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| [[Image:Measure-icon.svg]]
| | == Measure == |
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| ==About==
| | Read at https://help.sugarlabs.org/measure.html |
| This Activity draws a picture of the sound heard by the internal microphone or of the signal present on the microphone socket. More specifically it draws a graph of this input versus time, the input is on the vertical axis and time is on the horizontal axis. That is, the laptop functions like a machine called an oscilloscope.
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| As well as graphing signal as a function of time, Measure can also graph as a function of frequency.
| | The source file has been moved to [https://github.com/godiard/help-activity/blob/master/source/measure.rst GitHub] |
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| The XO-1 laptop is only capable of mono input, the XO-1.5 and XO-1.75 are capable of stereo input on their microphone socket and can graph two signals at once. | |
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| '''Note:''' As of Measure Version 37, old versions of Sugar, e.g. 0.84, are no longer supported.
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| [[File:Measure tut 1 24.jpg|center|300px]]
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| ==Using==
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| [[image:Measure-screen.JPG|600px|center]]
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| 1. Select secondary toolbar - allows the Activity's Journal entry to be renamed
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| 2. Select secondary toolbar - measurement settings
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| 3. Select secondary toolbar - tuning settings
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| 4. The selected input type - Sound (AC voltage), resistance or DC voltage
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| 5. The time scale
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| 6. Freeze the display
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| 7. Capture sample now - saves an image of the wave in the Journal
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| 8. Stop - exits the Activity
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| 9. Mute - mute/unmute channel
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| 10. Invert - invert the display
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| 11. Use these sliders to control the sensitivity
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| 12. The settings that are selected
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| [[File:Measure2ndtoolbar.JPG|600px|center]] | |
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| The sensor toolbar - measurement settings
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| 13. Sound - use this setting with the internal microphone, external microphone and external AC signals
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| 14. Resistance sensor - use with external resistive type transducers
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| 15. Voltage sensor - use with external sensors which generate a voltage
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| 16. Time base/frequency - graphs the signal vs. time or graphs amplitude vs. frequency
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| 17. Sample interval - a text file 'Measure Log' is saved to the journal, it contains one sample per interval
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| 18. Starts/stops saving a text file 'Measure Log' with measured values as readable text
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| 19. Trigger - synchronise the sample period to the waveform so that the sample will start on a rising edge or falling edge
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| [[File:Measure3rdtoolbar.JPG|600px|center]]
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| The tuning toolbar - frequency settings
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| '''Hint:''' Adjust the time scale (#5) to increase the spacing between the tuning lines.
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| 20. Instrument - select instrument to tune
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| 21. Note entry - select a note for tuning
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| 22. Frequency entry - enter a frequency to mark
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| 23. Show/hide tuning mark
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| 24. Show/hide harmonics
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| 25. Play a note
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| 26. Measured note
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| ==Applying==
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| Let the children experiment with the internal microphone, try singing, whistling, musical instruments, the Tam Tam musical Activity. The Turtle Blocks Activity can generate an audio tone.
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| The children should learn through guided discovery that:
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| * sound is a pressure wave
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| * the pitch of the sound is determined by the frequency or cycles per second (Hz)
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| * the loudness of a sound is determined by the amplitude
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| * sounds contain multiple frequency components or harmonics
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| * the more pure sounds have less harmonics
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| ==Sharing==
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| This Activity does not currently support sharing.
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| ==Extending==
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| Measure is able to take input from a wide range of external sensors including switches, photocells, temperature sensors, inductive loops, hall effect sensors, soil probes and many more.
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| Care should be taken not to exceed the allowable input voltage:
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| * XO-1 -0.5V to 5V
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| * XO-1.5 -6V to +9V
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| * XO-1.75 -6V to +9V
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| It is a good idea, particularly on the XO-1, to put a resistor of 680 ohms in the phono plug, this increases the allowable input voltage range.
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| [[image:Audio 680 ohm.jpg|center|300px]]
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| ===Plotting===
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| You can use save data from measure to the Sugar Journal using the Capture feature described above ([[Activities/Measure#Using|16]]). These data can then be imported into [[Activities/SimpleGraph#Graphing_Measure_data|SimpleGraph]], where they are displayed.
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| [[File:SimpleGraph8.png|center|300px]]
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| ===More ideas===
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| You can find ideas for fun science experiments at http://wiki.sugarlabs.org/go/Activities/TurtleArt/Using_Turtle_Art_Sensors and http://wiki.laptop.org/go/Measure
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| ===Building sensors===
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| There are detailed instructions for building sensors at [http://wiki.laptop.org/go/Measure#How_to_build_low_cost_sensors].
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| ===Adding instruments===
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| You can add new instruments to tune by modifying the instrument dictionary in config.py.
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| [[Category: Activity]]
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