actigraph/gt3x-file-format

Documentation of the ActiGraph .gt3x file format

gt3x-file-format's Issues

Fill out Epoch4 log record

Fill out this record: https://github.com/actigraph/GT3X-File-Format/blob/master/LogRecords/Epoch3.md

Changes in axes directions across device/firmware versions?

Hello, could you clarify whether the axes directions have changed across device/firmware versions? If yes, which device/firmware version should I use as rule to identify the orientation of the axes?

I am looking at gt3x files collected in 2016 with device serial numbers starting with CLE and firmware version 2.5.0, they were worn on the hip.

My impression from the raw data is that the x-axis represents the longitudinal axis because it has close to zero gravity throughout the night and more gravity during the day as opposed to the other axes which have time periods when they pick up a lot of gravity during the night.

This seems to contrast with the ActiGraph axes definitions I can find online where the y-axis is consistently shown as the longitudinal axis for an ActiGraph worn on the hip. For example in this post on your website.

I remember hearing that the axes definitions have changed at some point in time, but I cannot remember the details. If you could clarify that would be much appreciated.

UPDATE: I see that axis rotation specific to "wGT3X-BT (Serial Numbers "MOS") firmware version 1.6.0" is discussed in here but that would not explain my observations for CLE and firmware 2.5.0.

Fill out Epoch log record

Fill out this record: https://github.com/actigraph/GT3X-File-Format/blob/master/LogRecords/Epoch.md

Fill out Epoch2 log record

Fill out this record: https://github.com/actigraph/GT3X-File-Format/blob/master/LogRecords/Epoch2.md

Log record type 19?

I'm parsing a .gt3x file generated by a MOS2 device, firmware: 1.9.2, and I see records of type 19, which is not listed in https://github.com/actigraph/GT3X-File-Format#log-record-types.

Is this a new type? Is there any information at all about it?

thank you in advance!

Fill out Capsense log record

Fill out this record: https://github.com/actigraph/GT3X-File-Format/blob/master/LogRecords/Capsense.md

Fill out SensorData log record

Fill out this record: https://github.com/actigraph/GT3X-File-Format/blob/master/LogRecords/SensorData.md

Confusion around ```PARAMETERS Packet - ID 21```

I have been trying to reimplement the encoding and the decoding function for the floating number for the parameter packet, but the examples shown seem to deviate from c# code. Not sure which one is the right one to follow.

For instance, when encoding 30, the documentation gives us 1E 00 00 00 00 whereas the sample encode function yields:

01 00 0A 00 1E 00 00 00 | SAMPLE_RATE: 30 Hz.

Of course, some of the values in the reference match with the sample function but many don't. Is there a mistake in the documentation, if so what we should follow for the decoding for the floating point?

extra sample in SENSOR DATA packet

I am trying to read GT3X files from a GT9X IMU to get raw accelerometer/gyro/magnetometer readings. I am expecting every SENSOR DATA tagged packet to have 100 samples, but sometimes (infrequently but throughout all my GT3X files) a packet contains 101 samples, calculated from the payload size divided by the number of bytes per sample as determined from the corresponding sensor schema. Right now I'm assuming the first 100 samples are the good samples, and 'skip' the extra sample. Although the final data appears to be correct, I'm not sure if I am handling this issue correctly using this rule.

Fill out Tag log record

Fill out this record: https://github.com/actigraph/GT3X-File-Format/blob/master/LogRecords/Tag.md

Fill out Parameters log record

Fill out this record: https://github.com/actigraph/GT3X-File-Format/blob/master/LogRecords/Parameters.md

assert self.idle_sleep_mode_activated

I am getting an assert error for some gt3x files:
reader.py -> line 164 -> assert self.idle_sleep_mode_activated

Does GT3X file log the idle.sleep.mode setting?

Am I correct to conclude that the GT3X file does not log whether idle.sleep.mode was turned on or off?

At the moment I scan the file for timestamp gaps larger than 5 seconds, which I then use as a crude indicator of whether idle.sleep.mode was turned on.

If not, then it would be good if you could add this in future updates of the file format as it would provide a more complete description of the data and it would ease processing the files (knowing how much memory to allocate). Further, it may be good if you could store the number of samples (data points) in a file, which in combination with start-end time would also provide insight into the degree of timegaps.

Thanks

Fill out SensorSchema log record

Fill out this record: https://github.com/actigraph/GT3X-File-Format/blob/master/LogRecords/SensorSchema.md

Timezone and daylight saving questions

I am parsing an array of GT3XPlus data with Firmware version of 2.3.0. I just have a few questions around time zone which I had a hard time finding the solutions to.

1. All the timestamps are encoded in UNIX time format but they are not UTC time right but rather the local time w.r.t. GMT?
2. How is daylight saving being indicated? I have two files, one in standard time and the other one in DST, however, the TimeZones in info.txt are the same for these two files. Shouldn't DST being reflected there, i.e. the DST file will have the an additional time offset?

Fill out Activity2 log record

Fill out this record: https://github.com/actigraph/GT3X-File-Format/blob/master/LogRecords/Activity2.md

Fill out Epoch3 log record

Fill out this record: https://github.com/actigraph/GT3X-File-Format/blob/master/LogRecords/Epoch3.md

Activity records with 1 byte payload?

I'm parsing a .gt3x file generated by a MOS2 device, firmware: 1.9.2, and I get some Activity records (type 0) that have a payload of only 1 byte. So they can't be parsed as YXZ samples. What are these records? Do they have a meaning? Or is the file got corrupted somehow? The rest of the file parses just fine.

I did try contacting [email protected], like you suggested in another issue, but got a reply that this is "outside of the scope of what [they] can support".

Thank you in advance!

Fill out Heart_Rate_ANT log record

Fill out this record: https://github.com/actigraph/GT3X-File-Format/blob/master/LogRecords/HeartRateAnt.md

Is file format of .GT3X (upper case) the same as .gt3x (lower case)?

I recently learnt that the ActiGraph Center Point service generates .GT3X files, with the extension in upper case.
When I replace it by lower case extension I am able to process the file as if it was a .gt3x file.

Can you confirm that .gt3x and .GT3X are the same file format? Or are there subtle differences in the format that users need to be aware of?

Fill out HEART_RATE_BLE record