PSP Video Surveillance and CCTV 2 — Questions and Answers
Question 1: What does the term 'pixel density' mean in CCTV camera planning, and why is it important?
- The total megapixel count of the camera sensor
- The number of pixels covering a unit of space in the scene, determining the level of detail captured (Correct answer)
- The monitor resolution used to display camera footage
- The frames-per-second rate of the recorded video
Correct answer: The number of pixels covering a unit of space in the scene, determining the level of detail captured
Pixel density (pixels per foot/meter in the scene) determines how much detail is captured about subjects, directly affecting whether the system meets identification, recognition, or detection requirements.
Question 2: Under the Americans with Disabilities Act (ADA) and US privacy law, which area is generally PROHIBITED for video surveillance installation in a workplace?
- Break rooms and kitchens
- Restrooms and changing rooms (Correct answer)
- Parking lots and driveways
- Loading docks and shipping areas
Correct answer: Restrooms and changing rooms
Video surveillance in restrooms and changing rooms is prohibited under US federal and state privacy laws because individuals have a reasonable expectation of privacy in these locations.
Question 3: What is a 'video analytics' false positive in the context of a security surveillance system?
- The system fails to detect an actual intrusion event
- The system generates an alarm for a non-threatening event such as an animal or blowing debris (Correct answer)
- The recorded video has compression artifacts that obscure faces
- The system incorrectly records footage at the wrong frame rate
Correct answer: The system generates an alarm for a non-threatening event such as an animal or blowing debris
A false positive (nuisance alarm) occurs when the analytics system triggers an alert for a benign event, such as a shadow, animal, or environmental condition, wasting operator attention.
Question 4: For a camera monitoring a vehicle entry gate, what frame rate is the minimum recommended to reliably capture readable license plates on vehicles traveling at normal entry speeds?
- 5 frames per second (fps)
- 15 frames per second (fps)
- 25-30 frames per second (fps) (Correct answer)
- 60 frames per second (fps)
Correct answer: 25-30 frames per second (fps)
25-30 fps is the minimum recommended for license plate capture at vehicle entry gate speeds, as lower frame rates cause motion blur that makes plates unreadable.
Question 5: What is the purpose of an NVR (Network Video Recorder) as compared to a DVR (Digital Video Recorder) in modern IP surveillance systems?
- NVRs are analog while DVRs process IP camera streams
- NVRs process and record IP camera streams via the network without requiring direct connection to each camera (Correct answer)
- NVRs store video on tapes while DVRs use hard drives
- NVRs are only used in outdoor applications
Correct answer: NVRs process and record IP camera streams via the network without requiring direct connection to each camera
An NVR receives pre-compressed IP video streams from cameras over the network, while a DVR connects directly to analog cameras and encodes the video itself, limiting scalability and placement flexibility.
Question 6: What surveillance camera feature allows automatic adjustment of the iris aperture to maintain proper exposure as lighting conditions change throughout the day?
- Back Light Compensation (BLC)
- Auto Iris (AI) lens / Direct Drive Iris (DDI) (Correct answer)
- Digital Noise Reduction (DNR)
- Infrared Cut Filter (ICF)
Correct answer: Auto Iris (AI) lens / Direct Drive Iris (DDI)
An Auto Iris (AI) or Direct Drive Iris lens automatically adjusts its aperture in response to changing light levels, maintaining proper exposure from bright daylight to low-light evening conditions.
PSP Video Surveillance and CCTV 2
What does the term 'pixel density' mean in CCTV camera planning, and why is it important?