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Chap.2 Lens and Image Sensor Technology 

9

Iris is measured in F-number, which is the ratio of the focal length to the lens diameter. Iris size is inversely 

proportional to F-number. Every time the F-number increases towards a larger number, the exposure ratio will 

reduce by half (Figure 2.6).

Iris includes the following types in terms of control methods:

Manual-iris

Manual-iris is adjusted with a ring on the lens. It is used when light sources are steady.

Auto-iris

Auto-iris can automatically adjust the amount of light entering with a mechanism to have a camera stay in an 

optimal light level. As a result, it is mainly required for outdoor applications or the places where lights change 

frequently. 

There are two types of auto-iris: Video-drive iris and DC-drive iris.

  

• Video-drive iris:

 video signal is transmitted to a drive circuit in the lens and converted to currents to control the  

 iris motor. Because the amplifier circuit is built in the lens, a Video-drive iris lens is more expensive.

• DC-drive iris: 

the iris is controlled by DC currents. Due to the drive circuit is integrated in the camera instead of in  

  the lens, DC-drive iris lens features lower costs.

2.1.3 Lens Mount Types 

C- and CS-mount are two major lens mount standards developed for the purpose of changing lens. The main 

difference between C/CS-mount lenses lies in the flange focal distance. The flange focal distance for a CS-mount 

lens is 12.5mm while 17.526mm for a C-mount lens (Figure 2.7). A CS-mount lens has higher cost efficiency and 

smaller size because fewer glass components are used.

f/1.4

f/2

f/2.8

f/4

f/5.6 f/8

F-number

Exposure ratio

1.4

32

2

16

2.8

8

4

4

5.6

2

8

1

Figure 2.5   Relationship between F-number and aperture

Figure 2.6   F-number and corresponding exposure ratio

Summary of Contents for IP Surveillance

Page 1: ......

Page 2: ...ation of audio visual components into network operation Using sophisticated codec technologies VIVOTEK s innovative R D team develops a wide range of multimedia communication products In 2006 VIVOTEK...

Page 3: ...2 Iris 08 2 1 3 Lens Mount Types 09 2 2 Image Sensor 11 2 2 1 Sensor Types 11 2 2 2 Resolutions 11 2 2 3 Sensor Scan Modes 13 2 2 4 Wide Dynamic Range 14 2 3 Lens and Image Sensor Considerations 14 2...

Page 4: ...4 5 2 3GPP 32 4 5 3 WiMAX 32 4 6 Security 33 4 6 1 IP Filtering 33 4 6 2 Username and Password 33 4 6 3 Security Protocols 33 4 6 4 Security Wireless Transmission 34 4 7 PoE 35 Chap 5 Camera Housing...

Page 5: ...9 1 1 Viewing Considerations 53 9 1 2 Environmental Considerations 54 9 2 System Planning 58 9 2 1 Camera Considerations 58 9 2 2 Hardware Considerations 58 9 2 3 Software Considerations 58 9 3 Instal...

Page 6: ...lication fields which generally fall into the following four categories Professional applications transportation government industrial construction health care etc SMB applications banking education r...

Page 7: ...gh the Internet to back end devices to allow for viewing and storage Apart from video compression the SoC is built with a RISC CPU for processing system and network data The general interface of a net...

Page 8: ...ple can be aware of the camera s shooting direction in some cases it can deter vandalism and crimes A fixed network camera usually comes with a RS 232 422 485 interface that connects the cameras to a...

Page 9: ...om capability image stabilization and 360 degree endless pan a speed dome camera is mainly used for professional applications such as airports banks or city security Fixed Dome Type A fixed dome netwo...

Page 10: ...OTEK s full range network cameras and video servers helping customers establish a robust flexible and efficient platform for centralized video management Figure 1 10 Central management software 1 4 Ne...

Page 11: ...lso known as IP surveillance appeared in early 2000 The surveillance system uses network cameras and takes full advantage of the TCP IP Internet Users can remotely control monitor and record live vide...

