# Logging issue with sdlogger

**URL:** <https://discuss.px4.io/t/logging-issue-with-sdlogger/5042>\
**Category:** Flight Testing & Log Analysis\
**Created:** [December 5, 2017, 8:48am UTC](https://discuss.px4.io/t/logging-issue-with-sdlogger/5042 "2017-12-05T08:48:53Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![DQC](https://discuss.px4.io/letter_avatar_proxy/v4/letter/d/b77776/32.png) [@DQC](https://discuss.px4.io/u/DQC)\
**Post date:** [December 5, 2017, 8:48am UTC](https://discuss.px4.io/t/logging-issue-with-sdlogger/5042/1 "2017-12-05T08:48:53Z")

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I am trying to log some topics with `sdlogger` on a pixhawk with px4 v1.6.5 stable. I have several dropouts and strange sensor timestamps.

I have this `/etc/logging/logger_topics.txt`

```auto
vehicle_gps_position
actuator_outputs
sensor_accel
sensor_gyro
sensor_mag
sensor_baro
vehicle_local_position
vehicle_global_position
vehicle_attitude

```

With `ulog2csv` I get `10_53_20_sensor_accel_0.csv` and `10_53_20_sensor_accel_1.csv`. (Two IMUs are there on pixhawk, right?). If I look at the message timestamps (first column), both files start and end approximately at the same time, whereas the second has substantially less samples.

Here is a plot of the delta T between samples for the two files for a selected window of 10s. Why there is such apparent difference in the sampling rate for the two? One seem to operate at ~250Hz, whereas the other at 225. Is it correct, or there is something fundamental that I’ve misunderstood?

 ![](https://discuss.px4.io/uploads/default/original/2X/5/59fe56526dfe7cd25b301d87679652339547bff8.png)

Second, many dropouts are visible. Is this normal? I have a SanDisk Extreme U3 32GB as suggested [here](https://dev.px4.io/en/log/logging.html). Is it possible to get no dropouts for the aforesaid set of topics? Are they too many? Somewhere I’ve read that I should increase the logging buffer, but I can’t find out how.

Thanks for the help, the full log it’s [here](https://logs.px4.io/plot_app?log=52d1674b-03a9-481a-8556-7a04abedc4fa):