ActiGraph ACTITRAINER Uživatelský manuál stáhnout pdf (Strana 13)

13 | Page

15 W. Main St. Pensacola, FL 32502 tel 850.332-7900 fax 850-332-7904

Product Specifications and Functionality

Epochs and Data Storage

Data is stored on ActiGraph products in one of two ways: either post-filtered and accumulated or raw.

Post Filtered/Accumulated

Post-filtered and accumulated data is typically stored in time buckets referred to as “Epochs.” On ActiGraph devices,

“Epochs” are whole-second numbers (e.g., 1s, 5s, 60s, 120s, etc.). For each epoch interval, data samples taken from the

accelerometer inside the device at a rate of 30Hz are first filtered then accumulated before being stored in memory. For

example, a device set to collect 60 second epoch data will store 30 × 60 = 1800 accumulated samples for each enabled

axis on the device every 60 seconds.

GT3X+ devices do not store post-filtered/accumulated data – only raw data.

Raw

Devices can be set to store data in raw mode by selecting a sample frequency (12Hz or 30Hz) rather than a whole-

second number in the “Epoch” dropdown during the initialization process. When raw mode is set, devices store raw

(non-filtered/accumulated) accelerometer data (in units of gravity – G’s) directly into memory at the selected rate (12Hz

or 30Hz). When raw mode is enabled, non-accelerometer channels (steps, inclinometer, and lux) are disabled.

Data stored at 12Hz is stored at a resolution of 1/10 (0.1) G (unit of gravity). Data recorded at 30Hz is recorded at a

resolution of 1 milli-G (Plus or minus 3G limit).

The GT3X+ product stores data in raw mode at all times. Data collection frequency is variable (30Hz up to 100Hz in 10Hz

increments) and can be set during initialization. Similar to other devices, the GT3X+ stores raw accelerometer samples

in units of G’s at the indicated frequency. However, unlike other devices it also stores lux (ambient light) samples once

per second at all times. See

Appendix A for information about the *.gt3x file that is downloaded from the GT3X+ device.

The GT3X+ has a dynamic range of +/- 6 Gs.

Available Channels (Modes)

Table 8 in Memory Size and Data Storage outlines all of the data channels that can be logged on ActiGraph products and

includes the memory size for each product. For all devices except for the GT3X+, these modes can be selected during

initialization. Note that the GT3X+ collects all data channels regardless of initialization settings.

The following channel descriptions apply to several products as described in Table 8.

2-Axis/3-Axis Data

Two-Axis data collection refers to acceleration data parallel to Axis 1 and Axis 2 of a device. Individual axis data

collection is not permitted (e.g., “Only record Axis 2 data”). Axis selection options for the ASM, ActiTrainer, GT1M, and

1 2 ... 8 9 10 11 12 13 14 15 16 17 18 ... 93 94

Žádné komentáře

ActiGraph ACTITRAINER Uživatelský manuál Strana 13