Bluetooth & BLE · Study deck
Quizzes and Practice Problems
Worked example: For a 15-question quiz, target correct answers are ⌈0.8×15⌉=12.
Radio Remi is your guide for this deck.
After studying this chapter
Learning objectives
You will be able to:
- Explain: The scenario questions shift from recall to diagnosis: each stem gives you the product constraint, and the correct answer is the one that explains the failure mode without inventing extra evidence.
- Explain: The useful test is whether a learner can look at a product situation and choose the role, GATT model, pairing method, key behavior, implementation check, or debugging evidence that fits.
- Explain: The mathematical gist: At 20 dB SNR, Shannon’s ceiling is 6.66 Mbit/s for a 1 MHz channel and 13.3 Mbit/s for 2 MHz.
Major section
Putting Numbers to It · In 60 Seconds
Worked example: For a 15-question quiz, target correct answers are ⌈0.8×15⌉=12.
- The designer must decide how it advertises, connects, shares data, saves power, protects the user, and recovers when the phone disappears.
- A list of radio terms is not enough.
Major section
Phoebe's Field Notes: What The Channel Actually Carries · Key Concepts
The mathematical gist: At 20 dB SNR, Shannon’s ceiling is 6.66 Mbit/s for a 1 MHz channel and 13.3 Mbit/s for 2 MHz.
- Scatternet: Overlapping piconets where a device acts as master in one and slave in another, enabling extended range.
Major section
Minimum Viable Understanding · For Beginners: Bluetooth Assessment · The Bluetooth Challenge
Completing these questions will identify areas needing further study and reinforce practical design decision-making skills.
- This assessment tests your knowledge of Bluetooth and BLE (Bluetooth Low Energy) technology.
- Working through these questions helps solidify the concepts covered in earlier chapters.
- BLE sends short bursts and sleeps between them.
Major section
Scenario-Based Questions
This keeps the questions tied to product reasoning rather than isolated recall.
- The scenario questions shift from recall to diagnosis: each stem gives you the product constraint, and the correct answer is the one that explains the failure mode without inventing extra evidence.
Major section
Matching Questions · Calculation Problem
Advertising consumes 15mA for 2 ms per advertisement.
- The device uses a CR2032 battery (220mAh capacity).
- Self-discharge, cold temperature, and pulse-load voltage sag can shorten this idealized estimate; measure the actual battery and board before setting a replacement interval.
Major section
Code Challenge · Start With the Story
A Bluetooth assessment is not a memory contest.
- The useful test is whether a learner can look at a product situation and choose the role, GATT model, pairing method, key behavior, implementation check, or debugging evidence that fits.
- For each answer, ask what observable proof would make the claim true on a real device.
Major section
Assessment Drill: BLE Advertising Edge Cases · Checkpoint: Release Readiness
Advertising says a device exists and what interaction it permits; GATT carries application data after connection.
- Legacy advertising uses primary channels 37, 38, and 39 at 2402, 2426, and 2480 MHz.
- A legacy advertisement has a 31-byte payload budget.
- Active scanning adds the request-response exchange, but only for scannable advertising types.
Major section
Debate: Wi-Fi vs. BLE for Indoor Positioning
This scenario is drawn from a hospital asset-tracking deployment and is meant to be worked through as a design-decision exercise, not just read.
- The hospital wants room-level location, long tag life, and a system the support team can maintain.
- A strong signal on a plan does not prove a useful position.
Major section
Debate: Wi-Fi vs. BLE for Indoor Positioning (continued)
The nurse needs a quick useful place, not a perfect map.
- Wi-Fi is the local wireless network used by many phones and computers.
- Bluetooth Low Energy, or BLE, is a shorter-range radio designed for small, low-power exchanges.
- Under the Hood explains signal fingerprints, beacon geometry, reflections, calibration, and error bounds.
Major section
Debate: Wi-Fi vs. BLE for Indoor Positioning (continued)
The design team should first name the required area, update time, accuracy, battery life, privacy rule, and response when a tag is missing.
- The support worker needs a clear way to find dead tags and moved equipment.
- A basement store, lift, or crowded ward may decide whether the service is safe to trust.
- Scenario: A hospital needs to track 200 medical equipment items in a 50,000 sq ft facility with 1-meter accuracy.
