My friend Merv added a comment to a recent post on Class B AIS. He raises an important point:
So our newly acquired Class B AIS unit gives us the MMSI numbers and other information about vessels near us that we may well need to hail to agree on intentions, etc.
Now have you ever tried to input an MMSI # into your DSC radio while you are navigating? Particularly while you are navigating in fog or other difficult conditions when AIS, radar, etc. are intended to help.
Yes I have, and it’s NEARLY IMPOSSIBLE. I’m squinting into a tiny screen that is bouncing around like crazy (if there’s any breeze), and my fingers are fumbling the knob trying to dial in each digit. God help you if you make a mistake!
Since all these systems are linked by the miracles of modern electronic data busses, why can’t I have a simple option on my chartplotter (like I have with the autopilot “Go to” function) which says “Call” the MMSI that I have highlighted with my cursor or which has showed up as an alarm?
Seems to me that trying to input an MMSI by turning knobs and pressing buttons while driving a boat is defeating the object of a very good safety device. It’s probably about as bad as texting while driving a car.
Sure, I can simply put out a “public” call on 16 or bridge-bridge but why not use DSC and cut down on “chatter”??
Why, indeed? It has occurred to me before that the next “killer app” for modern mariners will be seamless, intuitive integration of all this technology and all these navigation and communication protocols.
I didn’t come up with this on my own, by the way, it just became obvious to me while reading Panbo, particularly this post from November 2007.
Since Panbo’s Ben Ellison is really the guy who keeps his “finger on the pulse” of this sort of thing, I decided to forward Merv’s question to him. Here’s what Ben said:
Merv is right on the money. This should be an easy AIS to DSC VHF feature, and I’m sure it will be, eventually. But right now only the Simrad AI50 supports it, and that’s only if wired via SimNet (NMEA 2000) to Simrad’s (expensive) N2K VHF.
I think the problem is that the message “call MMSI xxx on channell yy” is not in the NMEA 0183 standard, and not yet completely in the NMEA 2000 standard. But AIS and N2K VHF (like Garmin’s and Lowrance’s new radios) are multiplying, so there will be pressure to make this very useful feature work.
Please add more pressure!!!!
Consider the pressure added.
I’ll even put my money where my mouth is. Manufacturers, are you listening? I experiment with and review navigation equipment, but I don’t get it all for free, and not flush with cash right now. I’ve got to consider carefully how I’m going to spend my money.
Right now, I’m not planning to buy a new chartplotter, and I keep poking along with my Raymarine C-series despite the many incremental improvements available in newer gear.
Why? Because none of them (that I can afford) have the seamless, intuitive system integration that seems so obvious to me! The improvements, while nice, are too incremental to reach the “tipping point” that would motivate me to upgrade. They just aren’t compelling.
I doubt I’m alone in this assessment.
6 responses so far ↓
Chris // Jan 5, 2009 at 7:44 pm
Looking at the Simrad NAIS 300L manual, it seems that that Class B N2K transponder puts everything it hears onto the N2K bus including the position reports which in turn include the MMSIs. The next step towards nirvana would be for an N2K chartplotter to read this information which the Garmin 4208 clearly does in displaying AIS position reports as well as DSC calls.
Almost there. At this point we can conclude that it isn’t an N2K AIS problem. It’s an N2K DSC problem.
The N2K chartplotter needs a GUI interface and protocol support for initiating a DSC call and the N2K VHF (LVR-800) needs protocol support. Unfortunately, the Lowrance manual doesn’t list the PGNs it supports and the Garmin manual doesn’t even list the AIS PGNs (that it supports). Not enough information to render a judgment.
I don’t have the N2K protocol spec but the NMEA 2000 Parameter Group Numbers and Description as of August 2007 NMEA 2000 DB Ver.1.2100 says:
“DSC Call Information
This PGN provides Digital Selective Calling (DSC) data according to ITU M.493-9 with optional expansion according to ITU M.821-1. DSC is a paging system that is used to automate distress alerts sent over terrestrial communication systems such as VHF, MF and HF marine radio systems. DSC provides a mechanism to report significantly more information regarding a distress call rather than just the distress itself. Products equipped with DSC will transmit and receive this information. ”
So the AIS part already works. N2K protocol part including AIS and DSC ‘probably’ already works and the chartplotter/VHF hardware will work eventually. My stomach tells me that Lowrance will support this soon and that Garmin will support it in a software upgrade. Eventually.
b393capt // Jan 7, 2009 at 5:06 am
I want to see something added to the NMEA protocol ! It would especially helpful for people who are years away from connecting the VHF and chartplotters together.
Also, while the above sounds real good in a passing situation or other one-one communication … if I am in a fog with multiple boats, I don’t want to be making and answering multiple DSC calls (skipping between VHF channels) or taking the time to find a quite channel before initiating a DSC call. Note sure I described that right … but DSC does not have call waiting! If multiple people are trying to call each other, I bet it’s not opimal.
Instead what would be optimal is that everyone is on the same channel and can identify themselves by their boat names with making DSC calls, and I think a simple way to accomplish that …
Have a N2K and NMEA senteance the VHF radio sends to connected devices to offer it’s current selected channel and Y/N that volume is over a certain threshold (e.g. the VHF volume isn’t turned down so low it’s useless). –> This becomes input to the AIS transiever that then appends the current channel to the boat name in the AIS message. E.g. 69-BoatName, for channel 69.
