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DVR Connection, Inc.
CCTV Knowledge Base
&
Technical Manual
•
Introduction
•
Components of CCTV and their technologies
•
NTSC video standards
•
VCR and DVR technologies
•
Video compression and storage
•
Video format
•
Digital Video Recorder operation
•
A standard PC versus a DVR
•
Precaution consideration before installing a DVR
•
What are an embedded device and an Embedded OS?
•
What operating system is best for a DVR
•
Why a DCI DVR
•
TCP/IP networking basics
Revised April 2009
1
Introduction
Closed Circuit Television or CCTV is the technology behind capturing images from an object at one end
and transmitting it through some type of transmission media to a receiving display unit on another end for
the purpose of security and monitoring activities. The Video Surveillance market has become the fastest
growing segment of the security industry today. Whether it is used in a business or a residence, video
recording a crime in progress is a godsend. Understanding the fundamentals of CCTV components is
crucial in installing and maintaining a trouble free CCTV/DVR system as well as providing a high quality
video documentation of an incident. Our goal here is to provide basic knowledge about CCTV and its
components so we can improve customer relations and increase job profitability.
Components of CCTV and their technologies
A CCTV system comprises of four components:
Video Source
Transmission Media
Power Source
Recording Device
•
Video Source - A Video source consists of several components. These components
must work together flawlessly in order to achieve a proper image.
o
o
o
Camera
Lens
Lighting
a)
Camera - The starting point in any CCTV system is the camera. The images
recorded can only be as good as the images produced by the camera’s quality.
Selecting the right camera for a location is no easy task. There are many
different issues to consider when choosing a camera; Technology, Resolution,
light sensitivity and Signal to Noise Ratio are some the topics that will be
described here.
There are two types of imaging technologies available for cameras commonly
used in CCTV. The first is the solid state technology called Charged Coupled
Device also known as CCD. The other is Complementary Metal Oxide
Semiconductor or CMOS for short. Imagine a picture divided into small
checkerboard squares, each of the small squares is called a pixel. Both CCD
and CMOS imagers are comprised of hundreds of thousands of light sensitive
pixels. Just as the film in a photo camera recording the light reflected from an
object, both types of imagers convert light into electric charge and process it into
electronic signals that eventually becomes the image. Although there has been
numerous discussions as to which technology is a better choice, the fact remains
that only CCD sensors were developed and produced specifically for the camera
industry and imaging technologies, while CMOS sensors were implemented
within a standard technology used exclusively in microprocessors, memory chips
and other general purpose integrated circuit (IC) chips much like the components
within a personal computer.
In a CCD sensor all of the pixels can be devoted to light capture and every pixel's
charge is transferred generally through a single output node to be converted to
voltage, buffered, and sent off-chip as an analog signal. This uniformity in output
is a key factor in high image quality. In a CMOS sensor, each pixel has its own
charge-to-voltage conversion, and the sensor often includes amplifiers, noisecorrection, and digitization circuits, so that the chip outputs digital bits. These
2
other functions increase the design footprint and reduce the area available for
light capture. With each pixel doing its own conversion, uniformity is lower;
however, the chip can be built to require less off-chip circuitry for basic operation.
The recent advances in CMOS technology are closing the gap between the two
image sensors but CCD remains the imager of choice when it comes to higher
image quality.
Resolution is a term used to describe image quality. The higher the camera
resolution is, the better the picture quality will be. It is defined in number of Lines
of Resolution or TVL for an analog signal and number of Pixels for a digital signal.
The higher the number of lines of resolution or the higher number of pixels the
higher image detail a camera will produce. The terminology “Lines of resolution”
or TVL has been a confusing term in the analog video world. This type of
measurement is a carry over from the early days of analog video and television
and it is still in use in CCTV today. There are some common misconceptions;
"Lines of resolution" is not the same as the number of pixels (either horizontal or
vertical) found on a camera's CCD, or on a digital display monitor. It is also not
the same as the number of scanning lines used in an analog camera or television
system. In precise terms, "lines of resolution" refers to a visual measurement by
counting the number of horizontal or vertical black and white lines that can be
distinguished on an area that is as wide as the picture is high. There are two
types of measurement associated with the “lines of resolution” “TVL” and they
are "lines of horizontal resolution," and "lines of vertical resolution".
Horizontal resolution = number of vertical lines.
Imagine a lot of vertical lines drawn on a piece of white paper and all bunched up
together. If the system has a horizontal resolution of say 570 lines, then the
whole system (lens + camera + tape + electronics) can distinguish 285 black
lines and 285 white spaces in between. If you add any more vertical lines to the
picture, you can't tell where a black line stops, and the adjacent while space in
between, starts. In other words it can not distinguish between the lines and
spaces anymore; hence the system has reached its maximum detail resolution.
Picture 1
Theoretically horizontal resolution can be increased infinitely; However, It is
technologically difficult to increase the number of vertical lines or pixels in a chip.
As the number of lines or pixels increase, the size reduces which affects the
sensitivity. There is a trade off between resolution and sensitivity.
Vertical resolution = number of horizontal lines or pixels.
Picture 2
The vertical resolution cannot be greater than the number of TV scanning lines,
which are 525 lines in the US. However, not all these lines can be displayed on
3
a monitor. In fact, all CCTV Cameras (in the US) create exactly the same
number of vertical lines of resolution in a picture which happens to be 480 lines.
The video system (in the US) creates 525 sync pulses or horizontal lines per
picture, but only 480 produce visible lines. The rest of the 525 lines are "black"
and contain format information and after applying the Kell factor (Kell Factor is a
parameter used to determine the effective resolution of a discrete display device)
of 0.7 gives about 335 lines of vertical resolution for analog signals. This factor
may be as high as .85 to .9 for CCD sensors and displays.
Different manufacturers use different techniques to measure resolution; thus,
direct comparisons of different brands of cameras can be misleading. So when
there is a mention of TVL within a video specification of a device (camera,
monitor, etc.) and it is not specified if they are horizontal or vertical lines, then the
thing to remember is to be cautious and not use this as the main criteria in quality
decision making process. If a manufacturer does not make the reference clear,
then you can assume they are horizontal numbers, because they are always
bigger numbers, and therefore they sound more impressive. Some of the
common methods used to measure resolution are using Resolution Chart or
using Bandwidth.
Picture 3 shows a sample of a resolution chart used by some manufacturers to
measure the resolution of a video camera.
Picture 3
The camera is focused on the resolution chart and the vertical lines and
horizontal lines are measured on the monitor. The resolution measurement is the
point were the lines start merging and they cannot be separated. The problem
associated with this measurement tool is that the merging point can be subjective
as different people perceive it differently. The important thing to keep in mind
when using this tool is that, the resolution of the monitor must be higher than that
of the camera. This is not a problem with Black and white monitors, but it could
become a problem with many color monitors as they frequently have a lower
resolution as compared to a color camera due to design limitations.
The bandwidth method is a more scientific method in measuring the resolution.
The bandwidth of the video signal from the CCTV equipment is measured on an
oscilloscope. Multiply this bandwidth by 80 gives the resolution of the camera.
For example: If the bandwidth is 5 MHz, the camera resolution will be 5 * 80 =
400 lines of resolution.
Although the same techniques will apply to a digital system as a whole,
measuring the resolution of a digital camera is simplest when using the following:
4
CCD Resolution = # of Horizontal pixels X # of Vertical pixels
The camera light sensitivity is one of the most important parts of a camera
selection process. The means to measure the light sensitivity of a camera is by
the Lux rating of that camera. One Lux is equivalent to 1/10 foot candle which is
the measurement for the light available within a scene. The lower the Lux rating
the better the camera will perform under low light conditions. This area of a
camera specification determines the quality of a camera as well as the bandwidth
requirements by the camera to produce a visible image. For example when a
camera is rated at 1 Lux, it means that it would require about 10 foot candle to
produce a visible image on a monitor. As a reference a 10 foot candle is
equivalent to the amount of light available at dusk (refer to table 1).
