5343 HW3

In a Guided Wave Radar Level Transmitter for two liquids of different densities, a very short pulse of ___ is applied to the probe at the coupler.

microwave energy

In a Guided Wave Radar Level Transmitter for two liquids of different densities, a pulse encounters a discontinuity in the _ at the boundary between the air and the upper fluid level surface.

dielectric constant

In a Guided Wave Radar Level Transmitter for two liquids of different densities, software inside the electronics module measures the _ between the initial pulse and the reflected one.

time

In a Guided Wave Radar Level Transmitter for two liquids of different densities, the energy not reflected by the upper fluid is ___ through it.

transmitted

In a Guided Wave Radar Level Transmitter for two liquids of different densities, the electronics uses to reconstruct a waveform for both levels duplicating the actual real time signal, but at a much lower speed.

time domain reflectometry

In Frequency Modulated Continuous Wave (FMCW) technology a continuous signal is generated by a .

voltage-controlled oscillator

The signal in a Frequency Modulated Continuous Wave (FMCW) technology emits much more ___ than that of a pulsed radar system transmitter with the same peak amplitude.

energy

In Frequency Modulated Continuous Wave (FMCW) technology the higher energy signal mitigates the _ due to foam and turbulence at the liquid level.

signal attenuation**

In Frequency Modulated Continuous Wave (FMCW) technology the frequency of the continuous wave signal is linearly modulated over time, starting from the lowest ___ up to the highest one.

frequency

In Frequency Modulated Continuous Wave (FMCW) the sweep duration is chosen independently from the bandwidth, and the ___ of the signal is very high.

spectral purity

High frequency signals (75-85 GHz) suffer more _ than low frequency signals when propagating through a medium

attenuation

High frequency signals (75-85 GHz) are more likely than low frequency signals (6 – 11 GHz) to have problems with _, foam and dust.

condensation

High frequency signals are more susceptible than low frequency signals to of the antenna.

attenuation***

Microwaves remain unaffected by surface turbulence if the __ is larger than the ripple size.

wavelength

In an FMCW level transmitter foaming liquids may cause weak and varying surface echo ___.

amplitude

Microwaves are _ from a wet foam surface, which means that the foam level is detected, not that of the liquid.

reflected

FMCW level transmitters have a ___ handling function, which allows the user to select if the foam layer or product surface should be used as output.

double surface

In an FMCW level transmitter air purging may be required to prevent clogging of the _ in high condensation conditions

antenna

You can mount an FMCW level transmitter in a still-pipe to isolate the surface from _.

turbulence

FMCW technology is unaffected by mild _ and low-pressure steam.

condensation

LiDAR systems operate at much higher ___ than radar systems.

frequencies

In Continuous Wave (CW) LIDAR a __ in the receiver compares the phase shifted version of the received signal with the original signal.

phase comparator

A pulsed LIDAR system transmits a short, light pulse from a __ pulsed laser

semiconductor

In a pulsed LIDAR system light emitted by the laser is first focused by a to create a narrow beam.

lens

In a pulsed LIDAR system the optical detector is typically a PIN or _, which produces a small current proportional to the return signal.

avalanche photodiode

How does the range of a LIDAR system depend on the laser power?

It is proportional to the square root of the laser power

How do pulsed LIDAR systems meet both the safety limits and the performance requirements? (Check all that apply)

They have a high energy pulse for a short amount of time

They transmit their pulses at a very low duty cycle

Optical pressure sensors use an optical method of measuring __ .

deflection

As blood pressure increases, the membrane of an optical pressure sensor deflects inward, inducing a between two light beams created within the sensor assembly.

phase delay

In an optical pressure sensor a fiber optic light pipe connects the light source to the sensor, with the output light beams received by a _ .

photodiode

An optical pressure sensor is immune to _ because the sensor does not conduct electricity

EMI

Semiconductor temperature sensors make use of the temperature dependent relationship between the base-emitter voltage and the collector current of a _.

BJT

How does the voltage of a semiconductor temperature sensor depend on the temperature measured?

It is directly proportional to the temperature

How does the voltage of a semiconductor temperature sensor depend on the charge of an electron?

It is inversely proportional to the charge

Because of the non-linear temperature dependency of the collector current, many sensor designs use _circuits to eliminate the temperature impact of collector current and IS all together.

PTAT

Which one of these items below are challenges of designing a temperature measurement system for measuring human skin temperature? (Check all that apply)

The sensor must make good physical contact with the patient’s skin in order to assure effective thermal contact.

The sensor must be thermally isolated from all other heat sources.

You need to select material for the sensor that will not corrode when exposed to the skin.

Which one of these items correctly describes how Sensirion CMOSens® flow measurement technology works? (Check all that apply.)

A heating element on the microchip adds a small amount of heat to fluid passing in a microchannel.

It implements the principles of a thermal mass flow sensor