Posts Tagged ‘ High Definition Composite Video Interface’



The Science Behind HD-CVI

Written By:
Friday, April 4th, 2014

HD-CVI System

High Definition Composite Video Interface (HDCVI) is a brand new video transmission applied science in the CCTV world. This technology allows high definition video footage to be transmitted over coax cable at considerably longer distances than network based cameras. The overall cost of the HDCVI cameras are lower than most network cameras as well to further enhance their staying power.

The main feature that makes HDCVI cameras images so vibrant is the signal itself. The HDCVI technology modulates the image signal then transmits by using both base-band and quadrature amplitude modulation. Base-Band is a word that details signals that range of frequencies from zero hertz to a cut-off frequency or highest frequency signal. Digital base-band signal transfers the digital stream over baseband channels, normally an unfiltered wire such as coax.

Baseband Transmission

Quadrature amplitude modulation differs in implementation as QAM uses both analog and digital modulation. It can use either two analog signal messages or two digital streams. This is accomplished by modulating the amplitudes of the two carrier waves. QAM high efficiencies can be achieved by setting size limited by the noise for communication channels. Another way of describing QAM is the amplitude of the two carrier waves are 90 degrees out of phase with each other in quadrature. Making the way the signals are carried equivalently viewed as both while being phased modulated into a single carrier.

Quadrature

This new way to apply the science QAM effectively separates the brightness signal and hue to enhance image quality. Also the separation of the signals diminishes the cross talk or external radiation that interrupts the signal.

Currently the two camera types available are 1920H and 1280H which translates to 1080P and 720P respectively. These cameras are using a technology that is actually a group of technologies used as one called Auto Signal Compensation or ASC. A video signal such as the standard NTSC (National Television System Committee) has different synchronization pulses used for the receiver scan timing. The features of a waveform are in the details of the synchronization. Synchronization occurs in the video lines of the sequential scanning of horizontal lines starting in the upper left corner then going right until all lines are scanned. The operation will happen hundreds of times depending on how many TV lines. Once modifications of the horizontal sync are complete vertical synchronization waveforms are initiated. The actual shape of the wave form is affected in this application, ultimately giving an extremely vibrant color display. If you take the anti-interference ability of the HDSDI science and compare it with the HDCVI, the HDSDI is fairly poor when operating in a high frequency radiation areas. Radiation by definition is electric magnetic waves. This is considerably different than nuclear or thermal radiation. Electro-magnetic waves come from all electric devices. A standalone air-condition unit is a perfect example. The AC compressors inside puts off enough electromagnetic interference to scramble the video signals traveling down the coax cable should the lines be too close. By separating carrier waves and changing their shape the signal becomes resilient to interference.

Another aspect of the signal usage was a realization that other signals can be embedded in the blanking zone. Blanking interval was originally designed to blank out the receiver to allow time for retrace in the receiver.

It’s first implementation was the closed captioning system in TV for example.

Closed_Caption

We can now use the vertical blank for something else called two-way data communication. The end to end transmission can support features for PTZ control. Other non PTZ cameras that support RS485 control can be used. These cameras’ OSD menu can be accessed without having to run extra control wiring same as the PTZ. You will no longer have to pull extra cable for PTZ control either. Originally installers would use Cat5 cable to get around that old limitation on the analog systems. I would use a pair of wires for video. Another pair of wires for RS485 control. Then splice the remaining 2 pairs to have 2 wires for positive and 2 wires for negative on power supply. That is a nice little work around, but at long distances that does not work as single strand wire is not thick enough to carry the amps needed. With the new implementation of ASC it makes communication for control available.

HDCVI equipment is similar to HDSDI equipment in that you can you use RG6 or RG59 and not have any problems. You can use you standard connectors without any special requirements or the need to find obscure vendors for the connectors. Using standard cabling and connectors will allow for the same level of ease for installation as legacy CCTV cameras.

Comparing HDCVI to HDSDI both technologies can transmit an image at resolutions of 1080P and 720P. For distance of signal transmission the HDCVI has an enormous advantage over HDSDI. HDSDI can reach about 100 meters or 320 feet. HDCVI can transmit up to 500 meters or 1600 feet. To put those numbers into perspective HDSDI can have the camera at one end of a football field and the DVR at the other end. HDCVI can reach 5 times as far. If you have a huge piece of property you need to get High definition cameras HDCVI is the way to go. Of course keep in mind power for the cameras are subject to the same restrictions of older technologies when it comes to alternating or direct current electricity.

HDCVI technology uses a peer to peer type of transmission. This means there is a continuous transmission with no creation of packets such as in IP based cameras. IP cameras are subject to the normal rules of data transmission. That means packets are created then transmitted over the Ethernet cable. The packets need to arrive in the correct sequence and be spaced evenly apart.

Packets

Issues with network congestion, configuration mistakes, and improper queuing for the data stream will result in choppy and degraded video display. Those issues are inherent of an IP based system. There are extra steps an installer can take to reduce the jitter problem, but that takes advanced knowledge of the cameras themselves as well as advanced knowledge of networking in general.

To recap the HDCVI cameras do operate much better than IP camera systems or HDSDI systems. The HDCVI provide mega pixel quality like the HDSDI and IP cameras. They are not subject to the same outside interference the HDSDI devices are or IP systems. HDCVI have able to go 5 times the distance for video transmission than HDSDI or IP. The new technology is as simple to use as legacy equipment is. Lastly you get Mega pixel quality at analog camera prices.