Major section
Common Pitfalls · 1. Confusing Classic and BLE Assessment Questions
Classic Bluetooth and BLE have fundamentally different channel architectures (79 vs 40 channels), connection models (piconet vs central/peripheral), and power profiles.
- When answering assessment questions, identify which variant is being asked about.
- BLE advertising channels are specifically channels 37, 38, 39; all other 37 channels are data channels.
Major section
2. Misquoting Power Numbers Without Context · 3. Overlooking Bluetooth Mesh in Architecture Questions
Stating "BLE uses X mW" without specifying operating mode (advertising vs connected vs sleep) is incorrect.
- When asked about BLE network topologies for large deployments (>7 devices), the piconet 7-device limit is a Classic Bluetooth constraint.
Major section
4. Incorrect Version-Feature Mapping · Key Takeaway
Attributing features to wrong Bluetooth versions is a common error.
- Bluetooth assessment answers should justify the wireless choice, topology, connection mode, profile, security method, and power trade-off.
- Naming BLE or Classic is not enough without explaining why it fits the product constraint.
Deck summary
Key takeaways
Worked example: For a 15-question quiz, target correct answers are ⌈0.8×15⌉=12.
- The mathematical gist: At 20 dB SNR, Shannon’s ceiling is 6.66 Mbit/s for a 1 MHz channel and 13.3 Mbit/s for 2 MHz.
- Completing these questions will identify areas needing further study and reinforce practical design decision-making skills.
- This keeps the questions tied to product reasoning rather than isolated recall.
- Advertising consumes 15mA for 2 ms per advertisement.
Retrieval practice
Recall check 1 of 5
Radio Remi says: answer from memory, then check your reasoning.
Q1A Bluetooth review answer recommends a design choice. What makes the answer defensible?
Show answer
Answer: A Review answers should connect Bluetooth decisions to scenario evidence and explicit limits.
Retrieval practice
Recall check 2 of 5
Radio Remi says: answer from memory, then check your reasoning.
Q2Which Bluetooth profile is used for wireless keyboards?
Show answer
Answer: A HID Profile for keyboards, mice, game controllers.
Retrieval practice
Recall check 3 of 5
Radio Remi says: answer from memory, then check your reasoning.
Q3Your BLE temperature sensor advertises every 1 second with 31 bytes of data. After deployment, you notice smartphone battery drains faster than expected when the app is running. What's the optimization?
Show answer
Answer: D A GATT notification connection can be more efficient than continuous app scanning for this periodic sensor.
Retrieval practice
Recall check 4 of 5
Radio Remi says: answer from memory, then check your reasoning.
Q4What is Classic Bluetooth's nominal one-slot hopping rate?
Show answer
Answer: B Classic Bluetooth has 625 µs slots: 1 / 0.000625 s = 1600 one-slot channel selections per second. Longer dwell can increase exposure to interference; a multi-slot packet stays on its frequency, and BLE has different channel scheduling.
Q5Complete the BLE advertisement data parser for IoT sensor beacons:
Show answer
Answer: A BleakScanner supports a detection_callback for real-time processing.
Retrieval practice
Recall check 5 of 5
Radio Remi says: answer from memory, then check your reasoning.
Q6For a BLE-connected medical device that transmits patient health data, what is the minimum acceptable security configuration?
Show answer
Answer: C LE Secure Connections uses P-256 ECDH to derive the link key; an authenticated association method provides MITM protection.
Print reference
Answers 1 of 2
Answer key.
- A · Review answers should connect Bluetooth decisions to scenario evidence and explicit limits.
- A · HID Profile for keyboards, mice, game controllers.
- D · A GATT notification connection can be more efficient than continuous app scanning for this periodic sensor.
- B · Classic Bluetooth has 625 µs slots: 1 / 0.000625 s = 1600 one-slot channel selections per second. Longer dwell can increase exposure to interference; a multi-slot packet stays on its frequency, and BLE has different channel scheduling.
Print reference
Answers 2 of 2
Answer key.
- A · BleakScanner supports a detection_callback for real-time processing.
- C · LE Secure Connections uses P-256 ECDH to derive the link key; an authenticated association method provides MITM protection.