CST Video and Audio Surveillance Technology 3 — Questions and Answers
Question 1: What is the key difference between a DVR and an NVR in surveillance systems?
- DVRs record in HD while NVRs record in SD
- DVRs process analog camera signals while NVRs record from IP cameras over a network (Correct answer)
- DVRs store footage on cloud servers while NVRs use local hard drives
- DVRs support audio recording while NVRs do not
Correct answer: DVRs process analog camera signals while NVRs record from IP cameras over a network
A DVR (Digital Video Recorder) processes and records analog camera signals, while an NVR (Network Video Recorder) receives and stores pre-encoded digital streams from IP cameras over a network.
Question 2: Which video compression codec offers approximately 50% better compression efficiency than H.264 at the same video quality?
- MJPEG
- MPEG-2
- H.265 (HEVC) (Correct answer)
- VP8
Correct answer: H.265 (HEVC)
H.265 (HEVC) provides approximately 50% better compression efficiency than H.264, significantly reducing storage and bandwidth requirements while maintaining the same video quality.
Question 3: A CST is designing an outdoor surveillance system that must operate in temperatures ranging from -40°F to 140°F. Which camera specification addresses this requirement?
- IP66 ingress protection rating
- Operating temperature range (Correct answer)
- Wide Dynamic Range specification
- MTBF (Mean Time Between Failures)
Correct answer: Operating temperature range
The operating temperature range specification indicates the environmental temperatures within which a camera is designed to function reliably.
Question 4: What does a camera's signal-to-noise ratio (SNR) indicate about its performance?
- The ratio of video resolution to frame rate
- The balance between useful video signal and unwanted electronic noise, with higher values indicating cleaner images (Correct answer)
- The ratio of day to night recording capacity
- The proportion of compressed to uncompressed video data
Correct answer: The balance between useful video signal and unwanted electronic noise, with higher values indicating cleaner images
Signal-to-noise ratio (SNR) measures the ratio of useful video signal to electronic noise; a higher SNR (e.g., 50dB vs. 40dB) indicates a cleaner, less grainy image, especially in low-light conditions.
Question 5: In audio surveillance, what is the legal requirement in most US two-party consent states regarding covert audio recording?
- All parties to a conversation must be notified and consent to being recorded (Correct answer)
- Only the property owner must consent to the recording
- Federal law overrides state two-party consent laws for security purposes
- Audio recording is permitted in all public areas without consent
Correct answer: All parties to a conversation must be notified and consent to being recorded
In US two-party (all-party) consent states, all parties to a private conversation must consent to being recorded, making covert audio surveillance potentially illegal without all parties' knowledge.
Question 6: What is the purpose of video analytics' 'virtual tripwire' or 'line crossing' function?
- Automatically restart the camera if video signal is lost
- Trigger an alert when a person or object crosses a defined virtual line in the video (Correct answer)
- Measure the distance between detected objects in the frame
- Synchronize multiple cameras to the same timestamp
Correct answer: Trigger an alert when a person or object crosses a defined virtual line in the video
Virtual tripwire or line crossing detection triggers an alert when a person or object crosses a user-defined virtual line in the camera's field of view, enabling perimeter intrusion detection.
Question 7: Which type of camera mount allows horizontal and vertical adjustment but locks the camera in a fixed position after installation?
- Pan-Tilt-Zoom (PTZ) mount
- Fixed wall bracket (Correct answer)
- Pendant mount with swivel adjustment
- Gimbal mount
Correct answer: Fixed wall bracket
A fixed wall bracket allows adjustment of camera direction during installation but locks in position, unlike PTZ mounts which allow dynamic movement after installation.
CST Video and Audio Surveillance Technology 3
What is the key difference between a DVR and an NVR in surveillance systems?