Portable Gps/Plotter with AIS-Receiver Support
 

Paul wrote:
snip
Short summary: A 4800 bps NMEA link may very well overflow in
not-insanely-busy conditions. Explanation follows:

A couple of weeks ago...
snip

Paul,

Thank you for your most excellent report and very coherent explanation.

It was wonderful!

Jack

--
Jack Erbes in Ellsworth, Maine, USA (jackerbes at adelphia dot net)
(also receiving email at jacker at midmaine dot com)

Portable Gps/Plotter with AIS-Receiver Support
 

"Paul" wrote in
:

It would only take about 93 active ships
to fill a 4800 BPS NMEA link, and this assumes even spacing of the
messages, or very deep buffers.


You can see 90 ships on AIS from a stern rail antenna? How do you plot
these so it doesn't destroy the other navigation? The stern rail antenna
to a ship antenna 100' up would only have a range of 10 miles.

Ok, we can load up the crappy NMEA 1966 data link. I'll say "uncle". All
the more reason the whole damned boat should be on ethernet. But, alas,
how many pleasure boaters ever see 20 ships painted on an AIS display? I
doubt it's very many. I feel sorry for those who have to sail in those
conditions, just like boaters on the ICW in Florida stuck in a ditch so
dense with boats noone can ever have a fun time.

We South Carolinians need to look at ourselves, once in a while, and see
how lucky we are to be able to sail around and never see another boat for
hours, certainly not one that crosses our paths....lucky indeed.

Larry
--
http://www.youtube.com/watch?v=fEJmc...elated&search=

Portable Gps/Plotter with AIS-Receiver Support
 

"Larry" wrote in message
...
You can see 90 ships on AIS from a stern rail antenna? How do you plot
these so it doesn't destroy the other navigation? The stern rail antenna
to a ship antenna 100' up would only have a range of 10 miles.

Theoretically yes, but there's also refraction of the VHF signals around the
"edge" of the earth that makes the signals go further. You as a ham should
know that.

Ok, we can load up the crappy NMEA 1966 data link. I'll say "uncle". All
the more reason the whole damned boat should be on ethernet. But, alas,
how many pleasure boaters ever see 20 ships painted on an AIS display? I
doubt it's very many. I feel sorry for those who have to sail in those
conditions, just like boaters on the ICW in Florida stuck in a ditch so
dense with boats noone can ever have a fun time.

Cross the English channel and find out for yourself how busy it is. Or the
Solent area.

We South Carolinians need to look at ourselves, once in a while,
and see how lucky we are to be able to sail around and never see another
boat for hours, certainly not one that crosses our paths....lucky indeed

Yeah, you South Caronlinians are a bunch of pussies compared to the guys who
regularly cross the English Channel... ;-))

Meindert

Portable Gps/Plotter with AIS-Receiver Support
 

"Larry" wrote in message
...
"Paul" wrote in
:

It would only take about 93 active ships
to fill a 4800 BPS NMEA link, and this assumes even spacing of the
messages, or very deep buffers.


You can see 90 ships on AIS from a stern rail antenna? How do you plot
these so it doesn't destroy the other navigation? The stern rail antenna
to a ship antenna 100' up would only have a range of 10 miles.

Ok, we can load up the crappy NMEA 1966 data link. I'll say "uncle". All
the more reason the whole damned boat should be on ethernet. But, alas,
how many pleasure boaters ever see 20 ships painted on an AIS display? I
doubt it's very many. I feel sorry for those who have to sail in those
conditions, just like boaters on the ICW in Florida stuck in a ditch so
dense with boats noone can ever have a fun time.

We South Carolinians need to look at ourselves, once in a while, and see
how lucky we are to be able to sail around and never see another boat for
hours, certainly not one that crosses our paths....lucky indeed.

Larry

Larry and Jack,

I took a detailed look at my NMEA logfile to see if I could sanity-check
last night's calculations. It turns out that what I actually was receiving
is fairly close to the estimates -- but not quite as bad:

(and I lied -- on-board VALIS I have a SR-161 single-channel receiver. The
two-channel receiver is at home for the time being, as part of my
development platform)

During a ten-minute period on the Bay, just inside of the Golden Gate
Bridge, I received signals from 76 ships (a few of these were actually
base-stations). The maximum range was 21 statute miles, but remember that
the surrounding hills are pretty high in most directions. About half of the
ships were moored.

During this ten minutes there were 1401 AIVDM (AIS) NMEA sentences sent from
the AIS receiver, totalling 68581 bytes, or 754391 bits. This gives an
average datarate of 1257 bps. Using a dual-channel AIS receiver the rate
would double to 2515 bps. So, perhaps, even with the burstiness of the
data, a 4800bps NMEA link would work -- but the margin isn't comfortable,
and I have to think that with a mast-top antenna I might easily exceed the
link capacity.

In any case, it sounds like we all agree that 4800bps serial is not the
shining path to the future!

I am displaying the AIS targets on my PocketPC, which is usually velcro'd to
the navstation next to the chartplotter. I have a Bluetooth link from the
AIS receiver and the NMEA mux which carries the rest of the nav-data. My
Raymarine RL70 and RL80 chartplotters (now obsolete) don't support AIS, thus
the PocketPC.

