dcasey63
Posts: 7
Joined: Wed Jul 11, 2007 2:40 pm
Location: USA

No Lat/Lon seen by application software.

Wed Jul 11, 2007 2:48 pm

We have installed an Electronic flight bag using GpsGate 2.5 as a gateway to WXWorks and Jeppeson Flight Deck as well as other chart viewing sofware. We are feeding converted ARINC 429-NMEA formatted data to the EFB via rs232-USB converter to the USB port. Device manager assigns Com5 to the USB port. I Configured Gpsgate to look at com5. The tray icon turns green I click on settings, the settings box say I something like "GPS DATA POSITION VALID". I configure four Virtual output ports with different settings for each hoping to be able to get the various software to see position data. I have GPSVIEWER by Holux, which autodetects each vitual port I configured in GPSGATE. Yet when I select each one in GPSViewer, it shows strings of data with no position info. I put GPSGate in Simulation mode and GPSViewer sees position. My question is, why is the GPSGATE saying position valid yet nothing else is seeing position? I would like to know my aircraft systems are doing what they are supposed to do. Is there a GPSTOOL which can view lat/lon from the NMEA formatted data feeding GPSGATE? Is it sofware issues? What makes GPSGATE turn green, the data being there or lat/lon being there? Three software companies blame lack of data. How can I know for sure what is coming into Flight bag.
> Thanks
> Dan Casey
> Avionics tech
> Cessna Citation service center

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johan
GpsGate
Posts: 15293
Joined: Wed Aug 04, 2004 10:40 pm
Location: Sweden
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RE: No Lat/Lon seen by application software.

Wed Jul 11, 2007 2:58 pm

Sounds like the GPS is sending NMEA that says "valid" but it doesn't include position information. Maybe the GPS doesn't have enough satellite signals (indoors?). Normally a GPS says "invalid" in this situation.

Connect Hyperterminal to one of the virtual ports, and post the output you get as an answer here, and I can say for sure why.

Regards,
Johan

Franson Support

dcasey63
Posts: 7
Joined: Wed Jul 11, 2007 2:40 pm
Location: USA

RE: No Lat/Lon seen by application software.

Thu Aug 02, 2007 2:14 pm

Here are a couple of files I captured. One was the input, the nextwas the virtual com port out, and the last I am not sure. I tried NMEA DATA LOGGER as output. It asked for file location. I created it. Then let system run. I went to look at it using NMEA LOGGER and error 32 came up. Hopefully these files tell you what we need to know. I see the following.
$GPRMC,074446.00,V,0000.00,N,00000.00,E,0.0,0.0,020807,0.0,E*47.

The 0.0,0.0, is probably suppose to be position data in both files. I am working at same hours you are working so I'll monitor Email and get back quickly with responses to your questions. I have the airplane 1.5 days. Could you let me know what I can try.

Thanks
Dan Casey
Avionics Tech.
Cessna Citation Center

dcasey63
Posts: 7
Joined: Wed Jul 11, 2007 2:40 pm
Location: USA

RE: No Lat/Lon seen by application software.

Thu Aug 02, 2007 2:19 pm

Sorry forgot to attach files. How do I attach files. Do I copy text and paste?

*******Boot up of input port to Franson Gate************



GDC34
001B
04Aug2005

Flash memory CRC OK.

Extern RAM OK.

ARINC Port Speed: Lo
$GPRMC,074446.00,V,0000.00,N,00000.00,E,0.0,0.0,020807,0.0,E*47
$GPRMC,074447.00,A,,,,,,,020807,0.0,E*6A
$GPRMC,074448.00,A,,,,,,,020807,0.0,E*65
$GPRMC,074449.00,A,,,,,,,020807,0.0,E*64


