In the circuit provided in the practical for the IR transmitter-receiver (TCRT1000), how is the signal amplified?

A customer complains that the system occasionally triggers alerts for deviations smaller than the estimated just-noticeable difference. Which of the following best explains this behaviour, and how might the system be adjusted to better meet the customer’s expectations?

A robotic inspection system uses a proximity sensor to evaluate the height of stacked packages and raise an alert if there is a deviation from the target height of 10.0 cm.

To assess performance, engineers run 20 trials at various deviations from the standard height and record whether the system triggers an alert. They record the following alert frequencies for height differences from the reference (in mm):

Δh=[0.5,0.7,0.9,1.1,1.3,1.5]

and corresponding alert rates (%): [5,25,45,75,85,95]

Fit a logistic psychometric curve to these data and estimate the 50% detection threshold (i.e., the system’s effective JND in mm).

Give your answer as X.XX mm

Based on the relative permittivity you calculated, what is the most likely material that was introduced? 

Hint: Table A.5 has dielectric constants for a range of materials.

Using the formula for a parallel plate capacitor with a dielectric, C=\kappa\epsilon_0\frac{A}{d}, and knowing the plate separation is 0.5 mm and the plate area is 1.0 cm², determine the relative permittivity \kappa of the unknown material that would explain the increased capacitance.

A capacitive sensor is used to measure the level of a non-conductive liquid in a tank. The sensor consists of two vertical parallel plates. As the liquid level rises between the plates, what happens to the overall capacitance?

In a capacitive pressure sensor, what role does the silicon diaphragm play?

A capacitive sensor excited with a high-frequency signal includes a guard ring to improve its performance. If the guard ring is removed, what is the most likely impact on sensor performance?