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data logger

Multifunction Extended Life (MEL) Data Logger

The Multifunction Extended Life (MEL) data logger uses precise time stamped data logging, microSD memory storage, real-time data access and USB connectivity. Available with a 16g or a 2g accelerometer sensor. The additional GPS option provides location data and precision GPS time synchronization. The MEL data logger operates as a standard USB mass storage device containing the comma delimited text data files and user setup files. The commercial standard “D” batteries (IEC R20) provides extended life operation suitable to long term data acquisition applications.

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    • Accurate time stamped data using RTC disciplined to GPS time
    • Data recorded to a removable microSD card
    • Easily readable comma separated text data files
    • Data transfer compatible with Windows or Linux via Universal Serial Bus (USB) interface (no special software)
    • System appears as USB Mass Storage Device to Windows and Linux OS’s.
    • Standard replaceable “D” type batteries (IEC R20)
    • Weighs 500g (1.1lbs) with batteries

    MEL-x16 (16g Accelerometer)

    • Analog Devices ADXL345 3-axis 16-bit +/-16g digital accelerometer
    • User selectable sample rate of 12, 25, 50, 100, 200 and 400 Hertz

    MEL-x2 (2g Accelerometer)

    • Analog Devices ADXL355 3-axis high performance 20-bit +/-2g accelerometer
    • User selectable sample rates between 1 Hz and 1000Hz

    +GPS Option

    • The GPS option adds location data and precision time alignment to the MEL-x16 or MEL-x2
    • u-Blox CAM-M8 GPS receiver module, compatible with GPS/Galileo, BeiDou, GLONASS systems
    • Internal high gain patch antenna

For more details, specifications, and how to use the MEL, please refer to the user manual (.pdf). The user manual includes an example data file and instructions for converting the data and time stamps.

The MEL logger is configured using a simple text file called config.txt located on the microSD card. Below is an example config.txt file used for the MEL-x2+GPS:

                    ; PRODUCT_ID = X2-GPS
                    ; sync'd sample rates 1 to 16 in integer increments
                    ; adxl355 sample rates 3.9, 7.8, 15.6, 31.2, 62.5, 125, 250, 500, 1000
                    SampleRate = 5
                    gain= low
                    ; GPS PARAMETERS
                    gpsOn = 1
                    ; minimum hdop required, in meters
                    gps_MinLock = 40
                    ;gps_update interval, in seconds
                    gps_sampleinterval = 1.000
                    ; used in on/off mode number of good samples to collect before turning off
                    ; 10 samples = 10 seconds which ensures a GPS time sync
                    gps_numSamples = 10
                    ; used in on/off mode, time in seconds device will spend trying to collect good samples
                    ; allow 5 min to find GPS location
                    gps_powerOnTime = 300
                    ; used in on/off mode, time, in seconds bewteen on events
                    ; check GPS once per day
                    gps_powerPeriod = 86400
                    ; discipline RTC with GPS time 
                    gps_clockThreshold = 0.010
                    ; dynamic models 0-->portable 2-->stationary 3-->pedestran 4--> automotive, 5-->sea, 6,7,8-->airborn
                    gps_dynamicModel = 0
                    ; when enabled, polled mode saves power at the expense of timing accuracy
                    gps_pollmode = 1
                    ;gps_gnssGlonass = 0x01010001  ; enable
                    ; disable Glonass
                    ;gps_gnssGlonass = 0x01010000
                    ; discard gps readings that exceed the minimum HDOP
                    ; extra parameters to logger operation
                    ; FILE PARAMETERS
                    ;set file length to 1 day
                    samplesperfile = 86400
                    ; custom directory name
                    ;dirname = /DATA
                    ; custom file prefix
                    filename = thz
                    ; set timestamp to UTC seconds since Jan 1, 1970 instead of time since start of file
                    ; EVENT DETECTOR PARAMETERS
                    deadband = 0
                    DeadBandTimeout = 5
                    ;control brightness of LEDs, values are 'off' or 'high'
                    statusindicators = high
                    ;uncomment following line to activate logger upon disconnect from USB
                    ; wakeupTime uses crontab format 
                    ; rtc alarm to wake up system
                    ; wakeupTime = 5,35  wakes up system at 5 and 35 minute after the hour
                    ; wakeupTime = 0,15,30,45 wakes up system 
                    ; wakeupTime = * wakes up system every minute
                    ; wakeupTime = 0 2,8 wakes up system at 2 and 8 AM
                    ;wakeupTime = 0,2,4,6,8,10,12,14,16
                    ; default secsToRecord is 0 , (off)
                    ;secsToRecord = 60
                    ; logical, default is to remain turned on

Data is stored to simple text formatted .csv type files, which are easily imported into any spreadsheet or analysis software (Matlab, Octave, R, etc). Below is a example data file from the MEL-x16:

                    ;Title,, X2-6, Analog Dev ADXL355, GPS
                    ;Version, 2514, Build date, Jun 13 2023,  SN:CCDC1021D5409E0
                    ;Start_time, 2007-01-01, 00:01:05.341
                    ;Uptime, 6,sec,  Vbat, 2264, mv, EOL, 1800, mv
                    ;Deadband, 0, counts
                    ;DeadbandTimeout, 5.000,sec
                    ;ADXL355, SR,1,Hz, Range, +/-2g, Hpf,off*Sr, Sens,256000,LSB/g (typ)
                    ;BMP384, SI, 0.000,sec, Units, Pa, mdegC
                    ;Alt Trigger disabled
                    ;CAM_M8 Gps, SR,1,Hz
                    ;Gps Sats, TOW, 1000, ver, 1, numSat, 0
                    ;, gnssId, svId, cno, elev, azmith, prRes, flags,inUse
                    ;Time, Ax, Ay, Az, TOW, Lat,Lon, Height(m), MSL(m), hdop(m), vdop(m)
                    1167609858.003266,227116,-115432,-8197, 411730.000, 30.2957220,-89.3669477, -69.409,-41.922, 27.478,141.470
                    1167609866.003937,227615,28,-122988, 411738.000, 30.2957194,-89.3668899, -65.174,-37.687, 25.038,119.888
  • Over seas and long term freight monitoring
  • Monitoring weather coniditions and events
  • Longterm vibration monitoring of bridges and buildings
  • Seismic monitoring