THIS IS MONITORING FRANSON'S VIRTUAL COM 1 OUTPUT @9600

$GPRMC,075834.00,A,,,,,,,020807,0.0,E*63
$GPRMC,075835.00,A,,,,,,,020807,0.0,E*62
$GPRMC,075836.00,A,,,,,,,020807,0.0,E*61
$GPRMC,075837.00,A,,,,,,,020807,0.0,E*60
$GPRMC,075838.00,A,,,,,,,020807,0.0,E*6F
$GPRMC,075839.00,A,,,,,,,020807,0.0,E*6E
$GPRMC,075840.00,A,,,,,,,020807,0.0,E*60
$GPRMC,075841.00,A,,,,,,,020807,0.0,E*61
$GPRMC,075842.00,A,,,,,,,020807,0.0,E*62
$GPRMC,075843.00,A,,,,,,,020807,0.0,E*63
$GPRMC,075844.00,A,,,,,,,020807,0.0,E*64
$GPRMC,075845.00,A,,,,,,,020807,0.0,E*65
$GPRMC,075846.00,A,,,,,,,020807,0.0,E*66
$GPRMC,075847.00,A,,,,,,,020807,0.0,E*67
$GPRMC,075848.00,A,,,,,,,020807,0.0,E*68
$GPRMC,075849.00,A,,,,,,,020807,0.0,E*69
$GPRMC,075850.00,A,,,,,,,020807,0.0,E*61
$GPRMC,075851.00,A,,,,,,,020807,0.0,E*60
$GPRMC,075852.00,A,,,,,,,020807,0.0,E*63
$GPRMC,075853.00,A,,,,,,,020807,0.0,E*62
$GPRMC,075854.00,A,,,,,,,020807,0.0,E*65
$GPRMC,075855.00,A,,,,,,,020807,0.0,E*64
$GPRMC,075855.00,A,,,,,,,020807,0.0,E*64
$GPRMC,075855.00,A,,,,,,,020807,0.0,E*64
$GPRMC,075855.00,A,,,,,,,020807,0.0,E*64
$GPRMC,,A,,,,,,,,0.0,E*4D *****I pulled CB here.
$GPRMC,,A,,,,,,,,0.0,E*4D
$GPRMC,,A,,,,,,,,0.0,E*4D
$GPRMC,,A,,,,,,,,0.0,E*4D
$GPRMC,,A,,,,,,,,0.0,E*4D
$GPRMC,,A,,,,,,,,0.0,E*4D
$GPRMC,,A,,,,,,,,0.0,E*4D
$GPRMC,,A,,,,,,,,0.0,E*4D
$GPRMC,,A,,,,,,,,0.0,E*4D *****I Reset CB here
$GPRMC,235942.00,V,,,,,,,280707,0.0,E*75
$GPRMC,235948.00,V,,,,,,,280707,0.0,E*7F
$GPRMC,235948.00,V,,,,,,,280707,0.0,E*7F
$GPRMC,235948.00,V,,,,,,,280707,0.0,E*7F
$GPRMC,235948.00,V,,,,,,,280707,0.0,E*7F
$GPRMC,235948.00,V,,,,,,,280707,0.0,E*7F
$GPRMC,235948.00,V,,,,,,,280707,0.0,E*7F
$GPRMC,081331.00,A,,,,,,,020807,0.0,E*66
$GPRMC,081332.00,A,,,,,,,020807,0.0,E*65
$GPRMC,081333.00,A,,,,,,,020807,0.0,E*64

User avatar
johan
GpsGate
Posts: 15293
Joined: Wed Aug 04, 2004 10:40 pm
Location: Sweden
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RE: No Lat/Lon seen by application software.

Thu Aug 02, 2007 2:20 pm

The data you post says that the GPS doesn't know anything about its position. This means that you are under a roof (it cannot get any sat signals). Or that the GPS is broken.

Regards,
Johan

Franson Support

dcasey63
Posts: 7
Joined: Wed Jul 11, 2007 2:40 pm
Location: USA

RE: No Lat/Lon seen by application software.

Thu Aug 02, 2007 2:31 pm

We Have a repeater in our building and have no problem locking on. We picked off of the 429 feeding the aircrafts main Flight Managment System's arinc 429 . The FMS shows 12 sats and has locked on. The Franson icon on icon tray is green and say something like "Valid position data". You can see in the txt where I pulled Circuit breaker which killed Flight managment system's GPS input. It then flagged. It came back alive when GPS C.B. pushed back in. Could I be losing the data through a 429-NMEA converter OR RS232-USB converter?

dcasey63
Posts: 7
Joined: Wed Jul 11, 2007 2:40 pm
Location: USA

RE: No Lat/Lon seen by application software.

