UAS Communication Systems

Question 1

What affects data link quality?

Answer 1

frequency, medium, and length of link

Question 1

What is a data link?

Answer 1

When a source and receiver communicate electronically
3 parts:
- transmitter
- receiver
- medium (free space/air)

Question 2

How do data links transmit shit?

Answer 2

Electromagnetic waves bro. Short ones hurt like a bitch and r gammas, radios r normal. i love raidio eevjndcxkcvnkncjznjz

Question 3

formula for wavelength?

Answer 3

λ = v/f (frequency)

Question 4

What happens when the EMs are received?

Answer 4

It gets converted to electrical energy, and it also needs to be like amplified with a low noise amplifier that’s close to the antenna cuz the signal becomes weak when traveling between antennae

Question 5

What’s receiver sensitivity? How is it measured?

Answer 5

• The required signal-to-noise ratio for the receiver
• the minimum power required by the receiver to detect an RF signal and demodulate the
  data
• dBm, decibel milliwatts

Question 6

What can cause noise in wireless communication systems?

Answer 6

Electronic devices, mixing of two different signals, impulse noise, & crosstalk

Question 7

What’s FSK?

Answer 7

• Frequency Shift Keying
• method of transmitting digital data by shifting the frequency of a carrier signal to represent binary 1s and 0s

Question 8

What does despreading the signal mean and why is it used?

Answer 8

• signal spread over large frequency band and then the receiver knows how to piece together the spread out signal. They can do this because both the transmitter and receiver have a code that controls the frequency changes (this part wasn’t in the slides its just really cool)
• It reduces noise

Question 9

What does demodulation do?

Answer 9

Takes the despread data and turn it into a binary stream of data

Question 10

EMI?

Answer 10

Electromagnetic Interference

Question 11

How do electromagnetic interference and jamming impact UAVS?

Answer 11

• EMI: In crowded airspace, an antenna may receive signals intended for others, leading to interference
• Jamming: PPL LITERALLY JUST HIJACK THE DRONE. WILD. BUCK; WILD!
• Both GNSS signals and UAV-GCS links are susceptible to jamming threats.

Question 12

What can multipath signals do?

Answer 12

• interfere constructively or destructively with the direct signal
• GNSS addresses this through signal processing techniques