PNL COMMUNICATIONS | CCTV & Surveillance
We can help protect your business from shoplifting as well as employee theft.We always put our customers needs first and foremost.By working closely with each customer, and asking a lot of questions, PNL communications will design a state of the art CCTV surveillance camera system that best suits customers individual needs.
Common questions and answers
How does a cctv digital video recorder (DVR) work?
A CCTV Digital Video Recorder (or “DVR” for short) is essentially a computer that saves security video images to a hard drive. Most security cameras in use today capture an analog or DSP (Digital Signal Processing) picture. The DVR converts the analog signal to digital and then compresses it. Digital compression results in a much better picture than analog compression and its more efficient.Many cameras can be connected to one Digital Video Recorder (DVR). DVRs generally come with 4, 8, 16, or 32 camera inputs. The DVR will allow you to view all of these images at once or one at a time, and all of the video is saved to the hard drive. Additional switches, quads, or multiplexers are not required.
What is the difference between a PC-based DVR and an Embedded Digital Video Recorder (DVR)?
A PC-based digital video recorder is basically a personal computer that has been modified with hardware and software to work as a DVR. Because they are PC based, they can be unstable. An embedded digital video recorder is a machine that has been manufactured specifically to work as a DVR. In embedded Digital Video Recorders (DVRs) there is typically one circuit board with simple software burned into the chip. There are advantages and disadvantages to each type of DVR.The advantages of an embedded digital video recorder are that they are extremely stable and reliable since they contain fewer parts. The software is often written in basic machine code or Linux code which tends to be more stable than Windows software. Also the picture that you get on the monitor usually looks better (especially when viewed full screen) than PC-based DVRs because there is less compression. The disadvantages are that they have fewer options. Since they generally have less compression they use more hard drive space so you can fit fewer days of recorded video on it. And you do not have as many options to upgrade the hard drive space as the PC-based systems (some do not allow you to upgrade the hard drive space at all).
What features should I look for in a CCTV DVR?
The security digital video recorder that will work best for your application will depend on several factors including the number of cameras that you will have and the frames per second that you need. When determining the number of camera inputs, it is important to consider future needs as well as current needs.The frames per second (fps) relates to how many pictures it will record in a second. Real time recording is about 30 fps on each camera. To calculate the fps per camera take the total fps in the system and divide it by the number of video inputs. For example, a 60 fps digital video recorder with 4 video inputs would result in about 15 fps per camera. The technology is just getting to the point now where real time recording is affordable. If you are recording cash registers or something similar then you should invest in real time recording. If not, then a lesser recording speed should suffice. You can still see a clear picture even though it will have a little hesitation or jerkiness.
How do I see pictures from a remote site?
You can view the camera video over the internet using a modem which is slow but can display 1 or 2 frames every 5 seconds. Better is a DSL or cable modem connection which can generally display 1 frame per second. When viewing remotely, the refresh rate is restricted by the communications medium (your internet connection speed). When viewing or playing back locally, the display is dependent of the unit’s frame rate (fps).
What is ‘Smart Search’?
Many DVRs now come standard with smart search capability. This allows you to highlight one area of a captured image and look for changes just to that area. For example, if an item is stolen off of a counter… you can go to a moment in the video where the item is still on the counter, then highlight the area around the item and search automatically through the video for the moment in time when that particular area changes, that is precisely when the item is removed and then view that part of the video.
How much hard drive space will I need?
There are many variables that factor into how much hard drive space is used. The general rule of thumb is that each camera will use about 2 gig of space per day. So for example, if you have an 8 camera DVR you will use in the area of 16 gigs of hard drive space per day. If you are using motion detection the hard drive usage will likely be less (especially if there is little movement on each camera). The actual amount of hard drive space used varies widely and depends to a large extent on how much movement there is on the cameras. For example, a fast food restaurant (with a lot of activity) will use a lot more hard drive space per day than an office with a few employees. This is due to the way that the video is compressed for storage.As mentioned above, the embedded DVRs use much more hard drive space than the PC-based units, perhaps twice as much per camera, but again it varies from site to site. Also, on some of the embedded DVRs you can reduce the recording frame rate which will reduce the amount of hard drive space used (as well as the quality of the video).When the hard drive space is filled up, it will start over-writing the oldest pre-recorded video.