Outdoor Illumination (fc)
Direct sunlight = 10,000 to 13,000
Full sunlight = 1,000 to 2,000
Overcast day = 100
Dusk = 10
Twilight = 1
Deep twilight = 0.1
Full moon = 0.01
Quarter moon = 0.001
Moonless night = 0.0001
Overcast night = 0.00001
Indoor Illumination (fc)
Rough assembly line = 20
Fine assembly line = 100
Extra fine assembly line = 300
Retail stores = 50
Bank lobby & offices = 20
Hospital OR = 1800
Examination room = 50
General work areas = 30
Malls & grocery stores = 50
Accounting & offices = 50
Surface Reference (Rs)
Black asphalt = 0.05
Gravel surface = 0.13
Human face = 0.18 – 0.25
Green grass = 0.40
Red brick = 0.25
Old concrete = 0.25
New concrete = 0.40
Unpainted building = 0.40
New white paint = 0.75
Glass window = 0.70
Table 1
If the amount of available light were any lower the camera will not be able to
provide enough of an image detail and becomes darker. This increased
darkness within the image increases the bandwidth requirements for transmittal
of the signal.
Noise generated by the camera electronics is the biggest culprit in production of
a poor quality video signal. This noise appears as snow or graininess within the
image. There are several causes of noise including but not limited to bad
camera electronics, poor or improper amplification, heat or lack of proper lighting
in the scene. The camera specification that relates to this noise is referred to by
Signal to Noise Ratio (SNR). SNR is measured in dB (decibels) and the higher
the dB number is, the clearer the video image produced by the camera.
Cameras that provide SNR of 40dB to 46 dB have only a 100 to 1 ratio; hence,
most of the fine image detail would be lost. On the other hand a camera with a
60 dB SNR will provide a 1000 to 1 ration which results in a broadcast video
quality. On an average a CCTV camera should have a SNR value in between
48dB to 52dB (Refer to table 2).
S/N ratio dB
60dB
50dB
40dB
30dB
20dB
Signal-to-Noise Ratios (SNR)
S/N ratio:1
Picture Quality
1,000
316
100
32
10
Excellent, Broadcast Quality
Good, a small amount of noise
Reasonable, lost fine detail
Poor, great deal of noise
Unusable picture
Table 2
Selecting the proper camera should be the most important part of a CCTV
system. Evaluating the environment the camera will be place at and using the
selection criteria covered here will result in outstanding picture resolution, a
higher degree of reliability and a better customer relationship.
5
b)
Lens - A lens is a device that focuses the light reflected from an object onto a
CCD.
Lenses much like cameras come in many different formats and
characteristics. Some of the factors to consider when choosing a lens are the
lens format, the field of view and the type of IRIS.
Lens format is determined by the camera CCD size. The lens format must be
equal to or greater than that of the CCD size. You can use a 1/3” format lens
with a 1/4” CCD however, the reverse will not work. The smaller lens will cut the
corners of the image and limit the light gathering capability of the CCD. A lens
could be a board mount, C-mount, or CS-mount. A board mount lens is usually
connected directly to the CCD circuit board and has the smallest dimensions.
The C and CS lenses look very similar in size and shape. The main difference
between the two is the position of the lens from the CCD and the focal point of
the lens.
A CS-mount lens is located 12.5mm from the CCD where the C-mount lens is at
17.5mm from the CCD. In other words, the back of a CS mount lens is 5mm
closer to the chip than a C mount lens; hence the focal distance is different
between the two lenses. You can always use a C mount lens on a CS mount
camera by using a 5mm spacer ring but you can never use a CS mount lens on
an older style C mount camera. Because of the shorter focal distance, CS-mount
lenses can only be used on CS-mount cameras, otherwise your picture will be
out of focus if you use a CS-mount lens on a C-mount camera.
Field of view (FOV) or sometimes called the angle of view of a lens is the object
area that can be detected by the camera through the lens. It is comprised of the
vertical FOV and the horizontal FOV. In general a short focal length lens (i.e.
2.5mm) has wide fields of view (FOV). This is good for seeing a large area.
Objects appear smaller, rapidly, as distance from the camera increases. As lens
focal length increases, the field of view narrows and more distant objects are
easier to define. If, for instance, you wanted to be able to positively identify
people, 25' away from a camera, a short focal length lens (i.e. 3.6mm) would give
such a large field of view (37'x 26') that recognition would be uncertain. An 8mm
or even 12mm lens would be far better. Picture 4 demonstrates the FOV
changes for different size lenses.
Picture 4
6
Table 3 provides example of the FOV in horizontal and vertical for 1/3” lens
format as well as the angle of view for certain lenses and at a given distances.
Viewable
Angle
(degrees
)
5 feet
away
10 feet
away
15 feet
away
25 feet
away
50 feet
away
100 feet
away
Lens
Focal
Length
H
H
V
H
V
H
V
H
V
H
V
H
V
3.6 mm
74
7.5
5.2
15.1
10.4
22.6
15.6
37.7
26.1
75.4
52.1
151
104
6.0 mm
48
3.8
2.9
7.7
5.7
11.5
8.6
19.2
14.4
38.4
28.7
77
57
8.0 mm
33
2.9
2.1
5.7
4.3
8.6
6.4
14.4
10.7
28.7
21.3
57
43
12.0 mm
22
1.9
1.5
3.9
3.0
5.8
4.5
9.7
7.5
19.4
14.9
39
30
16.0 mm
17
1.3
1.0
2.6
1.9
3.9
2.9
6.6
4.8
13.2
9.6
26
19
50.0mm
8
.5
.4
.95
.72
1.45
1.08
2.5
1.8
4.8
3.6
9.6
7.2
Table 3
The IRIS in a CCTV lens works very much like a human eye. The purpose of the
iris is to adjust the lens opening so the proper amount of light would reach the
CCD. There are three types of IRIS control for CCTV lenses. Fixed or Manual,
Video-Drive, and DC-Drive.
Fixed or manual iris is generally used in fixed lighting conditions. The fixed iris
aperture is set when the lens is manufactured. A manual iris allows the user to
change the iris aperture based on the lighting condition during installation.
However, once set it becomes a fixed iris until it is manually changed. The
changes in lighting will affect the quality of the picture when a fixed or a manual
iris lens is used.
Video-Drive iris control is driven by a servo motor which is controlled by the iris
amplifier circuit built into the lens and its adjustment is controlled by the video
signal from the camera itself.
DC-Drive iris is the most commonly used and it is simpler, smaller and cheaper.
The motor moving the iris vanes is driven directly by the camera. There are no
active electronics inside the lens therefore it must be attached to a camera that
will provide DC-Drive iris output.
c)
Lighting - Before a camera can process an image, there must be enough light to
stimulate the CCD. The light must first reflect from the object before the CCD
can detect it. When a light reflected off an object hits a CCD chip, it generates a
charge in the pixels. This charge is proportional to the incoming light. The
brighter the light is the greater the charge will be. The intensity of this reflective
light to a large extent depends on the object’s reflective characteristics. These
characteristics include color, color wavelength, and temperature. For example,
the amount of light that is reflected from a dark object such as black asphalt on a
hot summer day is far less than the same asphalt on a snowy winter day.
To achieve the best quality images at the camera end, use table 1 as a guide to
select the best camera for the setting. If the setting is not providing enough
lighting for the camera to properly see the image, then additional lighting must be
installed or other types of cameras must be utilized to create a desirable image at
the recorder end.
7
In order to determine the minimum light required triggering a camera, first the
illumination at the scene must be evaluated. The best way to do this is with the
help of a light meter. However, if a light meter is not available then the following
equation and table 1 may give an idea as to the proper camera luminance (Lux)
to look for.
L=
Fc * Rs
10
Where:
Fc =
Rs =
the indoor or outdoor illumination rate
the surface Reflective reference
So far we have covered the basic selection process for each of the components
that comprise a video source. By itself a good video source does not result in a
good image quality at the recording end of a CCTV system. There are many
factors that affect the quality of a video signal generated by the video source
before it reaches the recording end. Transmission of the video signal with limited
losses is the most important part of a CCTV system design
•
Transmission Media - An image captured by a camera is not transported elsewhere without
the proper transmission media. The transmission media is by far the most important part of
an installation. More than 70% of installation and quality problems are cabling related. You
can have the highest quality camera and DVR components, but if the signal is not transmitted
through quality transmission media, your entire system will suffer. The best image quality
that a camera and a monitor can provide would be on a test bench with the shortest attached
cable. Once the images are transmitted over a distance, the losses in quality will become
greater and although the signal can be corrected by amplification and equalization, there are
no devices that will reproduce that exact image quality at the other end. Understanding the
components and characteristics of a transmission media is the key to a successful installation
as well as producing the best image quality at the recording end of the CCTV circuit. There
are two type of transmission media commonly used:
o
o
Coaxial
UTP (Unshielded Twisted Pair)
A coaxial cable consists of four different parts, center conductor, dielectric material,
braided shield and jacket. Since the video signal has both low and high frequency
components, it is important to use a cable that would transmit full range of frequencies
with as little distortion and attenuation as possible. Center conductor of a coaxial cable
must be of 100% copper. The reason for that is because a composite video is a low
frequency signal and copper provides a lower DC resistance than steel or copper
covered steel, and that will improve signal transmission.