Page 12: ...use the use of camera differs especially fixed type with C CS mount system installers themselves have to select and purchase a lens fitting their specific needs 2 1 1 Focal Length Focal length is the...

Page 13: ...gain Lenses include the following types Fixed lens the focal length cannot be changed Vari focal lens the focal length field of view can be manually adjusted The most common vari focal lens is 3 5 8 m...

Page 14: ...ve iris video signal is transmitted to a drive circuit in the lens and converted to currents to control the iris motor Because the amplifier circuit is built in the lens a Video drive iris lens is mor...

Page 15: ...7161 C CS mount Lens Note that a C mount lens can be used on a CS mount camera by adding a 5 mm spacer C CS adapter ring but a CS mount lens cannot VIVOTEK s IP7161 can fit in with either a CS mount o...

Page 16: ...n of the entire image is thus around 1 3 megapixel pixels The higher the resolution the more information can be rendered and thus the better image quality In traditional CCTV systems the maximum resol...

Page 17: ...TU T H 261 recommendation in 1990 CIF image size is 352x288 equal to 1 4 of a PAL image Its full frame rate is 30 frames per second the same as NTSC VGA VGA Video Graphics Array format was defined by...

Page 18: ...a scene into even and odd fields that contain even and odd lines respectively When rendering the entire scene the even field is displayed first followed by the odd field The time interval between the...

Page 19: ...ects under such conditions by appropriately exposing the entire scene both the darkest and brightest parts VIVOTEK s award winning IP7142 and FD7141 support WDR enabling the camera to cope with challe...

Page 20: ...7 58 33 25 41 25 19 31 17 12 21 a b Figure 2 15 View angle for different focal length with same sensor size Table 2 2 View angle for different focal length with a 1 4 and b 1 3 sensors 2 3 3 Day and N...

Page 21: ...ll block infrared light and allow only visible light to pass through When the ICR is switched off infrared light will be allowed and images will turn into black and white mode which is more sensitive...

Page 22: ...Figure 2 18 In the daytime images generated by an IR corrected and a Non IR corrected lens are of identical quality Figure 2 19 a During the night images generated by a Non IR corrected lens become b...

Page 23: ...2 Lens and Image Sensor Technology 18 IR LEDs To get a clear image under poor light environments purchasing additional IR LED accessories or choosing network cameras with built in IR LEDs will be requ...

Page 24: ...ferent applications and purposes 3 1 1 MJPEG MJPEG Motion JPEG announced by JPEG Joint Photographic Experts Group in 1992 and approved by ISO in 1994 is a multimedia format that compresses each video...

Page 25: ...s out redundant information and compresses only frame to frame differences This significantly reduces file size and bandwidth requirements Every encoded frame is independent from the previous or seque...

Page 26: ...of compression with more precise motion search and prediction however it requires more powerful CPU capability Table 3 1 shows H 264 has a higher compression ratio than MJPEG and MPEG 4 but its CPU lo...

Page 27: ...ile phones AMR bit rate ranges from 4 75 12 2 kbps It offers a higher compression ratio and suffers from a slighter loss compared with G 711 3 3 3 AAC Announced in 1997 AAC Advanced Audio Coding is an...

Page 28: ...and frame rates multiple streaming gives users a higher level of flexibility for dealing with camera images on different platforms Figure 3 6 3 3 2 Two way Audio Generally audio transmission methods c...

Page 29: ...o and receive voices from the monitored site So does the monitored site Router Figure 3 8 Half duplex allows communications in one direction at a time Figure 3 9 Full duplex allows communications in b...

Page 30: ...racter indicates the characteristics of the transmission medium For example 100BaseT is 100 Mbps over network cable Ethernet Cable RJ45 4 2 Network Devices Hub A hub is a network device that connects...

Page 31: ...easing IP address shortage has become a problem To solve the problem DHCP and NAT and IPv6 were developed DHCP DHCP Dynamic Host Configuration Protocol automatically assigns a valid IP address to a ne...

