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Tips and questions relating to the GPS modules from SFE
By wenoweur

My understanding from the sometimes poorly translated Geochron pdf manual is that the following settings should provide me with a log containing three lines of text at one second intervals.

Mode = 1
Log What = RMC;GGA;GSA
Time Between Logs = 00:00:01
Holdoff = 0
WAAS = 0

Instead I get the three lines somewhere between 5-7 seconds apart. After a lot of trials it seems that the following will give me logs of between 1-2 seconds apart.

Mode = 1
Log What = RMC;GGA;GSA
Time Between Logs = 00:00:00
Holdoff = 1
WAAS = 0

What bothers me is that this doesn't correspond at all to what I would expect after reading through the manual. I had, perhaps erroneously, assumed that the time between logs is a setting for the logging interval, and that the hold off was a setting to discard a certain number of position estimations since initial fix information is usually sketchy. What I also do not understand is why the logger can't actually log positions every second (not 1 or 2 seconds).

We have 110 of these loggers that we're using with accelerometers for a study and I've found this to be the case in 6 of them so far.

Any one else had any issues with the GLOGCON settings or can someone explain this behaviour (and possibly how to rectify it)?


By MontanaTrout
I had the same problem you had. Please post the details how to resolve the problem

By wenoweur
The issue I had was with the interpretation of the manual.

So, here's how it works. If in Mode 0 then the device logs everything

If in Mode 1 or 2 then you can specify the NMEA sentences but the 'time between logs' value is the time between log files NOT THE LOGGING INTERVALS. You use the holdoff to specify the logging time intervals, i.e. log the sentences every 1 s. However, I find that even if set at 1 s the logger values are saved at 1 or 2 s intervals.

Hope that helps. Must be a translation from the original manual.
By MontanaTrout
How do you control the log files? If I want per day per log file, what setting I should apply? Would you please post your config file? (GLOGON)

Hello Daniel,

I'm thinking of buying a Geochron for some work in Fairbanks, Alaska, but I would like to see the manual first. I didn't see it on the SparkFun website, and they haven't yet answered by phone message or email inquiries. Would you mind emailing me a copy? My email is

I want to make sure that I can, in some mode(s), log all of the following at least once every 2 seconds: time, date, lat, long, altitude. Some modes seem to do some of these, but I didn't see one mode that does all. Can I poll for several modes and still get all of this at least every other second?


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By FartingMonkey92
FDG, i think the datasheet is the manual... :wink: