Advanced Topics

Question 1

Living tissue

Answer 1

is a complex arrangement of primarily lossy dielectrics, often modelled as a saline solution

Question 2

RF radiation range

Answer 2

3 kHz- 300 GHz, non-ionizing and not conclusively tied to chronic health effects

Question 3

Nerve stimulation

Answer 3

below 10 MHz, tingling, discomfort, pain

Question 4

Tissue heating

Answer 4

several adverse effects for body temperature rising 1 degree C or more

Question 5

Health Canada’s Safety Code 6

Answer 5

defines limits to prevent adverse health effects from RF radiation

Question 6

RSS-102

Answer 6

The ISED adoptions of Health Code 6 for radio communication apparatus

Question 7

ISED

Answer 7

Innovation, Science and Economic Development Canada

Question 8

Basic restrictions

Answer 8

SAR (W/kg), APD (W/m^2), internal E-field (Vrms/m)

Question 9

ISED TN-261

Answer 9

reflected amplitude ~60% of the direct path

Question 10

Radiopropagation

Answer 10

attenuation on the order of 100dB, multipath leads to rapid fluctuations of 10’s of dB over time and space, relative motion of Tx and Rx or in the environments leads to Doppler shifts

Question 11

Components of the Superheterodyne Receiver

Answer 11

Rx Antenna
RF Amplifier
Mixer
Local Oscillator
Bandpass Filter
IF Amplifier (gain control)
Phase Lock Loop (frequency control)

Question 12

LO is tuned to

Answer 12

maintain a fixed intermediate frequency (IF)

Question 13

IF amp is tuned to

Answer 13

maintain a fixed IF output power

Question 14

Radio performance is limited by

Answer 14

noise

Question 15

Thermal noise

Answer 15

The most fundamental types of noise, all particles above absolute zero undergo thermal vibrations. Charges vibrating in a resistive medium produce random noise voltages.

Question 16

At RF thermal noise is

Answer 16

spectrally white, zero-mean and Gaussian distributed (AWGN)

Question 17

Radio receiver noise sources

Answer 17

shot noise, flicker noise

Question 18

Shot noise

Answer 18

tends to be similar to thermal noise so we add them (AWGN)

Question 19

Flicker noise

Answer 19

has 1/f characteristic, which we avoid by choosing a suitable IF

Question 20

Minimum acceptable SNR

Answer 20

10 dB

Question 21

Noise Figure

Answer 21

quantifies the reduction in SNR from input to output of a noisy device

Question 22

Noise figure assumes

Answer 22

matched on all ports and input noise temperature is To = 290K. Often quoted in dB

Question 23

Terrestrial Radio Propagation modes

Answer 23

Sky waves
Ground waves
Line of sight waves

Question 24

Sky wave significant frequency

Answer 24

3MHz and down

Question 25

Ground wave significant frequency

Answer 25

30MHz and down

Question 26

LOS wave significant frequency

Answer 26

VHF (30-300MHz) and up

Question 27

What increases the limit of LOS

Answer 27

radio signals bend back due to refraction