Page 32: ...connection between networking devices and the Internet The first type includes DNS and DDNS and the second type includes PPPoE and UPnP DNS When locating a network device you need to input a numerical...

Page 33: ...S Server Reconnection PC Internet DDNS Server Reconnection PC Internet 1 1 1 2 1 2 2 Access Video with The Same Domain Name john 1 safe100 net 2 DDNS Server Submit My IP 60 250 55 30 PC Camera Interne...

Page 34: ...rwarding enables network devices to easily communicate with each other over the Internet When both the network device and router support UPnP video streaming ports will be forwarded so called port for...

Page 35: ...a firewall can utilize this protocol to allow streaming data to come through Media Transmission RTSP RTSP Real Time Streaming Protocol which consists of RTP and RTCP is a protocol used to facilitate...

Page 36: ...pplications it is important to manage bandwidth allocation carefully As part of the IEEE 802 1p standard QoS Quality of Service aims to optimize bandwidth usage QoS ensures streaming performance at a...

Page 37: ...dard certified in 2008 Based on MIMO Multi input Multi output 802 11n boasts an amazing transfer rate of 600Mbps and a range of 50 meters indoors and 300 meters outdoors It can operate in the 2 4GHz o...

Page 38: ...the data and IPSec encrypts the transmission channel SSL TLS SSL Secure Sockets Layer encrypts data transmitting between the server and the client to ensure the confidentiality and integrity of the d...

Page 39: ...nown as Wireless Equivalent Privacy is designed to protect data on a wireless network because data transmitted by radio wave can be easily intercepted A key must be set in the wireless access point an...

Page 40: ...additional power cables Figure 4 11 A PoE switch can provide 48 volts of direct current over two out of four pairs on an Ethernet cable with maximum current of 400mA and maximum output power of 15 4W...

Page 41: ...Chap 4 IP Network 36 Figure 4 12 PoE enabled devices for retail application Power LAN UPS PC LAN LAN LAN LAN Retail Store Internet NR7401 with Built in PoE Switch...

Page 42: ...made of metal or polycarbonate plastic and can resist a violent impact force 5 1 2 Weather proof A weather proof housing protects cameras from damage caused by rain and dust allowing cameras to be use...

Page 43: ...mm diameter and larger 4 Protected against solid foreign objects 1 0 mm diameter and larger 5 Dust Protected 6 Dust tight 0 Non protected 1 Protected against drips 2 Protected against drips if the ho...

Page 44: ...e different level of protection for cameras Tamper resistant Mounting Tamper resistant mounting is used to prevent ill intentioned disassembly enabling cameras to operate in high risk public environme...

Page 45: ...Mounting 40 5 3 Scanner A network camera with a RS 232 422 485 interface can be connected to a pan tilt scanner With the scanner a fixed network camera can change shooting direction providing wider co...

Page 46: ...e quality the higher image quality the more bandwidth is required Frame rate the higher frame rate the more bandwidth is required 6 1 2 Calculation To assess bandwidth requirements you can use Calcula...

Page 47: ...DRAM as a buffer zone that enables temporary storage of pre and post event video images Images are stored in the buffer zone for a short period of time before being transmitted to the back end record...

Page 48: ...undant cable to avoid system downtime 6 3 2 RAID RAID Redundant Array of Independent Disks is an array of several hard disk drives that can be used as one single hard disk drive Data can be spanned ov...

Page 49: ...toring data the other for storing parity and its data security is more inferior In addition RAID 5 offers higher security than RAID 0 because parity can be used to restore data if a drive cracks RAID...

Page 50: ...the installation users have to figure out the system requirements such as CPU capability and operating system so as to achieve the expected performance Since it is easier for users to operate upgrade...

Page 51: ...surveillance systems Installation Wizard 2 is the new generation of VIVOTEK s installation software in which the embedded intelligent functions will guide users to set up a network camera with ease In...