A lower DC resistance in copper conductor will lower attenuation in the signal and
attenuation is the main cause of distortion in the video signal at the recorder end.
Selecting the proper dielectric material such as polyethylene or cellular composition will
provide a lower capacitance and a higher velocity of propagation. These characteristics
will result in a low-loss cable and reduced attenuation of video signal.
A 95% braided copper shield and an aluminum foil shield combination provides the
lowest DC resistance ground path and best shielding for outside interference such as RFI
and EMI in a coaxial cable. Cables with only 40-60 % (low coverage) aluminum braided
shield commonly used for CATV is not acceptable for CCTV environment.
8
The jacket serves two purposes. One is to protect the cable from the elements and the
second is to provide proper termination. Choosing the proper jacket depends on the
environment. An indoor cable should not be used for outside installations.
There are three commonly used coaxial cables for CCTV, RG59, RG6 and RG11. RG59
is the most widely used due to its smaller size and ease of handling. However RG59 has
the highest attenuation of the three and has a recommended maximum range of 600 feet.
The attenuation in some RG59 cable could be between 2-3 dB per 300 feet. There is a
signal loss of about 10% per 1dB of attenuation. What this means is that there is
approximately 30% loss of signal for the first 300 feet of RG59 installation. At 600 feet of
cable run more than 50% of the original signal is lost to attenuation even if everything
else was ideal.
RG6 is used in longer cable installation rather than RG59 due to its lower DC resistance
hence lower attenuation characteristics. However even RG6 has its limitation for
distance. The recommended maximum range of RG6 is about 1000 feet. The attenuation
in some RG6 cable could be nearly 2dB per 300 feet. RG11 at 10mm has the biggest
diameter of the three cables. However, it has the lowest DC resistance and lower
attenuation characteristics. RG11 has approximately 1 to 1.2dB of attenuation for every
300 feet which makes it ideal for installations of 1500 to 2000 feet in length.
A cable installation is not complete without the proper termination. The most commonly
used termination for coax cable is the BNC. There are three types of BNC terminators.
Solder, Twist-on and Crimp-on. They all have advantages and disadvantages. Solder
type can provide a solid electrical and mechanical connection, however, it takes more
time to complete and a common problem is cold solder joints. Twist-on is the quickest
way to terminate a cable, however, it costs more and it cuts into the center conductor
which too much twisting can break the center conductor and lose connection and that is
its most common problem.
The crimp-on is probably the most common type of termination. When performed
correctly, it provides the solid electrical and mechanical support needed for an ideal
termination of coaxial cable. Installing a CCTV system takes a vast amount of knowledge
about the cameras, the lenses and the environmental setting. However, do not forget the
most important and least thought of component, the transmission media. The quality of a
CCTV system is only as good as the quality of the coaxial cable selected and terminated.
UTP or Unshielded Twisted Pair cabling is a form of wiring in which two conductors are
wound around each other for the purposes of canceling out electromagnetic interference
from external sources (but not as much as coaxial cable) and crosstalk from neighboring
wires. In the recent years the use of Category 5 or Unshielded Twisted Pair (CAT 5 or
UTP) has become more common in installation of multiple cameras in one location.
Since the UTP has 100 ohm impedance, it requires a media conversion (baluns) to
modify the 75 ohm RF signal before transmitting.
Although there has been a push to promote the use of UTP (Cat 5e) cable for CCTV
systems there are a few facts that should be looked at before making the final decision in
using UTP cable. Many installers have found that there is very little difference in quality
of transmitted picture between high quality Cameras, Recorders, and Monitors versus low
quality equipment when used in conjunction with long UTP transmission media. The
reason is simple. All of the crisp high quality detail created by the high quality equipment
(cameras, etc.) is lost due entirely to losses that take place in the Twisted Pair wires and
the baluns used to connect into the Twisted Pairs. Twisted Pair wire and the associated
baluns both create signal losses across the entire 30 Hz to 4.5 MHz span of frequencies
encompasses by a video signal. The longer the wires the greater the loss of signal, until,
with a long enough wires, there will be no usable picture signal left. The higher
frequencies, which convey fine detail in a picture, suffer much greater losses than the
9
lower frequencies which mainly contribute to picture brightness. If the CCTV system is
comprised of Color Cameras and Color Monitors, there will be even higher losses and
noticeable reduction in color brightness or even no color at all due to higher bandwidth
required by these equipment and the greater losses at higher bandwidth built into UTP
cables.
As shown in table 4, due to higher bandwidth requirement, a high resolution Camera (say
570 Line Resolution) looses more of its rated Lines of Resolution while traversing the
Twisted Pairs than a low resolution Camera (say 380 Line Resolution) on any specific
length of wire. This signal loss can be corrected using CCTV video amplifiers and
equalizers equipment. It is also very important to realize that, in the case of twisted wire
equalization, "more is not better". Only the correct amount of equalization will do. More
of the same will only make the video picture worse, instead of better.
Required
Bandwidth
Lines of
Resolutions
330
380
400
460
470
480
570
3.1 MHz
3.6 MHz
3.7 MHz
4.3 MHz
4.4 MHz
4.5 MHz
5.3 MHz
Table 4 - Bandwidth
requirements for
different Lines of
Resolution produced by
the camera.
More description of the Lines of Resolution (resolution) is available under NTSC Video
Standards section.
Deciding on which transmission media to use depends on several factor; transmission
distance, cable characteristics, signal quality and additional component cost. Table 5
shows the signal attenuation (signal loss) for commonly used transmission media.
Keep in mind that 1 dB attenuation results in approximately 10% signal loss.
Mini Coax
RG59 Coax
RG56 Coax
Cat 5e (passive)
Cat 5e (active)
Fiber (multimode)
Cable Diameter
(inches)
0.146
0.242
0.272
0.2
0.2
.13x.23
Cable Weight
16
35
42
20.9
20.9
13.5
Attenuation
@ 5MHz (
dB/100' )
1.3
0.68
0.47
1.22
1.22
<0.5
Table 5
One frequently used measure of picture quality loss, is when more than ½ of the energy
at that frequency is lost. Thus at the cable length that ½ the energy at the desired quality
level is lost, that defines the maximum length of cable that can transmit that level of
quality. This leads to the following limits for maximum cable length at a given picture
quality levels as shown by table 6.
10
LINES
330
400
470
570
700
800
•
RG59/U COAX
686 Feet
615 Feet
585 Feet
521 Feet
471 Feet
444 Feet
UTP PAIR
282 Feet
254 Feet
234 Feet
215 Feet
189 Feet
175 Feet
Table 6
Power Source - Proper power supply conditions for the equipment is mandatory. Power
related problems account for more than 50% of service calls in either VCR or DVR based
CCTV. Some of these issues are related to bad grounding, unprotected or unstable power
source. Improper grounding of either cameras or a DVR will cause a hum or noise in the
video signal distorting the image. Consider the following:
Diagram 1
Camera is mounted at the field and is powered from Power Supply 1. Monitor is in a
building, powered with Power Supply 2. There may be a potential difference between the
Ground potential of supply 1 and supply 2, say 1 or 2 volts. This will result in a current
flow through the coaxial shield of the cable and the voltage drop in shield resistance gets
added to the video signal. This results in a hum noise signals in the video, causing
tearing / rolling bars in the picture (normally multiple dark gray lines moving up the
screen) as shown in diagram 2. Ground loops are an after-the-fact type of problem in
which the end-user blames the installer, the installer blames the manufacturer, and
actually nobody is at fault. Neither the manufacturer nor the installer can predict where a
loop will occur. Only after the system is installed can it be determined if a problem will
exist. The solution is to never connect both ends of a video cable to local grounds. Any
cable can be grounded at one end without inducing the ground loop current. When you
run coax cable from one building to another, it is acceptable to install through connection
11
points, but do not allow the shields to come into contact with one another or the local
ground. A coaxial connector lying in a cable tray or conduit box can accidentally contact
ground, don't let this happen. Use tape on the connector to prevent accidental grounding.
