5-Minute Tech Quiz
1. Cameras used in the U.S.
are typically based upon
the PAL standard.
a. True
b. False
2. What type of communication protocol can PTZ
signals to cameras utilize?
a. RS-422
b. RS-485
c. RS-232
d. Any of the above
e. None of the above
3. The unit of light given out by a source of 1 candela radiating equally is called a:
a. lumen
b. lux
c. back light
d. Any of the above
e. None of the above
4. The feature that automatically increases a camera's
sensitivity as light levels
fall is called:
a. back-light compensation
b. AGC
c. sync
d. Any of the above
e. None of the above
5. You must home run the
PTZ control cables from
each camera.
a. True
b. False
6. The feature that automatically adjusts for lighting
behind a subject is called:
a. back-light compensation
b. AGC
c. sync.
d. Any of the above
e. None of the above
7. PTZ cameras can be controlled from only
one location.
a. True
b. False
8. All CCTV cameras are capable of efficiently using
infrared illuminators.
a. True
b. False
9. Infrared illuminators
used for CCTV operate in
what range?
a. 715 nano-meters
b. 815 nano-meters
c. 950 nano-meters
d. Any of the above
e. None of the above
10. All PTZ cameras will
work with all DVRs.
a. True
b. False
11. Which of the following
settings is most sensitive
to light?
a. f0.08
b. f1.2
c. f2.8
d. f4.0
12. C and CS are examples
of PTZ formats.
a. True
b. False
13. A single Cat 5 cable can
be used with analog
CCTV cameras for video,
camera power and PTZ
control signals.
a. True
b. False
14. All PTZ cameras are domes.
a. True
b. False
15. Which of these lenses
will give the widest
angle of viewing?
a. 3.5mm
b. 8mm
c. 50mm
d. 100mm
What's Wrong with This?
Wally `Larman installed a DVR with four PTZ dome cameras using RS-422 protocol for PTZ control. He selected dome
cameras that were compatible with the DVR, ran the cables as shown in this diagram and correctly programmed the DVR and cameras, but when he tested the system, the PTZ functions did not work properly. Can you see what Wally did wrong and what he must do to correct the problem?
Answers found below.
5-Minute Tech Quiz Answers
1. b - Cameras used in the U.S. follow the NTSC standard.
2. d - Any of these communication protocols may be used by PTZ cameras. In addition, some manufacturers use a proprietary format. You should check which protocol is used by the manufacturers you select.
3. a
4. b - AGC (Automatic Gain Circuit) will automatically increase the camera's sensitivity to light as the amount of available light falls. Back-light compensation is the ability of a camera to display a usable image when the source of illumination is behind the subject.
5. b
6. a
7. b - Typically, PTZ functions can be controlled from many locations, even off-site, using dedicated controllers, DVRs or computer software.
8. b - Although all cameras may sense IR illumination, not all cameras are capable of using the IR to produce an enhanced image. Additionally, some cameras have filters to reduce the amount of IR reaching the imaging sensor.
9. d - Each IR range has different characteristics, and some cameras may be more sensitive to one of them. If you are planning on installing IR illuminators, you should check to see which one is best for the cameras you install.
10. b - Although the video signal may work with all DVRs, you may not be able to control all PTZ functions through the DVR interface. You should check which PTZ cameras are fully supported by the DVR that you use.
11. a
12. b
13. a - Adaptors are available to allow a single Cat 5 cable to provide power, video and PTZ control, which may reduce cabling costs.
14. b - PTZ cameras may be domes or standard "box" cameras.
15. a - The lower the millimeter rating of a lens, the wider the viewing angle.
CORRECTION: An error in September's Quiz pointed out by several readers was in the answer to question 15, which asked, "Which of the following cannot be used with a digital video recording system?" The correct answer is a double negative, answer e, "None of the above," not d, "Any of the above," which was listed. Thanks to those alert readers who figured out that "None of the above cannot be used" means all can be used.
Answer to: What's Wrong with This?
Wally's problem is caused by the type of cable he ran for the PTZ control circuit. RS-422 requires a twisted pair cable, not standard 22/4 station cable. Wally should replace the 22/4 with UTP cable and retest the system. He also should check to see if he has properly set the address switches in the cameras. Some DVRs require that the PTZ address match the camera number of the recorder and the terminator switch in the camera. Typically, RS-422 circuits require that a terminating resistor be installed at the last camera.
