CCTV CCTV Installation and Maintenance 4 — Questions and Answers
Question 1: What is the primary reason to use shielded twisted pair (STP) cable instead of unshielded (UTP) in a CCTV installation?
- STP supports higher PoE wattage
- STP provides greater resistance to electromagnetic interference (EMI) (Correct answer)
- STP allows longer runs without signal loss
- STP is required for 4K resolution cameras
Correct answer: STP provides greater resistance to electromagnetic interference (EMI)
STP cable's metallic shield protects signal integrity in environments with high EMI sources such as industrial equipment, fluorescent lighting, or motors.
Question 2: A technician is replacing a failed HDD in an NVR. What should be done before swapping the drive?
- Factory reset the NVR
- Power down the NVR and discharge static electricity before handling the drive (Correct answer)
- Delete all camera channels
- Update NVR firmware first
Correct answer: Power down the NVR and discharge static electricity before handling the drive
Powering down and grounding yourself (ESD precaution) before handling storage drives prevents data loss and protects both the drive and NVR electronics.
Question 3: Which of the following best describes the difference between DVR and NVR recording systems?
- DVRs record IP cameras; NVRs record analog cameras
- DVRs process video from analog cameras; NVRs process video from IP cameras over a network (Correct answer)
- DVRs use hard drives; NVRs use cloud storage only
- DVRs support higher resolution than NVRs
Correct answer: DVRs process video from analog cameras; NVRs process video from IP cameras over a network
A DVR encodes and records video from analog cameras locally, while an NVR records pre-encoded video streams from IP cameras transmitted over a network.
Question 4: What does 'continuous recording' mode mean on a CCTV recorder?
- The recorder records only when motion is detected
- The recorder records 24/7 regardless of activity (Correct answer)
- The recorder saves footage to the cloud continuously
- The recorder records only during business hours
Correct answer: The recorder records 24/7 regardless of activity
Continuous recording mode captures and stores video around the clock without any triggers, ensuring no events are missed but consuming more storage.
Question 5: A camera installed near a bright window consistently produces silhouetted subjects. Which camera setting adjustment would most directly fix this?
- Increase frame rate
- Enable Backlight Compensation (BLC) or WDR (Correct answer)
- Switch to black-and-white mode
- Reduce the camera's resolution
Correct answer: Enable Backlight Compensation (BLC) or WDR
Backlight Compensation (BLC) or WDR adjusts exposure to reveal detail in subjects positioned in front of a bright light source.
Question 6: What is the typical function of a video balun in CCTV systems?
- To convert analog video to digital format
- To transmit video signals over twisted pair cable instead of coaxial cable (Correct answer)
- To amplify video signals over fiber optic lines
- To split one video signal into four outputs
Correct answer: To transmit video signals over twisted pair cable instead of coaxial cable
A video balun converts the impedance of coaxial video to allow transmission over standard twisted pair (Cat5/Cat6) cable, enabling longer or more flexible cable runs.
Question 7: When reviewing a site survey for a new CCTV installation, which environmental factor most affects the choice between a fixed and PTZ camera?
- The color of the camera housing
- The size of the area to be monitored and whether active tracking is needed (Correct answer)
- The brand of the NVR being used
- The height of the ceiling in the room
Correct answer: The size of the area to be monitored and whether active tracking is needed
Large open areas that require active operator tracking or wide coverage justify a PTZ camera, while fixed cameras suit defined, static fields of view.
CCTV CCTV Installation and Maintenance 4
What is the primary reason to use shielded twisted pair (STP) cable instead of unshielded (UTP) in a CCTV installation?