ESP32S2 FTM Measurements

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Submitted by:
Valentin Barral
Last updated:
Wed, 07/07/2021 - 10:33
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This dataset includes FTM WiFi measurements made with several ESP32-S2 devices in different indoor and outdoor environments. The measurements include the actual distance between devices as well as the RTT (Round Trip Time) values generated by the module.


# ESP32 S2 FTM Measurements



FTM measurements were created using several ESP32-S2 devices. They are presented in two different formats: rosbag ( format and matlab format.


## ROS BAG records


The measurements can be found in the directories:


- AC

- Indoor

- Outdoor


The ROS messages are of type ESP32S2FTMRangingExtra and ESP32S2FTMRanging. These message types can be found in the following repository:


The following fields are included within each message:


- anchorId: Identifier of the module that acted as beaconin the measurement.

- rtt_raw:   RTT   value   averaged   among   the   differentframes sent. In nanoseconds.

- rtt_est:  RTT  estimation  created  by  the  ESP32-S2firmware. In nanoseconds.

- dist_est:  Distance  estimation.  Internally,  the  rttestvalue is used to calculate this value. In meters.

- num_frames: Number of frames successfully sent dur-ing the RTT communication.

- frames: A list of all successfully sent frames.


Each individual frame includes the following information:

- rssi: Received signal strength. In dBm.

- rtt: RTT value in that frame. In nanoseconds.

- t1:  Outgoing  timestamp  of  the  first  packet  from  thesender. In picoseconds.

- t2: Timestamp of reception of the ranging request at thereceiver. In picoseconds.

- t3: Timestamp of the response message at the receiver.In picoseconds.

- t4:  Timestamp  of  reception  of  the  response  messagefrom the receiver at the sender. In picoseconds.


## Matlab logs


The measurements in matlab format are in the .mat file. This file includes four 1x1 struc elements:


- indoor

- outdoor20

- outdoor40

- sa


Each of these structures has the following fields:


- actualDist: Actual distance.

- rttRaw: RTT   value   averaged   among   the   differentframes sent. In nanoseconds.

- estDistRaw: Distance estimate using rttRaw.

- absErrRaw: Absolute distance error of estDistRaw.

- rttEst: RTT  estimation  created  by  the  ESP32-S2firmware. In nanoseconds.

- estDistEst: Distance estimate using rttEst.

- absErrEst: Absolute distance error of estDistEst.

- varRtt: variance of RTT

- meanRtt: mean of RTT

- countRtt: count of RTT

- meanRss: mean RSSI

- distEst: Distance estimate using own algorithm.



More info about this measurements can be found in the next paper (under review):


Fine Time Measurement in low-cost microprocessors for the Internet of Things

Dataset Files

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