question

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GPS Sample Rate

I have a 4GModemGPS fitted with an external antenna connected to a Cerbo GX. When downloading my GPS track history KML file through VRM, Google Maps shows only some partial blue tracks. Do I need to increase the sample rate and if so, how do I do this?

gps
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2 Answers
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pwfarnell answered ·

Gaps in the KML file can be caused by losing the GPS signal so no position is logged, so if it is on a vehicle or boat this can happen if you travel into a dead spot such as a tunnel, narrow cutting or the antenna is shielded by something as the orientation changes.

You change the sample rate the same as the rest of VRM, menu, settings, VRM Portal, Log interval.

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Thanks pwfarnel, I travelled approx 70km along the M1 between Southport and Brisbane. Track log had very long sections of no data. I have increased the sample rate from 15mins to 1min. Will see next time I take the caravan out. Cheers
remigius avatar image
remigius answered ·

Pls note the shortest logbook interval time with VRM is 1 minute. Driving at 120 km/hr this results in one measurement per 2 kilometers. The GNSS receiver standard setting is likely 1 Hz = 60 times higher, one measurement per approx 33 meters (at 120 km/hr). A GX device combined with a GNSS receiver works fine for finding your vehicle once stolen.


Text in Cerbo GX manual concerning sample time:

Set to anything between 1 minute and 1 day. Choose longer times on systems with an unreliable connection. Note that this setting does not affect reporting problems and state changes (bulk → absorption) to the VRM Portal. These events initiate an immediate transmission of all parameters.

The last sentence explains why sometimes the resolution of GNSS data is higher.

Question:

can a cyclic event be created in the Cerbo GX which triggers transmission to VRM portal? This would improve the GNSS resolution. ie something connected to the external ports?


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