I have been using In-Flight on both my laptop and pda and in both cases I get no altitude information. The gps unit is a cheap one from Maplins which connects via bluetooth.



I monitered the incoming messages on the com port and get the following:



$GPGGA,081925.000,5134.2084,N,00022.1493,W,1,06,1.3,63.5,M,47.0,M,,0000*7C

$GPRMC,081925.000,A,5134.2084,N,00022.1493,W,0.19,114.94,310510,0,,A*4E



AFAICS the altitude is correctly reported in the GPGGA message as 63.5 metres. Why does this not display ?



Jim

Probably the unit is not reporting the vertical dilution of precision, in the GPGSA sentence. If SkyDemon doesn't know the precision of the vertical "fix" the data is not passed through to the instruments.

Well, that explains it, there is no GPGSA message coming out !



Is there any way to tell which gps receivers do issue this message ? I've been hunting on the internet and the closest I have got is to download the manual and look for pictures of the sample application the manufacturer supplies - in some cases it shows the output from the receiver and in one case I have seen a GPGSA message, but this doesn't seem a very reliable way.

I've never seen one that doesn't. One customer did have one that didn't, but discovered that there was a message that needed to be sent to the GPS chipset to tell it to output all messages, and sending this message before running SkyDemon solved the problem.