If you would like to know more about HDCVI, how it compares to IP and Analog and how to connect the system together, check out our What is HD-CVI page.

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HD-CVI is the next wave in CCTV

Written By:
Tuesday, February 25th, 2014
HD-CVI high definiteion composite video interface

Have you wanted to upgrade your existing analog camera system, but don’t know which way to go? Well I am going to throw you another curve ball. The introduction of High Definition Composite Video Interface or better known as HDCVI. You probably just heard HD bla bla bla, and I can completely understand that. No this isn’t just a new name for an old technology like High Definition Serial Digital Interface or HD-SDI. Yes the video quality is the or soon will be the same, but HD-SDI has many limitations that HDCVI has conquered and HDCVI has some limitations that HD-SDI still wins in at the moment. I am going to go into some of the disadvantages and advantages of HDCVI and HD-SDI in this article.

HDCVI

High Definition Composite Video Interface

HDCVI is the new wave of HD video transmission. At this point HDCVI does have some limitations, but the fact that HDCVI also conforms to the newer HDcctv Alliance standards. These limitations are just temporary. These standards not only incorporate the SMPTE-292M standard from the Society of Motion Picture and Television Engineers for the broadcast television studios, also known as the HD-SDI standard. It goes much further with addition of compliance certification and the multi-vendor interoperability and reliable electrical performance in mass production. HDcctv XR standard or extended reach standard is so that high definition video can travel upto 3 times further than HD-SDI can travel without any type of repeater. The HDcctv CX standard or CatX cable standard is that the system will work over any type of Cat cable on the market. HDcctv AT standard or Advanced Transmission standard means the system can transmit over all traditional closed circuit television cabling infrastructure. HDcctv 2.0 standard allows for the OSD’s of the cameras to be controlled up the cable.

At this point in time HDCVI is limited to only being able to transmit video in 720p high definition. In the very near future this technology will be able to transmit video in 1080p Bluray quality high definition. All this can be accomplished over existing cable infrastructure. Now you are probably asking can I use my existing plug and play cables? The answer is yes, as long as there is some amount of copper in the cable. A major advantage to HDCVI, High Definition Composite Video Interface, and HD-SDI, High Definition – Serial Digital Interface, is the fact that the video is transmitted with no delay in the video transmission, since the recording device the DVR or Digital Video Recorder, that is doing all the encoding after the video is transmitted. Where as with IP megapixel cameras, the camera does the encoding and then transmits the video causing a delay in the initial images coming from the camera to the recorder, the NVR or Network Video Recorder. HDCVI is bringing the closed circuit back to high definition closed circuit television HDCCTV, surveillance networks. This is because with an IP camera system, the cameras are placed on the network and the NVR is also on the network and all communication occurs over said network. This has a lot of devices on the network all communicating over the network. Granted these devices are secure, but they are not truly closed off back to the recorders like HDCVI, Analog, and HD-SDI camera systems.

A major advantage of HDCVI camera systems over IP Megapixel camera systems is the fact that you do not need the network infrastructure with HDCVI that you need with IP camera systems. With HDCVI all the cameras come back to the recorder directly, whereas in IP cameras the camera connects to the network as well as the NVR (Network Video Recorder) and communication between the devices occur through the router. This can cause network lag because of the amount data that each camera is sending over the network. This is why with an NVR and IP cameras you want to make sure that you either have a dedicated network just for the camera system or that you have upgraded the network to Gigabit speeds, with the proper router and devices to get you speeds of 10/100/1000. Most older networks and their devices only had Megabit speeds which are 10/100 Mbps, these networks work fine with older technology. Technology and data has changed drastically in the past few years, people expect higher and higher definition images which is fine but they also eat up more and more bandwidth. Think about this with a Megabit network you really only feasibly have 50Mbps that is usable, since half of the bandwidth is for transmitting and half is for receiving data. On average a 2mp IP camera will take about 8Mbps per camera, if you have a 8 camera system the cameras alone will eat up a standard networks resources and that is with nothing else on the network.

Currently HDCVI camera systems are lacking a few things that HD-SDI camera systems are not. One big thing is that HD-SDI camera systems can record at 1080p resolution, whereas HDCVI is currently limited to only 720p resolution. Another temporary disadvantage of HDCVI is that the DVRs are limited in the amount of hard drive space they can currently accept, whereas HD-SDI DVRs come in larger cases that can accept more hard drives. Another temporary advantage to HD-SDI is that every channel has the ability to record audio, where currently on HDCVI you can only record audio on channel 1.

differences in resolutions

Now look at the images above. Would you rather have the image on the left the D1 resolution or the 1.3mp resolution? Me personally when I can spend a few dollars more and get the 1.3mp resolution and not have to be a network engineer to get this, I would go with that. This is the resolution that HDCVI gives you standard, soon the image on the left will also be available and this will then kill analog and HD-SDI camera systems. To recap, with HDCVI you can use virtually any cable that is existing or even on a new install. You get High Definition imaging with virtually no delay in video. The cost is almost the same as high end analog camera systems. The video transmission is not limited like it is in both HD-SDI and IP camera systems. With both of those you need repeaters to go over 300 feet. Blow your friends and customers away without blowing your bank account.

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