I can’t figure this out and think the Venus634FLPx has at least one issue.
Speed is suppose to be in Knots and logging data to the Flash memory is giving an incorrect speed. I took this chip on a 30 mile ride to and from work and didn’t exceed 75 miles an hour on the highway but the Venus634FLPx is reporting a max speed over 100 knots for a good portion of the trip. I did the conversion from knots to miles/hr which actually would put me well over 100 miles/hr driving. So I think this chip is reporting wrong speeds. Position data looks good even when plotting to google maps. Maybe this needs a firmware update but I haven’t found one on the manufactures website. I will have to Email them I guess. Has anyone else put this chip to the test yet? Would like to see someone elses results before I email them. I have the chip with the sparkfun breakout board with the datalogging (Flash Mem) feature.
Thanks,
Brian
BrianS:
Speed is suppose to be in Knots and logging data to the Flash memory is giving an incorrect speed
In several places in AN0008_v1.4.11-datalogging.pdf it mentions speed in km/hr. That AN0008 doesn’t have the word knot when I search. See if your values are correct if you treat then as values in km/hr.
Ok, looking in the datasheet for the Chip it has speed in knots. But your right it is Km/hr. There are two Nema strings that give speed and one gives it in knots and the other is in km/hr. The datalogging feature is using km/hr. I was looking at the documentation thinking it was giving the speed results in knots. The SkyTraq software downloads and converts the logged data into 4 files as Data.log, Data.logg, rmc.nema, Data0.kml.
Data.log is a compressed data file containing captured log data. Data.logg contains decompressed data and it’s put into a text format. Data0.kml position data (google earth) works good. rmc.nema is strange because it does not show all rmc data only position,date and time. Does not show speed or altitude which it really should as that part of the $GPRMC. So, I guess speed data is actually coming from the $GPVTC string instead which displays it in km/hr units.
Well I guess I can’t complain as it is doing a good job at what does. Position data is very good. Some drifting as the unit is standing still. Drifts maybe about 3 meters max.
Thanks,
Brian