Instructor: Adi Hanuka By: Alon Berger Maor Itzhak Spring Semester 2014

1. Quick Review of the Last Presentation 2. What We Planned To Do Problems Encountered & Consequences 3. Our Progress So Far 4. What’s Next

 First “Intuition” of the signal  Plans for Future Experiments

 Main effects: ◦ Amplifies only the change from the reference voltage  Side effects: ◦ Amplitude – Frequency dependence ◦ Transient response

Hall Probe Amp Coupling A to D ABCD Analog Card

1. Frequency Dependence of Hall Sensor (Inductor Experiment) 2. Frequency Dependence of the System: 2.A: Motorized Experiment on test point A 2.C: Motorized Experiment on test point C 2.D: Motorized Experiment on test point D 3. Experiment on Glasses

 Goals: ◦ Understand the probe’s dependence on frequency ◦ Is there capacitance in the probe?  SetUp: ◦ Hall probe circuit ◦ Inductor circuit

 Results:

 Conclusion: ◦ The output amplitude is constant and independent of the frequency ◦ The hall sensor is not equipped with a built-in capacitor

 Goal: Understanding the Probe’s response to blink like motion in different frequencies  Setup: ◦ Hall probe circuit ◦ A magnet attached to a pole, controlled by a motor performing a periodical arced motion ◦ Magnet: Class = N50, Dimensions = 3x0.65mm A

 Video Demonstration ◦ Low Frequency Behavior (4Hz) ◦ High Frequency Behavior (8Hz)

 2Hz: ◦ Constant peak ◦ Two pulses per period  6Hz: ◦ Two pulses per period ◦ Different height each pulse ◦ Same height each period T = 0.5 sec T = sec

Technical Difficulties:  The system is not compatible with frequencies over 4Hz  Difficulties with keeping a fixed distance between the pole and the hall probe  Inability to set a fixed aperture for the pole’s motion  Difficulties with measuring the distance between the pole and the magnet in a sufficient scale

Results:  Near-field effects:

Results:  The peak amplitude is constant over the frequency. A new setup is required

Temporary Solution : Circular motion  New setup (*video demonstration): ◦ Hall probe circuit ◦ New pole ◦ A magnet (class N50, 3x0.65mm) attached to a pole, controlled by a motor performing fully circular motion

 Results: Amplitude ◦ Expected: constant

Conclusions:  Amplitude is constant regardless of the frequency  Near field effects  Width proportional to T (Period Time)  Better setup is still required

 Goal: Understand the output of the analog card  Set up: Same magnet, motor & pole. ◦ Analog card positioned in front ◦ Upper Sensor connected to scope  Tested 11 frequencies up to 2.8Hz C

 Results: (Frequency = 0.2Hz)

 Expected effect of the Analog Card: ◦ Transfer Function

 Results: Amplitude

Conclusions and points to note:  Frequency Response (Transfer Function) effects  Unexpected descent in the positive peak amplitude  Negative Peaks are an indication of velocity!  Is the pulse width actually that interesting?

 Goal: Understanding the output signal of the whole system  Set up: Same motor & pole. ◦ Analog card positioned in front of the pole while connected to the digital card  Tested 11 frequencies up to 2.8Hz D

 Results: (Frequency = 0.5Hz)

 Conclusions: ◦ Digitization of the signal – discrete voltage values ◦ Same frequency dependence as point C ◦ Points C, D – same signal ◦ Change in y axis’s scale Digital (Test Point D) Analog (Test Point C)

 Goal: ◦ Observation of response of the whole system to controlled blinks ◦ Comparison of blinks and arched motion setup  Experiment process – Controlled blinks: ◦ 5 slow blinks ◦ 5 fast blinks ◦ 5 very fast blinks

 Results: ◦ In fast successive blinks, amplitude rises ◦ Unexpected effects (horns)  Depends on the position of the probe? (Upper Sensor) (Lower Sensor) Eye shuts Eye opens

 Reduces risk of passing the probe! ◦ Graph: Eye closure followed by eye opening ◦ Blue line: Bent sensor. Red line: Original

 Signal changes drastically with the position of the glasses  Slight changes to the position of the probes affect the signal dramatically

 Amplitude Dependence on Frequency: ◦ In Hall Probe: None ◦ In Analog Card:  Transfer Function  Decreases as a result of an additional effect  Width: What can we learn from it?  Effects of the Capacitors in the Analog Card: Changes to the Signal Shape  Signal after A/D: Consistent with output of Analog Card  Position of Glasses: CRUCIAL for obtaining expected results  Bending the probes: A good idea to investigate

 We believe we know what signal to expect  It’s time to collect data from patients ◦ Learn about the variance between them  Find a mathematical model  New glasses are needed: ◦ Most up-to-date analog card scheme ◦ Bent probes ◦ Better positioned and more comfortable

למידה כללי איפיון הסיגנל מציאת מודל מתמטי  ספר פרוייקט, מצגת סוף  תקופת מבחנים