GPS Dropping Out

[fgd3]

Originally Posted by fgd3

What seems to be needed is some way to tell OpenCPN to look again for a GPS signal.

It seems you can force that by changing the com port, then changing it back.

Fabbian

[djmarchand]

Well sometime after one hour hyperterminal crapped out!!!

The only difference from what happened with OpnCPN is that the com port seemed to continue to be available from device manager. But no data was shown coming to Hyperterminal.

David

[donradcliffe]

I also have problems with the BU-353 and W7. Hyperterminal was giving good data, but Opencpn would not show any data flow on on the GPS/NMEA data screen.

Don't know if this is part of the problem, but the CMAPECS program with the BU-353 showed good data for position and SOG, but bad data for COG. Seems to me that I have found in the past the BU-353 does something weird with COG when it is not moving. I just gave up and went back to the XP machine--I'm developing a real dislike for my new netbook with W7 starter edition.

[CarCode]

I wonder how a GPS system should process COG when the receiver antenna is not moving?

Gerhard

[cagney]

Originally Posted by donradcliffe

I also have problems with the BU-353 and W7. Hyperterminal was giving good data, but Opencpn would not show any data flow on on the GPS/NMEA data screen.

Don't know if this is part of the problem, but the CMAPECS program with the BU-353 showed good data for position and SOG, but bad data for COG. Seems to me that I have found in the past the BU-353 does something weird with COG when it is not moving. I just gave up and went back to the XP machine--I'm developing a real dislike for my new netbook with W7 starter edition.

I have a BU-353 as well and have had to dig into the particulars of this little gps. I'm using Linux.
BU-353 has two different modes Sirf and NMEA. OpenCPN only shows a NMEA datastream with the NMEA mode on, and can't read the Sirfmode. On Linux most users has gpsd installed and gpsd handles the Sirfmode without problems, but shows no data stream.
I wonder if you for some reason are using the Sirfmode, and this could be the explanation for lack of data stream.
I have found the SirfDemo utility handy on Win to, among other things, change the output mode on BU 353.

Thomas

[CarCode]

SiRF Mode is often used for road navigation (automotive used street maps) while NMEA is the standard for nautical navigation systems. Most GPS units can be configured. See pic:

[champ8242]

Attached is my crash report from last night's run in debug mode.

The crash is not BU-353 specific, I suspect the driver is the problem! I have a Hicom with the prolific driver OpenCPN kept on running for more than 8 hours, with clean view of the satellites. I suspected a problem in previous tests.

The attached document is a word .doc document, pictures included. If there is a problem reading I can separate it in txt and jpg’s

Bart

[CarCode]

Nice documentation. As seen OpenCPN works correct: After the 6 sec timeout for the watchdog OpenCPN recognized the lost GPS signals. As I suggested already Dave (bcat) should implement a popup message into OpenCPN for such cases.

Gerhard

[champ8242]

I think the NMEA code need some handling after the watchdog to close and/or reopen the port kick.

This is why i wrote my own serial app so I can see whats happening and what to do after the crash of the driver to get it up and running again. Tonight i will let Prolific crash with my app. Will post tomorrow

Bart

[CarCode]

Some notes about BU353 and Prolific Chipset:

When our company has used RS232/USB converters to support USB for our own automotive serial devices years ago we soon found out that the Prolific converters have problems running with certain computer hardware. We have switched then to the KeySpan USA-19HS converters which never fails.
Later on we have produced our own serial devices with the FTDI chipset which provides Virtual COM Port (VCP) drivers and direct (D2XX) drivers for USB connection. A VCP driver emulates a standard PC serial port such that the USB device may be communicated with as a standard RS232 device. The D2XX driver allows direct access to a USB device via a DLL interface. This is the best solution but needs to write the appropiate software for.

You cannot change however the Prolific chipset of the BU353. So when using a BU353 you have to fiddle with the driver settings (FiFo memory and others) or even trying another computer hardware. We have had not investigated further on why Prolific fails sometimes years ago but simply abandonded it. Regarding the here reported problems it seems to me the stability of Prolific chipsets has not changed all the years.

Keep in mind also that Windows has the bad behavior that connecting an USB device into another USB connector as previously used results into a new driver installation.

[HotRod]

Just a reminder, you cannot use 2 programs at one comport at once. I don't know if you have tried to do so.
Also I would try to change the port number between com1-com4, if they are not free you could try to make some changes so that you free up one.
Vista is really "buggy" when it comes to comport handeling, and it is not every time that vista manages to drop a connection to a port after use.

As far as I know, OpenCPN is not litening for a GPS signal, but for the GPS sentences from the GPS.
There is no interaction between OpenCPN and the GPS, no triggering for start of any kind.

Another thing - I see that many people have trouble with the Globalsat BU-353, so you might want to investigate the GPS a bit more.

And David, a good GPS would be: Furuno GP-32, GP-33 (also requires a NMEA cable that does not come with the package), Garmin GPS 17x (smart sensor only, no display) something along that line should work fine.

[HotRod]

Originally Posted by CarCode

I wonder how a GPS system should process COG when the receiver antenna is not moving?

Gerhard

Usually it flickers/rotate due to inconsistent position.
It always set the coarse between two positions, so if there is a slight difference (there will always be) it will report some cog in one direction or the other..

[CarCode]

Originally Posted by HotRod

Usually it flickers/rotate due to inconsistent position.
It always set the coarse between two positions, so if there is a slight difference (there will always be) it will report some cog in one direction or the other..

Therefore OpenCPN processes an average to get a straight line of COG when you have a look into its sources. A not moving antenna results in a not usable COG as I wanted to point out with my statement.

Gerhard

P.S.
Do not use com port numbers 1 to 4 for virtual com ports e.g. with a prolific driver as they are reserved for real physical com ports.

[HotRod]

There is no such thing as a reservation of comports after win2000, you can alter the comport number as you see fit from windows XP and onwards.

But you will find many apps fail if you have the GPS on a comport higher than 10.

[cagney]

How come there is no problems on Linux with the prolific driver?
Perhaps the answer is in the drivers source code, pl2303.c, where little snippets like this can be found.

/* The PL2303 is reported to lose bytes if you change
serial settings even to the same values as before. Thus
we actually need to filter in this specific case */

Thomas