Also try not to attach the camera to any structure that is likely to be grounded. Remember
that the camera is already grounded at the opposite end of the coaxial cable by the
recording equipment.
At the recorder end you may have many pieces of equipment connected together, such
as a DVR, Monitor, amplifiers, etc. all of which plug into the main 60 cycle power. This
will not present a problem if you plug all of the equipment into the same power line at the
recorder point, ensuring sure that the entire connected equipment share the same ground
point at the recorder end. Try to keep the video cables between equipment, (the service
loops) as short as possible. If you already have an installation that has 60 cycle bars,
there are some steps you can take to solve the problem. If coaxial cable shields are
connected together anywhere in the system, separate them if possible. Similarly remove
all but one ground connection on each coaxial cable if possible; the ground is usually at
the recorder end of the coaxial cable because the recording equipment plugs into the 60
cycle main power supply which is grounded.
When using a 24VAC powered cameras, sometimes a ground loop problem can be
reduced by reversing the AC plug on the power transformer used to power the camera, or
reverse the 24 VAC power connections to the camera. However, this technique will not
work on DC powered cameras. With an understanding of Ground Loop problems and the
use of good single ended grounding techniques, you should be able to keep the 60 cycle
bars out of your CCTV installations.
Unprotected, unstable or inadequate power source to the camera or DVR will shorten the
life of the device and cause unpredicted failures such as shut down, loss of video signal
or corrupting the video database resulting in loss of recorded video. Designing a proper
camera surveillance system requires calculating the amount of power required to drive all
the cameras plus ample amount of headroom (usually 20% – 25%). The lack of
adequate power to the cameras will result in distorted images and washed out colors.
The length of a cable run as well as the gauge of that cable has a direct effect on the
amount of power supplied to the camera. The resistance associated with the cable
creates voltage drop relative to distance. Table 7 below shows the resistance per foot of
copper power cable.
Wire Gauge
16
18
20
22
24
Resistance
0.00395
0.00665
0.0104
0.0157
0.0262
Table 7
The amount of voltage lost between the originating power supply and the device being
powered can be significant. Improper selection of wire gauge can lead to an
unacceptable voltage drop at the load end.
The following equations are designed to help calculate voltage drop at any given distance
as well as the maximum distance of a cable run as a function of wire gauge.
V=
2*DIR
1000
12
Where:
D
I
=
=
R
=
Total distance of the cable run in feet
Camera operating current rating in milliamps (most manufacturers
incorrectly list this as power consumption)
Total resistance of the cable from table 7
NOTE: The result of the equation represented as “V” is the voltage drop across the
specified length of power cable. The voltage drop should not be more than 10% of
the input voltage requirements for the camera for proper design.
D=
V * 0.1
2 * I R * 0.001
Where:
V
I
R
=
=
=
Camera operating voltage (power supply)
Camera operating current rating in milliamps
Total resistance of the cable from table 7
NOTE: The result of the equation represented as “D” is the maximum distance the
power cable should be extended based on the selected wire gauge from the table
above.
It is recommended not to power accessories such as heaters and blowers from the same
power source as the cameras. Motorized accessories will generate interference and
noise on the video signal causing distortion.
•
Recording Device – A picture is worth a 1000 words. Without a recording device, detecting
an activity and transmitting it to a display monitor would not be of any importance if there is
no proof of it any where. Until just a few years ago a VCR was the only means of recording
the video signal from a CCTV camera. With the advent of the Digital Video Recorder (DVR)
that all has changed. DVRs are sweeping the market and have opened up new doors to
spectacular features and options. Choosing the type of recording device depends on the
application of the CCTV system. The proper design of the CCTV system to address the
user’s needs is the key factor in the selection process for the appropriate recording device.
There are many differences between an analog and a digital recording device that will be
covered in detail.
NTSC Video Standards
Short for National Television System Committee, the NTSC is responsible for setting television and
controlling the video standards in the United States. In 1954 a video color format that combines all video
signals, brightness/luminance (Y) and colors/chroma (U and V) into one channel was created. This video
signal is called Composite Video and transmits a multiplexed signal comprised of all the information
necessary to reproduce an image on a color monitor. The composite video must operate precisely within
specific video standards for proper production of the video signal.
The video signal standard was created and managed by the Institute of Radio Engineers (IRE). IRE is
used as a unit of measurement for a video signal. One unit of IRE is equal to .007142 V peak to peak.
The process in which the video signal is generated is very much the same between B/W and Color with
the exception of the CHROMA (color information) in the signal. Table 8 shows the units of measurement
for each of the video component in both IRE and voltage peak to peak. You will notice that only the B/W
video signal which consists of B/W picture and Sync Pulse would be easy to measure at 1 volt peak to
peak. Measuring the other components would be extremely difficult using standard equipment. There
are commercial IRE meters available that will provide exact measurements for all the components of a
video signal.
13
Video Component
B/W (picture only)
Color (picture only)
Sync Pulse
Color Burst
B/W (peak to peak)
Color (peak to peak)
IRE
Units
100
120
40
40
Volts peak-topeak
0.714285714
0.857142857
140
160
1.00
1.142857143
0.285714286
0.285714286
Table 8
Picture 5 is the actual graphical representation of a complete composite color video signal. The Sync
Pulse and Color Burst portion of a video signal are important in establishing the quality of a video signal.
Both have the standard amplitude of 40 I.R.E. Units.
Picture 5
A no loss signal would measure 40:40, a very easy number to remember to represent a perfect picture.
Any more or less will result in lower image quality. Table 9 shows an example of the result of lower IRE
levels for these signals based on the length of the video cable extending from the camera to the recording
device using twisted pair video cable.
Cable
Length
0
100
Sync Pulse
40
39
Color
Burst
40
36
Video
Results
Note # 1
Note # 2, 3
500
35
21
Note # 4, 5
1000
31
11
Note # 6, 7
1500
27
6
Note # 8,9
2000
24
3
Note # 10, 11
Note 1:
Good video level – Perfect quality
Note 2:
Sync Pulse low but in tolerance
Note 3:
Slight loss of color
Table 9
14
Note 4:
Note 5:
Note 6:
Note 7:
Note 8:
Note 9:
Note 10:
Note 11:
Sync Pulse within lower tolerance
Very weak color information
Sync Pulse out of tolerance – Low contrast and brightness
Faded color – Start of loss of image sharpness
Out of Tolerance - Lower contrast and brightness
Possible loss of color and poor picture sharpness
Very low brightness or contrast – Start of picture distortion
Possible total loss of picture color – Dull image
VCR and DVR technologies
Both VCR and Digital Video Recorder (DVR) systems receive the same video signals from the camera
through the same transmission media and that is where the similarities end. Once the image has been
transmitted from the camera to the recorder, many options are available that are not available for a VCR.
Analog images can only be displayed on a monitor, recorded to tape, or perhaps printed on a video
printer. With a DVR system, live or prerecorded stream of images can be transmitted to a simple PC,
cellular phone or PDA anywhere in the world via the Internet networks, via e-mail or interoffice Intranets.
There are many differences between them in storing and operation of the video signal. DVRs offer
instantaneous access to recorded, storage longer, and higher quality images that won’t degrade over time.
Ability to search multiple storage sites with a single query such as date/time or event and uninterrupted
and automatic storage to disk with triplex multi-tasking brings full flexibility to the user that is not available
with a VCR.
What does all this mean? DVR saves time, delivers more reliable information, lowers operational costs,
reduces the amount of required dedicated resources and increases productivity. Other differences
between a DVR and a VCR are, image quality, recording capacity, search and backup capability. A DVR
has between 50% to more than 400% better picture quality due to its higher resolution. The playback
quality of video on a DVR is far superior to that of a VCR without distortion or degradation. There is no
need for, motion detectors, video processors/multiplexers, callout boxes or in most cases a PTZ controller.
A DVR has it all.
Remembering to replace the tape, or not being able to clearly make out details in a scene has always
hampered a VCR based CCTV system. The time it takes and the additional equipment it requires to
search and archive an incident has been more than impractical with a VCR based CCTV system.
However, finding and archiving a suspicious activity is done in a matter of minutes with a DVR. By far the
biggest difference is the DVRs remote access and networking capabilities. Being able to view live video
and control a DVR from anywhere is a feature that no VCR could offer. The recording length is limited
with a VCR but not so with a DVR. There is no limit to the amount of storage a DVR could accommodate.