Thu Aug 02, 2007 2:39 pm

I will monitor Virtual port out of Franson Gate with Hyper terminal to see what is sent. In the past, the software still would not show aircraft position in simulator mode. Is there a trick. I bekieve it has you put Lat Lon and Alt.

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johan
GpsGate
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Joined: Wed Aug 04, 2004 10:40 pm
Location: Sweden
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RE: No Lat/Lon seen by application software.

Thu Aug 02, 2007 3:00 pm

$GPRMC,081333.00,A,,,,,,,020807,0.0,E*64

The "A" means "valid position data, but there is no data.

This means that your GPS does not work, and it does not follow the NMEA standards. There is simply no position information as simple as that, you need to examine your GPS, contact your dealer, or take any other action related to your GPS hardware.

Regards,
Johan

Franson Support

dcasey63
Posts: 7
Joined: Wed Jul 11, 2007 2:40 pm
Location: USA

RE: No Lat/Lon seen by application software.

Thu Aug 02, 2007 4:09 pm

Did not mean to make you angry.[B)] I understood you. I just wanted to make it clear we have position lock. Whether the converter is passing it on is another matter I have to deal with. The GPRMC format output may not be compatible or the 429-NMEA doesnt recognize the 429 format. I just have to answer to people and am covering my bases. Each manufacture blames the other and my customer get frustrated with us.[:(!]
Thanks

richardhula
Posts: 96
Joined: Sun Jul 17, 2005 6:33 pm

RE: No Lat/Lon seen by application software.

Fri Aug 03, 2007 2:01 am

Hi Dan

This is spec to NMEA RMC sentence, one of several that are output by GPS engines giving lat/long position:

$GPRMC
Recommended minimum specific GPS/Transit data.
NMEA 0183 version 3.00 adds the Mode indicator field #12. Earlier versions don't have this.

$GPRMC,hhmmss.ss,A,llll.ll,a,yyyyy.yy,a,x.x,x.x,ddmmyy,x.x,a,m*hh

Field #
1 = UTC time of fix
2 = Data status (A=Valid position, V=navigation receiver warning)
3 = Latitude of fix
4 = N or S of longitude
5 = Longitude of fix
6 = E or W of longitude
7 = Speed over ground in knots
8 = Track made good in degrees True
9 = UTC date of fix
10 = Magnetic variation degrees (Easterly var. subtracts from true course)
11 = E or W of magnetic variation
12 = Mode indicator, (A=Autonomous, D=Differential, E=Estimated, N=Data not valid)
13 = Checksum

Hopefully you can now see that your data is incomplete. The only reason that GpsGate icon turns green is that its is receiving some sort of NMEA & that status field shows "A" for valid data. In keeping with most other GPS applications, its this validity flag that GpsGate monitors in order to assert the presence of valid position data.

This suggests to me that your GPS is faulty or some hardware between it & GpsGate is filtering out the lat/long data & leaving the null fields.

As an avionics engineer you should be well able to find where things are going wrong.

Regards - Richard

dcasey63
Posts: 7
Joined: Wed Jul 11, 2007 2:40 pm
Location: USA

RE: No Lat/Lon seen by application software.

Fri Aug 03, 2007 1:28 pm

I believe I have figured out the discrepancy. Avionics systems are alot more expensive due to the nature of flight safety. We have status indicators that turn green only when really valid data is recieved. They are yellow when communication is established but data is incomplete. In your case the A or V status label is all that is being looked at. The 429/232 unit sending the valid isn't distinguishing real valid versus partial valid. The wording position valid threw me off. I went further up stream and found 429 data no containing Lat/Lon labels, but date and time were present. You would think the real Engineers that put the system together would have caught that. We are guinney (?) pigs. Rewire required. Sorry for taking the wording so literal. Thanks for the tolerance.

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