Max Logging Frequency with iBlue 747A+

E2nO's picture

Hi all,

I am not sure if this is the correct board for placing my question, but so far I have not foulnd any better place:

Does anyone know, what the maximal internal logging frequency in the iBlue 747A+ logger is? The only information that I have found so far was for the QStarz BT-Q1000x - which is supposed be be identical build than the iBlue:


My Travel Recorder can not log 5Hz data?


The update rate stands for the rate of GPS refreshing nmea data received from satellites. Thus 5Hz update rate only means GPS can receive or refresh nmea data 5 times per second, and it's irrelevant with 5Hz logging. So far all of Qstarz data loggers are only capable of 5Hz update rate but not 5Hz logging.

However this just tells me, what is NOT possible ... so I wonder if it would be possible to log (internally) more than one record per second with setting (fix freq 0,200s) trigger distance to 1m and speed limit to 18km/h. Because in this example a speed of 10km/h would trigger a fix all 0,36seconds ... I just wonder if this will work with this specific logger (or if you know any other modell that this will work correctly with).

Otherwise I will always have to carry my cell phone with me to do the NMEA logging ... (not sure if the old Nokia 6500C will be fast enough doing this ...)

Thank you already,

Regards Enno.

mdeweerd's picture

Hi The 747 A+ is capable of


The 747 A+ is capable of 5Hz logging.

You are partially correct in saying that a 5Hz update rate is not 5Hz logging.  You need to set 5Hz update rate to be able to have 5Hz logging.

The log conditions are evaluation when a new fix (valid or not) is available.  So if you have 5Hz update rate, this is every 0.2 seconds.  In your example, when you are doing 10km/h  your speed is 2.7m/s or 0.55m/0.2s.  Hence you would log a position every 0.4 seconds (and not every 0.36 seconds) because you only know the movement on the fix.

Further, some of these devices change the log conditions to what they consider 'acceptable'.  Holux is strong at this (limiting the device settings) which may be both for marketing reasons but also for support reasons (the less you accept the less unknown situations you have).  As far as I know, the iBlue 747A+ does not have that.  Qstarz did not go as far as Holux, but they do have some restrictions as I remember it.

The only thing that is a bit annoying is that the fix frequency is lost when power is lost (battery removed or empty).  In that case you need to reconfigure the device for a 5Hz fix.  The log conditions are maintained, but without the 5Hz fix, you'll not have 5Hz logging.


E2nO's picture

Thank you for your fast

Thank you for your fast response, Mario!

Your last sentence actually made me now understand and reproduce the "problem" with the logger: It is possible to configure 5Hz logging, if the logger is set to logging mode and you change the "time" parameter with the BT7474 application to "0.2". So you get 5HZ logging with no other condition (Speed/Distance) required.

However, as soon as you either turn the logger switch to navigation mode or off, the value will automatically be reset to 5 second intervall.

I think that behaviour is ok in terms to avoid unrecognized "flodding" of the buffer. But of course it would have been nice if this would have been documented somewhere ... but then then the "user documentation" of the iBlue 474A+ does not have earned this name anyway. Luckily we have web2.0 for this.

Anyway, I now completely understand (all) the configuration options that I have (thanks to the BT747 application and the documentation provided here and on Dirk's pages) for my iBlue 747A+. Now I only need to find out, what I really want to have .

Regards, Enno.