Since all of the required peripheral equipment is already built in, a DVR makes for an unprecedented
choice as a complete CCTV solution.
Video compression and storage
A single image at a resolution of 720x480 and a 24bit color depth would be more than 1MB in size (1012
KB) and is commonly referred to as bit-rate. Let’s assume that we need to store or transmit 5 minutes of
the video at 30 images per second to a remote location. Without compression it would require more than
9.1GB to store the video and it would take more than 15 days to transmit the video using a 56K telephone
line connection. Digital video transmission and storage would be impractical without compression.
Compression, in its basic form, is the art and the technology behind removing unnecessary, repetitive and
unimportant information from each frame or subsequent frames for the purpose of saving storage space.
Compression methods differ from each other as to the way the information is removed and processed.
There are four types of compression methods:
•
Discrete Cosine Transform or DCT
15
•
•
•
Vector Quantization or VQ
Fractal Compression or FC
Discrete Wavelet Transform DWT
DCT is a lossy compression algorithm that samples the image at regular intervals.
It analyzes the components and discards those that do not affect the image as
perceived by the human eye. JPEG (Motion Joint Photographic Expert Group),
MPEG (Motion Picture Experts Group which includes MPEG1, 2, 4 and under
development 7 and 21), H.26X (which consists of H.261, 263, and 264) are a few
compression standards that incorporate the DCT method.
VQ is also a lossy data compression method based on the principle of block coding.
VQ represent not individual values but usually small arrays of them. A typical
example is the picture of a forest which typically has a lot of green. VQ generalizes
what it detects, compresses the redundant information and tries to keep the
important information as close to the original as possible.
FC is a compression method used to compress images using fractals algorithm.
The FC method is best suited for photographs of natural scenes (trees, mountains,
ferns, clouds). The fractal compression technique relies on the fact that in certain
images, parts of the image resemble other parts of the same image; therefore, it
locates and compresses the similar sections of that image.
DWT compresses the image by frequency ranges. This type of compression filters
the entire image, both high and low frequencies, and repeats this procedure
several times. Wavelet compression utilizes the entire image, which is different
from many other types of standards used within DCT compression method.
Some of the commonly used compression standards are:
•
MJPEG – MJPEG (Motion Joint Photographic/Picture Expert Group) is designed to take
advantage of known limitations of the human eye, notably the fact that small color changes
are perceived less accurately than small changes in brightness. Thus, it is intended for
compressing images that will be viewed by humans. Based on the standard composite video,
the MJPEG could achieve a 20:1 compression with very little loss of image quality but with a
larger storage requirement many other standards.
•
MPEG – MPEG (Moving Picture Expert Group) is based on the compression across a group
of images called I-frame, P-frame and B-frame. The I-frame (intra) provides the starting point
and provides only a small amount of compression. P-frames (predicted) are coded with
reference to a previous picture which could be either an I-frame or other P-frames. B-frames
(bidirectional) are intended to be compressed with a low bit rate, using both previous and
future references. MPEG provides a very efficient and scalable ratio of compression. With a
ratio of 20:1 to more than 400:1, many manufacturers had moved towards using MPEG for
remote viewing and storing video. Some of the MPEG standards include MPEG1, 2, 4, and
currently under development MPEG7, 21.
•
H.264 – The advancement in compression technologies in the last couple of years has
resulted in development and increased implementation of the H.264 compression. The
H.264, also referred to as MPEG4 part 10 is the result of refinements made to a block-based
encoding methods well established with MPEG4. H.264 introduces smaller block sizes,
greater flexibility and greater precision in motion vectors.
•
SMICT – The SMICT (Super Motion Image Compression Technology) standard has almost
the same characteristics of H.264 and based on redundancy and motion, it combines DSP
(Digital Signal Processor) hardware compression with the CPU software based compression.
The SMICT intelligently analyzes the motion changes that occur within the frame, eliminating
the redundant portion of the image that does not need to be stored, and compress the
changes based on motion. This type of compression standard has a ratio of 2400:1.
16
•
Wavelet – Unlike other compression standards, the Wavelet not use DCT method of
compression. Wavelet compression uses frequency filtration to analyze the entire image
unlike MPEG, Wavelet does not divide the image into blocks. This characteristic of Wavelet
compression allows for a good compression ratio while maintaining image quality. The
frequency filtration technique relies on the image parts that are not noticed by the human eye.
The more often filtering occurs, the smaller the overall file size of the image and the lower the
image quality will be when compressed.
Not every compression method or standard is designed to be the solution to all requirements. Keep in
mind that image quality, remote viewing capability and performance as well as storage capacity
requirements is what dictates the best selection.
Video format
CIF (Common Intermediate Format) is used to standardize the horizontal and vertical resolutions in pixels
of YcbCr sequences in video signals. The original CIF, also known as Full CIF (FCIF) is the common
recording size for majority of the DVRs. Table 10 displays the CIF resolution formats commonly used in
the video industry.
Format
SQCIF
QCIF
QCIF+
CIF (Full CIF)
2CIF
4CIF
9CIF
16CIF
NTSC-based
176 × 120
176 × 220
352 × 240
704 × 240
704 × 480
1056 × 720
1408 × 960
PAL-based
128 × 96
176 × 144
176 × 220
352 × 288
704 × 288
704 × 576
1056 × 864
1408 × 1152
Table 10
The size of the image has a direct effect in the amount of storage required for the video and it is
measured in bit rate per second as described in compression section.
Digital Video Recorder operation
There are two common types of CCTV Digital Video Recorders (DVR). PC based and Stand-alone DVRs.
PC based DVR hardware comprises of a powerful specially configured computer with a complex video
processor and storage devices. However, this technology would be useless without a sophisticated
operating system and a feature packed graphical user interface software.
Most security cameras in use today capture an analog picture. This picture is transmitted via different
types of media to the DVR in an analog format. The DVR detects this signal and using Analog to Digital
converters, transforms the picture into digital bits of information. These bits of information are further
processed for accuracy in color and signal levels before it is transmitted through the DVRs internal
architecture to the video display and further compressed and stored onto the built in storage drives.
Due to the complexity in the design of the DVR as well as the speed in which the information is being
processed, it is very crucial to providing proper cameras signal levels to the DVR. The Stand-alone DVR
is very much the same in concept as the PC based DVR. The differences in the two are with internal
architecture, the operating system and the user interface. The stand-alone DVRs are more cost effective
to produce and easier to install, however it provides limited options and expandability.
A standard PC versus a DVR
With respect to the hardware components, there are no differences between a high end PC and a PC
based DVR. The differences are more evident in the operation and the type of usage. When a standard
PC is turned on and has finished its self test (POST), it reads and loads the preinstalled information (OS
17
and applications) into the RAM memory for the operator to use. The hard drive in a standard PC may
work the hardest during this time period, since that is where all the information requested resides.
However, once this information is loaded into the memory, the hard drive becomes idle until the next
application is requested.
In a PC, when using a standard word processor, email, web access or even balancing a checkbook, the
hard drive will not be accessed but a total of a minute or two per hour. The rest of the time the hard drive
is idle. This idle time allows the hard drive to spin down and even enter into hibernation where it may
vary and could measure in minutes to even hours. On other hand, with a DVR, although the same initial
process is followed, the hard drives read / write access does not end as the DVR application has finished
loading. Since the images captured from the camera have to be stored constantly on the hard drive, the
idle time for the hard drive is virtually non-existent.
A hard drive is a very sophisticated piece of electronics equipment which consists of several extremely
sensitive components such as Controller Board Electronics, Storage Platters and the Actuator Arm
/Read-Write assembly. A typical DVR hard drive has several storage platters disks that rotate at speeds
of more than 7200 rpm. These platters are made of layers of non-magnetic and magnetic material which
provides the storage media bits of data. The actuator arm/read-write head assembly, which handles data
reading and writing functions, is located in between the platters and can travel from the inside of a disc to
the outside in as little as six milliseconds. The space between the Read-Write heads and the platters are
less than 2 microns (approximately 78 millionth of an inch).
This back and forth operation of the actuator arm within the hard drive is performed several thousand
times a minute. While this precision techno-dance is occurring, data (video) files are being transferred
from the head to the rest of the computer and back in a seamless stream of coherent information. The
equivalent of this operation would be for an F20 jet fighter to be able to fly at an unimaginable speed of
MACH 813 (eight hundred thirteen) just 1/62 of an inch above the ground with the capability of landing on
a blade of grass!
