Accelerometer Real-Time Graph

Operation instructions for the Accelerometer Real-Time Graph screen

Windows macOS Linux RasPi

Overview

This refers to packets received from TWELITE CUE and TWELITE Motion Sensor PAL. It can display accelerometer data in real-time, and includes features for frequency analysis and CSV export.

In the Accelerometer Real-Time Graph, each sample data is processed separately. On the other hand, the Sensor Graph records one packet as one sample, even when continuous measurement with multiple samples per packet is performed.

It supports three modes: CUE mode, MOT mode, and 2525 FIFO mode.

When a continuous series of samples reaches a certain number (analysis window), frequency analysis of the XYZ axes is displayed. However, in 2525 FIFO mode, it is assumed to be always continuous.

When packet boundaries are explicit (e.g., when more than 3 seconds have elapsed since the previous packet, in CUE mode for each packet, or in MOT mode when the packet sequence number is discontinuous), four dummy samples are inserted and a pink background is shown.

Data from up to four nodes are stored on a first-come, first-served basis.

When operating multiple nodes, packet collisions cause many communication failures. Especially in FIFO mode, transmission intervals are almost fixed, and nodes try to transmit packets nearly simultaneously, which may cause prolonged transmission failures due to interference. As a rule, operate one node per wireless channel.

The factory default TWELITE CUE is set to TWELITE CUE mode.

For continuous data measurement, please switch to Motion Sensor PAL mode.

Typical settings for Motion Sensor PAL mode when using the Accelerometer Real-Time Graph are as follows:

To measure continuously at about 25Hz
- t: set Transmission Interval (0)
- p: set Sensor Parameter (03000000)
To measure continuously at about 50Hz
- t: set Transmission Interval (0)
- p: set Sensor Parameter (03000100)
To measure continuously at about 100Hz
- t: set Transmission Interval (0)
- p: set Sensor Parameter (03000200)
To measure 128 samples at about 100Hz every ~10 seconds
- t: set Transmission Interval (10)
- p: set Sensor Parameter (03000208)
To measure 256 samples at about 100Hz every ~10 seconds
- t: set Transmission Interval (10)
- p: set Sensor Parameter (03000210)
To measure 64 samples at about 50Hz every ~10 seconds
- t: set Transmission Interval (10)
- p: set Sensor Parameter (03000104)
To measure 128 samples at about 200Hz every ~10 seconds
- t: set Transmission Interval (10)
- p: set Sensor Parameter (03000308)

Operation

Operation	Description
Top right `(i)ID#` button	Click to switch the ID. (Note: Continuous sample data in FIFO mode is not suitable for multi-ID operation)
Top right `(f)SMP#` button	Click to change the analysis window size among 64, 128, and 256.
Bottom right `(c)Save Display Data` button	Exports data in CSV format to the `log` folder. Outputs from the oldest sample in the buffer to the latest sample at the right edge of the screen. (Note: The output is always 5120 samples, with the latest data at the end)
Bottom right `PAUSE( )` button	Pauses display updates. (Note: Samples are still collected until the internal temporary sample buffer is full)
Mouse drag (Graph area)	Moves the position of displayed samples.
Mouse drag (Bottom scrollbar)	Moves the displayed sample position in larger steps.
Arrow keys `→` `←`	Moves the sample display area.
Arrow keys `↑` `↓`	Zooms in/out on the horizontal axis of samples (1x / 2x / 3x / 4x). (Note: Up to 2x when the analysis sample count is 256)

Sample Rate Estimation

The sampling rate is calculated from the packet reception times. It averages the reception times of multiple past samples to estimate one sample interval, so packet drops may cause significant errors. Also, the related log timestamp (T_SMPL) is an estimated value and is delayed compared to the packet acquisition time. Once sample rate estimation completes, graph scrolling becomes smooth.

Opening the CUE Graph Mode on Startup

Specify 31 in [STAGE Common Settings → Startup App Selection].

