[rickp]

Managed a few days sailing using the iPad with iNavX as the main 'chartplotter'. So here are a few things that I'd like to see:

Selectable units for depth - metres please, to match my paper charts

AIS - sometimes I wasn't seeing a CPA for some of the AIS targets which had a CPA on MacENC. Was this because MacENC was on all the time (so had calculated a CPA, whereas the iPad wasn't on all the time)? How does iNavX calculate the CPA?

AIS - would be nice to have a list arranged by lowest CPA, then closest. I don't mind if the big ships are close as long as they're ahead of me

AIS - Need to know if the CPA is ahead of, or behind the particular target.

AIS - An alarm for CPA would be good, on an adjustable distance. Give me warning of anything that has a CPA of less than 1nm for instance.

Routes - didn't really get to play with this as we just worked out the course to steer and used the autopilot for that bit.

Currently, I'm working on an embedded device to take in several serial streams and multiplex them out over WiFi for iNavX and MacENC. Then I don't need to have the laptop on all the time. I'll have the device log position so I have my track, speed and wind etc. I can also make it track AIS targets and feed the 'static' information to any new TCP connection to prime things, so to speak. Any other suggestions for this?

Great product - looking forward to future enhancements.

Cheers,
Rick

[GPSNavX]

Units for depth is selected in iNavX main menu ->"Setup" -> "Units". "m" for meters for "Depth".

iNavX and MacENC use exact same code/logic for CPA/TCPCA calculation. Both require valid: COG and SOG of your vessel and valid SOG and COG of the AIS target to be computed.

[rickp]

Units for depth is selected in iNavX main menu ->"Setup" -> "Units". "m" for meters for "Depth".

Thanks! Keep forgetting there's a 'setup' on the main menu.

iNavX and MacENC use exact same code/logic for CPA/TCPCA calculation. Both require valid: COG and SOG of your vessel and valid SOG and COG of the AIS target to be computed.

Okay - so they should have been seeing the same data, given iNavX got its feed from the laptop which was hooked to the NMEA feed. We didn't spend long looking at it - we just popped inside to the laptop to check the CPA when we didn't see it on the iPad.

Will do some more exploration next time...

Cheers,
Rick

[GPSNavX]

Did you have "AIS Targets Only" set to "ON" in the TCP/IP NMEA Client setup? If so then COG and SOG would be coming from the iPad versus from the laptop. I would recommend you make sure it is "OFF" so all NMEA data is used.

Another thing to realize is MacENC is running non stop, but each time iNavX is started you need to give it some time to receive all the AIS target info..

http://www.navcen.uscg.gov/?pageName=AISBroadcasts

It may be that iNavX had not yet received the targets position, course or speed which is needed to compute CPA and TCPA.

With iOS 4.2 (November release) this will be less of an issue because apps won't be exited, but only suspended.

[rickp]

Did you have "AIS Targets Only" set to "ON" in the TCP/IP NMEA Client setup? If so then COG and SOG would be coming from the iPad versus from the laptop. I would recommend you make sure it is "OFF" so all NMEA data is used.

Yes, that is off.

Another thing to realize is MacENC is running non stop, but each time iNavX is started you need to give it some time to receive all the AIS target info..

Understood - but this was occuring even after iNavX had been on a while - or so it seems. I'll do more investigation next time we're out.

I plan to have my nmea->wifi box cache the AIS info and the moment a new tcp connection arrives (when the iPad is switch on), I'll send down all the AIS information immediately - to improve things. I'll start with just the static info (type 5 and type 24 messages I guess). No reason why this couldn't be extended to the latest position reports for each target (given appropriate expiry mechanisms in the cache of course).

With iOS 4.2 (November release) this will be less of an issue because apps won't be exited, but only suspended.

Does that mean the iNavX application will maintain the tcp connection when I switch to another app? What about if the iPad is switched off?

Cheers,
Rick

[GPSNavX]

iNavX will not maintain the TCP/IP connection when suspended (or exited), but does re-establish the connection when unsuspended (or re-launched).

The important difference with iOS 4, is iNavX is not exited and hence loses all the AIS data previously received.