Picture 6 will help you visualize just how fine the tolerances are in a disc drive.
Picture 6
Now imagine the computer case or drive casing being bumped, knocked around, scooted across the desk,
tipped over or otherwise mishandled while running. The resulting motion causes the actuator arm/readwrite head assembly to impact the platter surface, resulting in what is called as head slap. As a result of
18
the impact, tiny indentations can be formed. The material ejected from this impact is scattered about the
disc, while the drive is powered up the heads will pass over this indentation and the ejected material. This
can be the equivalent of running over a bowling ball in a go-cart traveling at the above mentioned speed
of Mach 813.
Another fact to consider is that the hard drive is a mechanical device, the longer it operates the more heat
it will generate. This heat when trapped inside the DVR will increase the temperature within it to unsafe
levels for the hard drive and other components to operate efficiently. At high temperatures, the
components start to break down and eventually fail. On average, the life expectancy of a DVR is 1/3 to ½
of that of a PC within the same environment. Although a DVR has a shorter life than a PC, it can certainly
be extended by following a few simple steps such as:
•
•
•
•
•
•
•
DVR must be installed in a well ventilated area.
DVR must not be installed near magnetic field generating equipment such as generators, radios,
wireless equipment or share plug-in with appliances such as refrigerators, heater, coolers , etc.
Dedicated power line is highly recommended.
Do not install the DVR in extremely hot or cold area (60° to 70° F is highly recommended)
Do not install the DVR in a smoky or dusty environment.
Keep all sides of the DVR clear for proper air circulation.
The DVR must not be enclosed in a cabinet without adequate air flow.
Do not cover the top of the DVR with any object.
Precautions consideration before installing a DVR
In addition to the steps mentioned in the previous section, the following precautions are crucial in
improving the operation and life expectancy of the DVR. These precautions are as follows:
•
•
•
•
•
•
•
•
Make your camera cables the same length to prevent stress on cable ends and the DVR board.
Ensure the camera input cables are properly terminated and tested for proper impedance.
Ensure the camera power cables are properly made with the correct polarity when applies.
Using a field monitor or a video level meter, ensure the cameras are in good working order prior to
attaching to the DVR.
Do not use the DVR as the test equipment for camera troubleshooting.
Ensure the power is off prior to all cable installations.
Attach camera cables to the wall or table for extra support to prevent damage to the BNC board on the
back of the DVR.
Do not open the DVR cover.
What are an Embedded devices and an Embedded OS?
Typically, embedded device refers to any computer system or computing device that performs a
dedicated function or is designed for use with a specific embedded software application. These are
systems that the end user typically cannot modify. Embedded operating systems are usually highly
customized for a specific task or function. They may be optimized for specialized hardware or a specific
application. Since the configuration can be "locked down" and therefore rigorously tested, manufacturers
of these systems can control costs and deliver highly reliable devices optimized for specialized tasks.
What Operating system is best for a DVR?
One of the biggest decisions a DVR manufacturer has to make is what operating system to use for their
DVR. The main players have been Linux and Windows. Although windows XP Professional turns every
PC into a powerful and flexible tool that can be used for a wide range of purposes, this operating system
is inherently susceptible to environmental hazards, such as viruses, worms, spyware and hackers. That
is why a few of the DVR manufacturers invested massive amount of time in developing Linux based
DVRs. Linux is immune to viruses and other hazards that plague Windows XP Professional. It seemed
like Linux would have made perfect sense for the DVR manufacturers to choose as the DVR operating
19
system, until a few years ago. Since Windows XP Embedded (XPe) has become available, more and
more developers are moving towards this operating system for its unique capabilities.
Windows XPe is immune to viruses, and other hazards just as Linux embedded. Windows XPe
environment is user friendly and are more acceptable by the users than the Linux environment. The
Windows XPe performs better in multimedia and web applications than Linux. There are far more support
available for the Windows XPe operating system than Linux. The faster development process from
inception to implementation lowers the development cost, resulting in Windows XP Embedded operating
systems as a more viable choice as the operating system within the DVR industry.
Why a DCI DVR?
A DVR Connection DVR unit is different in many aspects. As mentioned before a DVR with an
embedded operating system is far more superior than a DVR operating from a standard operating system
such as standard Windows or standard Linux. All DCI DVRs operate on Windows XP Embedded OS.
But that is not all. A DCI DVR unit has been designed to operate in harsher environments than other
DVRs in the market by the use of additional ventilations and additional built in exhaust fans. The
manufacturing of the DCI DVRs are a precise process by ensuring proper compatibility and
implementation of components. The embedded operating system and DVR user interface software is
customized with the end user in mind. By using text for the interface buttons, learning to maneuver
through the software is quicker and more efficient than other DVRs using graphical icons. DCI
incorporates a hard disk write protection utility which enables the operating system and all applications to
stay intact and unchanged in the case of accidental corruption or intentional virus and spyware attacks.
Each unit is equipped with a complete restore and recovery software for a speedy recovery in the case of
a hard drive malfunction. Additional to all the software differences, each DCI DVR is accompanied by a
powerful uninterrupted power supply, preventing damage caused by brownouts and power surges to any
of the components within the DVR. Each and every DCI DVR is tested rigorously before shipping to
ensure quality and trouble free installation.
TCP/IP networking basics
Networking is by far the most complex task in installing a DVR that would be remotely monitored. There
are many networking basics knowledge requirements for a successful and quick remote connection
configuration. In this section you will learn the very basic knowledge about networking and configuring a
DVR for remote access via the Internet Protocol.
TCP/IP - TCP/IP stands for "Transmission Control Protocol / Internet (working) Protocol". It is a
description of a networking protocol (protocol is simply a description of the method by which devices (or
humans) communicate between themselves) that has evolved over several decades and is now the most
widely used networking protocol. It is also the protocol that forms the "backbone" of the way the internet
works. TCP/IP networks in general are made up of the following parts:
•
•
•
•
IP Address
Subnet Mask
Gateway
Domain Name Service (DNS)
IP Address – As shown in picture 7 an IP address is a set of numbers that designate an exact location
for a device on a network.
Picture 7
20
•
•
•
There are EXACTLY (no more, no less) four sets of numbers separated by a "period".
Each number MUST be equal or greater than 0 and no more than 255.
We know that this IP address is on a "Private" network. (More on this later)
The example in picture 7 shows us a set of numbers that are easily read by humans. The computers
however, read these numbers in different ways. Computers think & communicate in ones and zeros
where humans think & communicate in diverse ways such as different cultural languages. Our number
system is based on the concept of ten (10).
Diagram 4
Networks are made of two things, Computers or Devices (referred to as HOSTS) and the Network
(defined as bunch of computers or devices hooked up together) itself. Diagram 4 shows a simple network
of computers and devices connected together. The important things that you need to understand at this
point are:
There are HOSTS and NETWORKS
A HOST exists in a NETWORK
A HOST can be any connected device (just like the diagram 4 shows!)
Diagram 5
21
Diagram 5 now adds some more information relating to actual TCP/IP. You will notice that Network "N" is
designated as 192.168.1.x. The “x” represents each device’s unique address also known as Host ID.
Having a network like this is great and means that all of our devices can talk to each other. However, the
real advantages of networking come when we hook networks together. For example, at home or in the
office, we might want to hook our network up to the Internet (it's just another network!) so that all of our
computers can send/receive email or get on the internet. Let's look at this in the next diagram.
Diagram 6
Diagram 6 shows nearly the same thing as diagram 5 in terms of an individual network. However, the
main thing it shows is how multiple networks can be hooked up together. If you might have noticed
another device has been added into the diagram. This device is known as the Gateway or the Router,
that is now included in both networks. A router is simply another device connected to a network. It is
responsible for "routing" any TCP/IP traffic to and from other networks. Every network that needs to "talk"
to another network needs some form of router.
Note: Network "B" in the diagram could just as easily be the Internet in general. So, if we are
thinking about how to hook our network up to The Internet, our network “N” would look very
similar to diagram 6.
To understand what HOSTS and NETWORKS actually are, let's relate this back to TCP/IP designations.
A HOST Identifier uniquely identifies a device on a network. For example, if your IP address on your
network is 192.168.1.1, your HOST ID will be "1". A NETWORK Identifier uniquely identifies your network.
For example, if your IP address on your network is 192.168.1.1, your NETWORK ID will be "192.168.1.x".
