Most new technology Mobile DVRs employ a business model of “Camera Obsolescence & Pollution”.
This means they force the purchase of new technology cameras with every new DVR even if the bus already has cameras already installed from the previous system they are not upgrading or replacing.
This costs school districts millions in wasted tax dollar funding, necessitates the removal of hundreds of thousands of fully functioning cameras, pollutes the land and water with functional cameras and cables that were replaced, not to mention the hundreds of thousands of installation hours required to remove and reinstall the cables behind the bus sheet metal paneling.
Analog High Definition (AHD) mobile DVRs, which are currently sold for the 720P and new 1080P system have the added advantage of employing older tech enology Analog cameras, so by design, it can make use of older existing Analog cameras in your older buses, and not require the district to constantly replace functional cameras with more expensive cameras and the much more time-consuming process of reinstallation of said cameras in the older buses every time the DVR technology changes.
AHD (Analog High Definition) DVRs are an Eco-Friendly green technology solution that can greatly extend the service life of the existing cameras in your school bus video surveillance systems while at the same time reducing the gargantuan waste of tax dollars while lowering the land and water pollution caused by filling waste dump sites with functional cameras and camera cables.
When you are searching for a standalone digital video recorder, you will see QCIF, CIF, D1, 960H, 720, 1080 parameters in every standalone DVR technical information table.
CIF, D1, 960H, 770, 1080 are the recording and playback resolutions for security DVR. These parameters are very important factors in determining your video recording surveillance performance and resolution.
What is D1 ?
D1 in CCTV technology is a resolution of 720 x 480 TV lines.
However in the world of Digital Technologies, D1 is a DIGITAL technology is system standard format, it is divided into the following categories:
-D1: 480i format (525i): 720 x 480 (resolution 480tv lines, Interlaced), and NTSC tv system with same resolution, Line frequency 15.25kHz, the equivalent of what we call 4CIF (720 × 576).
-D2: 480P format (525p), 720 x 480 (resolution 480tv, progressive scan), with more clear compared to the D1 interlaced, is the equivalent of DVD resolution.
-D3: 1080i format (1125i): 1920 x 1080 (resolution 1080 tv lines, interlaced scan), high definition video format, resolution 1920 x 1080i/60Hz, Line frequency 33.75kHz.
-D4: 720P format (750p), 1280 x 720 (horizontal resolution 720 tv lines, progressive scan), a low resolution compared to D3, but with the reason of progressive scan, many people feel D3 is more clear than D4, especially when displaying the characters, resolution 1280 x 720p/ 60Hz, line frequency 45kHz.
-D5: 1080P format (1125P), 1920 x 1080 (horizontal resolution 1080tv lines, progressive scan), the highest standard resolution in tv system, resolution 1920 x 1080P/60Hz, line frequency 67.5KHz.
As the image above demonstrates the relative size differential between the different video resolution formats is substantial, and it is this differential between the lower resolutions and the High Definition that provides the image quality and increased resolution that provides crystal clear definition in the video images captured in the full High Definition of 1080P.
It might help to think of this in the following way:
- The old VHS video recorders were recorded in VGA resolution of 640 x 480 TVL.
- VHS videocassette recorders recorded in D1 resolution of 720 x 480 TVL.
- High Definition TV was 1/2 High Definition aka 720P resolution of 1,280 x 720 TVL.
- Blu-Ray movies are Full High Definition aka 1080P resolution of 1,920 x 1080 TVL.
Differences in TV or monitor formats have also driven the technology as most TVs now are widescreen full formats so they can show a much wider horizontal view as the movies are now being created in much wider formats.
Whether investing in School Bus Safety Cameras for student surveillance systems, or Driver Safety Cameras in fleet vehicles, the same constant that drives the video and photo image resolution industries should be observed; “Image clarity” is the number 1 desired attribute of the system.
While the above will change with the advent and introduction of newer technology higher definition systems, currently the Full High Definition of the 1080P system is the standard for modern mobile video surveillance camera systems whether they be for school bus cameras for contractor student transportation camera applications or fleet driver safety camera systems.
