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GprsModemPowerOff debug log and its impact on uptime calculation

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AtaydeMM-8256
Original Poster

Hi everyone,

We are currently evaluating the performance and connectivity of GO9B devices. In our evaluation strategy, we established that logs associated with the GprsModemPowerOff state do not necessarily imply a loss of connectivity. We consider this to be the standard operational behavior of the device when the vehicle is stationary and transmitting data at 30-minute intervals.

Since our measurement methodology accounts for this time with the GPRS module disabled, this period is excluded from the actual disconnection calculation. This allows us to obtain a more accurate assessment of the average device availability (uptime) during the analyzed period.

When analyzing our data to confirm this, we found a clear power cycle sequence in the devices that validates this behavior: the system transitions from GprsModemPowerOff to GprsModemPowerOn and finally to ModemConnectionSuccess.

However, a question has arisen internally regarding whether the presence of the GprsModemPowerOff log is completely normal within the device's communication cycle.

My main question is: Does this state actually affect connectivity time and should it decrease the uptime percentage, or is it correct to exclude it from the total calculation as we have been doing?

I did some research and found a related query here: https://support.geotab.com/community/post/2194/records-found-in-collisions-and-log-data, but I would like to get specific guidance on how this impacts availability metrics.

Kind regards,

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EishiFUN
Community Administrator

Hi@AtaydeMM-8256 , great question!

Your interpretation is generally correct, with one important distinction: GprsModemPowerOff should not be treated as a connectivity failure by itself.

When a GO9B is stationary, it can enter a low-power state and power down the cellular modem between scheduled communications. General GO device guidance indicates that, after a vehicle stops, the device normally communicates approximately every 30 minutes for the first 48 hours. After an extended period of inactivity, the heartbeat interval can change to approximately every 23 hours. Low power mode also reduces heartbeats to approximately every 23 hours.

A sequence such as:

GprsModemPowerOff → GprsModemPowerOn → ModemConnectionSuccess

is consistent with the device waking for a scheduled heartbeat and successfully reconnecting. In that situation, the modem-off period is expected power management, not a cellular outage or device fault.

For availability calculations, I recommend measuring against the device's expected communication opportunities, rather than treating every modem-off interval as downtime:

- Do not count an expected modem sleep interval as a connectivity failure.
- Do not count that interval as active connected uptime either.
- Use a grace period based on the applicable heartbeat interval, plus reasonable processing and transmission tolerance.
- Treat the device as having a genuine communication outage when it fails to wake and reconnect within the expected interval.

I would not automatically exclude every GprsModemPowerOff record. The surrounding sequence and timing are important. A normal sleep cycle should be followed by a modem wake-up and successful reconnection. Repeated connection failures, missing expected heartbeats, or a gap extending beyond the expected interval would require further investigation.

In short, for a stationary GO9B, it is reasonable to exclude expected modem sleep time from the connectivity denominator, provided the device wakes and reconnects as expected. I would report planned sleep time separately from both connected uptime and genuine communication outages.

Hope that helps clarify the methodology!
Eishi FUN

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