Diagram 7
22
Subnet Mask - The subnet mask simply defines which sections of an IP address is the NETWORK ID
and which section(s) is the HOST ID. Therefore a subnet mask defines the network to the HOSTS. For
example, if HOSTS "A" and "B" are both connected together, and both have the same subnet mask
defined, they are deemed to be on the same network as each other. Diagram 7 shows us an exploded
view of a HOST on a NETWORK including a new set of address called Mask or Subnet Mask.
Gateway - The Gateway (also known as Default Gateway) is simply the address of the router on your
network that is responsible for communicating with the outside networks. Looking at diagram 6, for
HOSTS in different networks to be able to connect and communicate, they have to communicate via a
series of routers.
Domain Name Service (DNS) - The Domain Name System (DNS) is a distributed internet directory
service. DNS is used mostly to translate between domain names and IP addresses, and to control email
delivery. What that means is that, it is difficult for most people to remember the host IP address of a
particular website as 64.236.29.120, but it is very easy to remember www.cnn.com. Most internet
services rely on DNS to work. If DNS fails or is too slow, web sites cannot be located and service delivery
stalls.
Note: To configure a network for the DVR we must first establish if our network is independent
(private) or will it be attached to an outside network (Public).
Private Network (LAN) - A private network could be like the one that you have at home or in the office. It
may (optionally) be connected to a public network (i.e. Internet). IP addresses in a private network need
to be unique but do not need to be globally unique. It is important that you follow international standards
when setting up private networks. You must use IP addresses that are in certain ranges so as not to
duplicate ones already in use on public networks. This is particularly important where your private
network is connected up to the internet. Diagram 5 is an example of a private network.
The standards (as defined by Internet Assigned Numbers Authority (IANA)) for private network addresses
are:
10.0.0.0 to 10.255.255.255
172.16.0.0 to 172.31.255.255
192.168.0.0 to 192.168.255.255
Also, IP addresses in the range of 169.254.0.0 to 169.254.255.255 are reserved for Automatic Private IP
Addressing (such as in Windows XP)
Diagram 8
23
Public Network (WAN) - The Internet is a public network. A public network in fact is comprised of
literally millions of smaller private networks across the world connected to each other through gateway
routers. The purpose of a public network is to allow sharing of information and resources between
smaller private networks. Every IP address on The Internet must be globally unique. Diagram 8 shows
the typical configuration of small networks connected to the Internet by a Broadband Router. Looking at
diagram 8, in order for a host on the private network to be accessible from the hosts within other private
networks or in this case the Internet, the router for the network must allow incoming communications to
have access to the particular host within the private network. The process of providing this access is
called Port Forwarding or IP Routing. As with a telephone switchboard, the router receives a request for
communication with particular software on a particular host. The port forwarding feature of the router
verifies the information with its internal pre programmed configuration and if the information for the host is
available and correct, then it forwards it to the targeted host. Configuring Port Forwarding or IP Routing
within a router is done through a special program provided by the manufacturer of the router. This
program differs from one manufacturer to the next, making it difficult to have one standard procedure for
all the routers. The networking information provided here is for reference only and should not be used as
a guideline or instruction for installing or configuring networks or the programming of routers. Routers are
a very crucial part of a network and incorrect configuration will result in the shut down of both the private
and the public network access. Programming of routers should be left to more experienced network
managers.
24
FAQ
Although each and every DVR has been fully tested prior to shipping, some trouble may arise from shipping,
improper installation and operation as well as environmental factors. The following suggestions are easy solutions to
some common problems. For solutions to more serious problems that may require disassembling the DVR, contact
the help desk. Do not attempt to disassemble the DVR yourself.
Symptoms (Power)
Solution
The DVR will not power up.
Ensure the UPS, and the DVR power supply switches
are turned on (position I). Ensure all power cables are
plugged in to the DVR, Monitor, cameras and the UPS.
The DVR is powered up with a message “No
signal” displayed on the screen.
Check the Video cable for the monitor. Ensure none of
the pins on the connector has been bent during
installation. If pins are straight then press and hold the
power button in front of the DVR for 5 seconds to power
the DVR down. Unplug and reconnect the video and
power cables and try again.
The DVR is only showing blue squares where
the camera images should be.
The cameras are not receiving power. Ensure the
camera power supplies are connected and you have
voltage at the camera end.
The DVR shuts down when the electricity
flickers.
Ensure that the DVR and the monitor are connected to
the battery side of the UPS and not the surge side.
The UPS keeps beeping every second when
everything is powered up.
The UPS is intended to provide power for the DVR and
the monitor only. Ensure there are no other devices
attached to the battery side of the UPS.
The electricity went out and the DVR shut
down after several minutes.
The UPS beeps every so often without
anything changing.
The UPS is intended to provide power for the DVR for
about 10 minutes. After 10 minutes it will shut down if it
was not turned off manually. However once the power
is restored the DVR will detect that and restarts itself.
The electricity provided to the UPS may not be stable or
clean. The UPS detects and adjusts itself for power
fluctuations and surges. The beep represents power
source problems at the outlet or the breaker box that
may need to be looked at by a certified electrician.
Symptoms (Operation)
Solution
The time is not correct. It is off by 6 hours.
This is an embedded DVR unit.
Click on Setup and under Standard tab, click on Time
Setup. Click on Time Zone and ensure that the option
"Automatically adjust clock...." is unchecked. Change
the time to the correct time and Save and Apply. If the
option is Checked, then unprotect the DVR and reboot
the DVR, click on Setup and Time Setup, uncheck the
option, correct the time, Save and Apply, re-protect the
DVR and reboot.
Keyboard or mouse will not operate.
Power down the DVR. Ensure the Keyboard and
mouse are plugged in to the correct ports and are
plugged in all the way. Restart the DVR.
After the DVR was turned on and had booted
into the software it stopped responding before
the cameras are displayed.
The problem may be the camera signals to the
DVR. Shut the DVR down. Check the power source to
the cameras for proper polarity. Restart the
DVR. Once the camera input windows are displayed,
turn on the power to the cameras.
25
Some or all the camera input windows are
black.
This could be caused by: 1- Wrong power voltage to the
cameras. 2- Bad BNC cable ends. 3- The camera
switch settings are wrong (BLC, DC vs. Video Iris, etc.)
The colors and lighting for the cameras are not
correct.
Using the instructions in the manual for Color Control,
adjust the Brightness, Contrast, Hue and Saturation to
get the desired signal.
The camera pictures jump and the frames
change very slowly with black lines through
them.
The DVR will stop recording on one or several
cameras at random during the day.
The DVR keeps shutting down and rebooting.
Why are some of the images frozen for a while
when playing back multiple cameras in search
mode?
The camera images keep getting lighter or
darker frequently or may change color.
The system is set to record based on motion
but it is recording continuously.
The recording frame rate drops at night.
When a frame is zoomed in the picture
becomes grainy.
The System Info has been displaying 5% on
the hard drive space for a few days. Why is it
not changing?
The video playback is very grainy and it shows
small squares like pixels.
The video signal strength is very low at the DVR
input. 1- Make sure the signal is not split. 2- Shorten
the cable runs. 3- Remove any other devices attached
to the cameras before the DVR (i.e. TVS, Multiplexer,
etc.). In some cases if the signal is below 1V P-P, a
signal booster must be used to compensate for signal
loss.
The software is set to detect camera failure due to
lowered input signal, voltage drops, or distorted
images. When that happens it will shut the camera
down and will not record until the camera has returned
to proper operation. This could sometimes be caused
by heat or power fluctuations at the camera side.
The DVR may be infected by a virus from a remote PC.
Disconnect the DVR from the Internet. Restore the DVR
to original software. Clean the remote PC from any
virus before accessing the DVR.
The DVR plays back all camera images of the same
time frame at the same time. The cameras that are
frozen must be ahead of the rest in time. Once the
other cameras reach the same exact time, then they will
start playing again.
If this is happening where the camera is placed directly
under Fluorescent lighting, either move the camera
away from the light or check the ballast for proper
operation.
The motion sensitivity is set too high. Refer to the
manual and adjust it to three to four notches below
maximum. Use the motion area setting and select only
the areas needed for motion detections (i.e. Doors,
Windows, etc.).
Lighting effects recording frame rate and storage
capacity. If the area is dark then it uses more hard
drive to record the darker area as well as dropping
frame rate to compensate for the excessive amount of
information being recorded. If the area is too dark for a
color camera to properly see, it is suggested to use
black and white or appropriate night vision cameras
instead.
