LoRa modulation technique in IOT Protocols - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to set the spreading factor in LoRa modulation.

IOT Protocols

lora.set_spreading_factor([1])

Drag options to blanks, or click blank then click option'

A15

B7

C5

D12

Attempts:

3 left

💡 Hint

Common Mistakes

Using a spreading factor outside the 7-12 range causes errors.

The spreading factor in LoRa modulation ranges from 7 to 12. Setting it to 12 provides the highest sensitivity and longest range.

2fill in blank

medium

Complete the code to set the bandwidth for LoRa modulation.

IOT Protocols

lora.set_bandwidth([1])

Drag options to blanks, or click blank then click option'

A125000

B500000

C200000

D1000000

Attempts:

3 left

💡 Hint

Common Mistakes

Using bandwidth values not supported by the hardware.

LoRa bandwidth is commonly set to 125 kHz (125000 Hz) for a balance between range and data rate.

3fill in blank

hard

Fix the error in the code to set the coding rate in LoRa modulation.

IOT Protocols

lora.set_coding_rate([1])

Drag options to blanks, or click blank then click option'

A5/4

B4/5

C"4/5"

D"5/4"

Attempts:

3 left

💡 Hint

Common Mistakes

Passing coding rate as a numeric expression instead of a string.

The coding rate must be passed as a string like "4/5" to the LoRa library function.

4fill in blank

hard

Fill both blanks to create a LoRa packet with payload and set the header mode.

IOT Protocols

packet = lora.create_packet([1])
lora.set_header_mode([2])

Drag options to blanks, or click blank then click option'

A"Hello LoRa"

BTrue

CFalse

D"World"

Attempts:

3 left

💡 Hint

Common Mistakes

Using non-string payload or wrong boolean for header mode.

The payload is the string "Hello LoRa" and the header mode is set to False for implicit header mode.

5fill in blank

hard

Fill all three blanks to configure LoRa with spreading factor, bandwidth, and coding rate.

IOT Protocols

lora.set_spreading_factor([1])
lora.set_bandwidth([2])
lora.set_coding_rate([3])

Drag options to blanks, or click blank then click option'

A10

B125000

C"4/5"

D7

Attempts:

3 left

💡 Hint

Common Mistakes

Using numeric coding rate or invalid spreading factor.

Spreading factor 7, bandwidth 125000 Hz, and coding rate "4/5" are common LoRa settings for balanced performance.

Practice

1. What is the main modulation technique used by LoRa for long-range communication?

easy

A. Amplitude Modulation

B. Frequency Modulation

C. Phase Shift Keying

D. Chirp Spread Spectrum

Solution

1. Step 1: Understand LoRa modulation basics

   LoRa uses a special modulation technique designed for long-range and low power.

2. Step 2: Identify the specific technique

   LoRa uses Chirp Spread Spectrum, which spreads the signal over a wide frequency band.

3. Final Answer:

   Chirp Spread Spectrum -> Option D

4. Quick Check:

   LoRa = Chirp Spread Spectrum [OK]

Hint: Remember LoRa uses chirps, not simple frequency or amplitude shifts [OK]

Common Mistakes:

• Confusing LoRa with traditional Frequency Modulation
• Thinking LoRa uses Amplitude Modulation
• Assuming Phase Shift Keying is used

2. Which of the following is a valid spreading factor value in LoRa modulation?

easy

A. SF7

B. SF3

C. SF12.5

D. SF15

Solution

1. Step 1: Recall valid spreading factors

   LoRa spreading factors range from SF7 to SF12 in whole numbers.

2. Step 2: Check each option

   SF7 is valid; SF3 is too low, SF12.5 and SF15 are invalid as they are not integers or out of range.

3. Final Answer:

   SF7 -> Option A

4. Quick Check:

   Valid SF = 7 to 12 integers [OK]

Hint: Spreading factors are whole numbers between 7 and 12 [OK]

Common Mistakes:

• Choosing non-integer spreading factors
• Selecting values outside the 7-12 range
• Confusing spreading factor with bandwidth

3. Given a LoRa device configured with Spreading Factor 10, Bandwidth 125 kHz, and Coding Rate 4/5, what is the expected effect on data rate compared to SF7 with the same bandwidth and coding rate?

medium

A. Data rate increases

B. Data rate becomes zero

C. Data rate decreases

D. Data rate stays the same

Solution

1. Step 1: Understand spreading factor impact

   Higher spreading factor means longer chirps, which lowers data rate but increases range.

2. Step 2: Compare SF10 to SF7

   SF10 is higher than SF7, so data rate decreases compared to SF7 with same bandwidth and coding rate.

3. Final Answer:

   Data rate decreases -> Option C

4. Quick Check:

   Higher SF = lower data rate [OK]

Hint: Higher spreading factor means slower data rate [OK]

Common Mistakes:

• Assuming data rate increases with spreading factor
• Ignoring bandwidth and coding rate effects
• Confusing data rate with signal range

4. A LoRa device is set with Bandwidth 250 kHz but the receiver only supports 125 kHz. What is the likely problem?

medium

A. Communication will fail due to bandwidth mismatch

B. Device will automatically adjust bandwidth

C. Data rate will double without issues

D. Spreading factor will compensate for bandwidth

Solution

1. Step 1: Check bandwidth compatibility

   Both sender and receiver must use the same bandwidth for successful communication.

2. Step 2: Analyze mismatch effect

   If device uses 250 kHz but receiver supports only 125 kHz, signals won't match, causing failure.

3. Final Answer:

   Communication will fail due to bandwidth mismatch -> Option A

4. Quick Check:

   Bandwidth mismatch = communication failure [OK]

Hint: Sender and receiver bandwidth must match exactly [OK]

Common Mistakes:

• Assuming automatic bandwidth adjustment
• Thinking spreading factor fixes bandwidth issues
• Believing data rate doubles without problems

5. You want to maximize battery life for a LoRa IoT sensor that sends data once per hour over a long distance. Which combination of settings is best?

hard

A. Low Spreading Factor (SF7), High Bandwidth (500 kHz), Low Coding Rate (4/5)

B. High Spreading Factor (SF12), Low Bandwidth (125 kHz), High Coding Rate (4/8)

C. Medium Spreading Factor (SF9), Medium Bandwidth (250 kHz), Medium Coding Rate (4/6)

D. High Spreading Factor (SF12), High Bandwidth (500 kHz), Low Coding Rate (4/5)

Solution

1. Step 1: Understand battery life factors

   Higher spreading factor and coding rate increase time on air but improve range and reliability, reducing retransmissions.

2. Step 2: Match settings to long distance and low power

   High SF and low bandwidth increase range; high coding rate improves error correction, reducing retries and saving battery.

3. Step 3: Evaluate options

   High Spreading Factor (SF12), Low Bandwidth (125 kHz), High Coding Rate (4/8) uses high SF, low bandwidth, and high coding rate, best for long range and battery life. Others sacrifice range or reliability.

4. Final Answer:

   High Spreading Factor (SF12), Low Bandwidth (125 kHz), High Coding Rate (4/8) -> Option B

5. Quick Check:

   Max battery life = high SF + low BW + high CR [OK]

Hint: Use high SF and coding rate with low bandwidth for long range and battery life [OK]

Common Mistakes:

• Choosing low SF for long distance
• Using high bandwidth that wastes power
• Ignoring coding rate's effect on retries