The PPC, running a program I wrote, has a display (for AIS) that looks more
or less like the NASA "AIS Radar", with no chart overlay. It still gets
pretty crowded, but I can turn off ship name display and then it is usable
during crowded conditions. The PPC calculates CPA, TCPA, sounds an alarm if
appropriate, etc -- all the stuff that I expect my new chartplotters to do
well, on a much larger screen. The PPC program also shows other nav data,
using dials, numeric displays, etc. I mainly use it as a "black box" to log
filtered nav and AIS data, so I can postprocess it later and remind myself
(when I am programming) of how much I enjoy sailing. I have some
interesting (to me, at least) Google-Earth tracks created from the PPC
logfiles, posted on the VALIS blog: http://www.sailvalis.com/wordpress_1/ .
The most recent posting has the tracks for VALIS and the AIS-equipped ships
heard during the Queen Mary 2 excursion. I use the PPC rather than a laptop
for this in order to keep the power consumption under control.

-Paul

Portable Gps/Plotter with AIS-Receiver Support
 

Thank you for sharing this info with us ... Very interesting and
impressive visualization!

Unfortunately, I have some older Raymarine equipment (RC530+) , that is
not compatible with any AIS-system, that I know of. Would you know, if
this is correct?

If you should recommend a well working AIS-system that can be used on a
notebook running Windows XP ... What would be your advice? - Software
and hardware? Pls note I run the RNS-5 application on the notebook using
C-Map charts, and I sail in Scandinavian waters (12V-DC/230V-AC) - if
that is of any importance for your advice. TIA!

--
Flemming Torp
Gimle/DEN-61

"Paul" skrev i en meddelelse
...

SNIP

Larry and Jack,

I took a detailed look at my NMEA logfile to see if I could
sanity-check last night's calculations. It turns out that what I
actually was receiving is fairly close to the estimates -- but not
quite as bad:

SNIP

The PPC, running a program I wrote, has a display (for AIS) that looks
more or less like the NASA "AIS Radar", with no chart overlay. It
still gets pretty crowded, but I can turn off ship name display and
then it is usable during crowded conditions. The PPC calculates CPA,
TCPA, sounds an alarm if appropriate, etc -- all the stuff that I
expect my new chartplotters to do well, on a much larger screen. The
PPC program also shows other nav data, using dials, numeric displays,
etc. I mainly use it as a "black box" to log filtered nav and AIS
data, so I can postprocess it later and remind myself (when I am
programming) of how much I enjoy sailing. I have some interesting (to
me, at least) Google-Earth tracks created from the PPC logfiles,
posted on the VALIS blog: http://www.sailvalis.com/wordpress_1/ . The
most recent posting has the tracks for VALIS and the AIS-equipped
ships heard during the Queen Mary 2 excursion. I use the PPC rather
than a laptop for this in order to keep the power consumption under
control.

-Paul

Portable Gps/Plotter with AIS-Receiver Support
 

"Flemming Torp" fletopkanelbolle2rp.danmark wrote in message
. ..
Thank you for sharing this info with us ... Very interesting and
impressive visualization!

Unfortunately, I have some older Raymarine equipment (RC530+) , that is
not compatible with any AIS-system, that I know of. Would you know, if
this is correct?

If you should recommend a well working AIS-system that can be used on a
notebook running Windows XP ... What would be your advice? - Software
and hardware? Pls note I run the RNS-5 application on the notebook using
C-Map charts, and I sail in Scandinavian waters (12V-DC/230V-AC) - if
that is of any importance for your advice. TIA!

Just across the water from where you live is a company called Seacom
(Egersund, NO). They make and sell Winchart. This software does AIS and uses
C-Map charts. A good AIS receiver would be the SR-161. They might be able to
supply the receiver too and if not, I can for EUR 199 incl. Dutch VAT.

Meindert
www.shipmodul.com

Portable Gps/Plotter with AIS-Receiver Support
 

Hi Flemming,

1) Softwa I think that If you have RN5, could be that you can
upgrade to RN6 for free? And maybe RN6 already support AIS or no?
Another option is SOB (Software On Board) from Digiboat which supports
C-Map charts too and could be free or very cheap ... In any case you
could install SeaClear (very good free software) to make the initial
tests using raster BSB or Nos/Geo Charts, and it supports home scanned
charts too.


2) Hardwa both Smart Radio SR161 and EasyAis are very good Ais
receivers, you should consider a VHF antenna splitter for ease
installation and good reception, and perhaps you could use the
"AirCable" Bluetooth Serial/Usb adapters to eliminate cables as
suggested here from someone in the beginning.


Regards

Pascal



..... should recommend a well working AIS-system that can be used on a
notebook running Windows XP ... What would be your advice? - Software
and hardware? Pls note I run the RNS-5 application on the notebook using
C-Map charts, and I sail in Scandinavian waters (12V-DC/230V-AC) - if
that is of any importance for your advice. TIA!