The DVR is equipped with a Digital zoom. The number
of pixels contained in a picture is constant. As the
picture is getting bigger so do the pixels. Therefore
what is being looked at is the actual pixel within the
picture. Higher resolution cameras will yield better
quality zoom factor than lower resolution cameras.
The DVR is designed to fill up the entire storage area
before erasing the oldest video. The 3-7% that may be
showing is the buffer zone. Once it reaches that, it will
start erasing the oldest video and will remain at that %
unless the storage is manually formatted.
Ensure the quality setting is set to 1 or 2 below the
maximum if MPEG4+ is being used.
26
The video is showing nighttime during the day
and the opposite at night.
The video shows a two-minute blank (no
recording) every morning at a specific time.
The DVR is recording only 1 day and it used to
record many days before.
The DVR is not recording the same number of
days at all times when set to motion recording
without any changes to the settings.
Why are the recordings not showing up in the
24-hour record lines?
The DVR is displaying a message “Disk is full,
Change diskR”.
The DVR is asking for Administrator Password
(Windows 2000 only) and it will not go into the
camera software.
DVR boots up and gets into the camera
software and then it comes right out of the
software into Windows.
There is a square label flashing AF and M (or
R) in place of the M (or R) that is normally
displayed on the top right corner of the camera
images and it is not recording properly.
I have an ED800 and I cannot find the place to
connect to a TV.
The picture quality on the TV is poor.
I recorded ten minutes of video on CD but it
only showed about 2 ½ minutes (motion
recording)
The clock is setup incorrectly. Use the time setup and
correct the clock setting.
That is part of the watchdog feature. The DVR is set to
shut down and reboot at a specified time set within
Standard Setup screen for an optimized
operations. The time can be set to any other time if
desired or completely disabled. However it is
recommended to restart the DVR at least once a week
manually.
Make sure that the second drive letter D is shown in the
Standard setup section under Managing Disk. If it is
only showing drive letter C, then there is an issue with
the hard disk and the technical support should be
contacted.
The recording based on motion is dependent on several
factors. Frame rate, lighting, detection, and traffic. If all
the settings are constant then the reason for the varying
recording days is due to environment changes such is
lighting or amount of traffic in front of the camera and it
is a normal phenomenon. Creating detection zones
and adjusting the lighting will help the situation but will
not eliminate the varying recording process.
The database may not have had time to update the
index file before Search was activated. Refer to the
Maintenance section of the manual and refresh the
database.
The “record after delete” option in the standard setup
is unchecked. Access setup and check the box next to
Record after delete in Standard setup section.
The last person using the DVR has changed the
network workgroup or user profile. Try and enter the
DVR by typing “ password “ in the password. Exit the
DVR software to Windows and change the workgroup
to WORKGROUP and restart (Contact technical
support for more detail).
This is caused by changes made in the DVR setting
without saving and rebooting. Double click the icon for
the DVR software and try again. If not successful
restart the DVR and let it redetect the changes.
The Pre and Post is set to a number other than 0 in the
recording type part of the setup. Reset the pre and post
to 0 and then Save and Apply.
The TV out is not available on ED400 and ED800 DVRs
as a standard option. However a device such as scan
converter can be attached to the DVR to provide TV out
for displaying the images on the TV.
The resolution of a standard TV is only 525 lines. The
DVR is displaying at 768 lines. In order for the images
to properly display on a standard TV some of the
graphic information must be removed from the original
image through scan converter electronics. Therefore
the images are not as crisp as the images on the DVR
monitor. The bigger the TV the grainier the images will
appear.
The DVR only records when it detects motion. It may
have only detected 2 ½ minutes of video during the tenminute segment.
27
I recorded an incident as AVI on the CD and
am not able to play it back on my office PC.
Some CDROM drives are not able to read all the CD
medias currently in the market. Try a different media or
upgrade your CDROM driver software utility.
How can I edit and enhance the AVI file of the
incident I copied onto the CD?
There is software available In the market that allows
you to edit and enhance the quality of an AVI video
file. DCI does not promote or support any third party
software.
Why does the saved AVI pause every few
seconds when playing back from a different
CDROM drive?
The media is not a high speed or ultra speed media or
the CDROM drive cannot read high speed or ultra
speed CD media.
I tried to format a CDRW media and after a few
minutes it gave an error message and quit.
How can I find the speed of my CDRW drive?
I do not have access to CDRW media. What
should I do?
Can I reuse my CD media?
The DVR is equipped with either a High-speed or Ultra
speed CDRW drive. An Ultra-speed CDRW media
cannot be formatted in a high-speed drive. The CDRW
media must match the speed of the DVR CDRW drive.
The speed of the drive is written vertically on the side of
the CDRW Disk emblem in front of the drive.
You can use a CDR media instead. However it too
needs to be preformatted before use. If no media is
available at the time of the incident, then record the AVI
onto the ‘ C ‘ drive My Document directory and then
copy it onto the CDR media when one becomes
available.
Your CDRW media can be used over and over
again. However the CDR media can only be used
again if the session was not closed and the CD was not
locked after the last recording.
Symptoms (Remote Access)
Solution
How can I find out if I am on Static or Dynamic
IP addressing?
That information is available from your Internet Service
Provider.
When I click on Check IP Control User Access
it shows 127.0.0.1 and not the IP address my
ISP provided.
Your connection to the ISP is not established or the
settings are not entered correctly in the Windows
network environment of the DVR.
The DVR is attached to a Router and I have no
access to the DVR from remote with the IP
address the router has assigned.
I am not allowed to install the remote SW on
my PC at work. How else can I monitor
remotely?
I have a 16 channel DVR but only 4 cameras
are being displayed at a time when using IE.
The IP address assigned to the DVR must be a public
IP address and accessible through the Internet. The
router must be programmed to allow the DVR to be
accessible on the Internet. Contact your network
(router) administrator (installer) for support. DCI will not
have That information.
DCI embedded the direct browser access SW starting
with version 408 of the server software. If your DVR
has version 408 or newer, then you can access the
DVR from any computer without Remote software by
using Internet Explorer. Bring up IE and type only the
DVR IP address in the Address filed and press enter (It
may have to install the Active X drivers on the PC).
The browser software is only capable of displaying 4
cameras at a time through IE due to IE limitations.
28
The images sometimes turn purple or green
when viewing from remote PC.
That is due to lack of overlay support from your PC
video card or loss of information in transmission of live
data.
The remote software came up with the
message “This SW version does not match the
Server”.
The DVR software may have been upgraded without
the matching remote software. Contact the dealer for
the updated remote software.
The remote software cannot find the server
and will not connect.
Make sure the instruction described in the manual for
remote access is followed in entirety for proper remote
access operation.
The DVR is not answering the phone or the
line is busy.
The images are moving very slowly on remote
PC using telephone connection.
Why does the message “connecting to server”
come up every so often when connected via
telephone lines?
Why is the image from a camera frozen for a
while and then starts again while viewing from
remote?
The DVR requires a dedicated telephone line for proper
operation. If the line is being shared with another
device it may cause the DVR to lock up the modem
relay closed and keep the line busy or open and not
answering. The solution is to disconnect the DVR from
telephone line for a couple of minutes or restart the
DVR in order to release the line.
Telephone connection is the slowest means of
communicating with the DVR. If your connection is
faster than 36000 bps then the images will change at a
rate of 2 to 3 FPS. If not, then, the video information is
above the capability of the telephone lines and could be
as little as ½ FPS.
The telephone connection is not always stable. Static
on the telephone lines, very slow connection, call
waiting are some of the causes for losing connection
with the DVR.
The DVR is set to motion detection. Once the motion is
not detected at the DVR, the last image that was
detected is broadcasted (displayed on remote) until the
camera detects motion again.
I am connected to the DVR but I cannot see
any of the control buttons on my screen.
The remote PC display adapter must be set to a
resolution of 1024 x 768 and 24-bit color for proper
display.
I am connected to the DVR but the camera
images are black.
Your PC video card is not able to display 24-bit color
overlays in windows. Try and upgrade the display
drivers for it or replace your video card.
I am connected to the DVR but the camera
images are washed out and very grainy.
The remote PC display adapter must be set to a
resolution of 1024 x 768 and 24-bit color for proper
display.
I am connected to the DVR via Internet
Explorer and when I click on Search, nothing
happens.
When the passwords are setup for the Search within
the DVR setup, the access to the search is denied while
using IE.
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