Page 52: ...playback remote monitoring in multiple monitors etc to achieve efficient flexible video management 7 2 1 Monitoring Users can view live video images with a web browser such as Internet Explorer on a m...

Page 53: ...users can set the system to use a lower frame rate during live monitoring for low bandwidth usage while shifting to a full frame rate during event triggered recording to ensure good image quality Fig...

Page 54: ...lems more efficiently 7 4 Digital I O Devices Digital input and output ports connect network cameras to external security devices such as alarms and sensors strengthening the surveillance system s det...

Page 55: ...management on a large scale system and benefits from a robust IP surveillance system Internet Glass Break Sensor Smoke Sensor Passive IR Active IR PC Figure 7 10 Connection of digital input devices 7...

Page 56: ...pplications IP surveillance systems are used not only for home security but also for keeping track of the activities in the home when parents are away from home 3GPP applications allow for real time m...

Page 57: ...ms Places with moving objects highways train bus stations etc High contrast places ATMs parking lot entrances etc Day and night vandal proof IP66 rated pan tilt zoom megapixel intelligent weather proo...

Page 58: ...and camera types placement or even the coverage of a camera Bear in mind that cameras shooting direction should be in line with the direction of illumination to minimize the influence of backlighting...

Page 59: ...and loading areas cameras with WDR can still cope with the challenging light to generate identifiable image with ease Mounting After deciding the shooting direction and the height for camera placement...

Page 60: ...ditionally dome type allows cables to be hidden so as to better fit in with the decor of the building DI DO If you customers need to connect external deices for different application network cameras w...

Page 61: ...required Wireless required Power supply UPS Audio 2 way audio required Section 4 Environmental considerations Bandwidth Mbps Where is the camera sited camera location Large outdoor places Small outdoo...

Page 62: ...ation to be recorded with the image Compression techniques for recording Equipment should be in good working order well maintained and serviced on a regular basis Cameras should be protected from any...

Page 63: ...eo data from sharing the storage space of PCs 9 2 3 Software Considerations Internet Browser Internet Explorer 6 0 or above and Mozilla Firefox must be installed so as to view video images on PCs For...

Page 64: ...on 5 Export Archiving 9 4 Operational Training Security staff system operators and managers must be trained to know how to operate the system and what they should do when an incident occurs Table 9 3...

Page 65: ...ure every component is available when replacement is needed VIVOTEK provides a warranty of one to three years depending on different products With 130 distributors worldwide VIVOTEK can provide compre...

Page 66: ...o provide more prompt response has contributed to the development of intelligent video systems The architecture of an intelligent video system mainly includes the centralized and distributed types 10...

Page 67: ...in deployment costs bandwidth requirements and content accuracy Table 10 1 Table 10 1 Comparison of centralized and distributed intelligent video systems PC Video Audio Management Video Audio Storage...

Page 68: ...nt and needed information is transmitted to the back end system server workload is significantly reduced It also cuts down bandwidth usage and storage requirements Scalability and Integration Intellig...

Page 69: ...gure 10 5 Comparison of conventional and intelligent motion detection 10 4 2 Intelligent Motion Detection Intelligent motion detection can distinguish moving objects of interest motions from natural m...

Page 70: ...damage is caused 10 4 4 License Plate Recognition License plate recognition can identify the plate number of a vehicle and match the information with the data in the police database Besides tracking...

Page 71: ...le Counting People counting can calculate the amount of people in an area and provide the information for business management such as the number of customers entering the shop or the number of custome...

Page 72: ...make indirect network connections to other network services Proxy server will save the previous data or resource in a cache when the request is made for first To provide it when the same request is m...

Page 73: ...192 Lien Cheng Rd Chung Ho New Taipei City 235 Taiwan R O C T 886 2 82455282 F 886 2 82455532 E sales vivotek com VIVOTEK USA INC 2050 Ringwood Avenue San Jose CA 95131 T 408 773 8686 F 408 773 8298 E...

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