Effects of Digital Conversion on Image Quality The recording medium for most analogue CCTV systems today is a DVR. This enables the analogue signals to be digitised for recording and network distribution. While a DVR system is a cost-effective alternative to IP video and offers consumers vital features like digital storage and remote access, it also has downsides. The first is a small deterioration in image quality. Simply said, the many analog-to-digital conversions that occur from the camera to the recorder make it more difficult to maintain image quality in this type of arrangement. Cabling distance also plays a role, as the video signals become weaker the further they travel. Nevertheless, for customers who want to get some of the benefits of digital IP surveillance while using lower-cost CCTV security cameras, a DVR-based solution is a great option. Understanding TVL Resolution The picture detail of an analogue CCTV surveillance camera is commonly expressed in TVL (TV Lines) (or TV Lines). Consider the video image as a series of active horizontal lines. In two off-set fields, these lines are transmitted to a monitor or recording device. Even-numbered lines appear in one field, while odd-numbered lines appear in the other. Because the lines are interlaced, the spectator perceives a complete picture. Because the image has a 3×4 aspect ratio, the horizontal TVL resolution is determined by the amount of detail you can see in 3/4 of the image’s width. Most basic CCTV cameras have a TVL resolution of roughly 380, whereas high-resolution cameras have a TVL resolution of around 540.