Log Output (Save Display Data)

Pressing the (c) Save Display Data button outputs up to 512 samples starting from the current display position (rightmost sample).

Note that the latest samples are recorded at the end, so there may be no data at the beginning.

Log file name is {log folder}/acc_snap_{timestamp}.csv.

Data has the newest sample at the right edge as sample number 512 (file end).
When frequency analysis is performed, the last samples used for frequency analysis are included.
Frequency analysis results are added to rows containing frequency analysis target samples (for 64 samples, results appear from sample 449 for 32 rows, showing from DC to high frequency components).

Label	Item Name	Description
`#`	Sample Number
`T_PKT[ms]`	Packet Reception Time	Multiple samples may be included in one packet, so samples with the same timestamp are listed.
`SEQ`	Packet Sequence Number	Assigned to each packet; continuity indicates no packet loss.
`T_SMPL[ms]`	Sample Time (Virtual/Estimated)	Timestamp generated for each sample from packet reception time. Does not match the actual sampling time. (Note: Sample rate is estimated from packet reception intervals, and sample times are cumulatively added, so timestamps are delayed by one packet interval compared to actual sample time)
`X[G]`	X-axis Sample Value	Unit is `G`. Based on sensor values.
`Y[G]`	Y-axis Sample Value	Unit is `G`. Based on sensor values.
`Z[G]`	Z-axis Sample Value	Unit is `G`. Based on sensor values.
`FD#`	Frequency Analysis Calculation Index	For 64 samples, ordered as `DC,1,2,...,31`.
`Hz`	Frequency Analysis Frequency Axis Value	Estimated frequency, calculated as `(FD# / FD_Len) * FD_Freq`.
`X`	Frequency Analysis Value on X-axis
`Y`	Frequency Analysis Value on Y-axis
`Z`	Frequency Analysis Value on Z-axis
`Label`	Additional Info Name	See table below
`Info`	Additional Info	See table below

Additional Information

Info Name	Description
`ModuleSID`	Serial number of the sender
`Tick[ms]`	System time when the log file was opened (Note: TWELITE STAGE app side)
`Date`	Date when the log file was opened
`Time`	Time when the log file was opened
`Time_Msec_part`	Sub-second part of time when the log file was opened [ms]
`Samples`	Valid sample data
`FD_Len`	Frequency analysis sample count
`FD_Start#`	Frequency analysis start sample number
`FD_Freq`	Estimated frequency range for frequency analysis [Hz] (Note: estimated from sample reception interval)

Log Output (Auto Save)

When the Accelerometer Real-Time Graph screen is opened and data is input, log files are automatically saved.

Log file name is log folder/accel_{serial number}_{timestamp}.csv.

While the screen is open, files are being written, so they may not be available for reading or may be incomplete.

Label	Item Name	Description
`#`	Sample Number
`T_PKT[ms]`	Packet Reception Time	Multiple samples may be included in one packet, so samples with the same timestamp are listed.
`SEQ`	Packet Sequence Number	Assigned to each packet; continuity indicates no packet loss.
`T_SMPL[ms]`	Sample Time (Virtual/Estimated)	Timestamp generated for each sample from packet reception time. Does not match the actual sampling time. (Note: Sample rate is estimated from packet reception intervals, and sample times are cumulatively added, so timestamps are delayed by one packet interval compared to actual sample time)
`X[G]`	X-axis Sample Value	Unit is `G`. Based on sensor values.
`Y[G]`	Y-axis Sample Value	Unit is `G`. Based on sensor values.
`Z[G]`	Z-axis Sample Value	Unit is `G`. Based on sensor values.
`Label`	Additional Info Name	See table below
`Info`	Additional Info	See table below

Additional Information

Info Name	Description
`ModuleSID`	Serial number of the sender
`Tick[ms]`	System time when the log file was opened (Note: TWELITE STAGE app side)
`Date`	Date when the log file was opened
`Time`	Time when the log file was opened
`Time_Msec_part`	Sub-second part of time when the log file was opened [ms]