Now, when someone wants me, they just turn their VHF radio to the frequency I am on … wait for a gap in conversation … and talk. In a fog situation, starting at 16, the first boats to choose a channel to communicate in a passing situation would become apparent by looking at their boatnames in AIS.. and nearby boaters would naturally start gravitating to the same channel.
Few or no DSC calls need to be made or answered, and only a small proportion of boats need to be rigged such that their VHF channel appears on AIS to others, for this to work most of the time as it can be augmented by making just a few DSC calls to those boats that don’t have this feature … and request they meet on channel xx.
Do this … and the fog situation will be improved years faster (with those boats that have AIS) with the adoption of just a few boats (20%) that have their VHF radios linked to AIS.
What I also like in this idea, even on a clear sunny day, is anyone with an AIS receiver can easily contact me without knowing how to use the user unfriendly DSC feature of their old VHF radio. This comes in handy when I am traveling with other boats, they can see if I am on the channel I should be on (usually we use 68) or am off at 16 or something else and forgot to switch back.
b393capt // Jan 7, 2009 at 5:15 am
I want to see something added to the NMEA protocol! It would especially helpful for people who are years away from connecting their VHF and chartplotters together.
Also, while the above sounds real good in a passing situation or other one-to-one communication, if I am in a fog with multiple boats, I don’t want to be making and answering multiple DSC calls (skipping between VHF channels) or taking the time to find a quiet channel before initiating a DSC call. Note sure I described that right…but DSC does not have call waiting! If multiple people are trying to call each other, I bet it’s not optimal. Also not optimal is that those one-to-one calls are happening such that nearby boats are split between channels 16,9, 11, 12, 13, 14, 68, 69 etc. when they should really be listening to each other.
What would be optimal is that everyone is on the same channel and can identify themselves by their boat names WITHOUT making DSC calls, and I think there is a simple way to accomplish that:
Have an N2K and NMEA sentence the VHF radio sends to connected devices to offer its current selected channel and Y/N that volume is over a certain threshold (e.g. the VHF volume isn’t turned down so low it’s useless). –> This becomes input to the AIS transiever that then appends the current channel to the boat name in the AIS message. E.g. 69-BoatName, for channel 69.
Now, when someone wants me, they just turn their VHF radio to the frequency I am on, wait for a gap in conversation, and talk. Very simple.
How does this avoid being split between 16,9, 11, 12, 13, 14, 68, 29, etc.? Well in a fog situation, starting at 16, the first boats to choose a channel to communicate in a passing situation would become apparent to others by looking at their boatnames in AIS, and nearby boaters would naturally start gravitating to the same channel. As a boat moves several miles towards the next group of boats, they can easily see the channel the next group of boaters is using, and switch to that.
Few or no DSC calls need to be made or answered, and only a small proportion of boats need to be rigged such that their VHF channel appears on AIS to others for this to work most of the time, as it can be augmented by making just a few DSC calls to those boats that don’t have this feature, and request they meet on channel xx.
Do this, and the fog situation will be improved years faster (with those boats that have AIS) with the adoption of just a few (20%?) boats with VHF and AIS units capable of displaying the VHF channel within the boat-name field of AIS.
What I also like in this idea: Even on a clear sunny day there are benefits, as anyone with an AIS receiver can easily contact me without knowing how to use the user unfriendly DSC feature of their old VHF radio. This comes in handy when I am traveling with other boats, they can see if I am on the channel I should be on (usually we use 68) or am off at 69, 16 or something else and forgot to switch back. For example all our inter-boat communication breaks down when we all arrive at a port and have to switch between talking to each other and the harbormaster. Problem solved.
b393capt // Jan 7, 2009 at 4:29 pm
Example for above,
If Boatname in AIS unit = BreezePleeze & VHF is sending channel 16 as it’s current selected channel, the AIS unit would transmit the boat name as “16-BreezePleeze”
Sandy Daugherty // Jan 20, 2009 at 8:04 am
An immediate solution to the mmsi dialing dilemma is to use a mike with a numeric key pad. Then it’s as easy as [or as hard as] dialing a long distance telephone number.
Jak // Mar 4, 2009 at 4:50 pm
There maybe some simpler solutions to some of this.
First, AIS is just a VHF radio that switches back and forth between two channels quickly. AIS should be a feature of a normal VHF radio to cut costs. I already had to buy an antenna splitter to share the mast-top antenna. Maybe now that class B is approved, some vendors will work on this.
Second, If you are trying to call a class A ship, you have their name. They could ignore you, but it is less likely than in the old days when you just called “westbound freighter” or whatever. Class B and C need to send names, which I believe most don’t. You should not need the MMSI.
Third, as far as congestion, DSC is digital and should make it or not. The initial call will be a fairly short burst of information compared to voice, so it has an better chance of getting through. Many radios have a retry until method, if you don’t get an acknowledgment.
I hope that VHF radios get a little more programmable like SSBs with pactor modems. ICom’s command interface is not well documented or supported for my IC-M502. If the command language would work the integration could be written in a few hours for a PC chart plotter and an NMEA bus.
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