eventually, I chose to send it directly over a high speed NMEA 0183 port directly into my Garmin 5208 chartplotter. After using a multimeter to figure out which pins were which (you need pin 2 and 5), and cabling it up, all that was left was to power it and my chartplotter up, and configure my chartplotter to show AIS information. In about 30 seconds, I started to see AIS targets and information. That was it for configuration in terms of the AIS receiver.

A few notes:
First, your chartplotter or other software needs to support AIS. Check your specs first.

Second, my chartplotter did support AIS, but it does add delay to the system overall when it’s running in a wide scan mode. One thing I don’t like about the Garmin solution is that you can’t see AIS wider than 2 nautical miles maximum. In addition, their alarms are based on MMSI or AIS targets that are within a specific distance, not necessarily based on TCPA. If you don’t know what those acronyms mean, go look on some AIS sites.

It takes quite a while for the AIS target information to update to a decent usable level – this is by design of the AIS spec, so I’m not surprised. I would recommend turning these systems on early when you think you’re going to navigate sometime soon.

In general, I’ve been very happy with the unit, and AIS in general. It’s basically set-and-forget technology, and it allows me to see things around corners and ahead of time that I would have listened for on the VHF in the past. It doesn’t replace being attentive at the helm, but it sure adds more safety to sailing. It’s already helped me prevent course changes into shipping lanes in the few weeks I’ve been using it.

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2 thoughts on “AIS receiver”

  1. Need some guidance. We up-graded our GPS about a year ago, had a professional do the install and no longer see the AIS info one the screen of our Garman742XS. After reading your article above I am now guessing that there is no connection from our SR161 to our NEMA2000 to bring the data to the GPS. So with that how do I cone t the SR161 to the GPS via the NEMA2000 port? Any advice would be a great help.
    Thanks in Advance.

    • I think there might be some confusion on what devices work with each other. I would need a lot more information on each of the devices you’re talking about to even make an accurate guess.

      You are correct in that the SR161 was NMEA0183 only. You likely had it directly connected to one of your chart plotters, or to a hub/multiplexer to allow other devices to see its data. It sounds like you also have a NMEA 2000 network as well, but I’m not sure what is connected to that.

      When you say you upgraded your GPS, do you mean you got a new GPS antenna, or did you upgrade a chart plotter? Is the AIS data not showing up at all, not showing up on one of multiple Garmin units, or?

      Ideally, I would need to understand all of the devices on your network, which network they are connected to or how they are connected before I could theorize why your SR161 isn’t showing. Combining older and newer networks and upgrading parts can always lead to some confusion.

      I’m also happy to continue this discussion in email if you want to contact me at


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