On Wed, Apr 28, 2010 at 10:32 AM, Ken Tossell wrote: > We've been using a message based on gpsd's gps_data_t. It should have > all of the fields you'd need for any GPS device, but it's pretty big: > > http://www.ros.org/doc/api/gpsd_client/html/msg/GPSStatus.html I was not aware of that message, thanks for mentioning it. As you say, it seems to have all we'd need. Providing all the gpsd information is a good proof of concept. That looks like a good starting point for a shared ROS message definition. For me, the imbedded GPSFix message would nearly suffice. It could be published on a separate topic, I suppose. I chose to add the UTM easting, northing and zone to our GpsInfo message. That is obviously unnecessary since those data can be computed from the raw latitude and longitude by anyone interested. But, it's a bit of a pain to do that, so I added those fields for our own convenience. They should *not* be included in any general-purpose GPS messages. I also included the "quality" field from the Player message. That is useful for detecting when differential GPS is or is not available. That seems to correspond to the gps_data_t status field of , but not the gps_fix_t mode field. It seems slightly odd that GPSStatus has two Header fields (including the one in GPSFix), but that makes it easy to publish GPSFix separately. Perhaps the other status fields could be published by themselves in a separate topic with the same time stamp. Then only those needing the extra information would see it and there would be no message passing overhead if no other node subscribed to it. -- joq