Physics 3: Maxwell's Top Data Acquisition

Maxwell's Top First Week

Before using the Data Acquisition (DAQ) scrips you must start matlab.
Placing a semicolon at the end of a matlab command will turn off the echo on the screen of the returning values.

Torsional Pendulum Measurements
Use the command MTPeriod to measure the total time to complete a given number of oscillations. Example:

>>MTPeriod(20)

Note that the first count should not be considered to estimate the oscillation period.

Constant Acceleration Measurement
Use the command MTCounterSave to measure the top's revolutions versus time. Example:

>>MTCounterSave('MyData.out',60);

Data will be collected for 60s, and counts vs. time will be saved into the file 'MyData.out'.

Maxwell's Top Second Week

Revolution Period Measurement
Tachometer GUI program to measure the revolution frequency (in minutes) and indirectly measure the precession frequency. Click once on the ph3 desktop icon called "Tachometer" to launch the program.

Matlab scripts for the Maxwell's Top Experiment

Parameters' name are written in italics. Each parameter's name must be replaced with a proper value. Optional parameters are enclosed in curly brackets. Curly brackets don't have to be typed.

Placing a semicolon at the end of a command will turn off the returning values echo on the screen.

Command List

MTCounter
MTCounterSave
MTPeriod
MTPeriodDisplay

MTCounter

Purpose: Counts the Maxwell's Top oscillations or revolutions using the acquired pulses.

Synopsis: C = MTCounter({AcquTime {, Threshold}})

Parameters:

AcquTime: total acquisition time in seconds. Optional parameter. Default 60s
Threshold: voltage level to trigger the pulse. Optional parameter. Default values 1/2 of the pulse height

Return values:

C : matrix. First column time in seconds, second column counts.
Return Error:
C = -1, if the program is unable to count.and the following error message is shown:
'cannot count, sensor is not close enough to the Maxwell Top, or something is broken'
Examples:
C = MTCounter;
C = MTCounter(100);

MTCounterSave

Purpose: Count Maxwell's Top oscillations/revolutions using the reflective sensor and save results into a file

Synopsis: C = MTCounterSave(Filename{, SamplingTime {, Threshold}})

Parameters:

Filename: File name where data will be saved.
SamplingTime: data acquisition time in seconds. Optional parameter. Default values is 60.
Threshold: Voltage level to trigger the pulse. Optional parameter. Default values 1/3 of the peak's height

Return values:

C : matrix. First column time in seconds, second column counts.
A plot oscillations/Revolutions versus time is shown.
Return Error:
C = -1, and the following error message is shown:
'cannot count, sensor is not close enough to the Maxwell Top, or something is broken'
Examples:
MTCounterSave('Harvey.txt');
C = MTCounterSave('Harvey.txt',100);

MTPeriod

Purpose: estimate the average revolution or oscillation period T using the Maxwell's Top reflective sensor.

Synopsis: [Period, Periods, Max] = MTPeriod({SamplingPeriod{,Threshold}})

Parameters:

SamplingTime: data acquisition time in seconds. Optional parameter. Default values is 2.
Threshold: voltage level to trigger the pulse. Optional parameter. Default values 1/3 of the peak's height
Return values:

Period: revolution/oscillation period in seconds.
Periods: Number revolution/oscillation period found.
Max: maximum peak height value in volts.

Return Error:
Period = -1, and the following error message is shown:
'something wrong in the acquired data. Check raw data in plotted in the current figure'
Examples:
MTPeriod;
[T, N , Vmax] = MTPeriod(100);

MTPeriodDisplay

Purpose: estimate the average revolution or oscillation period T using the Maxwell's Top reflective sensor, and continuosly display the result on the screen.

Synopsis: MTPeriodDisplay({SamplingPeriod{,Threshold{,Threshold}}})

Parameters:

SamplingTime: data acquisition time in seconds. Optional parameter. Default values is 2.
Threshold: voltage level to trigger the pulse. Optional parameter. Default values 1/3 of the peak's height
N: number of measurements
Return values:

None
Return Error:
The following error message is shown:
'cannot count, sensor is not close enough to the Maxwell Top, or something is broken.'
Examples:
MTPeriodDisplay;

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