--
Flemming Torp
Gimle/DEN-61

Portable Gps/Plotter with AIS-Receiver Support
 

"Meindert Sprang" skrev i en meddelelse
...
"Flemming Torp" fletopkanelbolle2rp.danmark wrote in message
. ..
Thank you for sharing this info with us ... Very interesting and
impressive visualization!

Unfortunately, I have some older Raymarine equipment (RC530+) , that
is
not compatible with any AIS-system, that I know of. Would you know,
if
this is correct?

If you should recommend a well working AIS-system that can be used on
a
notebook running Windows XP ... What would be your advice? - Software
and hardware? Pls note I run the RNS-5 application on the notebook
using
C-Map charts, and I sail in Scandinavian waters (12V-DC/230V-AC) - if
that is of any importance for your advice. TIA!

Just across the water from where you live is a company called Seacom
(Egersund, NO). They make and sell Winchart. This software does AIS
and uses
C-Map charts. A good AIS receiver would be the SR-161. They might be
able to
supply the receiver too and if not, I can for EUR 199 incl. Dutch VAT.

Meindert
www.shipmodul.com


Thank you very much Meindert. Very useful. I have already been to their
homepage.

My only "concern" is, that I have to invest (time & money) in one more
navigation application ... I have already invested in RNS-5, Maptech's
Offshore Navigator, and a Danish Package, called "The Living Sea-map"
.... But I can not find any of these on an "AIS-compatibility list" ...
(I wonder why, as the two first mentioned systems come from pretty large
suppliers ?...). But I understand your answer like this: There is no
alternative to installing one more software package on my PC, if I want
to integrate AIS and C-Map charts on my notebook - right?

Do you have any idea of the possibility of using (i.e. getting access
to) the C-Maps when they are placed in the Raymarine chartplotter with a
hsb2 interface to the notebook PC running the Winchart application?
Normally, I run the RNS 5 application on the PC with the C-Map charts
residing in the chartplotter (C530+), but I'm not sure whether another
application will get access to the C-Map charts? Do you know anything
about this?

I wish, the Dutch VAT would suffice ... ;o) ... In Denmark the VAT is
25% ... It is, however, often possible to purchase things like that from
Germany or UK at reasonable prices ... incl. VAT + CIF. I will look
further into info about the SR-161 in the coming days. Do you see any
problems (technical/safety) in using a VHF antenna splitter supplying my
FM radio, the VHF and the AIS-receiver - may be even a DVB-T antenna?

Thank you for your help.

--
Flemming Torp
Gimle/DEN-61

Portable Gps/Plotter with AIS-Receiver Support
 

Hi Pacal,

"Pascal" skrev i en meddelelse
ups.com...
Hi Flemming,

1) Softwa I think that If you have RN5, could be that you can
upgrade to RN6 for free? And maybe RN6 already support AIS or no?

When I asked the Danish importer of Raymarine, I was informed, that the
major difference between RNS.5 and RNS.6 was the support of Navionics
charts in the new release ... As I'm using C-Map charts, in don't think
ver. 6 is relevant for me ...

Another option is SOB (Software On Board) from Digiboat which supports
C-Map charts too and could be free or very cheap ... In any case you
could install SeaClear (very good free software) to make the initial
tests using raster BSB or Nos/Geo Charts, and it supports home scanned
charts too.

Good idea! I have now downloaded the Australian system -SOB -, and using
my C-Map card reader, I have tried to run this system on my PC (in
simulation mode, that is, as the boat is on land and almost covered by
snow ...), and SOB reads my C-Map cassettes without problems. Seems to
be a very user friendly package with all the facilities I need ... and
from the cocumentation, I can see, the system supports AIS ... Very
interesting ...

2) Hardwa both Smart Radio SR161 and EasyAis are very good Ais
receivers, you should consider a VHF antenna splitter for ease
installation and good reception, and perhaps you could use the
"AirCable" Bluetooth Serial/Usb adapters to eliminate cables as
suggested here from someone in the beginning.

Based on yours and Meinderts response (and Bjarkes comment ...), SR161
or EasyAIS seems to be the "winners" ... I'm unfortunately a complete
amateur, when it somes to electricity/cabling etc. ... As my notebook PC
(close to the VHF) is hidden in the chart table controlling a remote
monitor, visible from the cockpit, I may not need BT - and the inherent
problems ... right? I can control the application from the cockpit using
a wireless/remote mouse.
Is the use of a VHF antenna splitter "safe"? ... I have heard some
"warnings", that in case of a malfunction of the splitter, you run the
risk of destroying the AIS receiver when using the VHF sender? Or is it
just nonsense? ...

Regards

Pascal

Regards, and thank you so much for your help!

--
Flemming Torp
Gimle/DEN-61

Portable Gps/Plotter with AIS-Receiver Support
 

Flemming,

I can see that your boat is very well equipped... I suggest strongly
that you give a visit to the web page of another sailor very well
equipped and very well documented ... It has a excellent home page
with interesting information about his experience with AIS and
specially with SOB... See the link below:

http://www.svsarah.com/Sarah/Upgrades/AIS.htm

Pascal